Textiles- History, Properties and Performance and Application 2014

CHEMISTRY RESEARCH AND APPLICATIONS

TEXTILES HISTORY, PROPERTIES AND PERFORMANCE AND APPLICATIONS

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CHEMISTRY RESEARCH AND APPLICATIONS

TEXTILES HISTORY, PROPERTIES AND PERFORMANCE AND APPLICATIONS

MD. IBRAHIM H. MONDAL EDITOR

New York

Copyright © 2014 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works. Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book.

Library of Congress Cataloging-in-Publication Data ISBN:  (eBook)

Published by Nova Science Publishers, Inc. † New York

CONTENTS Preface

vii

Contributor Contact Details Andrej Javoršek, Cesar Pulgarin, Eva Bou-Belda, Gordana S. Ušćumlić, Ignacio Montava, Jaime Gisbert and Sami Rtimi

ix

Chapter 1

An Exploration of Vintage Fashion Retailing Julie McColl, Catherine Canning, Louise McBride, Karina Nobbs and Linda Shearer

1

Chapter 2

Developing Sustainable Design on Denim Ready-Made Apparels by Stone and Enzymatic Washing Md. Ibrahim H. Mondal and Md. Mashiur Rahman Khan

Chapter 3

Digital Textile Printing Using Color Management Dejana Javoršek, Primož Weingerl and Marica Starešinič

Chapter 4

Inkjet Printed Photo-Responsive Textiles for Conventional and High-Tech Applications Shah M. Reduwan Billah

Chapter 5

Synthesis and Grafting of Cellulose Derivatives from Cellulosic Wastes of the Textile Industry Md. Ibrahim H. Mondal and A. B. M. Fakrul Alam

Chapter 6

History, Synthesis and Properties of Azo Pyridone Dyes Dušan Ž. Mijin, Gordana S. Ušćumlić and Nataša V. Valentić

Chapter 7

Smart Textiles and the Effective Uses of Photochromic, Thermochromic, Ionochromic and Electrochromic Molecular Switches Shah M. Reduwan Billah

19 53

81

123 157

187

Chapter 8

Smart Textiles Ali Akbar Merati

239

Chapter 9

Overview of Textiles Excavated in Greece Christina Margariti, Stavroula Moraitou and Maria Retsa

259

vi Chapter 10

Contents Innovative Ag-Textiles Prepared by Colloidal, Conventional Sputtering and HIPIMS Including Fast Bacterial Inactivation: Critical Issues Sami Rtimi, Cesar Pulgarin, Rosendo Sanjines and John Kiwi

277

Chapter 11

Fungal Deterioration of Aged Textiles Katja Kavkler, Nina Gunde-Cimerman, Polona Zalar and Andrej Demšar

315

Chapter 12

Durability of Functionalized Textiles by Microcapsules Lucia Capablanca, Pablo Monllor, Pablo Díaz and Maria Ángeles Bonet

343

Chapter 13

New Approaches and Applications on Cellulosic Fabric Crosslinking Eva Bou-Belda, Maria Ángeles Bonet, Pablo Monllor, Pablo Díaz, Ignacio Montava and Jaime Gisbert

Chapter 14

Wrinkle Resistant and Comfort Finishing of Cotton Textiles Vahid Ameri Dehabadi and Hans-Jürgen Buschmann

Chapter 15

Evaluation of Physical and Thermal Comfort Properties of Copper/Alginate Treated Wool Fabrics by Using Ultrasonic Energy Muhammet Uzun

355

367

383

Chapter 16

Hemp Fibers: Old Fibers - New Applications Mirjana Kostic, Marija Vukcevic, Biljana Pejic and Ana Kalijadis

399

Chapter 17

Textiles Using Electronic Applications Marica Starešinič, Andrej Javoršek and Dejana Javoršek

447

Chapter 18

Textiles for Cardiac Care Narayanan Gokarneshan, Palaniappan P. Gopalakrishnan, Venkatachalam Rajendran and Dharmarajan Anita Rachel

465

Chapter 19

Effect of Clothing Materials on Thermoregulatory Responses of the Human Body P. Kandha Vadivu

483

Designing of Jute–Based Thermal Insulating Materials and Their Properties Sanjoy Debnath

499

Effects of Ring Flange Type, Traveler Weight and Coating on Cotton Yarn Properties Muhammet Uzun and Ismail Usta

519

Chapter 20

Chapter 21

Chapter 22 Index

Optical Fiber Examination by Confocal Laser Scanning Microscopy Andrea Ehrmann

531 547

PREFACE This book reveals the expanding opportunity of textiles in a wide range of industrial applications. No longer limited to apparels and home furnishings, textiles are being used in many sciences and technologies, such as clothing and fashionable materials, smart textiles, technical textiles, medical textiles, agro-textiles, geo-textiles, electronics, photonics, intelligent sensors, etc. This book is intended for all those who are interested and engaged in the latest developments in the field of textiles, especially chemists, engineers, technologists, application technicians and colorists of the textile industry, technical colleges and universities. Textiles are essential and one of the most important classes of materials used by all people since ancient time. Despite textiles having been around and in use for so long, advances and improvements continue to be made. This book contains 22 invited contributions written by leading experts in the field of textiles. Each contribution presents an updated science and technological advances that have happened during this period and are fully discussed. The first chapter discusses the present and future prospects of vintage fashion clothing, i.e., an old fashion clothing and its retailing. Chapter 2 searches for the dynamic best method for producing specific washing effects and designs on denim ready-made apparels. The chapters 3 and 4 present a discussion on color management application in the field of digital printing onto textile substrates, and inject printed photo-responsive textiles used in fashion and design, self indicating security alert systems, anti-counterfeit and brand protection. In chapter 5 and 6, an attempt has been made to cover the most up-to-date information regarding synthesis, and application of cellulose derivatives and azo dyes on textiles. Smart textiles incorporated with different functionalities have many uses in a variety of fields, some of them are widely used in the fields of biomedical or healthcare applications. The smart textiles and its multi-disciplinary applications have been well discussed in chapters 7 and 8. In chapters 9, 10 and 11, preservation of textile objects in different environments like home, stores, museums etc. have been discussed. These chapters also discussed how to protect textiles from bacterial and fungal deterioration. An elaborative discussion has been made in Chapters 12, 13, 14, 15 and 16 on the new applications of textile materials through modification by physico-chemical methods. The modification has been done to obtain durable, comfort, sustainable and environment friendly finished products using various organic and inorganic chemicals for much better performance. Use of micro-capsulation techniques to modify textiles offers extra-properties, e.g., durable fragrances, skin softeners to textiles. Electronic applications of textiles have been discussed in chapter 17. Textiles, from

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Md. Ibrahim H. Mondal

fibers to fabric, with integrated special electronics are more and more used as special materials in newly developed smart clothing. The chapter 18 specifically focuses on the technological advances with regard to development of textiles for cardiology purpose, i.e., cardiac care. The thermoregulatory process of human body, the thermal comfort properties of fabrics and the effect of clothing material on the thermoregulatory process of human body in different weather conditions has been discussed in Chapter 19. In chapter 20, effort has been made on diversification of jute specifically, development of jute-based materials for thermal insulating applications. The main aim of chapter 21 is to utilize the ring flanges and travellers of ring spinning, which is the most effective staple yarn production process, for the yarn quality in terms of hairiness, twist, breaking strength and irregularity. The last chapter 22 gives an introduction into the techniques of confocal laser spinning microscopy, and depicts optical differences between several textile fibers, enabling a non-destructive examination of natural and chemical fibers. I am very much grateful to all the specialized contributing authors of this book. My special appreciation is also extended to Ms. Carra Feagaiga of Nova Science Publishers, Inc., for her good collaboration, support and numerous discussions throughout the project for this book. I wish thank to my colleagues Professor C. M. Mustafa, Professor F. I. Farouqui, and Professor M. A. Sayeed for their constant support and encouragement. I also thank my graduate students, Dr. Md. Mashiur Rahman Khan, Md. Raihan Sharif, Md. Saifur Rahman and Md. Tariqul Islam for their help during editing this book. Lastly I am thankful to Khadijatul Qubra and Ishrat Rafia for their constant encouragement, understanding and support. Any constructive suggestions and comments are therefore welcome for future revisions and corrections.

Department of Applied Chemistry & Chemical Engineering, Rajshahi University, Bangladesh November 2013 Professor Md. Ibrahim H. Mondal

CONTRIBUTOR CONTACT DETAILS A. B. M. Fakrul Alam Polymer and Textiles Research Lab, Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Bangladesh

Ali Akbar Merati Advanced Textile Materials and Technology Research Institute (ATMT), Amirkabir University of Technology, Tehran, Iran E-mail: [email protected] Ana Kalijadis Laboratory of Physics, Vinca Institute of Nuclear Sciences, University of Belgrade, Mike Petrovica Alasa 12-14, 11000 Belgrade, Serbia Andrea Ehrmann Niederrhein University of Applied Sciences, Faculty of Textile and Clothing Technology, Webschulstr. 31, 41065 Moenchengladbach, Germany E-mail: [email protected] Andrej Demšar Faculty of Natural Sciences and Engineering, University of Ljubljana, Ljubljana, Slovenia Andrej Javoršek University of Ljubljana, Faculty of Natural Sciences and Engineering, Snežniška 5,1000 Ljubljana, Slovenia

x

Md. Ibrahim H. Mondal Biljana Pejic Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia Catherine Canning Department of Fashion, Marketing and Retailing, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4OBA, Scotland Cesar Pulgarin EPFL-SB-ISIC-GPAO, Ecole Polytechnique Fédérale de Lausanne, Station 6, CH-1015, Lausanne, Switzerland. Christina Margariti Textile conservator, Directorate of Conservation of Ancient and Modern Monuments / Hellenic Ministry of Culture, 81 Peiraios Avenue, 10553 Athens, Greece E-mail: [email protected] Dejana Javoršek University of Ljubljana, Faculty of Natural Sciences and Engineering, Snežniška 5, 1000 Ljubljana, Slovenia E-mail: [email protected] Dharmarajan Anita Rachel NIFT TEA College of knitwear fashion, Tiruppur 641 606, India E-mail: [email protected] Dušan Ž. Mijin Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia E-mail: [email protected] Eva Bou-Belda Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain Gordana S. Ušćumlić Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia

Contributor Contact Details

xi

Hans-Jürgen Buschmann Deutsches Textilforschungszentrum Nord-West gGmbH, Universität Duisburg-Essen, NETZ / DTNW gGmbH, Carl-Benz-Straße 199, D-47057, Duisburg, Germany Ignacio Montava Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain Ismail Usta Department of Textile Engineering, Faculty of Technology, Marmara University, Goztepe, Istanbul 34722, Turkey Jaime Gisbert Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain John Kiwi EPFL-SB-ISIC-LPI, Ecole Polytechnique Fédérale de Lausanne, Bâtiment Chimie, Station 6, CH-1015, Lausanne, Switzerland

Julie McColl Department of Fashion, Marketing and Retailing, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4OBA, Scotland E-mail: [email protected]

Karina Nobbs London College of Fashion, 272 Holborn, London WCIV 7CY, UK

Katja Kavkler Restoration Centre, Institute for the Protection of Cultural Heritage of Slovenia, Ljubljana, Slovenia E-mail: [email protected]

Linda Shearer Department of Fashion, Marketing and Retailing, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4OBA, Scotland

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Md. Ibrahim H. Mondal Louise McBride Department of Fashion, Marketing and Retailing, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4OBA, Scotland

Lucia Capablanca Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain

Maria Bonet Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain E-mail: [email protected]

Maria Retsa Textile conservator, Directorate of Conservation of Ancient and Modern Monuments / Hellenic Ministry of Culture, 81 Peiraios Avenue, 10553 Athens, Greece Marica Starešinič University of Ljubljana, Faculty of Natural Sciences and Engineering, Snežniška 5, 1000 Ljubljana, Slovenia E-mail: [email protected]

Marija Vukcevic Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia E-mail: [email protected]

Mashiur Rahman Khan Polymer and Textile Research Lab., Department of Applied Chemistry and Chemical Engineering, Rajshahi University, Rajshahi- 6205, Bangladesh and Department of Apparel Manufacturing Engineering, Bangladesh University of Textiles, Tejgaon, Dhaka-1208, Bangladesh

Md. Ibrahim H. Mondal Polymer and Textiles Research Lab, Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Bangladesh E-mail: [email protected]

Contributor Contact Details

xiii

Mirjana Kostic Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia

Muhammet Uzun Institute for Materials Research and Innovation, University of Bolton, Deane Road, Bolton, BL3 5AB, UK, and Department of Textile Engineering, Faculty of Technology, Marmara University, Goztepe, Istanbul 34722, Turkey E-mail: [email protected]

Narayanan Gokarneshan NIFT TEA College of knitwear fashion, Tiruppur 641 606, India E-mail: [email protected]

Nataša V. Valentić Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia

Nina Gunde-Cimerman Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia, and Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CIPKeBiP), Jamova 39, SI-1000, Ljubljana, Slovenia

P. Kandha Vadivu Department of Fashion Technology, PSG College of Technology, Coimbatore 641004, India E-mail: [email protected]

Pablo Díaz Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain

Pablo Monllor Departamento de Ingeniería Textil y Papelera, Universitat Politécnica de València, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy, Spain

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Md. Ibrahim H. Mondal Palaniappan P. Gopalakrishnan NIFT TEA College of knitwear fashion, Tiruppur 641 606, India

Polona Zalar Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia

Primož Weingerl University of Ljubljana, Faculty of Natural Sciences and Engineering, Snežniška 5,1000 Ljubljana, Slovenia

Rosendo Sanjines EPFL-SB-IPMC-LNNME Ecole Polytechnique Fédérale de Lausanne, Bat PH, Station 3, CH-1015, Lausanne, Switzerland

Sami Rtimi EPFL-SB-ISIC-GPAO, Ecole Polytechnique Fédérale de Lausanne, Station 6, CH-1015, Lausanne, Switzerland. E-mail: [email protected]

Sanjoy Debnath National Institute of Research on Jute & Allied Fibre Technology, Indian Council of Agricultural Research 12, Regent Park, Kolkata – 700 040, West Bengal, India E-mail: [email protected]; [email protected]

Shah M. Reduwan Billah Department of Chemistry, Durham University, Durham DH1 3LE, UK and The School of Textiles and Design, Heriot-Watt University, Galashiels TD1 3HF, UK E-mail: [email protected] or [email protected]

Stavroula Moraitou Textile conservator, Directorate of Conservation of Ancient and Modern Monuments / Hellenic Ministry of Culture, 81 Peiraios Avenue, 10553 Athens, Greece Vahid Ameri Dehabadi Deutsches Textilforschungszentrum Nord-West gGmbH, Universität Duisburg-Essen, NETZ / DTNW gGmbH, Carl-Benz-Straße 199, D-47057, Duisburg, Germany E-mail: [email protected]

Contributor Contact Details Venkatachalam Rajendran NIFT TEA College of knitwear fashion, Tiruppur 641 606, India E-mail: [email protected]

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In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 1

AN EXPLORATION OF VINTAGE FASHION RETAILING Julie McColl1,, Catherine Canning1, Louise McBride1, Karina Nobbs2 and Linda Shearer1 1

Department of Business Management, Glasgow Caledonian University, Glasgow, Scotland 2 London College of Fashion, London, UK

ABSTRACT The purpose of this research is to offer a definition of vintage fashion and consider the characteristics of the vintage fashion consumer and the positioning of the vintage fashion store from the perspective of fifteen vintage fashion retailers. The research indicates that vintage fashion retailers position themselves on the basis of their uniqueness, based upon their experience, knowledge and skills.

Keywords: Vintage, fashion, definition, customer characteristics, positioning

INTRODUCTION Over the past decade there has been an increasing trend for vintage fashion clothing [1]. Indeed, McMeekin [2] and Wilson and Thorpe [3] have identified that vintage fashion is a multimillion pound industry. Previously, second-hand clothing was purchased by low income groups, economically disadvantaged in terms of mainstream fashion. More recently, however, vintage clothing has become an alternative or an additional choice to high street fashion [4, 5]. Tolkien [6] has proposed that vintage stores and markets have become a desirable source for acquiring fashion items. This may be the result of increasing societal acceptance of an aesthetic shift, with vintage fashion being intended as a means of self-expression and differentiation [4, 7, 8]. 

Corresponding author: Julie McColl. Department of Business Management, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4OBA, Scotland. E-mail: [email protected].

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The acceptance of second hand clothing as an alternative to high street fashion is partly due to the resurgence of fashion styles from the 1960s, 1970s and the 1980s [9], and the influence of celebrity culture [4, 10]. Consumers are increasingly aware of unethical practices in the fashion industry [10-12], and have become less tolerant towards disposable fashion and more suspicious of the behavior of global brands [8, 13]. The move of vintage from niche sub-culture to mainstream may be evidenced by the increased vintage offerings by high street, luxury and online retailers and by the plethora of guides on selecting and assembling vintage clothing outfits [4, 14, 15, 8, 16]. This apparent increase in vintage offerings has broadened the opportunities for the consumption of vintage clothing. The term vintage is widely used yet has never been clearly defined [4, 7], in terms of the parameters, characteristics and the positioning of the vintage fashion retail store. The literature on the retailer positioning strategies is clearly established [17-26], however, there is little published research on vintage fashion retailing, and developments in the market and their implications for vintage fashion retailers has not been addressed. This exploratory study defines the concept of vintage fashion and the vintage fashion consumer. It evaluates the positioning strategies of vintage fashion retailers, explores how they differentiate themselves in the face of increased competition and considers the implications of the more recent vintage trend for traditional vintage retailers.

LITERATURE REVIEW Definition of Vintage It is difficult to define the concept of vintage, partly due to the lack of agreement regarding the specific time periods of ‘vintage’, ‘antique’ and ‘retro’ but also due to differences in opinion about the constituents of such clothing items. According to De Long [7, p. 23] “in clothing, vintage usually involves the recognition of a special type or model, and knowing and appreciating such specifics as year or period when produced or worn”. Furthermore, they suggest that vintage clothing is concerned with a specific time period or setting and is distinguished from “antique, historical, consignment, reused or second-hand”. Palmer and Clark [4, p. 175], define the term more broadly proposing that it is “used to cover a huge spectrum of clothes that are not newly designed”. Tungate [8, p. 221] offers a more focused definition which highlights the evolution and complexity of the term, identifying that “any one particular item may change through time and usage by the fashion media, so that second hand becomes known as retro then in turn as vintage”. The increase in availability of vintage and the growth of on-line availability of vintage clothing has added confusion to the array of vintage definitions [4]. From the customer view point, Tungate [8], proposes that vintage is an intangible concept which is more about attitude than style of dress. Similarly Palmer [4], characterises vintage fashion as a symbol of individuality and originality. A primary aim of this research was to define vintage from the perspective of the vintage fashion retailer.

An Exploration of Vintage Fashion Retailing

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Characteristics of the Vintage Consumer Traditionally the buying of second-hand apparel has been subject to negative meanings as a mark of poverty [27, 28]. Tseëlon [29] acknowledged that this type of social judgment has been discounted by the vintage consumer in their quest for non-conformity to fashion trends. Silverman [30], recognized increased demand for vintage goods amongst the young consumer and the middle class consumer. Crewe and Forster [31], agree with this explanation, adding that these groups acquire vintage fashion for excitement and as a means of displaying themselves in public. Hansen [32], segments the vintage consumers into young professionals who want good quality apparel at modest prices, or young people keen on retro subculture looks like Punk, Rave or Mod styles. In addition, Woodward’s [16] study explored younger consumer’s affection for vintage clothing and recognized that the incentive for consumption was to achieve a level of differentiation from their peers. Additionally, a substantial consumer group has been acknowledged as taste-makers: stylists, designers and image makers who use it as a means of inspiration and creativity [33-35]. The ownership, or the wearing of vintage items along with high street clothes, has become anindication of how fashionable the wearer is, with an increasing prominence on how the items are sourced, and not just on how the person looks [16]. The increase in mass market vintage has possibly weakened the authentic charm of vintage among ‘fashion’ orientated consumers, i.e., those more concerned with how things look and being individual in style, than having a deferential concern with the historic and representative links of these sometimes uncommon items which the vintage connoisseur and retail experts so value [7, 36, 38].

History and Key Drivers Vintage as mainstream fashion emerged as a trend in the 1980’s [38]. Tolkien [6] has identified vintage as stemming from the New York social fashion elite, influenced by sentimental pictures of 1940’s couture. In addition, celebrities fueled demand and popularity of the style by wearing luxury vintage gowns to major award ceremonies and fashion shows. Others credit Barbra Streisand as the first vintage-couture advocate [39]. In turn, this encouraged designers such as Marc Jacobs, in the 1990s to create the ‘nouveau vintage’ look by reinventing older styles [40]. This trend also occurred in the UK and Europe with designers and celebrities such as Stella McCartney and Kate Moss inspiring mainstream adoption of vintage fashion [41, 42]. The appreciation of vintage aesthetics which grew in the 1990s helped to decrease the stigma of wearing second hand clothing, and permitted them to develop in to acceptable sources of fashion. This resulted in a differentiation both in-store and in the consumer’s mind, between vintage and clothing purchased from charity stores [1, 4, 6, 43]. The media has endorsed vintage fashion as a means of conveying connoisseurship and uniqueness, more recently extended by the juxtaposition of vintage and contemporary in one ensemble [4, 8]. Jackson and Shaw [44] highlight an important driver in the vintage movement is media attention on the unethical practices which exist in the fashion industry, resulting in a consumer backlash against disposable fashion and the beginnings of a ‘slow fashion’ movement, who emphasize the importance of quality as opposed to quantity [45].

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An additional driver acknowledged by Tungate [8] is customer defiance of expensive, branded products and trends promoted through marketing communications. In recent years, the economic downturn has witnessed ‘upcycled’ fashion items becoming a mainstream phenomenon; this is the re-working of old clothes into more modern-day, higher value pieces [46, 47]. The influential ‘retail guru’, author and broadcaster Mary Portas, successfully developed a media campaign in 2009 called ‘Living and Giving’ which improved the image of charity shops and further increased demand in vintage clothing [48]. More recently, in a study of street style Woodward [16], indicated that the trend for vintage has reached maturity and might now be perceived as commonplace or omnipresent. In the case of both the retailer and the consumer alike, the uptake of the vintage trend in the ‘noughties’ has caused a reduction in the availability of interesting and unusual items, affecting the market in two ways. Firstly key pieces have increased in value and vintage fashion has grown to be an investment prospectrivaling the collection of artwork [49-50]. Agins [51] has identified that this is as a result of the widely broadcast view that the couture industry is declining, with prices accelerating and skilled workmanship growing scarcer. Secondly it means that traditional vintage consumers are being forced to search extensively and even globally to source the desired article [52]. In total there are three key drivers of vintage fashion trends. Firstly, the trickle down feature from celebrities and designers, secondly, the ethical aspect of the fashion industry and finally the need for individual uniqueness and authenticity. Palmer [4, p. 197) proposes that “vintage has now shifted from subculture to mass culture because of the disappointing fact that, regardless of price, fashion today is rarely exclusive”.

Market Structure and Vintage Retail Formats Mhango and Niehm [53] suggest that vintage clothing retailers are focused within the small business sector, and are characteristically independently owned. These include secondhand stores for example thrift or charity shops, estate sales, garage sales, flea markets and auctions, usually the province of commercially-mediated lateral recycling [31, 54]. Nevertheless, vintage clothing retailers have now developed to comprise multifaceted retail support functions such as sourcing, supply chain management and visual merchandising [55]. Moreover many charity stores in Great Britain have re-invented themselves as ‘vintage’ to increase their apparent brand value and to distinguish themselves from others in the sector [12]. Mainstream high street retailers such as Top Shop and Urban Outfitters have successfully sold vintage clothing ranges for a number of years [15]. Tolkien [6] ascertains that the internet as a significant channel in the distribution of vintage clothing, however this phenomenon requires an alternative research approach and can be addressed in future studies.

Retail Positioning Porter's [56, 57] theory of positioning theory has had an lasting impact on the marketing literature [58-65], and practice [66, 67], as one of the most significant concepts and fundamental principles of marketing [63, 64], central to strategic marketing success [68].

An Exploration of Vintage Fashion Retailing

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The positioning strategy implemented by any company is grounded in the needs of the customer, the behaviour of the competition, and is ultimately how companies can achieve competitive advantage [69-73]. It is commonly acknowledged that although there are a number of positioning typologies developed within the marketing planning framework [59, 73-74], there is a lack of empirical research testing these typologies [61, 64]. Yip [75] has proposed that a number of the positioning approaches suggested within the literature, are incomplete and may be confusing. Table 1 offers a summary of positioning typologies. The concepts of these positioning typologies are considered by the authors as the central means by which the organisation can attain differentiation, increase competitive advantage and therefore position themselves within the market [64]. Table 1. Summary of positioning typologies Author

Aaker and Shansby [59]; Berry [78]; Buskirk [76]; Brown and Sims [77]; Crawford [79]; Hooley, et al. [63]; Wind [73]

Ries and Trout [66]

Easingwood and Mahajan [80]

Arnott [61, 58]

Kalafatis, et al. [72]

Positioning constructs i.e., concepts Features and Benefits Features, price, advertising, distribution, problem solved, usage situation, users, competitors, value, time efficiency, high contact, sensory, benefits, product class dissociation, attributes, price, quality, use or application, product/service user, product/service class, competition, direct/indirect, surrogates: nonpareil, parentage (brand, company, person), manufacture, target, rank, endorsements, experience, predecessor, innovation-imitation, superior service-limited service, differentiated benefitsundifferentiated features, tailored offering-standard offering. Strategic positioning Market leader, follower, reposition the competition, use the name, line extension (use of house name). Reputation/capabilities of organisation: expertise, reliability, innovativeness, performance, augmentation of product offering: product augmentation, extra service, people advantage, more attractive package offering, a superior product through technology, accessibility, extra attention given to individual requirements through customisation, satisfaction of more user needs within the sector through offering a complete product line. Empathy, solvency, promotions, administrative time, helpfulness, reliability, attentiveness, staff competence, flexible products, access to people, reputation, customisation, incentives, social awareness, security, technology. Easy to do business, personal contact, product performance, range of offerings, presence, safety, leadership, distinct identity, status, country identity, differentiation, attractiveness.

Source: Adapted from Blankson and Kalafatis [64].

Blankson and Kalafatis [64], however, consider existing studies to be descriptive, difficult to put into practice and based on limited empirical testing, principally in terms of their representation within consumer marketplaces, their propensity being to represent the

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views of management. They propose that the literature lacks an empirically based consumer/ customer derived typology, which can measure the effectiveness of positioning strategies employed. Having carried out extensive empirical research, they have proposed a positioning typology based on customer opinions, which they advise is suitable for both product and service markets and recommend that managers develop their positioning based on consumer perceptions of prestige, service, reliability, attractiveness, country of origin and brand name. These, they propose, are the key differentiating features within the marketplace and can be successfully deployed in marketing communication. In the retailing literature, Cook and Walters [19] suggest that a company’s market position is its reaction to its understanding of the needs, desires and behavioural characteristics of its target customer profile. Retail positioning is defined by Wortzel [81, p. 47] who proposes: “For a retailer, strategic positioning involves providing unique value. Strategic positioning involves selecting and then bringing to bear an integrated set of tools and communication techniques that identify and explain the store to the customer.”

Walters [18] offers a model of positioning developed as the consequence of wide-ranging empirical research within the retail sector. The fundamentals of the positioning strategy in retailing, he suggests, are a visible response to the needs and wants of the identified target market. The key decision areas for retailers in evolving their marketing strategy are those of trading format, merchandise strategy, customer service and customer communications strategy. These decision areas define the retailer positioning strategy, and position them in terms of what the customer anticipates and customer satisfaction, creating a point of distinction which separates retailers from their competitors and represents the retail brand [82, 26]. While established as a theoretical model, the strategic elements of Walters’s [18] value added positioning statement are still recognised in the retail marketing literature as the means by which retailers should position themselves in the market [17-26]. Therefore it forms the basis of a number of empirical studies on retailer brand positioning [20, 26, 81, 83-88, 89, 90], which stress the possible benefits of developing a clear and distinctive positioning statement using the elements of the retailing mix. Consequently it was thought to be the most suitable framework for application within this study. However, although there are a number of positioning typologies developed in the marketing and retailing planning context [59, 73-74], there is still a lack of empirical research testing these typologies [61, 64]. The literature suggests that small retailers, like those addressed within this study, are different from larger companies in terms of management systems and resources, and that planning, control and strategy are a result of the personal objectives and personality of the owner manager [91-93]. However, within the vintage retail sector, this proposition has not been tested. This research serves to help address this issue.

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METHODOLOGY Small companies are dominant within the vintage retail sector and generally evolve from the entrepreneurs who are enthusiastic about vintage themselves [12, 14]. The decision to focus on small scale companies is also supported by evidence provided in the vintage retailing literature, as existing research focuses on small companies [53, 54]. To be selected for this study the vintage retailers had to meet some or all of the specifications within the literature. They had to have high levels of experience in both buying and merchandising and so had to have been in business for at least two years. The participants of the study therefore had between two and twenty three years experience of running a vintage retailing company. To ensure consistency of trading practices, participants were required to trade as bricks and mortar businesses. Therefore, participants would provide credible information as to the concept, positioning and differentiation of small vintage fashion retailers. Thirty nine vintage fashion retailers from Scottish towns and cities were identified from The Yellow Pages, trade journals and company websites. Of these, twenty seven were found to have been in business for over two years, however one was found to sell only on an online basis. A letter was sent to these twenty six vintage fashion retailers from the population sample of thirty nine in September of 2009. A follow up phone call was made a week later. Sixteen retailers responded that they were willing to participate in the study, however, one potential participant remained unavailable. Therefore fifteen interviews were carried out with owner/managers of vintage retail stores. All participants had direct experience in the areas of buying and merchandising within the vintage retail sector. The owner managers were between twenty three and fifty eight years old. The interviews took place within the retail premises and were approximately two hours long. Confidentiality was assured. The interviews were taped, transcribed and retained as Microsoft Word documents. Analysis was carried out by one member of the research team to ensure consistency. First of all the transcripts were analysed to identify common characteristics and emerging themes and issues. At this stage, a “cluster” approach was adopted and a framework for theoretical development began to emerge [94]. These clusters were selected on the basis of significance, mutual exclusivity and ability to stand by themselves [95]. Yin [95] suggests that data analysis consists of examining, categorising, tabulating, and testing the content to address the initial propositions of the research. Interviews were analysed one at a time individually and then on a cross interview analysis. Patton [96] suggests that the analysis involves the application of the existing theoretical framework, developed from the literature, and the subsequent analysis of the interviews to allow for an examination of emerging patterns. According to the theories and concepts extracted from the literature, the interviewees were asked open-ended questions about their definition of vintage, the vintage customer, merchandising and the positioning of the vintage store. The results and discussion section is therefore divided into three sections. Firstly, the research seeks to define vintage fashion and investigate the vintage fashion movement, secondly, the research explores the characteristics of the vintage fashion consumer from the perspective of the store owner/managers, and finally it explores positioning in relation to the retail vintage fashion sector.

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RESULTS Defining Vintage Fashion There was no unified or clear definition of vintage with each vintage retailer offering differing opinions and suggestions. However, three dimensions emerged. Firstly the age of the apparel, secondly the style, (a piece of clothing which sums up the era), and finally the quality of the vintage clothing. The majority stated that fashion which predates the 1990s would be considered to be vintage. To a number of interviewees ‘vintage’ could be categorised as anything up until the 1950s, with anything that pre dates 1980 being classified as ‘retro’, and anything before the 1920s being considered as ‘antique’. “Probably not the 1990s but anything before that, especially the 1980s at the moment. Only the fashion forward are looking for 1990’s articles”

Some items of clothing were seen to represent the zeitgeist of bygone eras and these were particularly important to vintage consumers. Examples included a 1950’s prom dress or Dior’s ‘New Look’ full skirt. In 1960, ‘Twiggy-style’ 1960’s mini dress, in the 1970’s platform shoes and bell bottom trousers and 1980’s pedal pusher short trousers and frilled shirts from the New Romantic movement. All participants agreed that, in order to satisfy customers, articles have to be of good quality. Almost all the participants agreed that vintage fashion was second hand, however, a few retailers sold old clothing manufactured in the past which was unworn. One retailer was selling unworn “Brutus” and “Lee” denim jeans from the 1970s which had been discovered in a warehouse. The most desirable items were those which had been bought in a past era but had rarely or never been worn, for example items which have been kept for special occasions and were in pristine condition. Examples included evening dresses, a wedding dress or a formal suit. One participant summed up the general opinion stating: Vintage fashion isn’t something that is just old. If a ‘50’s dress is an ugly hideous rag- that is what it is, an ugly hideous rag. Vintage is the very, very best of its type.

Characteristics of the Vintage Consumer Retailers were invited to define the vintage consumer from their own viewpoint. Participants stated that many of their customers were “fashion conscious” and “young” consumers, with an average age of between eighteen and twenty (many of them students), however all participants stated that the age range of their consumers was very diverse. It was found that he 18-25 year old consumers are most likely to be influenced by fashion trends. It was recognised that this particular segment had adopted the ongoing vintage trend which had positively increased demand for vintage clothing overall. These younger consumers were seen to be setting the trend for current trickle up fashion looks such the “nerd college look”, and “geek chic” (spectacles, drainpipe trousers or retro skirts with blouses and tank tops). The interviewees proposed that these trends had also extended to celebrities and were linked to sub-culture music trends.

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Young consumers were seen to purchase for originality and enjoyment, to display aspects of their own individual style, and in many cases, price. Participants stressed their ability to offer uniqueness which people see as a method of individual self expression. There was a certain status provided by the originality of rare clothing. One proposed: You always feel quite smug when you say ‘Oh its Vintage’ there’s no way the person can go out and copy you

The next most important group of consumers identified were older customers (aged 3070) who tended to purchase on price and nostalgia rather than trend. This segment were likely to invest more time, money and effort in their purchases and were generally more motivated about the authenticity of the product. For example, a number of participants discussed the importance to the customer of the story behind the garment; what one termed as “vintage magic.” Consumers were buying ‘more than a skirt or shirt,’ they were buying a piece of history, and often enjoyed hearing a story behind an item or ‘a treasure.’ Additionally, participants highlighted an increase in the number of ethical consumers, conscious of environmental issues and recycling. This customer group was diverse in age and nature. Finally, a small proportion of customers were collectors and business customers, for example television, film and theatre wardrobe designers and stylists for fashion magazines.

Vintage Retailer Positioning Merchandising Strategy The main concern by the retailers in sourcing garments was the authenticity of vintage fashion. Most considered vintage fashion to be authentic by the perceived age and its level of originality. They particularly sought garments which had been handmade and were therefore exclusive. Exclusivity is of particular importance as it allows premium pricing and provides differentiation for the store. Older designer clothing from fashion brands such as Chanel and Biba are becoming rare and difficult to source. Some of these older garments particularly with brand names are highly sought after. Products that are mass produced (even older clothing from the 1980s for example) are less likely to be perceived as authentic and are therefore less desirable. One retailer stated: Authentic vintage is an original garment and not a vintage label from a high street store. They are obviously complete one offs and that in my mind is worth a lot more than some dress that’s been churned out by Marks and Spencer. Back in the ‘40s, ‘50s and ‘60s people were making their own clothes, which are highly desirable now.

Participants explained that they were able to verify the authenticity of garments through their personal expertise, gained through experience of sourcing and buying. Many retailers considered themselves to have expert technical knowledge, and could determine garment authenticity by the stitching, (e.g., of hand sewn products rather than machine produced) the fabric quality, and the smell of the garments. Because of the increasing difficulty in sourcing good quality vintage items some retailers had decided to sell more modern items that had been manufactured more recently but were made to an appropriate vintage design.

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They understood that the authenticity of these garments was debatable; however they agreed that consumers wanted to purchase this type of ‘pseudo-vintage’ product due to the desire to follow the vintage trend. Retailers sourced second hand merchandise from a wide variety of second hand stores and markets both at home and abroad, charity and second hand clothing stores, car boot sales, recycling plants and many garments are donated by customers or other shoppers who wish to recycle. Vintage retailers will also recycle clothing back to recycling plants or ‘rag yards’ if they are unable to sell the garments. Merchandise was both bought in bulk ‘by the sack’ or ‘large load’, or handpicked. Retailers occasionally sourced more exclusive merchandise from private individuals who perhaps were collectors themselves and chose to trade their personal vintage garments to be enjoyed by other enthusiasts or vintage collectors. Some store representatives discussed of more recent emerging markets in Eastern Europe which offer opportunities for trade and sourcing of vintage clothing, offering alternatives to what is still available in the UK market. Participants also highlighted France and the US as fruitful sources. One stated that the US was particularly good for 1920’s dresses. One retailer observed: I am sure there is a totally untapped market in Russia. I would like to visit there and raid some wardrobes. Russia is so large and many people don’t know the value of vintage garments yet.

Retailers selected merchandise according to ‘gut feel’ and intuition and was therefore a very personal issue. Participants sourced according to their personal expertise of the market, their customers and their personal knowledge of fashion history. The research found therefore that this personal expertise was highlighted by all participants as their main point of differentiation and competitive advantage. In many cases they proposed that a synergy existed between themselves, their knowledge of style and their customers. In most cases retailers explained that they understood their regular customers’ needs and wants and were able to buy accordingly. The most popular brands were found to be Biba, Bus Stop, Mary Quant, Burberry, Dior and Chanel. Unlike high street fast fashion models, stock was not ‘turned around’ in weeks however, there is a seasonal approach to vintage merchandise. During the spring and summer, female consumers were looking for summer dresses, 1950’s style dirndl skirts (full skirt gathered at the waist), miniskirts and more recently in line with changing fashion trends, maxi dresses. During the winter, the demand was for heavier outerwear and coats, hats, gloves and scarves. Retailers explained that as a result of catwalk trends, there is still demand for real fur coats. Participants explained that consumers believed that the wearing of old, second hand fur coats was acceptable to many of their customers because these items were manufactured prior to increased ethical awareness of animal rights issues. Older fur therefore was perceived as glamorous and stylish despite the recent concerns surrounding new fur products. ‘Occasion’ dresses from any vintage era were always in demand and at Christmas, customers were looking for appropriate glamorous party wear. A table of the most popular items is outlined in Table 2 below. Selection of these items was based on more than half of the sample highlighting these product categories:

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Table 2. Most popular vintage items for men and women Ladies vintage items 1950s prom dresses 1960s shift dresses, 1970s maxi dresses Evening wear – glamorous gowns, sequined and embroidered dresses Real and fake fur coats and jackets Cashmere jumpers and cardigans Jewellery and watches Handbags, scarves and belts High heels and flat boots for ladies from the 1960s, 1970s and 1980s

Men’s vintage items Formal wear Evening suits Suits from the 1950s and 1960s Traditional dress (Kilts) Retro Adidas tracksuit tops from the 1970s Levis jeans and denim jackets Cowboy boots Military dress Leather briefcases Ties

One of the key challenges that participants highlighted was the procurement of appropriate, second hand stock which is in good condition. Due to the popularity of the trend, there is an increasing scarcity of stock as older garments become more worn and therefore less appealing due to reduced quality. This was seen to be an enduring problem which has heightened competition in the vintage sector. There was a level of preparation required for all second hand garments. All the vintage retailers washed or dry cleaned items before sale. Some items required repairs such as sewing on buttons or zips, or making alterations such as altering hem lines. However, normally alterations were minimal so that the authenticity of the garments was not compromised. In some cases however, participants created new garments by combining two pieces together. If a part of a garment was too ‘worn out’ to be sold, sections of garments and fabrics could be ‘rescued’. One participant proposed: We buy dresses that are full length and we cut them to mini dresses. We actually have a tailor next door who does all that for us. We have bought blazers and put accessories on them to make them look more interesting

Customer Service Personal service was found to be essential to the success of most of the retailers. Most employees were owner/managers, assisted by partners, friends or family members who had a vested interest in the success of the store. All retailers explained that they know a high proportion of their customers very well, considering individual customer tastes, needs and style when sourcing garments. Some participants would store items for particular customers. In addition, customers frequently request the sourcing of specific items. Therefore, the basis of much of the customer service for vintage retailers was the building of relationships. Additionally, all had a loyal and regular customer base. Many proposed that the development of these relationships allowed retailers to offer a personalised service. A number of retailers offered an alteration service for their customers. Therefore differentiation was possible for these retailers due to the relationships and customer service they developed with their consumers.

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Most proposed that they themselves personally were the differentiation through their passion for the vintage concept, their choice of merchandise, their expert knowledge and expertise. One participant stated: It’s me. The company is built around my personality, personal style and taste. My customers like that and they trust my judgement.

Communications Store image elements were the most important methods of communication for vintage stores. That is, the window display and the store interior. The window display was seen as vitally important to generate interest and curiosity from passersby and the unique store interior and merchandise communicated a distinctive brand image. In terms of traditional communications, most of the retailers did not use print advertising often due to expense and due to limited success using this method in the past. A few advertised in local directories and the Yellow Pages. Many participants explained that local press editorial had proved to be very effective in increasing awareness and enhancing business profile. The main type of communication reported that was thought to be essential by all interviewees is word of mouth (WoM) marketing due to the high levels of personal service outlined above. Positive customer experiences were thought to be vitally important for promotion and generating custom. The group was divided in relation to e-marketing. Only half of the participants operated a website. However, several participants interacted with social media platforms (at varying levels) in order to connect with the vintage fashion community, to increase brand awareness and generate enquires and consumer awareness. Store Trading Format All the participants in the study were small-scale retailers who were independently owned. Typically, most stores were single units which were 700-1100sq.ft. in size. Many were located in secondary geographical locations with a ‘neighbourhood feel.’ All of the retailers included in this research described themselves as traditional ‘bricks and mortar’ boutique-style shops. Of those that operated websites, most were non transactional, and two of the stores had their own on-line stores. The majority of sales were traditional, meaning in store retailer to consumer business. Interestingly, a few retailers had evolved their stores from market stalls and indicated that a proportion of vintage trade still took place on that basis. All proprietors explained that the store image was essential to vintage retailing. Many participants stated that the window styling, store layout and product display was important to create the atmosphere of “a bygone era” and many described the stores as “quirky” and “individual”. Each store represented the personality of the owner, with one retailer explaining that he wanted to “create the right kind of vibe” with music from a previous era and choosing items carefully to represent his sense of taste and style. Many displayed interesting pieces that were collectors’ items or were appropriate to present the vintage image. Old gramophones, old bicycles, wallpaper from the 1970s and 1980s, old pictures and pieces of art and various other pieces of memorabilia were displayed according to the proprietors’ preference. The product display varied from store to store. Most displayed clothing in racks similar to new modern high street retailing and many had containers such as baskets and boxes and shelves of mixed accessories and jewellery that consumers enjoyed “sifting through” and “hunting for a treasure or a bargain.”

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CONCLUSION The vintage movement was mainly something of a “fad” that was followed by a small group of innovators such as art school and fashion students. However more recently it would appear to be an enduring trend, increasing in popularity, growing into a mainstream fashion phenomenon. This is evidenced by its diverse customer base, adopted by young, fashion conscious consumers and maintaining a group of diverse traditional vintage customers of a variety of age groups. The movement has also gained interest due to more recent concerns over ethical issues such as recycling and sustainability. This study discovered two main groups of consumers; young and fashion conscious, interested in current trends and mix and matching from various styles, high street and vintage and also an older customer with a greater focus on price and interest in nostalgia. An emerging issue for many customers were their ethical concerns. This research explores the retailer perspective of the vintage fashion trend. Future research is necessary, to investigate consumer motivation buying vintage fashion of these different groups. This research set out to define the concept of vintage fashion within its current context. Therefore, vintage fashion can be defined as: Garments and accessories which are more than twenty years old, which represent a particular fashion era, and which are valued for their uniqueness and authenticity.

Positioning strategies of vintage fashion retailers was also explored. Table 3 highlights the key areas of positioning within vintage retailing. The research therefore revealed that vintage retailers position themselves through their distinctive retailing mix. Vintage proprietors explained they could source items that were totally individual and unique. As one store owner stated, You are buying a piece of history… a treasure. This was the main difference between other independent stores. Table 3. Vintage Retailer Positioning Elements Customer communication

Trading format

Individual retail brand image, quirky and constantly evolving, distinctive store environment, window and interior displays, retro props, localised PR, word of mouth, growing importance of social media

Small scale, independent, single site, secondary geographical location, multichannel participation, boutique style, unique store image which represents the personality of the owner

Source: adapted from Walters [22].

Merchandise strategy Sourcing: personal, diverse, intuitive, expert and historical knowledge, global Product: authentic, original, exclusive, rare brands, preowned, handpicked, limited supply of merchandise

Customer service Personal, individual, relationship based, long term, synergy between business owner and customer, availability of adjustments and alterations, employee passion for the vintage concept

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Sourcing therefore was an extensive challenging and time consuming process which reflected the personality and expertise of the proprietors. The “quirkiness” of the store interior and environment was also of importance and word of mouth communication was also found to be very important in terms of promotions. Vintage retailers are often small scale, ownermanaged businesses, and are because of this, closer to their customers and able to form individual relationships through merchandise supply and customer service. The influence of the owner/manager, their style and personality is consequently reflected and embedded in the positioning of the company, offering differentiation of their individual stores in the market. There remains a gap in the literature in terms of analysis of the vintage customer. The positioning model above could, in future studies, be used to establish consumer responses to vintage retailer strategy.

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[67] Dovel, G. (1990). Stake it out: positioning success, step by step. In: Business Marketing: A Global Perspective. Hayes, H. M., Jenster, P. V., Aaby, N.-E. (Eds), Chicago, Irwin: pp. 270-278. [68] Devlin, J., Ennew, C., et al. (1995). Organisational positioning in retail financial services. Journal of Marketing Management 11(1-3), 119-132. [69] Brooksbank, R. (1994). The anatomy of marketing positioning strategy. Marketing Intelligence and Planning 12(4), 10-14. [70] Doyle, P. (1994). Marketing Management and Strategy. Hemel Hempstead, PrenticeHall. [71] Dibb, S. (1998). Market Segmentation: strategies for success. Marketing Intelligence and Planning 16(7), 394-406. [72] Kalafatis, S. P., Tsogas, M. H., et al. (2000). Positioning strategies in business markets. Journal of Business and Industrial Marketing 15(6), 416-437. [73] Wind, Y. (1982). Product Policy, Concepts, Methods and Strategy. Reading MA, Addison-Wesley Publishing. [74] Hooley, G., Broderick, A., et al. (1998). Competitive positioning and the resource based view of the firm. Journal of Strategic Marketing 6, 97-115. [75] Yip, G. S. (1997). Patterns and Determinants of Global Marketing. Journal of Marketing Management 13, 153-164. [76] Buskirk, R. K. (1975). Principles of Marketing. London, Dryden Press. [77] Brown, H. E., Sims, J. T. (1976). Market segmentation, product differentiation, and market positioning as alternative marketing strategies. Marketing: 1776-1976 and Beyond, Educators Conference Proceedings Series No. 39. Chicago, IL, American Marketing Association. [78] Berry, L. L. (1982). Retail positioning strategies for the 1980s. Business Horizons 25 (6), 54-60. [79] Crawford, C. (1985). A new positioning typology. Journal of Product Innovation Management 4, 243-253. [80] Easingwood, C. J., Mahajan, V. (1989). Positioning of financial services for competitive strategy. Journal of Product Innovation Management 6 (September), 207219. [81] Wortzel, L. H. (1987). Retailing Strategies for Today's Mature Marketplace. Journal of Business Strategy 7(4), 45-56. [82] Bridson, K., Evans, J. (2004). The Secret to a Fashion Advantage Is Brand Orientation. International Journal of Retail and Distribution Management 32(8), 403-411. [83] Corstjens, M., Doyle, P. (1989). Evaluating alternative retail repositioning strategies. Marketing Science 8(2), 170-180. [84] Knee, D., Walters, D. (1989). "Competitive Strategies in Retailing". Long Range Planning 8 (Spring), 45-56. [85] Davies, G. (1992). The two ways in which retailers can be brands, International Journal of Retail and Distribution Management 20(2), 24-34. [86] Ellis, B., Kelly, S. W. (1992). Competitive Advantage in Retailing, The International Review of Retail, Distribution and Consumer Research, 2(4), 381-96. [87] Conant, J., Smart, D., et al. (1993). Generic retailing types, distinctive marketing competancies, and competitive advantage. Journal of Retailing 69(3), 254-279.

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[88] Warnaby, G. (1993). Laura Ashley - An international retail brand. Management Decision 32(3), 42-48. [89] Birtwistle, G., Clarke, I., Freathy, P. (1999). Store image in the UK fashion sector: consumerversus retailer perceptions. The International Review of Retail, Distribution and Consumer Research 9(1), 1-16. [90] Morschett, D., Swoboda, B., et al. (2006). Competitive strategies in retailing-an investigation of the applicability of Porter's framework for food retailers. Journal of Retailing and Consumer Services 13, 275-287. [91] Shuman, J. C., Seeger, J. A. (1986). The theory and practice of strategic management in smaller rapid growth firms. American Journal of Small Business 11, 7-18. [92] McAuley, A. (2001). International Marketing. Wiley, Chichester. [93] Hutchinson, K., Quinn, B. (2011). Identifying the characteristics of small specialist international retailers. European Business Review 23(3), 314-327. [94] Guba, E. G., Lincoln, Y. S. (1994). Competing Paradigms in Qualitative Research. In: Handbook of Qualitative Research. Denzin, N. K., Lincoln, Y. S., Thousand Oaks, CA., 105-117. [95] Yin, R. K. (2003). Case Study Research. Thousand Oakes, SAGE Publications. [96] Patton, M. Q. (2002). Qualitative Research and Evaluation Methods. Thousand Oakes, SAGE Publications.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 2

DEVELOPING SUSTAINABLE DESIGN ON DENIM READY-MADE APPARELS BY STONE AND ENZYMATIC WASHING Md. Ibrahim H. Mondal1, and Md. Mashiur Rahman Khan1,2,† 1

Polymer and Textile Research Lab., Department of Applied Chemistry and Chemical Engineering, Rajshahi University, Rajshahi, Bangladesh 2 Department of Apparel Manufacturing Engineering, Bangladesh University of Textiles, Tejgaon, Dhaka, Bangladesh

ABSTRACT Denim is the most preferable apparel of today’s youth. Washing is one of the fundamental chemical processing steps prior to finishing fresh-assembled denim readymade apparels and has the largest effect on outlook appearance and other physicomechanical properties of finished denim apparel. The fresh denim trousers, twill 3/1 weave and composition 100% cotton, have been processed by enzyme washing and pumice stone-enzyme washing technique using various parameters namely concentrations of pumice stone (10 to 70%) (owg), concentration of cellulase enzyme (0.5 to 3.5%) (owg), washing temperatures (40 to 65oC) and treatment times (20 to 60 min) with fixed pH (4.8) in fiber to liquor ratio of 1:10 in an industrial sample washing machine. In order to evaluate the influence of these washing parameters on the properties of denim apparel like tensile strength, fabric weight, color change, stiffness and water absorption has been determined. Fabric surface was also examined by scanning electron microscope (SEM) and fluorescence microscope (FM). The washing parameters has a great influences on the properties of denim. Stone washing increased the softness (by reducing stiffness) and flexibility (in terms of bending length) of denim apparels and gave a used look appearance on denim apparel distinctly. The properties of denim apparels are varied depending on the amount of pumice stone used. 

Md. Ibrahim H. Mondal: Polymer and Textile Research Lab., Department of Applied Chemistry and Chemical Engineering, Rajshahi University, Rajshahi- 6205, Bangladesh. E-mail: [email protected]. † Md. Mashiur Rahman Khan: Polymer and Textile Research Lab., Department of Applied Chemistry and Chemical Engineering, Rajshahi University, Rajshahi- 6205, Bangladesh. Department of Apparel Manufacturing Engineering, Bangladesh University of Textiles, Tejgaon, Dhaka-1208, Bangladesh.

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan The results indicate that for producing sustainable denim apparel the optimized washing condition for the best value is 30% pumice stone with 2.0% cellulase enzyme at 55 oC for 40 min.

Keywords: Denim apparel, cotton, cellulase enzyme, pumice stone, tensile strength, washing, color fading

1. INTRODUCTION The increasing demand of denim apparel in the world market has imposed extreme pressures on the textile industries. The use of chemicals in the textile industry has been known and applied commercially for many years. In particular, textile washing industries are using various chemicals in processing denim ready-made apparels for producing specific washing effects and designs. The research attempts to examine different washing techniques for the modification of denim apparels and searches for the dynamic best method for producing sustainable denim apparel designs. Understandably, this concern motivates many efforts to modify denim apparels with new designs in order to face the challenges of fastchanging fashion trends. Although denim apparel has been popular since the early1980’s, the term “sustainable denim” is a relatively new concept to the apparel industry. Sustainable denim has become to be a dominating factor in the apparel industry. Now-a-days, there is awareness on environmental concern among the customers and buyers. In this respect, present work has been undertaken to fulfill the current demand of customers using environment friendly chemicals for denim washing. Therefore, the study investigated evaluative specifications used by designers and buyers for producing denim apparel with sustainability. Bangladesh is a textile industry based developing country. At present, Bangladesh earns about 80% foreign currency from the textile and RMG sectors. Bangladesh started RMG export in 1977-78 and continues export under quota to the US till 2004. In January 2005, the RMG sector of Bangladesh faced new challenges due to the withdrawn of quota by US government. From that time, the US market is open for all and highly competitive. Currently there are about 5600 ready-made garment industries in Bangladesh and from these RMG industries Bangladesh earns about 21.51 billion US dollar [1]. To sustain the RMG sector of Bangladesh in the competitive world market, it is essential to produce new design and fashion apparel with sustainability. Denim apparel is produced from very strong and stiff denim fabric and its popularity is increasing day by day in the world market. Without washing/finishing treatment denim apparel is uncomfortable to wear, hence it can be modified by washing and introduces new look and fashion. There have been many attempts to use chemicals in various washing techniques like bleach wash, enzyme wash, stone wash, etc. The washing of denim apparel by enzymatic process, specially cellulases that would degrade the color of denim and improve the handle and drape, dimensional stability and surface characteristics reported by Kawamura and Wakida [2], Tyndall [3], Kumar et al. [4], Duran and Marcela [5], Gubitz and Cavaco-Paulo [6] and Cortez et al. [7]. Cellulases are introduced to replace aggressive chlorine bleach in denim washing [8] but the enzymatic attack of cellulase is not only limited to the surfaces, act synergistically in hydrolysing cellulose to glucose [9], causing unacceptable weight and strength loss to the fibers.

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It is believed that if the denim apparels are chemically washed with enzyme and stoneenzyme separately in order to decrease their minimum strength and weight for producing specific washing effects and designs, their chemical attack would be restricted only to the surface of the fabric, which is the main purpose of this research work. Thus, the work proposes the use of bio-degradable cellulase enzyme and stone-enzyme in place of harmful chemicals and attempts to optimize the process parameters, such as, concentrations of chemicals, concentrations of pumice stone, temperatures, and times with high wear performance like durability and longevity (with minimum strength losses) of apparel in producing sustainable denim apparel.

1.1. Denim Apparel Washing The washing of apparel generally means cleaning of dirty apparels with soap or detergent. But industrial apparel washing is a technology which is used to modify the appearance, outlook, comfort ability and fashion of the apparels. With the changes of time, human choices, demands, and apparel’s design and fashion changing very quickly. To meet the present demand of consumers, apparel manufacturers are adapting new technology and processes in washing. The washing technology needs various types of chemicals for washing apparels. Denim washing is the aesthetic finishing process given to the denim apparel to enhance the fabric properties and provides fashion effects. Various chemicals are used in various washing processes, e.g., bleaches are used in bleach washing process, enzymes are used in enzyme washing process, pumice stones are used in stone washing process etc.

1.2. Denim Denim is a yarn-dyed cotton twill fabric, basically warp yarns are dyed with indigo and weft yarns are white [10]. Indigo is insoluble dye and diffused on yarn surface [11]. Indigo dye is popular for denim because it washes down easily and clear bright blue shades are achieved by washing [12]. Today denim has various washing aspects for designs, it can be stone washed, bleach washed or enzyme washed. The word denim is derived from the French word ‘Nimes’, the Nimes was the French city where the denim was first produced. The fabric which was produced in Nimes was called ‘Serge’ in French. Resultant it was called ‘Serge De Nimes’ means ‘fabric of Nimes,’ later the name was shortened to DENIM.

1.3. Sustainable Design Sustainability is a vital topic within the design world. Sustainable practices are now growing in the apparel industry. In the past, apparel designers and merchandisers have emphasized a product’s functional, aesthetic, and economic aspects during the design process [13]. With increased consumer interest in the environmental implications of apparel production, many companies have introduced sustainable practices [14, 15]. Consumers are also interested to get fashion products [16] which are a challenge to sustainable practices in the apparel industry.

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Figure 1.1. Flow chart of denim manufacturing.

Designers seek to practice environmental responsibility and discover solutions for current problems [17]. Literature suggests that sustainable practices in the textile and apparel industries include the use of renewable and non-harmful materials [18-20], applying lowimpact processes [21, 22], the re-cycling of waste materials [23], the eco-friendly, green and environmental friendly process [24], and fashion product which is one of the biggest barriers encountered in the apparel industry [25]. Along with increasing global awareness of environmental problems, consumers’ awareness of sustainability has risen and consumers are seeking environmentally friendly clothing, and producers are exploring ways to meet these demands while processing clothing. Sustainable design includes production processes also. In producing sustainable design, the designers determine the properties of the products with sustainability [26]. Sustainability requires a delicate balance of choices. Therefore, sustainable denim designs represent an apparel product which is fashion oriented, performance based; and environmental friendly. Therefore, sustainable denim apparel refers to eco-friendly, fashionable, aesthetic, durable and high wear performance apparel, based on customers’ choice. Sustainable practices are growing in the apparel washing industry. In denim washing industry, bleaches are commonly used with other chemicals. Most of the cases, textile and apparel manufacturers are using traditional hydrogen peroxides and hypochlorite bleaches in processing textile and denim apparels, which has more or less negative-impact in the environment. Enzymatic washing and stone-enzyme washing processes are now popular and increasing its use in textile and apparel washing industry, because it is eco-friendly, support the green chemistry and safe for the environment.

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In the textile and apparel industries, the concepts of sustainable washing for denim apparel explore to the enzymatic washing and stone-enzyme washing processes which can be used to develop sustainable denim designs.

1.4. Literature Review In the last few years, the popularity of denim apparel washing has been increased and many researchers have investigated the effect of the washing for denim apparels. Some important works of various washes on denim apparels are presented below.

Enzymatic Treatment in Denim Apparel Washing The study of enzymatic washing on denim apparel is important for physical, aesthetical and environmental point of view. Denim apparel manufactures have washed their apparels for many years with chemicals to achieve a soft-hand as well as desirable washing effects. Indigo-dyed denim apparel is the most popular for youth [27]. Therefore, the properties of denim apparels have been widely studied due to its fundamental importance and its many applications in current fashion trends. The existing literature in this domain has focused considerable attention with enzymatic washing for denim apparels. The use of environmentally friendly, nontoxic, fully biodegradable enzymes have been using in the modern textile wet process industries for decades. Enzymes are produced by living organism and one kind of protein that is obtained from fermentations method from naturally existing bacteria and fungi and attack to a specific molecular group. Structurally, enzyme is a biological polymer. Cellulases are enzymes and commonly used in textile industry. According to their amino acid sequences, it consists of either a catalytic domain (CD), or a cellulose-binding domain (CBD) or both domains [28]. Most of the cellulases used in the denim washing are fungal (with a CBD of family I, cellulose-binding domain) [29]. CavacoPaulo et al. [30] reported that the cellulases used in the denim washing industry have CBDs from family I (30-36 amino acids, i.e., fungal cellulases from Trichoderma ressei and Humicola insolens), whereas CBDs of cellumonas fimi bacteria belong to family II (103-146 amino acids). Commercially, there are mainly two kinds of cellulase being used for denim washing, namely acid cellulose and neutral cellulase. Acid cellulases are more aggressive on cotton [31]. Cellulase hydrolyses the cellulose, yielding long chain cellulose polymer to a short-chain polysaccharides and glucose. The enzymatic action also loosens the indigo dye, which is more easily removed by the mechanical abrasion of rotating cylinder washing machine. Cellulases are inducible enzymes synthesized only in the presence of cellulosic materials or other appropriate inducers [32-36]. Today approximately 80% denim apparels are treated with cellulase enzymes [37]. Cavaco-Paulo [38] reported that desizing with amylases was the first applications of enzymes in textile industry [38]. Enzymatic treatment with amylase enzymes has replaced the harsh processes since the beginning of the last century [39]. Many commercial α-amylases are available now and it is estimated that approximately 15% of all commercial textile enzymes are used in desizing processes [40]. In order to prevent the yarn breaking during weaving, warp yarns are sized with starch and its derivatives. The starch is a natural, biodegradable, and a mixture of two polysaccharides, amylase and amylopectin consisting mainly of α-1, 4-linked glucose units [41].

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Cavaco-Paulo et al. [30, 42] carried out a series of studies to investigate the washing effects of denim garments by cellulase treatment. From their studies reported that cellulases are most successful in producing the stone-washed look denim apparels with modified appearance. Aged/old looked denim with cellulase is the non-homogeneous removal of dye, giving the fashionable contrast of various blue shades. Cavaco-Paulo [43] reported that cellulases are always applied in washing processes where strong mechanical action on the fabric is provided. As a result, the weight and strength loss increased. Nevell [44] reported that, the primary wall of cotton contains waxes, proteins, lipids, pectins, organic acids and noncellulosic polysaccharides constituting up to 10% of the total fiber weight and by washing the fiber loss weight mostly. The secondary wall contains a mature fiber and consists almost entirely of fibrils of cellulose arranged spirally around the fiber axis [45] and by enzymatic washing the fibrils of cellulose in secondary wall is slightly disoriented and partly damaged and strength is lost and softens apparels are produced. Cavaco-Paulo et al. [30] explained that the slow kinetics of enzymatic degradation of crystalline cellulose improves fabric and fiber properties (remove fuzz fibers) without excessive damage. Mori et al. [46] showed that cellulase treatment improves the handle of cotton fabric. They found that the primary wall of the cotton fiber is eliminated in the initial step of hydrolysis; as a result a reduction in the fineness of the cotton fibers takes place. They also suggested that enzymatic hydrolysis occurs in the secondary wall of the cotton fibers, even during the initial step of hydrolysis so that cotton fabric becomes soft and loses strength. Also, Walker and Wilson [47], Pedersen et al. [48], Duran and Marcela [5] studied cellulase on cotton and found that cellulase improves fabric hand and enhance aesthetic properties. Similar, many studies of cellulase applications on textiles and the properties of cotton fabrics were reported by Buschle-Diller et al. [49] and Radhakrishnaiah et al. [50]. Heikinheimo et al. [8] reported that cellulases are introduced to replace aggressive chlorine bleach in textile industry.

Pumice Stone in Denim Apparel Washing The fundamental problem of enzyme in denim wash has received considerable attention from researchers. Such a problem is usually overcome by stone wash. A few but some important studies of the stone washes are given below. Pumice stone is generally used on the denim apparel to achieve a soft handle as well as a desirable bleached-out character. In denim washing, pumice stones are mixed with enzymatic processes to obtain irregular, nice stone-wash look effects. The surface of pumice stone is rough, irregular, light weight and perforated and floats on water during washing in machine. The use of stone makes brushing action on the apparel surface; as a result irregular color fading effect is produced rapidly. But stone wash causes processing and equipment problems. The main disadvantages of stone washing are the difficulty of removing residual pumice from processed clothing items and the damage to the equipment by the overload of tumbling stones [51]. In spite of these disadvantages, pumice stone is still used in denim washing industries and researchers using certain researches with pumice stones [52]. Pumice stones combined with cellulases cause the desired fading and softening of the apparel [53]. They concluded that mechanical action by pumice stone opens the outermost layers in secondary cell of cellulosic crystals, thus increasing the part of the cellulose accessible to enzymes and enhancing enzymatic removal of the dye in presence of pumice stone. Again, pumice stone with cellulases reduces time in washing process [54].

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High levels of mechanical friction with pumice stone will produce strong mechanical abrasion of yarn surfaces, releasing the indigo dye quickly and produced the stone-wash effect [30, 42]. Feki et al. [55] examined the effect of stone-washing on denim garments and evaluated compressibility, bending rigidity, shear rigidity and breaking work, but they did not worked on the other properties like water absorption, elongation at break, tensile strength and color fading.

1.5. Motivation From the literature review it is clear that very little investigational study have been carried out on the effect of chemicals in denim apparel washing. The study of denim apparel washing with sustainable designs is important for the apparel designers and manufacturers and is the new challenge in the fast changing current trends. The consumer’s has interest now in eco-fashion. To apply a system as an effective wash method for denim with chemicals is important. Thus to produce specific washing effect, considering sustainability, the analysis of the effect of parameters in denim washing is necessary. Previously, majority of the studies on denim apparels were carried out with dry processes. Thus, so far, none have conducted studies involving the effect of chemical wash for producing sustainable denim apparels, although denim is very popular apparel. Therefore, from the buyer’s point of view, consumers are concern now on sustainable denim designs, which forms the basis of the motivation behind the present study.

1.6. Present Problems Previously no work has been reported on denim apparel washing considering sustainability. The present study is an investigation with the best value for the purpose of sustainable designs production. In the present investigation, two different types of washes are considered. One is cellulase washing with various concentrations, temperatures and times in a fixed amount of washing liquor. Second one is cellulase with pumice stone in denim garment washing with various concentrations of pumice stones, temperatures and times. The proposed studies are expected to reveal that the denim performance in such washings are very much important from those studied in the above literature and it will therefore prove useful from the manufacturer’s and designer’s point of view in choosing the best that suit them.

1.7. Objectives The aim of this work was to define the optimum conditions for washing of denim readymade apparels in order to achieve the desired finishing effects with minimum negative impacts in environment and properties. However, the specific aims of the study were: ● ●

To investigate the chemical effects and the mechanisms of these effects on denim apparel washing. To study the effects of different cellulases on denim apparel properties.

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan ● ● ●

To describe how to produce a sustainable denim apparel. To develop a dynamic washing method for denim apparels. To carry out the validation of the present wash methods for denim washing includes enzyme wash, and stone-enzyme wash.

To find out the best washing conditions with specifications for washing denim apparel with enzyme and /or stone-enzyme that will develop existing method and new dynamic method will be introduced.

2. EXPERIMENTAL DETAILS 2.1. Materials The denim apparel and chemicals used in these experiments are listed as:

2.1.1. Denim Apparel Fabric: All fabric used in this investigation was of 100% cotton twill weave (3/1 LHT. 381 g/m2) denim, manufactured in a Textile mill in Bangladesh. Apparel: Denim apparels (trouser) were manufactured using the stated denim fabric. The denim apparel used in these experiments is shown in Figure 2.1 and a summary of the denim fabric properties is listed in Table 2.1.

Figure 2.1. A portion of denim apparel used.

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Table 2.1. Properties of the denim fabric used Property Material Warp count, weft count EPI, PPI Weight (g/m2) Weave Type of dyestuff Tensile strength-warp (kg-f) Tensile strength-weft (kg-f) Elongation-warp (%) Elongation-weft (%) Dimensional stability (%)

Denim fabric 100% Cotton 10 Ne, 9 Ne 70, 42 381 3/1 LHT Indigo 246 137 24 16 2.25

Table 2.2. Properties of the pumice stone used Property Material /composition Size (cm) Surface Color Nature Weight (g/pc) Source Origin

Specifications SiO2 73.14%, Al2O3 12.36%, Fe2O3 1.38%, Na2O 3.79%, K2O 2.7%, MgO 0.13%, CaO 0.88%, FeO 0.66%, TiO2 0.1%, others-rest 4-5 Rough White-slightly Perforated, water floated Light (10-12) Volcanic explosion Turkey

2.1.2. Cellulase Enzyme Two different natures of cellulase enzymes, acid cellulase (Genzyme SL, Multichemi Ltd, Sri Lanka) and neutral cellulase (Bactosol JCP, Clariant Ltd, Swizerland) were used. In addition, mixtures of acid and neutral cellulases 50/50 were also used. The cellulases are biochemical substance that behaves as a catalyst toward specific reactions. According to manufacturer, the activity of enzymes; acid enzyme- pH 4.5-5.5, temp 45-650C; neutral enzyme- pH 6.0-7.0, temp 40-550C. In washing, the enzymes break some of the fibers on the surface and hence give the fabric a soft, faded and old look effect. The cellulose loosens the indigo dye and fading effect is produced rapidly during washing. 2.1.3. Pumice Stone Fresh pumice stones were used for the treatments of stone-enzyme washing. The stones are available in three sizes i.e., small (2-3 cm), medium (4-5 cm) and large (5-7 cm). Medium size stone was used for the experiments. These stones are perforated, rough surface, light weight and floats on water. The pumice stone used in these experiments is shown in Figure 2.2. A summary of the pumice stone properties is listed in Table 2.2.

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Figure 2.2. Pumice stone used in the experiments.

2.2. Methods Following processes have been used to perform washing. These are as follows –

2.2.1. Desizing The desizing was conducted in liquor containing Hostapur WCTH 0.6 g/L (a detergent, BASF, Germany), Luzyme FR-HP 1.2 g/L (a desizing agent, BASF, Germany), AntistainLP30 0.4 g/L (an anti-back staining agent, GDS, India) and material to liquor ratio of 1:10 in an industrial horizontal sample washing machine (model-NS 2205, Ngai Shing, Hong Kong) at temperature 60°C for 20 min in order to remove the size materials of warp yarns which was applied in fabric manufacturing to reduce yarn breakage. After that washed with hot water at 70°C, followed by cold water wash at 25°C. 2.2.2. Washing Desized denim trousers were treated with chemicals (depends on wash type) in a sample washing machine at different concentrations of chemicals, temperatures and times using the enzyme and stone-enzyme washing methods followed by the standard washing procedure. All treatments were involved in a rotary cylindrical washing machine at 30 rpm. 2.2.3. Hydro-Extracting Process Chemically processed denim trousers were squeezed in a laboratory scale hydro-extractor machine (Roaches, England) to remove excess water from the apparels at 200 rpm for 4 min. The hydro-extracting machine is shown in Figure 2.4.

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Figure 2.3. Industrial sample washing machine.

Figure 2.4. The hydro-extracting machine.

2.2.4. Drying Process The hydro-extracted denim trousers were dried in a steam tumble drier (Opti-Dry, England) at 75°C for 40 min. Treated denim apparels were then evaluated by characterizing of their physical and mechanical properties. The drying machine is shown in Figure 2.5.

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Figure 2.5. The tumble drying machine.

2.3. Analysis Various instruments and machines are used to determine physical and mechanical properties of denim apparels. The fabric analyses carried out during this study are listed in Table 2.3.

2.3.1. Measurement of Tensile Strength and Elongation at Break Tensile strength and elongation at break of denim samples were carried out using a horizontal (Goodbrand, UK) tensile strength tester according to ASTM D 5034 Grab test method [56]. Tensile strength and elongation were measured in the warp and weft directions in treated samples. The Grab test uses two jaws. The specimens are cut to a size of 5 in wide and 10 in long and then frayed down in the width 4 in (10 cm). The sample is then placed between the jaws and set the distance 6 in (15 cm) between the jaws, then pulled away from other. The sample is broken in 20 ± 3sec. At the point of break, tensile force was taken from the dial and at the same time the value of elongation was taken from the attached scale in the machine. The force and elongation at this point are noted. Any breaks that occur within 1 cm of the jaws should be rejected. The mean breaking force and mean extension as a percentage of initial length are reported. 2.3.2. Measurement of Weight Loss Fabric weight loss of treated denim samples was measured after conditioning for 24 h at 200C and 65% RH (ASTM D 1776) [57] with a standard cutter and digital balance according to ASTM D 3776 [58].

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The weight loss (%) was calculated from the difference in fabric weight (grams/square meter) before and after the chemical treatments. The apparatus used for weight loss measurement consists of a circular cutter with a rubber board and a digital balance. First apparel was placed on a flat table and using scissor fabric is cut 12 x 12 in. Then placed on rubber board and fabric was cut by circular cutter (dia. 10.1 cm) and then kept the cut sample on digital balance and taken weight. The weight loss was calculated as percentage using the weight of untreated and treated samples.

2.3.3. Measurement of Color Change The effects of the chemical treatments on denim apparel color were evaluated by estimating the color change value with an AATCC Gray scale to color change according to AATCC Evaluation Procedure 1 [59]. According to this standard, the changes in the color of the fabric being tested, that is color fading. A numerical assessment of each effect is made by comparing the changes with standard Gray scale to color change. The visual difference between the original and treated denim fabric is compared with the differences represented by the Gray scale. The difference in the color change is given a numerical value ranging from 5 to 1. Class 5 indicates no change in the original color/shade. Class 1 indicates a noticeable change in color/shade. Gray scale for color change consists of nine pairs of standard gray chips, each corresponds a difference in color/shade corresponding to a numerical color change rating. In order to evaluate color change rating, the specimen was cut from the untreated denim trouser. Then another specimen was cut from the chemically treated denim trouser and these two specimens were placed side by side in the same plane and compare with the Gray scale. 2.3.4. Measurement of Fabric Stiffness In order to determine the fabric stiffness for this study, a stiffness test were conducted and measured the bending length of denim samples by Shirley stiffness tester according to BS 3356 [60] at 200C and 65% RH. The higher the bending length, the stiffer is the fabric. To measure the bending length a horizontal strip of fabric as specimen was cut to a size of 1 in wide and 6 in long. The fabric sample was then placed under a template. When the tip of the specimen reaches a plane inclined at 41.50 below the horizontal, the overhanging length was then observed in centimeters directly from the Shirley apparatus. The bending length is dependent on the weight of the fabric and its flexibility. 2.3.5. Measurement of Water Absorption The effects of the chemical treatments on water absorption (rate of uptake) of denim fabric were measured according to BS 3449 [61]. The water absorption (%) was calculated from the difference in water absorbed before and after the chemical treatments. The static immersion test was used for measuring the total amount of water that a fabric will absorb. In the test weighted samples of the fabric were immersed in water for a given length of time (20 min), taken out and the excess water removed by shaking. They were then weighted again and the weight of water absorbed was calculated as a percentage of the dry weight of the fabric. The specimens were cut to a size of 80 x 80 mm at 450 to the warp direction. Then the samples was conditioned and was taken weight each sample. The samples were then immersed in distilled water at a temperature of 20 ± 10C to a depth of 10 cm.

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A sinker was used to hold the specimen at the required depth. In this position the samples were left for 20 min. After that the samples were taken from the water and the surface water was removed immediately by shaking them ten times. Then the samples were reweighted and mean percentage absorption is calculated from the formula: Absorption = mass of water absorbed / original mass of fabric x 100%

2.3.6. SEM Analysis Scanning Electronic Microscopy photographs (SEM) were obtained of the chemically treated denim samples and monitored surface appearance and morphological value. The scanning electronic microscope (model-S 3400N, Hitachi, Japan) used in this experiment is shown in Figure 2.6. 2.3.7. FM Analysis Fluorescence Microscopy photographs (FM) were obtained from the chemically treated denim samples and analyzed physical changes of yarns in fabrics. The fluorescence microscope (model- IX71, Olympus, Japan) used in this experiment is shown in Figure 2.7.

3. RESULTS AND DISCUSSION 3.1. Effects of Cellulase Enzyme Concentration In this experiment, enzymatic treatment of denim apparels with acid, neutral and mixture of acid and neutral cellulases was performed in the washing machine under the concentrations of 0.5, 1.0, 2.0, 3.0 and 3.5% (owg).

Figure 2.6. The view of scanning electronic microscope.

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Figure 2.7. The view of fluorescence microscope.

Table 2.3. Analyses used for denim sample Analysis Tensile strength Stiffness Color change Weight Water absorption Microscopy Microscopy

Method used Grab test Bending length Gray scale Dry weight, conditioning Static immersion test SEM FM

Ref. ASTM D 5034 BS 3356 AATCC Evaluation 1 ASTM D 3776 BS 3449

The cellulase enzyme hydrolyse cellulose and allowing changes on color and fiber polymer chain which affects on the fabric properties. The effect of cellulase enzymes with various concentrations of 0.5-3.5% on the properties of denim apparels in terms of tensile strength, stiffness, color fading, weight and water absorption was determined and is shown in Tables 3.1-3.4. From these Tables 3.1-3.4, it can clearly be understood the washing effects from the each others. Tensile strength is the measure of the breaking force of the fabric which affects fabric mechanical property. The tensile strength evolution after enzyme washing with various concentrations can be seen in Table 3.1. On washing at various concentrations of cellulase enzymes the tensile strength decreased due to the cellulose hydrolysis by enzymes. As a result, the warp and weft both yarns in the fabric are affected by enzyme and the weft yarns are more affected in its strength than warp due to the undyed weft yarns are more hydrolysed by enzyme.

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan

It can be seen from Table 3.1 that, at low concentration (0.5%) of enzyme, 6.5%, 5.6% and 5.0% strength losses were observed in warp direction when the apparels were treated with acid, neutral and mixed enzymes; and 22.7%, 19.5% and 18.5% strength losses, respectively were observed with higher enzyme concentrations (upto 3.5%). Whereas, 11.0%, 8.8% and 8.0% strength loss and 33.0%, 30.8, and 28.6% strength losses were observed in weft respectively. The decrease in tensile strength at 0.5 to 3.5% was higher with acid cellulase than neutral cellulose due to the different amino acid compositions of acid and neutral celluloses. Campos et al. [62] reported that differences in amino acid residues of acid and neutral cellulases seem to be the main reason for their hydrolysis behavior to cellulose. Hydrolysis of cellulose would certainly affect fabric tensile strength. Cavaco-Paulo et al. [42] investigated that during dyeing the insoluble indigo is known to form agglomerates in aqueous solutions and these indigo molecules bind on warp yarn surface. As a result, in denim washing, firstly indigo agglomerates are fractioned into smaller particle with cellulases, and then hydrolyse the cotton yarn/cellulose. On the other hand, cellulases directly hydrolyse the undyed weft yarns. This seems to be the main reason for high strength loss in undyed weft than colored warp. Buchert and Heikinheimo [37] and Kleman-Leyer et al. [63] have previously been obtained similar results for tensile strength with undyed cotton cellulose. Table 3.1. Effect of enzyme washing with different concentrations of cellulase on the tensile strength of denim apparel in warp and weft directions

Cellulase conc. (%) 0.0 0.5 1.0 2.0 3.0 3.5

Loss in tensile strength in warp direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 6.5 5.6 5.0 10.5 8.9 8.5 16.6 13.4 12.6 22.7 17.0 16.6 22.7 19.5 18.5

Loss in tensile strength in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 11.0 8.8 8.0 13.9 11.7 11.0 22.0 21.3 19.1 28.6 27.2 26.4 33.0 30.8 28.6

Table 3.2. Effect of enzyme washing with different concentrations of cellulase on the fabric weight and color shade of denim apparel in warp and weft directions Cellulase conc. (%) 0.0 0.5 1.0 2.0 3.0 3.5

Fabric weight loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 1.6 1.4 1.1 2.9 2.4 2.5 3.4 3.3 3.2 4.2 3.7 3.4 4.5 4.2 3.7

Color shade loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 10 10 10 20 10 20 30 20 30 40 30 30 40 30 40

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Table 3.3. Effect of enzyme washing with different concentrations of cellulase on the stiffness of denim apparel in warp and weft directions Cellulase conc. (%) 0.0 0.5 1.0 2.0 3.0 3.5

Stiffness loss in warp direction,(%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 28.9 22.2 22.2 31.1 28.9 28.9 44.0 43.1 43.1 44.7 43.3 43.1 44.9 44.0 43.1

Stiffness loss in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 6.2 6.2 6.2 9.3 9.3 6.2 15.6 12.5 12.5 18.7 15.6 12.5 18.7 15.6 12.5

Table 3.4. Effect of enzyme washing with different concentrations of cellulase on the water absorption of denim apparel Cellulase conc. (%) 0.0 0.5 1.0 2.0 3.0 3.5

Acid enzyme 0 15.1 19.1 23.0 23.8 23.8

Water absorption, (%) Neutral enzyme 0 17.5 20.6 21.4 23.0 23.0

Mixed enzyme 0 16.7 20.6 23.8 25.4 25.4

It is seen from Table 3.2 that, treatment of denim garments under investigation with acid, neutral and mixed cellulase decreased the weight loss and this decrease is little bit higher at higher enzyme concentrations up to 3.5%. The main reason of weight losses is the hydrolysis behavior to cellulose by enzymes. With higher enzyme concentration the rate of hydrolysis increased and weight loss is increased. During washing, acid and neutral both cellulases are hydrolysed cotton. First, it attacked on projecting fibers (micro-fibrils) on surface, then attacked on yarn portion, hydrolyzed them slowly and penetrated inside the fabric. As a result, fibers are hydrolysed and broken down quicker with the friction of rotating cylinder of the washing machine. Hydrolysis of cellulose would certainly affect fabric weight losses in washing process. Table 3.2 shows that acid cellulase caused up to 4.5% weight loss, neutral cellulase up to 4.2% loss and mixed cellulase up to 3.7% loss at the concentrations of 3.5%.. It is observed that the weight loss decreased more in acid enzyme than neutral enzyme, and weight loss is less when denim apparel washed with mixed enzymes. Again, denim hydrolysis was measured by monitoring the color shade change. It can be seen from the Table 3.2 that the color shade decreased with higher concentrations from 0.5% to 3.0%. The color shade is not decreased more, with the increasing of concentration from 3.0 to 3.5%. In enzyme washing, the part of the primary wall of indigo-dyed denim apparel is always in contact with cellulase. At the contact point, the surface dyes are partly detached from the main fiber chain and indigo dye bonds are broken from the yarn surface. As a result, the treated denim apparel becomes duller and color is faded. In addition, mechanical friction inside washing machine accelerate cellulose hydrolyses and destroy color.

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan

Grieve et al. (2006) has previously been obtained similar result for color fading of denim apparels. The results disclose that increasing the cellulase concentration from 0.5 to 3.0% has effect on color fading and from 3.0 to 3.5% has no effect on color shade change, because most indigo agglomerates are fractioned into smaller particle at 3.0% cellulase concentration, and with increased concentration up to 3.5% cellulases, remaining indigo agglomerates are not fractioned into smaller particle, as a result color will not fade further. It can be seen from the Table that acid cellulase caused 10 - 40% color loss, neutral cellulase 10 - 30% loss and mixed cellulase caused 10 - 40% loss. It is observed that the decrease in color shade at 3.5% was higher with acid cellulase than neutral cellulose. This means that indigo color fading also depends on the nature of cellulase enzymes with increasing cellulose concentrations. It can be seen from the Table 3.3 that the stiffness of denim apparels decreased after they were exposed to acid, neutral, and mixed enzymes at concentrations of 0.5 - 3.5%. After treatments, the starch of warp yarns are removed first, then it hydrolyzed cellulose similar to color fading mechanism by cellulases discussed earlier. As a result, bending length was less and stiffness decreased in comparison to untreated denim for all the three cases. The decrease in stiffness at concentrations of 0.5 to 3.5% was higher with acid cellulase than neutral cellulase. Cavaco-Paulo et al. [42] investigated that acid cellulases have a higher affinity for indigo than neutral cellulases. Thus, more hydrolyses occurred by acid cellulase and stiffness decreased. It can be seen from the Table that acid cellulase caused 28.9-44.9%, neutral cellulase 22.2-44.0% and mixed cellulase caused 22.2-43.1% stiffness loss in warp direction and 6.2-18.7%, 6.2-15.6%, 6.2-12.5% respectively in weft direction. Water absorption is the measure of the level of water in the denim apparel which affects fabric properties. Table 3.4 shows the changes in water absorption with the increasing of concentration of cellulases from 0.5-3.5% in denim washing, due to the loosening of surface fibers by enzymatic treatment. The loosening of surface fibers would certainly affect fabric water absorption. From the Table it can be seen that, the water absorption increased 15.1-23.8% at 0.5-3.0% concentration with acid cellulase, 17.5-23.0% with neutral enzyme, and 16.7-25.4% with mixed cellulase, and does not cause any further increase of water absorption when the concentration increased from 3.0 to 3.5%. With increased water absorption, the denim apparel shows increased water vapor permeability that means comfortness or softness increased. Therefore, there is a strong relationship between water absorption and fabric comfortness and softness; which affects the properties of denim apparels.

3.2. Effect of Temperature in Cellulase Enzyme Treatment of denim apparels with acid, neutral and mixed cellulase was performed under the influence of 40, 50, 55, 60 and 65 °C. The onset of temperature on loss in tensile strength, stiffness, color fading and fabric weight, and gain in water absorption is shown in Tables. The changed /modified value of different physico-mechanical properties of acid, neutral, and mixrd cellulases treated denim apparels against the effect of various temperatures are listed in Tables 3.5 - 3.8. Enzyme washing with the effect of temperatures on the strength properties of denim apparels was measured and is shown in Table 3.5. The effect of temperature at 400C had practically little effect on the strength properties of denim apparels (6.5-9.3% loss in warp and 11.0-13.2% loss in weft direction); those at the highest temperature of 650C big effects on tensile strength (21.5-22.7% in warp and 27.2-30.1% in weft direction) were observed.

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Table 3.5. Effect of enzyme washing with different temperatures of cellulase on the tensile strength of denim apparel in warp and weft directions

Temp. (oC) 0.0 40 50 55 60 65

Loss in tensile strength in warp direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 9.3 6.5 8.1 13.4 12.1 9.7 16.6 13.4 12.6 21.5 17.8 17.4 22.7 21.5 22.3

Loss in tensile strength in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 13.2 11.0 11.7 19.1 16.1 14.7 22.0 21.3 19.1 27.9 22.7 25.0 30.1 27.9 27.2

Table 3.6. Effect of enzyme washing with different temperatures of cellulase on the fabric weight and color shade of denim apparel in warp and weft directions

Temp. (oC) 0.0 40 50 55 60 65

Fabric weight loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 2.3 1.8 1.8 2.8 2.3 2.3 3.4 3.3 3.2 4.9 4.4 4.4 5.5 4.5 4.4

Color shade loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 10 10 10 20 10 20 30 20 30 40 30 30 40 40 40

However, by increasing the temperature upto 650C, 22.7% loss in strength in warp and 30.1% loss in weft direction by acid enzyme was obtained, whereas 21.5% loss in warp and 27.9% loss in weft by neutral enzyme, and 22.35 loss in warp and 27.2% loss in weft by mixed enzymes was obtained. From the Table 3.5, it is observed that decrease in tensile strength at 40 to 650C was higher with acid cellulase than neutral cellulase. This is occurred, due to more fiber degradation with raising temperature in cellulose washing with acid enzyme than neutral and mixed enzymes. Table 3.6 shows the decreases in weight of fabric with the increasing of temperature from 40 to 650C. This is due to the removal of projecting fuzz fibers from the fabric surface with the effect of temperature. With higher temperature, at 650C, the weight loss was higher for the acid enzyme (5.5%) than for the neutral (4.5%) and mixed enzyme treated (4.4%) denim apparels. It can be seen from the Table that acid cellulase caused 2.3-5.5% weight loss, neutral cellulase caused 1.84.5% loss and mixed cellulase caused 1.8-4.4% loss. The effect of temperature on color fading was monitored and also shown in the same Table. It can be seen from the Table 3.6 that the denim apparel washing with acid, neutral, and mixed enzymes decreased the color shade with the increase of temperature from 40 to 650C. From the Table, it is observed that the decreases in color shade from 40 to 600C was higher for the acid enzyme (40%) than for the neutral enzyme (30%). In cellulase washing, raising

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan

the temperature enhanced the color fading quicker, due to more hydrolysis of cellulose by the effect of temperature. The effect of temperature on stiffness was monitored. It can be seen from the Table 3.7 that the decreases in stiffness of denim apparel with the increasing of temperature from 40 to 650C. From the Table 3.7, it is observed that the decreases in stiffness from 40 to 650C were higher for the mixed enzyme (45.3%) in warp direction than for the acid (44.8%) and the neutral enzymes (44.4%), whereas, the decreases in stiffness from 40 to 650C were almost similar in weft direction for the acid enzyme (15.6%), neutral enzyme (15.6%) and the mixed enzymes (15.6%). In cellulase washing, raising the temperature decreases the stiffness, due to more hydrolysis of cellulose. Table 3.8 shows enzyme washing at 400C caused increase in water absorption to 13.4%, 15.1% and 15.8% for acid, neutral and mixed enzymes respectively and the increase was higher at higher temperature up to 650C. After enzyme treatment, the water absorption increased to 26.1% at 600C by the mixed enzyme, 24.6% with neutral enzyme and 23.8% with acid. Therefore, the mixture of acid and neutral enzymes is the most effective enzyme to increase water absorption when washing was performed at 600C. The water absorption does not cause further increase when temperature increased from 60 to 65°C in all the three cases. Table 3.7. Effect of enzyme washing with different temperatures of cellulase on the stiffness of denim apparel in warp and weft directions

o

Temp. ( C) 0.0 40 50 55 60 65

Stiffness loss in warp direction,(%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 33.3 31.1 28.8 38.2 37.7 36.8 44.0 43.1 43.1 44.7 44.4 44.8 44.8 44.4 45.3

Stiffness loss in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 6.2 3.1 3.1 12.5 9.3 6.2 15.6 12.5 12.5 15.6 15.6 15.6 15.6 15.6 15.6

Table 3.8. Effect of enzyme washing with different temperatures of cellulase on the water absorption of denim apparel Temp. (oC) 0.0 40 50 55 60 65

Acid enzyme 0 13.4 15.8 23.0 23.8 23.8

Water absorption, (%) Neutral enzyme 0 15.1 15.8 21.4 24.6 24.6

Mixed enzyme 0 15.8 19.8 23.8 26.1 26.1

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3.3. Effects of Time in Cellulase Enzyme Treatment of denim apparels with acid, neutral and mixed cellulase was performed under the influence of treatment time 20, 30, 40, 50 and 60 min. The onset of time on loss in tensile strength, stiffness, color fading, fabric weight and gain in water absorption is shown in Tables 3.9 - 3.12. It can be seen from the Table 3.9 that the decreases in tensile strength of denim apparel decreases with the increase of washing time from 20 to 60 min. From the Table 3.9, it is observed that the decrease in tensile strength from 20 to 60 min are higher for the acid enzyme (22.7% in warp direction) than for the neutral enzyme (21.9%) and for the mixed enzyme (44.4%), whereas, the decrease in tensile strength in weft direction are 30.1%, 27.2% and 25.2% respectively. Table 3.9. Effect of enzyme washing with different times of cellulase on the tensile strength of denim apparel in warp and weft directions

Time (min) 0.0 20 30 40 50 60

Loss in tensile strength in warp direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 9.3 8.9 8.9 13.4 12.1 11.3 16.6 13.4 12.6 20.7 18.6 16.6 22.7 21.9 20.7

Loss in tensile strength in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 13.2 11.0 12.5 19.1 14.7 17.6 22.0 21.3 19.1 27.9 26.4 22.7 30.1 27.2 25.2

Table 3.10. Effect of enzyme washing with different times of cellulase on the fabric weight and color shade of denim apparel in warp and weft directions

Time (min) 0.0 20 30 40 50 60

Acid enzyme 0 1.8 2.3 3.4 4.4 5.2

Fabric weight loss, (%) Neutral Mixed enzyme enzyme 0 0 1.0 1.5 1.5 2.0 3.3 3.2 3.6 3.9 4.9 4.0

Acid enzyme 0 10 20 30 30 40

Color shade loss, (%) Neutral Mixed enzyme enzyme 0 0 10 10 10 20 20 30 30 30 40 40

In enzyme washing, raising the washing time decreases the tensile strength, due to more hydrolysis of cellulose with longer time. The decrease in strength mostly occurred with the time between 40 and 60 min. Increasing the time from 20 to 60 min affects on fabric strength as well as the durability of apparels. With increasing time, the loss in tensile strength in weft is higher than warp direction; due to the direct hydrolysis on the undyed weft yarns by

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan

enzymes than colored warp yarns. This seems to be the main reason for high strength loss in weft yarns than warp yarns. Table 3.11. Effect of enzyme washing with different times of cellulase on the stiffness of denim apparel in warp and weft directions

Time (min) 0.0 20 30 40 50 60

Stiffness loss in warp direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 33.3 24.4 33.7 35.7 31.1 36.4 44.0 43.1 43.1 44.5 44.0 44.4 44.8 44.0 44.8

Stiffness loss in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 3.1 3.1 3.1 12.5 9.3 12.5 15.6 12.5 12.5 16.6 15.6 16.0 18.7 15.6 18.7

Table 3.12. Effect of enzyme washing with different times on the water absorption Time (min) 0.0 20 30 40 50 60

Acid enzyme 0 15.0 19.0 23.0 23.8 25.3

Water absorption, (%) Neutral enzyme 0 11.1 15.0 21.4 23.0 24.6

Mixed enzyme 0 17.4 22.2 23.8 26.9 28.5

Table 3.10 shows the decrease in weight of fabric after enzyme washing with the increasing of time from 20 to 60 min. With higher time for 60 min, the weight loss was higher for the acid enzyme (5.2%) than for the neutral enzyme (4.9%) and mixed enzyme (4.0%). It can be seen from the Table 3.10 that the color shade of denim apparel decreases with the increasing washing time from 20 to 60 min. The decrease in color shade from 20 to 40 min were higher for the acid enzyme (30%) than for the neutral enzyme (20%), whereas, with increasing time more than 40 min similar results obtained for all the three cases. The changes in color shade with the increasing of time which affects worn look of denim garments. Table 3.11 shows the decreases in stiffness with the increase of time from 20 to 60 min which affects softness of the denim apparels. Table 3.12 shows the changes in water absorption of denim apparels after washing with acid enzyme, neutral enzyme, and mixed enzyme from 20 to 60 min. Enzyme washing for 20 min caused increases in water absorption of 15.0%, 11.1% and 17.4% for acid, neutral and mixed enzymes respectively and this increase was higher at higher time up to 60 min. The water absorption of denim fabrics treated with mixed enzymes, acid enzyme and neutral enzyme for 60 min are 28.5%, 25.3% and 24.6%, respectively.

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3.4. Effects of Pumice Stone Concentration In this study, mechanical abrasion was achieved by pumice stone in the washing machine. The addition of pumice stone in cellulase treatments accelerates more mechanical abrasion and allowing enzymatic hydrolysis quicker which affects on the fabric properties. Cavaco-Paulo et al. [30] have pointed out the importance of mechanical agitation on cellulose hydrolysis in enzymatic treatments. Liu et al. [64] reported that mechanical agitation depends on rotation speed, liquor ratio, load size and processing time. In this study, stone washing effects in presence of enzyme on fabric properties were determined. A combination of high level of abrasion by pumice stone and enzyme action may generate fibrillar material on the fabric surface reported by CavacoPaulo et al. [30] Pumice stone gives a used look appearance on denim distinctly. In this part of study, mechanical abrasion was achieved by pumice stone in the rotating cylinder of the washing machine at 30 rpm. The effect of pumice stone with various concentrations (10-70%) (owg) on the properties of denim apparels was determined and is shown in Tables 3.13-3.16. Table 3.13. Effect of pumice stone-enzyme washing on the tensile strength of denim apparel in warp and weft directions

Pumice stone, (%) 0.0 10 20 30 40 50 60 70

Loss in tensile strength in warp direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 14.6 9.7 7.3 18.3 14.6 13.0 22.3 17.8 15.8 27.2 24.3 20.7 29.3 25.2 23.5 33.3 26.4 25.2 34.9 30.0 28.4

Loss in tensile strength in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 11.0 11.0 9.5 16.1 14.7 12.5 24.2 22.0 19.8 30.1 29.4 28.6 33.8 31.6 30.8 34.5 33.0 32.3 34.5 33.8 33.8

Table 3.14. Effect of pumice stone-enzyme washing on the fabric weight and color shade of denim apparel Pumice stone, (%) 0.0 10 20 30

Fabric weight loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 2.3 1.8 1.8 3.4 2.6 2.9 4.2 3.4 3.9

Color shade loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0 30 20 10 30 20 20 40 30 40

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan Table 3.14. (Continued)

Pumice stone, (%) 40 50 60 70

Fabric weight loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 4.5 3.9 4.5 4.9 4.5 4.5 5.2 4.9 4.9 5.5 4.9 5.2

Color shade loss, (%) Acid Neutral Mixed enzyme enzyme enzyme 50 40 50 60 50 60 60 60 60 60 60 60

Table 3.15. Effect of pumice stone-enzyme washing on the stiffness of denim apparel in warp and weft directions

0.0

Loss in stiffness in warp direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0

Loss in stiffness in weft direction, (%) Acid Neutral Mixed enzyme enzyme enzyme 0 0 0

10

31.1

28.9

33.3

9.3

6.2

6.2

20

37.7

35.5

40.0

12.5

9.3

12.5

30

44.4

40.0

46.6

15.6

12.5

15.6

40

46.6

44.4

46.6

15.6

12.5

15.6

50

46.6

44.4

46.6

18.7

18.7

18.7

60

48.8

46.6

51.1

18.7

18.7

18.7

70

48.8

48.8

51.1

18.7

18.7

18.7

Pumice stone, (%)

Table 3.16. Effect of pumice stone-enzyme washing on the water absorption of denim apparel Pumice stone, (%) 0.0 10 20 30 40 50 60 70

Acid enzyme 0 15.8 19.8 25.4 26.1 26.9 27.7 27.7

Water absorption, (%) Neutral enzyme 0 17.5 20.6 22.2 23.8 25.4 25.4 25.4

Mixed enzyme 0 16.7 20.6 26.1 26.9 27.7 28.5 28.5

The tensile strength evolution after stone-enzyme washing can be seen in Table 3.13. On washing at various concentrations of pumice stones the tensile strength decreased due to the rubbing action provided by the pumice stones. The weave of the fabric used in this study is a 3/1 twill, so the effect of abrasion is more concentrated on warp yarns than weft yarns. When

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garments are washed with stone, the surface yarns are aggressively affected by the stone rub action thereby underside yarn surfaces can be retained away from the rub directly. As a result, warp yarns are more affected by stone in acid enzyme than neutral and mixed enzymes. When the pumice stone and the mixture enzyme are combined in the washing solution, the fiber’s degradation become more important and causes an intensive increase of hydrolysis, which effects on fabric tensile strength. Klahorst et al. [31] reported that cellulase hydrolyses the cellulose, yielding long chain cellulose polymer to a short chain polymer. The hydrolysis of cellulose link breaks the molecule in several pieces, which decompose fiber, consequently the tensile strength are greatly reduced. It is observed that, at low concentration of pumice stone (10%), the decreases in tensile strength were 14.6%, 9.7% and 7.3% in warp for acid, neutral and mixed enzymes. However, at high concentration of pumice stone (70%), high reduction in strength of denim was obtained for the case of acid enzyme than the neutral and mixed enzyme. The cellulase attacks and mechanical agitation may have caused more damage on the fabric surface by cutting the cellulose chains. Acid enzyme with pumice stone (70%) caused the highest strength loss (34.9%), whereas the neutral enzyme (30%) and mixed enzyme (28.4%) had less effect on the strength properties. In practice such high strength loss values are not acceptable. Table 3.14 shows the impact of pumice stone on the weight loss of denim apparels. High weight loss of 5.5% was obtained with 70% pumice stone for acid enzyme, compared to the weight losses of 4.9% for neutral enzyme and 5.2% for mixed enzyme. Treatments showed that the mechanical action by pumice stone caused higher weight loss of fabric. It can be seen from the Table 3.14 that the color shade decreased after they were treated to acid, neutral, and mixed enzymes at higher pumice stone concentrations particularly from 30 -70%. From the Table 3.14, it can be observed that the decrease in color shade at 10-70% was higher for acid enzyme than for neutral enzyme and pumice stone with acid, neutral, and mixed enzyme caused 10 - 60% color loss. Table 3.15 shows the losses in stiffness of denim garment. It can be seen from the Table 3.15 that pumice stone with acid cellulase caused 31-49% stiffness loss, neutral cellulase caused 29-49% loss and mixed cellulases caused 33-51% loss. The stiffness loss is highest in mixed cellulase than acid and neutral cellulases. From the Table 3.15, it can clearly be differentiated each value from the others due to the differences in amino acid residues in cellulases and abrasion by pumice stone. Table 3.16 shows the effect of pumice stone concentration on water absorption. The water absorption is increased when washing was performed by pumice stone with acid, neutral and mixed cellulases due to the loosening of surface fibers by the abrasion of pumice stones. The water absorption increased approximately 15-26% at 10-30% concentration of pumice stones. Water absorption does not cause any further increase when the pumice stone concentration increased from 50 to 70% for all the three cases.

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Md. Ibrahim H. Mondal and Mashiur Rahman Khan

3.5. SEM Analysis The changes in surface appearance of the denim apparels after enzyme washing and stone-enzyme washing were examined by scanning electron microscope (Model 3400N, Hitachi, Japan). The surface appearances of the untreated denim samples were also examined by SEM. The surface appearances as well as denim apparel properties are affected by enzyme washing and stone-enzyme washing. Figure 3.1 shows the SEM image of untreated cotton denim apparel. The Figure shows parallel ridges and no fibrils (projecting fibers) and ruptures visible in the image, because the yarns are coated with size materials and projecting fibers are not visible on surface. The Figure 3.2 shows the Scanning Electron Microscopy photograph of enzyme treated cotton denim apparel. The enzyme treatment was carried out according to the method described in this chapter with an enzyme concentration of 2.0% (owg) acid cellulase at 550C for 40 min. After enzyme treatment, a clear increase of cracks, disorients and wrinkle surface was observed compare to unwashed sample. Figure 3.3 shows stone-enzyme treated sample and damaged surface in the image are due to fiber degradation by hydrolysis and abrasion by pumice stone in the washing machine during processing. As observed in Figure 3.3 there are more cracks on the surface of fibers. This is caused by cellulase washing of cotton denim garments and pumice stone enhances more cracks on surface.

Figure 3.1. Scanning electron microscopy image of untreated denim sample.

Developing Sustainable Design on Denim Ready-Made Apparels …

Figure 3.2. Scanning electron microscopy image of enzyme treated denim sample.

Figure 3.3. Scanning electron microscopy image of stone-enzyme treated denim sample (hydrolysed and damaged form).

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3.6. FM Analysis Figures 3.5-3.6 shows the changes in physical appearance on the yarn surface of denim apparel after washing with cellulase enzyme and stone-enzyme treatment which were observed by fluorescence microscope (FM) (model IX71, Olympus, Japan). Figure 3.4 shows the FM image of untreated warp yarn.

Figure 3.4. Fluorescence microscopy image of untreated warp yarn.

Figure 3.5. Fluorescence microscopy image of enzyme treated warp yarn.

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Figure 3.6. Fluorescence microscopy image of stone-enzyme treated warp yarn.

As the yarns are dyed and coated with size materials, the surface is smooth and fibrils or projecting fibers are not visible on surface. Figure 3.5 shows the fluorescence microscopy photograph of warp yarn treated with the 2.0% concentration of acid cellulase at 550C for 40 min. It is observed that the yarn surface is somewhat damaged by the action of cellulase enzyme and the extent of damage is increased with the increasing of enzyme concentration. The Figure 3.6 shows the FM photograph of warp yarn of denim fabric treated with 30% pumice stone combined with 2.0% (owg) acid cellulase at 550C for 40 min. It is observed that the yarn surface is highly damaged by the rubbing action of pumice stone and the extent of damage is increased with the increasing of stone concentration in washing.

CONCLUSION An experimental study on the effect of chemicals in denim apparel washing has been studied by enzyme and stone-enzyme treatments. The works reported in this research are basically dependent on parameters namely: (i) chemical concentrations (ii) treatment temperatures (iii) times and (iv) pumice stone concentrations. Cellulase enzymes and pumice stone-enzyme washing are important chemicals in the apparel washing industry for processing denim ready-made apparels. Cellulase enzymes provide an ecological way to treat cotton denim apparels. Although cellulases have been used for biofinishing cotton in textile industry since the 1980s, many varieties of cellulases are still used in textile processes today and recently used in denim washing industries. Pumice stones mixed with cellulases have been used for biostoning denim to get distressed worn look.

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A problem associated with treatments with cellulases and mixtures with pumice stone is that the treated garments exhibit high strength and weight losses. Pumice stones mixed with cellulase enzyme have been used for denim washing to get more worn look appearance. The study has been confined to the modification of denim apparels with chemicals in washing processes. In case of enzymatic treatment the effect of cellulase enzyme on the fabric properties as well as the characteristics of denim apparels in washing process with the introduction of parameters has been determined. In case of enzymatic treatment with pumice stone the effect of pumice stone on the fabric properties as well as the characteristics of denim apparels has also been determined in this research. On the basis of the analysis the following conclusions have been drawn: i)

The results obtained provide new information on the effects of acid, neutral and mixture of acid and neutral cellulases on denim apparels. The use of 2.0g/L mixed cellulase was found to be the most effective in preventing strength and weight loss, determined the most positive results with specific washing effects. In addition, the results obtained with defined cellulase mixtures provided useful knowledge for designing new production. It was also shown that neutral cellulase improves water absorption. Acid cellulase is the most effective at removing color from denim fabrics. Treatment temperature, time and concentrations of cellulase had a major impact on enzymatic treatments. ii) Pumice stone has influence on the properties of denim apparels. The results obtained in enzymatic washing with pumice stone provide new information on the effects of pumice stone in acid, neutral and mixture of acid and neutral cellulases on denim apparels. The use of 30% pumice stone in cellulase washing for all cases was found to be the most effective in preventing strength and weight loss, determined the most positive results with washing effects.

For optimal performance in denim apparel washing, the process parameters should be selected on the basis of fabric type and quality in order to achieve the desired finishing effect with minimum negative impact. Pumice stone in cellulase treatments gives a used look appearance on denim apparel distinctly and the properties of denim fabrics are varied depending on the amount of pumice stone used. It is possible to suggest that any or all of the parameters in both enzyme washing and stone-enzyme washing methods are responsible to damage denim apparel through excessive hydrolysis/unwanted abrasion by pumice stone and changes the values of denim properties. The washing condition should be predetermined for optimum result.

ACKNOWLEDGMENTS One of the authors research work was supported by the NSICT Fellowship under the Ministry of Science, Information and Communication Technology of The People’s Republic of Bangladesh.

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[41] Fornelli, S. (1992). Magic enzymes, product information leaflet. Sandoz Chemicals Ltd, Muttenz-Basel, Switzerland. [42] Cavaco-Paulo, A., Morgado, J., Almeida, L., Kilburn, D. (1998b). Indigo back-staining during cellulase washing. Text. Res. J. 68(6), 398-401. [43] Cavaco-Paulo, A. (1998b). Mechanism of cellulase action in textile processes. Carbohydr. Polym. 37, 273–277. [44] Nevell, T. (1995). Cellulose, structure, properties and behaviour in the dyeing process. In: Cellulose dyeing. Shore, J. (Ed.). Society of Dyers and Colorists 1-26. [45] Hartzell, M. M., Hsieh, Y. L. (1998). Enzymatic scouring to improve cotton fabric wettability. Text. Res. J. 68(4), 233-241. [46] Mori, R., Haga, T., Takagisi, T. (1999). Bending and shear properties of cotton fabrics subjected to cellulase treatment. Text. Res. J. 69(10), 742-746. [47] Walker, L. P., Wilson, D. B. (1991). Enzymatic hydrolysis of cellulose: An overview. Bioresource Technology 36, 3-14. [48] Pederson, G. L., Screws, G. A., Cedroni, D. M. (1992). Biopolishing of cellulosic textile fabrics. Can. Text. J. 109, 301-305. [49] Buschle-Diller, G., Zeronian, S. H., Pan, N., Yoon, M. Y. (1994). Enzymatic hydrolysis of cotton, linen, ramie, and viscose rayon fabrics. Text. Res. J. 61(5), 270-279. [50] Radhakrishnaiah, P., Meng, X., Huang, G., Buschle-Diller, G., Walsh, W. K. (1999). Mechanical agitation of cotton fabrics during enzyme treatment and its effect on tactile properties. Text. Res. J. 69(10), 708-713. [51] Heine, E., Hocker, H. (1995). Enzyme treatments for wool and cotton. Rev. Prog. Coloration. 25, 57-63. [52] Tarhan, M., Sariisik, M. (2009). A comparison among performance characteristics of various denim fading processes. Text. Res. J. 79(4), 301-309. [53] Zeyer, C., Rucker, J. W., Joyce, T. W., Heitmann, J. A. (1994). Enzymatic deinking of cellulose fabric. Textile Chemist and Colorist 26(3), 26-31. [54] Kochavi, D., Videbaek, T., Cadroni, D. (1990). Optimizing processing conditions in enzymatic stone washing. American Dyestuff Reporter 9, 24-28. [55] Feki, I., Ghith, A., Sakli, F. (2004). Effect of stone wash treatment on the denim’s mechanical properties, world textile conference, 4th AUTEX Conference, Roubaix, France. [56] ASTM D 5034 (2001). Standard test method for breaking force and elongation of textile fabrics (Grab test), American Society for Testing and Materials, Annual Book of ASTM Standards, Vol. 07.01., ASTM International, West Conshohocken, PA, US. [57] ASTM D 1776 (2008). Standard practice for conditioning textiles for testing, American Society for Testing and Materials, Annual Book of ASTM Standards, Vol. 07.01., ASTM International, West Conshohocken, PA, US. [58] ASTM D 3776 (1996). Standard test methods for mass per unit area (weight) of woven fabric, American Society for Testing and Materials, Annual book of ASTM Standards, Vol. 07.02., ASTM International, West Conshohocken, PA, US. [59] AATCC evaluation procedure 1 (2007). Gray scale for color change, American Association of Textile Chemists and Colorists, Technical Manual of the AATCC, Research Triangle Park, N.C., US. [60] BS 3356 (1990). Method for determination of bending length and flexural rigidity of fabrics.

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[61] BS 3449 (1990). Testing the resistance of fabrics of water absorption (static immersion test). [62] Campos, R., Cavaco-Paulo, A., Andreaus, J., Gubitz, G. (2000). Indigo-cellulase interactions. Text. Res. J. 70(6), 532-536. [63] Kleman-Leyer, K., Gilkes, N., Miller, R., Kirk, K. (1994). Changes in the molecularsize distribution of insoluble celluloses by the action of recombinant Cellulomonas fimi cellulases. Biochem. J. 302, 463-469. [64] Liu, J., Otto, E., Lange, N., Husain, P., Condon, B., Lund, H. (2000). Selecting cellulases for bio-polishing based on enzyme selectivity and process conditions. Textile Chemist and Colorist and American Dyestuff Reporter 32(5), 30-36.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 3

DIGITAL TEXTILE PRINTING USING COLOR MANAGEMENT Dejana Javoršek*, Primož Weingerl and Marica Starešinič University of Ljubljana, Faculty of Natural Sciences and Engineering, Ljubljana, Slovenia

ABSTRACT The chapter presents the possibilities and a correct procedure for a color management application in the field of digital printing onto textile substrates. The introduction of color management into the field of digital textile printing enables better quality control, faster prepress, reduction in the use of material and better repeatable color prints on textile substrates. Due to the high price of printing colors used in digital textile printing, and the costs connected with the pre- and aftertreatment of printed fabrics, an appropriate preparation of color patterns and simulated prints is of even greater importance. The aim of this chapter is hence to present how long-term and expensive pre- and aftertreatments of textile substrates can be avoided with the help of an appropriate use of printer color profiles for all print devices included in the workflow, e.g., print simulation on paper printed with a laser or inkjet printer. On the basis of simulated prints on paper, a customer can decide on the color that gives the best results on a selected pattern. Digital printing on a textile substrate – a banner made for indoor and outdoor applications, using the color profiles is presented as well. This includes experimental data and the methods for testing the lightfastness and weatherability of the substrate with a Xenotest, and for defining the uniformity of prints – mottling. The method for defining the uniformity of prints is included in the draft of the standard ISO 15311 and is also proposed by the German Printing Association FOGRA. In addition, the importance of the optical brightener used for the improvement of substrate whiteness in digital textile printing is discussed. Furthermore, the calculation of the color inconstancy index CMCCON02 when defining the influence of different illuminants on the color change of substrates is presented. *

Corresponding author: Dejana Javoršek, University of Ljubljana, Faculty of Natural Sciences and Engineering, Snežniška 5, 1000 Ljubljana, Slovenia, E-mail: [email protected].

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Keywords: Color management, ICC profiles, digital textile printing, print simulation, color inconstancy index CMCCON02

INTRODUCTION The technology of digital printing is more and more established [1] in the field of textile printing [2–5] as it allows unlimited color sampling and good durability of prints, as well as in the field of pharmaceutical research [6,7], electronics and micro-engineering industries for printing electronic materials, such as printed circuit boards (PCB) [8, 9] and a humidity sensor directly printed on a textile using the inkjet printing technology [10], and even food decorating uses the digital printing technique as a major working tool. Recently, the inkjet technology has also been successfully applied in the biomedical field [11], where the DNA molecules have been directly printed onto glass slides using commercially available inkjet printers for the high-density DNA microarray fabrication [12], and inkjet printers were used to print cells and biomaterials for 3D cellular scaffolds [13]. In the case of inkjet technology, printing on various substrates is performed by means of non-impact printing or jetting drops of ink on a substrate. The most important component of inkjet technologies is the printing ink alone, which greatly affects the quality and reliability of the output [14]. Thus, in the digital textile printing, various inks that are designed for different needs and requirements are used, including reactive, acid, disperse and pigment dyes [15]. Despite the advantages and widespread use of pigment dyes [16–18], reactive dyes still occupy an important position in the printing of textiles, especially with thermal (bubble) inkjet printers. Reactive dyes are used for the printing on cotton fabrics and their blends, and on linen and silk fabrics. Reactive dyes for the printing with inkjet printers are now widely accessible to everyone yet relatively expensive. Therefore, a number of studies aimed at the improvement of digital printing on cotton with reactive dyes. Yang and Naarani researched the printing of cotton with reactive dyes using the inkjet printer. They studied the impact of matting conditions on the cotton print and how to improve the lightfastness of printed cotton with reactive dyes [19,20]. Digital textile printing with reactive dyes is different from conventional printing, especially: 



in the substrate pretreatment with appropriate chemicals, as ink due to viscosity and stability does not contain chemicals that are necessary for the binding of the dye to fibers, and in the aftertreatment when a chemical bond between the fibers and the reactive dye is formed, resulting in excellent wet fastness of color prints.

A lot of research has been conducted in this area [21–23]. It is known that these two, preand post-processing treatments, are essential as they further influence the change in color tone [24]. Moreover, the dimensional stability of the fabric patterned with the inkjet printer was controlled as well [25]. Weiguo et al. also analyzed the color print on the cationic agent printed cotton with reactive dyes and established that a color print is better on the cotton which was treated with a cationic agent than on the cotton treated with alkali, urea and

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thickener [26], while some other researchers preferred modified chitosan pretreatment of polyester fabric for the printing with inkjet ink where the pretreated fabrics produced a much better color quality than the untreated fabrics [27], and preferred the pretreatments of the silk fabric with amino compounds for the inkjet printing where the amino compound pretreatments held and fixed the additional ink on the fabric surfaces resulting in a wider color gamut of the inks [28]. Kaimouz et al. provided a quantitative insight into the effect of pretreatment chemicals on the color strength, dye fixation and ink penetration on the inkjet printed Lyocell and cotton fibers, using a statistical analysis approach [29]. The trend in small print collections and unique products requires greater flexibility of printing companies and a fast production of color patterns and products. By using graphic programs, the expectations of textile and clothing designers and of small businesses are growing. In most cases, they require that a specific color pattern or color sample presented on paper be exactly reproduced on the textile substrate. However, the path from the model presented on paper to the final product printed on a textile substrate is relatively complex. Problems arise when discrepancies between the color patterns on paper, computer screen and the textile substrate occur. In graphic technology, color management and the use of ICC (International Color Consortium) color profiles ensure a consistent color reproduction throughout the technological process and on all kinds of devices, regardless of the color space, including the original, scanner, digital camera, display screen and color printer. Color management has been used in graphics for a number of years, which is evident from the literature [30–35]. By introducing color management into the field of digital textile printing, the time required for prepress could be shortened and the use of materials could be reduced, which would lower the printing process costs [36]. Due to the high price of printing colors used in the digital textile printing and the costs connected with the pre- and aftertreatment of printed fabrics, an appropriate preparation of color patterns and simulated prints is very important. A print simulation in textile printing can be observed on a screen (i.e., soft proof) or conducted on another printer (i.e., hard proof), which enables – with appropriately built profiles for any device and their correct use – a simulation of particular color patterns on a different output device. In one typical research [36], the linearization and characterization of three printers for paper and textiles, two inkjet and one electrophotographic (“laser”) printer, were implemented. It was demonstrated that an accurate creation of color profiles ensured the top quality of prints and successful hard proof on both laser and inkjet printers. While digital printing has become a link between the traditional and electronic media, the need for an accurate color reproduction is increasing. The users’ expectations have risen, representing new challenges for both, the color reproduction and manufacturers of a variety of substrates. In the textile industry, more and more optical brightening agents (OBA) are used in order to increase the whiteness of a fabric. With the same purpose, they are integrated in detergents, wherein they optically increase the whiteness of washed goods. Nevertheless, the performance of optical brighteners can be the source of incorrect and inaccurate measurements caused by errors in the measurements. In one study, they assessed the impact of the optical brightener in the fabric, before and after the treatment with washing agents [37]. This means that in addition to the initial treatment of the fabric with an optical brightener, the perception of the fabric color and the printed colors is clearly affected by the amount of optical brighteners in detergents that bond with the fabric during the washing process.

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When color profiles for all devices involved in the process of printing (i.e., display screen, printer and printer for hard proof) are generated, it is recommended to test the colors under different illumination, since patterns are usually observed under various light conditions. This can be predicted by calculating the color inconstancy index, which is described below [38, 39]. The quality of prints can be controlled in different ways. One possibility is the calculation of the heterogeneity footprint with the M-Score method [40].

EXPERIMENTAL In our research, three substrates were used:  

textile cotton fabric which was printed with the inkjet printer Mimaki Textile Jet Tx2-1600 (Mimaki, Japan) using 8 reactive dyes [36], and two textile synthetic fabrics, i.e., banner and textile banner made for indoor and outdoor applications, which were printed with Canon Image Prograf W8400.

In the first case [36], we focused on hard proofing, where the matching between the original colors and hard copy simulation of the colors was investigated using the color difference equations ∆E00. The purpose of the researches was to establish whether a print on a textile made with a digital printer produced by Mimaki can be simulated with a print on a paper with an inkjet (Canon Image Prograf W8400, Canon, Japan) and laser (Canon Image Press C1+, Canon, Japan) printer. In the second case, we focused on defining the print quality of presentational posters substrate – banner, using the color difference equations ∆E00. This included experimental data and methods for testing the lightfastness and weatherability of the substrate with a Xenotest Alpha (Atlas, USA), and for defining the uniformity of prints – mottling. The method for defining the uniformity of prints is included in the draft of the standard ISO 15311 and is also proposed by the German Printing Association FOGRA.

Materials The cotton fabric used in the research was provided by Tekstina Plc, Ajdovščina, Slovenia. The basic fabric properties are as follows: raw material: 100% cotton, plain weave, warp thread density: 54 threads/cm, weft thread density: 29 threads/cm, mass per square meter: 130 g/m2, breaking force in warp direction: 38.0 daN, breaking force in weft direction: 26.0 daN, breaking elongation in warp direction: 17.6%, breaking elongation in weft direction: 12.0% and fineness of warp and weft threads: 14 tex. Two textile synthetic substrates, namely the high-impact, highly durable textile substrates were used, i.e., a vinyl banner (in the text called banner) and a textile (in the text called textile) produced in China. The basic fabric properties are as follows: material: PES (polyester), plain weave, Sample 1: mass: 1.1213 g/dm2, thickness: base – 0.180 mm, print – 0.182 mm; Sample 2: material: PES (polyester), mass: 1.9526 g/dm2, thickness: base – 0.321 mm, print – 0.322 mm. Since the substrates were treated with a coating, only warp thread

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density: 23 threads/cm, weft thread density: 30 threads/cm for Sample 1 (cf. Figures 1 and 3) was defined. The analysis performed under a stereomicroscope (Leica EZ 40) and SEM microscope JEOL 6060LV is presented in Figures 1–4.

Figure 1. Sample 1, Print/Base, Leica EZ 40.

Figure 2. Sample 1, SEM microscope JEOL 6060LV.

Figure 3. Sample 2, Print/Base, Leica EZ 40.

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Figure 4. Sample 2, SEM microscope JEOL 6060LV.

Color Measurements After a few days of color stabilization, the measurements with the instrument EyeOne (XRite, USA) were performed. Instead of diffuse geometry, the measurement geometry 45/0 was used, as it is supported by the color management program (Texprint) for digital textile printing. The differences in the color between the original colors (print on inkjet printer Mimaki) and simulated prints (prints on inkjet printer Canon and laser printer Canon), and the differences between the prints made on a banner and textile were calculated with the ∆E00 color differences equation [41]. The color differences between the original colors on a banner and textile, and the colors after the treatment on a Xenotest were calculated using the ∆E00 color differences equation. The results are presented as the calculated average color differences of all samples. All calculations were performed using the program Octave 3.0.0 [42].

LINEARIZATION AND CHARACTERIZATION OF INKJET PRINTER Defining Parameters The first step was to define the substrate type (cotton, linen, blend of cotton and polyester), the number and type of colors, and print quality. Each time, the type of substrate, finishing and colors were changed to create a new color profile. In one research [43], the quality of prints made with the inkjet printer Canon Image Prograf W8400 using two different papers, matt coated and glossy photo paper, was determined. In addition, the impact of Wasatch softRIP settings – draft and high – on the print quality was researched. The software package ProfileMaker 5.0.8 was employed for the creation of the ICC color profiles for both printing quality settings and both papers. The results show that the changes in the RIP printing quality settings (draft vs. high) produced only small differences in prints and when calculating color differences; it can hence be

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concluded that the printing quality parameters, colorimetrically speaking, do not have any special effect on the prints.

Achieving Repeatability and Optimal Color Gamut In the second step, the printer was set to achieve the repeatability and optimal color gamut:

A. Defining Ink Limit of Individual Color The linearization chart (i.e., chart that contains color patches from 0 to 100% area coverage of an individual CMYK color) was made in the ProfileMaker Pro 5.0 Measure Tool (X-Rite, USA) and printed without color management. After the printing, spectral data were measured using the spectrophotometer EyeOne, and the CIELAB and CIELCh values were calculated. The CIELAB values were used to define the ink limit from the a*, b* diagram for CMY (C – cyan, M – magenta and Y – yellow) and from lightness L* in dependence of the area coverage of K (K – key, black ink) expressed in percent, L* (area coverage). An example of the a*, b* diagram is represented in Figure 5. On the a*, b* diagram, the point (percent of the area coverage) where the chromaticity C*ab stops increasing and the color hue hab starts changing was determined, this point defining the ink limit. In the end, the ink limit was set on Wasatch SoftRIP software (RIP – Raster Image Processor). Figure 1 also represents the difference in defining the ink limit on banner and textile substrates. It is evident that a banner could accept more ink than the textile substrate. B. Linearization Afterwards, another linearization chart chosen from the Wasatch SoftRIP software was printed and measured (Wasatch SoftRIP – Setup – Color Properties – Halftone Properties – Calibration – Calibration Curves). After the measuring and final linearization process, the linearization chart was printed and measured once again to ensure that the linearization was performed appropriately. C. Defining Total Ink Limit (TIL) This step included the printing of a chart with black patches printed with all four inks (area coverage 0–400%) and defining the color patch where the ink was not bleeding. In general, this parameter was important when the test chart and the final ICC profile were elaborated.

Creation of Test Chart In the third step, the test chart was made in the program ProfileMaker Pro 5.0 Measure Tool and printed. The views of the professional public about how many patches are required for a quality color description of devices vary; however, mostly there are generic test charts on which the number of patches is related to the chosen type of print quality (draft, medium or high).

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Figure 5. Defining maximum ink limit of cyan, magenta and yellow (above) and black (below).

The number of color patches also depends on the instrument used, since manually measuring of test charts with a large number of color patches is very time consuming. There are frequent speculations about the adequacy of too many color patches on generic color test

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charts, which are used sometimes. The reflection in this direction is also triggered by the fact that the process of the color profile creation is time consuming and expensive, as the creation of the profile for a digital printer generally requires first pre- and then aftertreatments of the textile substrate. At the same time, the digital printing technique, where it is necessary to follow the customer requirements, results in frequent changes of textile substrates, which should be followed by the color profiles. In practice, therefore, for the reasons described above, color management is not yet fully implemented and most printers, instead of proper color profiles for each substrate, use a color profile designed only for one type of textile substrates. Accordingly, optimal results cannot be achieved and printers are only wasting their time by editing colors in one of the programs. This method can be used in the case of very small differences between the base substrate (for which the basic color profile was made) and the new one. In digital inkjet printing, a color test chart can be made, using programs which are payable, e.g., ProfileMaker Pro 5.0 Measure Tool or free open source software, e.g., Argyll CMS by Graeme Gill [44]. Although the creation of a color test chart and later the creation of the ICC color profile using programs bring good results, the possibility to determine the parameters and settings of the program is rather limited. With Argyll CMS, it is possible to change a larger number of these parameters and, in this case, we know for certain, that the algorithm used is OFPS (Optimized Farthest Point Sampling) for the production of the color test chart with the help of which a point in the 4-dimensional space of the device (C, M, Y, K) is allocated so that the distance between two individual points is minimized. The color test charts differ in form, depending on the type of the instrument used for measuring. An example of a color test chart for making the printer profile, made in the program ProfileMaker, is shown in Figure 6.

Figure 6. Example of test chart for printer characterization.

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For a color test chart made in one of the programs that make this possible (Measure Tool, Argyll), we took into consideration the following: 

      

number of colors with CMYK; we can also use other non-processing (spot) colors, e.g., orange, green, blue (in case of additional colors, it is usually necessary to know the CIELAB value), maximum area coverage, GCR (Gray Component Replacement), black max – maximum black (typically 100), black start – start adding black component (usually 10), black width – adding black component in saturated tones, determine the number of fields of color on the color plate and determination of the instrument used to measure the color test chart, as the layout and size of the color patch depend on that.

After the color test chart is created, printing takes place the following day and the measurement with the instrument which was set in its creation.

Figure 7. Comparison of color gamut for banner and textile in CIE a*, b* color diagram.

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Creation of Color Profile In the fourth step, the printed test chart was measured using the spectrophotometer EyeOne and the ICC profile was made using ProfileMaker Pro 5.0. The generated color profile has the extension.icc and contains information about the connection between the color values of the device (in this case the printer), i.e., CMYK, and the color values independent of the device, i.e., CIELAB or CIEXYZ. The appropriately generated color profiles were used afterwards, for the print of a newly designed plate with 725 color fields on the two media – banner and textile. Figure 7 shows a comparison of the color gamut for two different materials on which we wanted to achieve the best possible reproduction by retaining all the details with the lowest optimal area coverage of all colors (in both cases 100%). The details were controlled during the creation of a color profile by adding extra color patches or boxes made of thin lines. Despite the same maximum area coverage (TIL), i.e., 100%, the textile has a slightly larger color gamut, especially in the area of blue and magenta (cf. Figure 7).

USE OF OPTICAL BRIGHTENERS

Figure 8. Reflection spectra of cotton fabrics, O1 – treated with optical brightener, B – bleached, O2 – treated with optical brightener, instrument EyeOne, measured without UV-cut filter (O1 and B) and with UV-cut filter (O2).

In the textile industry, optical brighteners (Optical Brightening Agents, OBAs or fluorescent Brightening Agents, FBAs) – colorless organic compound that fluoresces, are used to enhance the whiteness on chemically bleached fabrics [47]. For the same reason, they are used in detergents to optically increase the whiteness of laundered goods, in the manufacture of plastics (added in the phase of polymer dissolution), in the fashion industry

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and certain warning signs (emergency vehicles, buses, traffic signs etc) [46]. In one research, a preparation of inkjet inks with fluorescent brighteners as antifraud markers for inkjet printing on polyester and polyamide substrates was performed [47]. High whiteness of the textile substrate enhances the contrast on the printed surface, allowing a more specific appearance of the printed pattern and increases the color gamut of the print. Optical brighteners absorb invisible ultraviolet light and convert it into visible light [48]. UV radiation is near the blue area of the spectrum and therefore increases the reflection of light in the blue area of the spectrum. Therefore, the substrate observed under natural daylight, which also contains UV radiation, appears whiter. The most commonly used optical brighteners absorb light at the wavelengths between 300 nm and 400 nm, and reflect it in the range of the visible part between 400 nm and 480 nm [45], which results in increased reflection of blue. The reflection spectra of the used materials are shown in Figure 9. The ISO whiteness (R at 457 nm) for the banner is 87.69 and for the textile 95.84, measurements being made with EyeOne without a UV-cut filter.

Figure 9. Reflection spectra of used materials.

Usually, spectrophotometers have a tungsten lamp with the color temperature of 2800 K. A spectrophotometer measures the light reflected from the sample at selected wavelengths and the result is given as a spectral reflection value between 0 and 100% (cf. Figure 8 – Sample B). To produce an ICC color profile, the standard illuminant D50 is used. It is therefore clear that the instrument measures the reflected light on a single type of light (standard light A or white LED) and the result is given as the value of CIEXYZ under different light (e.g., D50) with the use of a simple calculation.

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The problem occurs when the measurement is performed on the substrate, which was treated with optical brighteners. The latter disrupts the simple calculation, as the light is reflected at a different wavelength than absorbed. This can lead to a shift in hue [49]. The experiment results showed that the proportion of UV radiation of the light source affects the color printed on the substrate which contains optical brighteners. Due to the impact of the proportion of UV radiation, the color shade moves to the blue shade. The experiment results also show that the proportion of UV radiation in the light source affects the colors close to white and blue more than the colors close to yellow and black. One solution is to use spectrophotometers containing a UV-cut filter, which can retain UV radiation, whereas the second solution is to avoid the substrates with optical brighteners for test prints – the latter nowadays being almost impossible. A better solution is to use the software which takes into account the effect of optical brighteners. To create a color profile in ProfileMaker 5.0 (X-Rite), an optical brightener compensation (OBC) module is used to compensate for optical brighteners in combination with the instrument i1iSis for an automatic spectral measurement of color patches on the test chart with an included UV-cut filter, using only UV radiation [50]. The Argyll program uses the algorithm FWA (Fluorescent Whitening Agent) [51], which can successfully compensate for optical brighteners; however, it requires the measurement of quantity and types of optical brighteners used on the substrate, and sufficient information on the observation environment to predict the behavior/impact of optical brighteners. To determine the amount of optical brighteners in the substrate, the instrument must enable illumination of the sample with a certain level of UV radiation. In the field of color management, for the creation of printer color profiles for a variety of substrates that contain different amounts of optical brighteners, it is recommended to use instruments which do not contain a UV-cut filter (cf. Figure 8) [51]. If the instrument contains a UV-cut filter, it is not suitable to compensate for optical brighteners since they cannot be activated. For this purpose, Greame Gill developed the algorithm to compensate for them. The X-Rite’s compensation module (OBC) is the industry’s first integrated module that takes into account the amount of the optical brightener on various substrates [50]. The most common example of using the FWA compensation is the creation of test prints (hard proof) when the two media contain a different level and type of optical brighteners, i.e., the paper on which the hard proof is performed and the print. The use of the FWA compensation in the generation of color profiles for output devices and for the devices on which we are going to perform a test print, and also the use of the absolute colorimetric rendering intent can lead to very good colorimetric matching.

TEST PRINTS A test print presents in the process of printing a very important step, since it accurately displays the appearance of the final print. The test print can be seen on the display screen (soft proof) or it can be printed on a different printer or on a dedicated printing machine (hard proof). Using print simulations on a screen or test print allows us to simulate certain color patterns on any other output device with a proper creation of color profiles for any device – both input and output. A simulation of the print on a screen is cheaper than the test print on a

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printer. In this case, we encounter two media, i.e., observation on the screen and observation of prints on paper [52, 53]. This could lead to variations in the color perception: 1 2 3

due to possible differences in the color gamut of devices – a screen usually has a larger color gamut than a printer or printing machine, when performing the simulation of a print on the screen, only substrate whiteness can be simulated and not the feel of the substrate, simulation of the print on a screen depends on the screen light source, which means that in this case, we are dealing with a self-luminous medium and in the case of the print, with a reflective medium.

The introduction of color management in the field of textiles has increased the possibility of faster and easier preparation of the color pattern for printing. Moreover, it can lead to controlled, high quality and repeatable color print on a textile substrate. Due to the high price of inks for digital textile printing and costs associated with the preparation and then aftertreatment of printed textiles, especially when using reactive dyes, a simulation of the print on a display screen and the execution of the test print on paper are even more important.

Figure 10. Comparison of color gamut of printers in CIE a*, b* diagram.

The simulation of prints was conducted with a laser printer (Canon Image Press C1+) and an inkjet printer (Canon Image Prograf W8400), using CMYK [37]. For the color transformations from the source printer (Mimaki) to proof printers (both Canon), an absolute

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colorimetric rendering intent was used for the simulation of prints. This intent colorimetrically transforms in-gamut colors from the source to the destination color space taking into account the change of the media white point (using chromatic adaptation transform to the standard illuminant D50), while the out-of-gamut colors are clipped to the gamut boundary of the destination color space. On the basis of the average values of color differences of all samples between the original colors (print on inkjet printer Mimaki) and simulated prints (print on inkjet printer Canon and laser printer Canon), it was established that a print simulation on an inkjet printer is better than the simulation on a laser printer. The color gamut of the inkjet printer, i.e., Canon 1, is in the whole color range larger than the color gamut of the laser printer, i.e., Canon 2, while it is the smallest at the inkjet printer for textiles, i.e., Mimaki (cf. Figure 10). The CIELAB diagram shows that the inkjet printer colors are more saturated than the colors from the laser printer (cf. Figure 10). Prior to the analysis, each sample was categorized according to the magnitude of its ∆E00 value into one of the four groups: 0–1 (color difference undetectable with a human eye), 1–3 (small color difference between two patches) [54], 3–6 (perceivable difference) or > 6 (large difference). At the average color differences for 0 < ∆E00 < 1, it was established that both printers simulate very well to approximately the same extent. Nevertheless, differences occurred with regard to the number of colors, since the inkjet printer simulated well (1 < ∆E00 < 3) a larger number of samples (733) than the laser printer (457) (cf. Table 1). Both printers simulated equally well a larger number of colors for 3 < ∆E00 < 6. Table 1. Number of color patches in dependence of ∆E00, simulated with laser and inkjet printer ∆E00 0–1 1–3 3–6 >6

laser Canon 32 457 983 400

inkjet Canon 40 733 914 185

COLOR INCONSTANCY INDEX CMCCON02 An important component that creates a visual impression of the color and color change, apart from the observer, is light. To ensure the matching of two colors, samples should be observed under a number of different light sources. While most offices have illuminations that include fluorescent lights (illuminants from F1 to F12) and at home, the incandescent light (illuminant A) is used most frequently, daylight is most important outdoors [55]. The CIE recommended several standard daylight illuminants with the color temperatures at 5000 K (known as D50), 5500 K (D55), 6500 K (D65) and 7500 K (D75) [56]. A problem arises when the colors of two materials with a different surface structure (textile substrate and paper) should match under a particular illuminant. To determine the illuminant influence on the change in the color appearance of samples, i.e., textile fabric and their proofs on paper under different illumination, the color constancy of samples was defined as well. The color constancy was computed using the color inconstancy index CMCCON02, which uses the

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CAT02 chromatic adaptation transform and is the current recommendation by CIE [40, 57]. Furthermore, the recommendation has been incorporated into the ISO Standard 105 [40].

Calculation of CMCCON02 The color constancy of samples was investigated with the calculation of the color inconstancy index CMCCON02. To calculate the color inconstancy index, R, G and B, which describe cone responses, were calculated with Equation 1 [40, 41, 58]:

R  X  G   M   CAT 02 Y     B   Z 

(1)

where

M CAT 02

 0.7328 0.4296  0.1624   0.7036 1.6975 0.0061   0.0030 0.0136 0.9834 

(2)

Rw, Gw and Bw were calculated from tristimulus values under the test illuminant (Equation 3):

 Rw  X w  G   M   CAT 02 Yw   w  Bw   Z w 

(3)

Rc, Gc and Bc are cone responses for the reference illuminant (D65) (Equations 4–6):

 R Rc  R  D wr   Rw

    1  D   

(4)

 G Gc  G  D wr   Gw

    1  D   

(5)

 B Bc  B  D wr   Bw

    1  D   

(6)

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where Rwr, Gwr and Bwr represent the cone responses to the reference white under D65 reference illumination. D is the degree of adaptation. The calculation of the CMCCON02 index for the samples of such textiles recommends that D be set to 1. The calculation of tristimulus values of a corresponding color in the illuminant D65 is represented in Equation 7:

 Rc  Xc  Y   M 1 G  CAT 02  c   c   Bc   Z c 

(7)

where

M

1 CAT 02

 1.096124  0.278869 0.182745   0.454369 0.473533 0.072098  0.009628  0.005698 1.015326 

(8)

On the basis of the color difference (where the CMC (1 : 1) equation was used) between the reference (XYZ values under reference illuminant D65) and chromatic adaptationtransformed values, the CMCCON02 index was computed. Usually, it is important to calculate the CMCCON02 index, since the standard illuminants A (incandescent light), F2 (CWF – cold white fluorescent light) and standard daylight illuminants, e.g., D50, D55 and D75, are the most commonly used.

Figure 11. Average color inconstancy index for illuminants A, D50, F2, D55 and D75, reference illuminant D65 for prints made on cotton fabric (Mimaki) and paper (laser and inkjet Canon).

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Figure 12. Average color inconstancy index for illuminants A, D50, F2, D55 and D75, reference illuminant D65 for prints made on banner and textile (inkjet Canon).

Figure 13. Spectral power distributions of A, D50, D55, D65, D75 and F2.

The results of the average CMCCON02 index lead to the conclusion that lower average index values were obtained when using daylight D75 followed by D55, D50, while A and F2 had the highest CMCCON02 index (cf. Figures 11 and 12) [37]. The latter was also expected, since the illuminants D50, D55 and D75 are according to the spectral power distribution fairly similar to the illuminant D65 (cf. Figure 13), while the illuminants A and F2 have a fundamentally different spectral power distribution. The highest average CMCCON02 index was acquired when the transition from the fluorescent light F2 to D65 was performed. In the case of prints made on the cotton fabric and Mimaki printer, the CMCCON02 index was lower than in the transition from A to D65, whereas in the case of prints made on

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the textile and Canon inkjet printer, the CMCCON02 index was higher than in the transition from A to D65. From the research results, it could be concluded that the illuminants A and F2 are not appropriate for the comparison of all colors, especially in the case of a simulation with an inkjet printer Canon, since the average CMCCON02 index > 5 in the first case (cf. Figure 11) and > 3 in the second case (cf. Figure 12).

MOTTLING Print mottle can be defined as perceived inhomogeneity in the solid print area due to the variations in the reflectance of the printed surface. The emphasis is on perceived inhomogeneity, since perception is often not in linear correlation with the physical characteristics of the print. Print mottle can be stochastic, with randomly distributed noise, or systematic, with periodic and/or regular pattern (bands, streaks or even more complex textures). Both forms are common on the prints made with inkjet printing systems. From the aspect of inkjet printing, mottle is primarily caused by incompetent properties of the printing substrate or a malfunction of the printing process (print head or substrate movement) [59]. In recent years, several methods have been proposed for the evaluation of print mottling [60–64]. In spite of the similarity in some segments, they differ from each other in basic principles, their complexity and limitations. In this paper, the method proposed by the German Printing Association FOGRA was used to determine the level of print mottle on both materials. The M-Score (i.e., Melcer-Score) method is based on analyzing the color difference (CIE DE2000 is recommended) in the vertical and horizontal direction. Despite M-Score not taking the human visual system directly into account, the results correlate well with the perception of mottling when mottling takes a systematic form [42]. For the sake of simplicity, M-Score computes a single value between 0 (“poor reproduction – clearly visible mottling) and 100 (no mottling present). For more precise interpretations of the obtained values confer Table 2. Table 2. Interpretation of M-Score values M-Score > 95

Meaning Perfect

> 80

Very Good

> 70

Good

> 60

Satisfactory

> 50

Adequate

< 50

Poor

Comments No visible inhomogeneity Print with slightly visible inhomogeneity. Randomly distributed noise, no periodic or systematic structures. Print with visible randomly distributed inhomogeneity, but almost no visible periodic or systematic structures. Visible randomly distributed and systematic inhomogeneity. Still accepted by most observers. Clearly visible randomly distributed and systematic inhomogeneity. Acceptance is dependent on printed image. Clearly visible randomly distributed and systematic inhomogeneity. Not accepted as high quality print.

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The test form used in this study was generated on the basis of ISO 12647-8 [65] and consists of three large solid areas of sizes 29.2 × 18.4 cm. The following tone value combinations were used (cf. Figure 14): a).= C: 65%, M: 50%, Y: 50%, K: 50%; b).= C: 40%, M: 30%, Y: 30%, K: 30%; c).= C: 20%, M: 15%, Y: 15%, K: 15%.

Figure 14. Test form based on ISO 12647-8.

According to the size of solid area, 984 measurements (41 patches in the horizontal and 24 patches in the vertical direction) were performed by the spectrophotometer EyeOne Pro and automated scanning table iO (X-Rite, USA). Algorithm: 1 2 3

Print test forms with large solid (uniform tint) areas, using tone value combinations defined in ISO 12647-8. Measure all patches in each test form with a spectrophotometer and average CIELAB measurements across the lines and columns to get vertical and horizontal “profiles”. Compute CIELAB color differences (ΔE00) between neighbor profiles and sum them up separately for the vertical and horizontal projection, according to Equation 9:

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Digital Textile Printing Using Color Management n1

Evertical  10  Ei (LABi , LABi1 ) i1

m1

Ehorizontal  10 Ei (LABi , LABi1 )

(9)

i1

where m is the number of patches in the vertical direction and n is the number of patches in the horizontal direction. 4

Normalize and sum up color differences to get general ΔEgen (Equation 10):

Egen  5

Ehorizontal Evertical  m 1 n 1

(10)

Compute M-Score based on exponential transformation of general ΔE00, as shown in Equation 11:

1

M  Score  100 2

 2 Egen   15 

(11)

Table 3. Computed M-Score values Tone Value Combinations (%) 20/15/15/15 40/30/30/30 65/50/50/50 Average

Figure 15. Results of mottling analysis.

M-Score values textile 70.42 75.59 84.16 76.72

banner 81.77 70.72 65.31 72.60

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It is evident from the results that inhomogeneity occurred on both materials, commonly as randomly distributed noise and rarely as periodic or systematic structures. As it can be seen from Figure 15 and Table 3, inhomogeneity is slightly more visible on the banner, especially on the prints with larger tone value combinations (darker area). However, on the prints with small tone value combinations (light area), inhomogeneity is more distinguishable on the prints made on the textile substrate. It should be noted that the testing performance of the M-Score method (correlation between results and visual perception) is not within the scope of this paper and could be included in future work.

TESTS FOR COLOR FASTNESS For the material printed on a textile substrate, for an indoor and outdoor presentation, to be exposed to light for a longer period of time in various weather conditions – sun and rain, it makes sense to analyze the stability of color patterns to these conditions. The tests for color fastness on both substrates – banner and textile, were made on a Xenotest Alpha (Atlas, USA) according to the standard SIST ISO 105-B02 [66], SIST ISO 105-B04 [67] under the following conditions:    

measurement and control of irradiance (42 W/m²), temperature in test chamber (35°C), relative humidity (dry conditions: 70%, wet conditions: 35% for 29 min and 100% water spray for 1 min), filter: WINDOW GLASS (320 nm) in the case of SIST ISO 105-B02 and XENOCHROME 300 (300 nm) in the case of SIST ISO 105-B04.

The results of color fastness are represented in Tables 4–7. Color measurements were performed with the instrument EyeOne after 16 and 32 h in the case of exposure to water spray, and after 30 and 72 h in the case of exposure to artificial light. Table 4. Tests for color fastness after exposure to rain made on banner Ink/area coverage (100%) C/100 M/100 Y/100 K/100 C/50 M/50 Y/50 K/50

ΔE00 after 16 h 2.78 1.95 1.24 1.56 2.71 2.62 1.00 3.01

after 32 h 2.74 2.28 1.66 1.78 2.76 2.95 1.47 3.15

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The color differences in the case of the banner after the exposure to rain are within the acceptable ranges (less than 6, maximum value is 3). The differences between 16 and 32 h are very small, regardless of the coverage area (50 or 100%). Table 5. Tests for color fastness after exposure to artificial light made on banner Ink/area coverage (100%) C/100 M/100 Y/100 K/100 C/50 M/50 Y/50 K/50

ΔE00 after 30 h 1.90 1.01 1.03 1.26 2.60 2.33 1.04 2.59

after 72 h 2.27 1.45 1.05 0.79 2.67 2.63 0.81 2.98

The color differences in the case of the banner after the exposure to artificial light are acceptable, in the case of cyan, magenta and black with the area coverage of 50% being slightly higher. From the color differences calculated for the banner, it can be concluded that the printed substrate, i.e., banner, is appropriate for both indoor and outdoor posters for promotional purposes, since the color differences are still acceptable after 32 h of exposure to rain and 72 h of exposure to artificial light. Table 6. Tests for color fastness after exposure to rain made on textile Ink/area coverage (100%) C/100 M/100 Y/100 K/100 C/50 M/50 Y/50 K/50

ΔE00 after 16 h 2.87 2.84 2.93 4.03 1.67 2.37 2.37 0.59

after 32 h 2.65 3.69 3.39 3.56 1.62 2.83 2.82 0.99

The color differences in the case of textiles after the exposure to rain are acceptable in all cases. The maximum ΔE00 is in the case of black (100%) after 16 h. The color differences on textiles after the exposure to illumination after 30 h and 72 h are acceptable (less than 6). The maximum value of ΔE00 is 3.46 in the case of yellow (50%) after 72 h. From these results, it can be concluded that the printed textile substrate is also suitable for indoor and outdoor applications, the same as the banner. The results on the banner are slightly better, as ΔE00 is smaller.

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Dejana Javoršek, Primož Weingerl and Marica Starešinič Table 7. Tests for color fastness after exposure to artificial light made on textile

Ink/area coverage (100%) C/100 M/100 Y/100 K/100 C/50 M/50 Y/50 K/50

ΔE00 after 30 h 1.81 1.76 1.83 2.16 1.50 2.05 2.15 0.31

after 72 h 3.03 1.90 1.96 2.75 2.41 2.80 3.46 0.51

CONCLUSION In this work, we presented digital inkjet printing on textile substrates and the importance of using color profiles made for a particular substrate, ink and pretreatment chemicals. The reactive dyes are the most commonly used dyes that create the covalent chemical bond between the dye and fibers, while the unreacted dye is washed off from the fabric with an aftertreatment in various washing baths. On the paper itself and on the promotional substrates printed with the inkjet printer Canon, the whole print remains on the surface; therefore, the simulation procedure is a complex process, which requires apart from the knowledge on the textile substrate and printing ink, and their physical-chemical characteristics also the knowledge in the fields of color measuring, physical principles of the printing and the knowledge of hardware and software. By calculating the color inconstancy index CMCCON02, the illuminant influence on the color change of the substrates under different illumination could be determined. From the results of the CMCCON02 index, it could be concluded that simulated colors should be compared with original colors under daylight illuminants (D50, D55 and D75), while the indoor illuminants A and F2 are not appropriate for a comparison of all colors. The research results of the print simulation on paper demonstrated that most colors from the printer Mimaki (color difference up to 6) could be fairly successfully simulated on a Canon laser and inkjet printer, whereby slightly better results were acquired with an inkjet printer. The experimental prints on paper are cost- and time-saving, since the pre- and aftertreatment of the textile substrate are in comparison with paper obligatory. In order to determine the level of inhomogeneity on both materials, we examined test charts with three different tone value combinations using the M-Score method, described in the methodology section. It is evident from the results that inhomogeneity occurred on both materials, commonly as randomly distributed noise and rarely as periodic or systematic structures. The results of testing the lightfastness and weatherability of the substrate with a Xenotest shows that the printed substrate, banner and textile, are both appropriated for both indoor and outdoor posters for the promotional purposes, the results of ΔE00 being slightly better in the case of the banner.

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Link, N., Lampert, S., Gurka, R., Liberzon, A., Hetsroni, G., Semiat, R. (2009). Ink drop motion in wide-format printers: II. Airflow investigation. Chemical Engineering and Processing: Process Intensification 48, 84–91. Carr, W.W., Zhu, J. (2001). Interactions of a single inkjet droplet with textile printing surfaces. IS&T's NIP17: International Conference on Digital Printing Technologies, 438–441. Li, S., Boyter, H., Stewart, N. (2004). Ultraviolet (UV) curing processes for textile coloration. AATCC Review 4 (8), 44–49. Eckman, A. L. (2004). Developments in textile inkjet printing. AATCC Review 4 (8), 8– 11. Agosta, M., Savastano, D., (2003). Inkjet inks make gains in textiles. Ink World 9(6), 48–50. Gong, P., Grainger, D.W. (2004). Analysis of regenerated amine-reactive polymer microarray slides. Biomed. Sci. Instrum 40, 18–23. Kuroiwa, T., Ishikawa, N., Obara, Vinet, D. F., Ang, E.S., Guelbi, A., Soucemarianadin, A. (2003). Dispensing of polymeric fluids for bio-MEMS applications. IS&T's NIP19: International Conference on Digital Printing Technologies, 884–890. Fritz, H. (2005). Commercial applications of digital printing technologies on PCBs. Circuit World 31 (1), 16–20. Petherbridge, K., Evans, P., Harrison, D. (2005). Origins and evolution of the PCB. Circuit World 31 (1), 41–45. Weremczuk, J., Tarapata, G., Jachowicz, R. (2012). Humidity Sensor Printed on Textile with Use of Ink-Jet Technology. Procedia Engineering 47, 1366–1369. Boland, T., Xu, T., Damon, B., Cui, X. (2006). Application of inkjet printing to tissue engineering. Biotechnology Journal 1, 910–917. Okamoto, T., Suzuki, T., Yamamoto, N. (2000). Microarray fabrication with covalent attachment of DNA using Bubble Jet technology. Nature Biotechnology 18, 438–441. Wilson, W. C., Boland, T. (2003). Cell and organ printing 1. Protein and cell printers Anatomical Record Part a-Discoveries in Molecular Cellular and Evolutionary Biology 272A, 491–496. Clark, D. (2005). Digital Printing of Textiles: A “How-To” Discussion. SGIA Journal, 41-44. Petrinić, I., Šostar-Turk, S., Neral, B. (2001). Digitalni tisak tekstila. Tekstil 50(7), 351– 356. Xue, C., Shi, M., Chen, H., Wu, G., Wang, M. (2006). Preparation and application of nanoscale microemulsion as binder for fabric inkjet printing. Colloids and Surfaces A: Physicochemical and Engineering Aspects 287(1–3), 147–152. Zhang, J., Li, X., Shi, X., Hua, M., Zhou, X., Wang, X. (2012). Synthesis of core–shell acrylic–polyurethane hybrid latex as binder of aqueous pigment inks for digital inkjet printing. Progress in Natural Science: Materials International 22 (1), 71–78.

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[18] Leelajariyakula, S., Noguchib, H., Kiatkamjornwonga, S. (2008). Surface-modified and micro-encapsulated pigmented inks for ink jet printing on textile fabrics. Progress in Organic Coatings 62 (2), 145–161. [19] Yang, Y., Naarani, V. (2004). Effect of steaming Conditions on Color and Consistency of Inkjet Printed Cotton Using Reactive Dyes. Coloration Technology 120 (3), 127– 131. [20] Yang, Y., Naarani, V. (2007). Improvement of the lightfastness of reactive inkjet printed cotton. Dyes and Pigments 74 (1), 154–160. [21] Yuen, C. W. M., Ku, S. K. A., Choi, P. S. R., Kan, C. W. (2004). The Effect of the Pretreatment Print Paste Contents on Color Yield of an Ink-jet Printed Cotton Fabric. Fibers Polymer 5 (2), 117–121. [22] Yuen, C. W. M., Ku, S. K. A., Choi, P. S. R., Kan, C. W. (2005). Factors Affecting the Color Yield of an Ink-Jet Printed Cotton Fabric. Textile Research Journal 75(4), 319– 325. [23] Aston, S.O., Provost, J. R., Masselink, H., (1993). Jet Printing with Reactive Dyes. Journal of the Society of Dyers and Colourists 109(4), 147–152. [24] Fan, Q., Kim, Y.-K., Lewis, A.-F., Peruzzi, M.-K. (2002). Effects of Pretreatments on Print Qualities of Digital Textile Printing. IS&T NIP18: International Conference on Digital Printing Technologies, 236–241. [25] May-Plumlee, T., Bae, J. (2005). Behavior of Prepared-For-Print Fabric in Digital Printing. Journal of Textile and Apparel: Technology and Management 4(3), 1–13. [26] 26Weiguo, C., Shichao, Z., Xungai, W. (2004). Improving the Color Yield of Ink-Jet Printing on Cationized Cotton. Textile Research Journal 74(1), 68–71. [27] Noppakundilograt, S., Buranagul, P., Graisuwan, W., Koopipat, C., Kiatkamjornwong, S. (2010). Modified chitosan pretreatment of polyester fabric for printing by ink jet ink. Carbohydrate Polymers 82 (4), 1124–1135. [28] Phattanarudee, S., Chakvattanatham, K., Kiatkamjornwong, S. (2009). Pretreatment of silk fabric surface with amino compounds for ink jet printing. Progress in Organic Coatings 64 (4), 405–418. [29] Kaimouz, A. W., Wardman, R. H., Christie, R. M. (2010). The inkjet printing process for Lyocell and cotton fibres: The significance of pre-treatment chemicals and their relationship with color strength, absorbed dye fixation and ink penetration. Dyes and Pigments 84(1), 79–87. [30] International Color Consortium [E-text type]. (2006). http://www.color.org. [31] Giorgianni, E. J., Madden, T. E. (1998). Digital Color Management: Encoding Solutions. Reading: Addison-Wesley, 203–317. [32] Drew, J. T., Meyer, S. A. (2005). Color management: A comprehensive guide for graphic designers. Hove: Rotovision, 162–194. [33] Plaisted, P., Chung, R. (1997). Construction Features of Color Output Device Profiles. IS&T/SID Fifth Color Imaging Conference, Scottsdale, Ariz., 141–146. [34] Fairchild, M. D. (1998). Color appearance models. Reading: Addison-Wesley, 337–362. [35] ISO 12646:2004. Graphic technology – Displays for color proofing – Characteristics and viewing conditions, 12. [36] Javoršek, D., Javoršek, A. (2011). Color management in digital textile printing. Coloration Technology 127(4), 235–239.

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[37] Esteves, M. F., Noronha, A. C., Marinho, R. M. (2004). Optical Brighteners Effect on White And Colored Textiles. World textile Conference – 4th AUTEX Conference, 1–6. [38] Luo, M. R., Li, C. J., Hunt, R. W. G., Rigg, B., Smith, K. J. (2003). CMC 2002 color inconstancy index: CMCCON02. Coloration Technology 119, 280–285. [39] ISO 105-J05:2007(E). Textiles – Test for color fastness – Part J05: Method for the instrumental assessment of the color inconstancy of a specimen with change in illuminant (CMCCON02), 1–2. [40] Evaluation of ‘within sheet uniformity’ by means of the M-Score, FOGRA [E-text type]. (2012).http://www.fogra.org/dokumente/upload/dbd47_2010_en_mscorev1_ ak.pdf [41] Guarav, S., Wu, W., Dalal, E. N. (2004). The CIEDE2000 Color-Difference Formula: Implementation Notes, Supplementary Test Data, and Mathematical Observation. Submitted to Color Research and Applications, 21–30. [42] Octave [E-text type]. (2012). http://www.gnu.org/software/octave/ [43] Javoršek, D., Veselič, D., Weingerl, P., Hladnik, A. (2012). Study of inkjet print quality using colorimetry and principal components analysis. Tekstilec 55(3), 169–175. [44] Argyll color management system home page [E-text type]. (2012). http://www. argyllcms.com [45] Simončič, B. (2009). Teoretične osnove barvanja (1. Izdaja). Ljubljana: Naravoslovnotehniška fakulteta, Oddelek za tekstilstvo, 29–32. [46] Adams, R. (2009). Whiter Than White – With Optical Brightener & Without UV Quenchers. Focus on Pigments 2012 (8), 1–4. [47] Karanikas, E. K., Nikolaidis, N. F., Tsatsaroni, E. G. (2012). Novel digital printing inkjet inks with “antifraud markers” used as additives. Progress in Organic Coatings 75(1–2), 1–7. [48] Aspland, J. R. (2000). Whither textile color application research?. Dyes and Pigments 47(1–2), 201–206. [49] Liu, W. (2008). The Influence of UV Light in Color Measurement. CSSE '08 Proceedings of the 2008 International Conference on Computer Science and Software Engineering, Washington: IEEE Computer Society Washington, 268–271. [50] i1 iSis Optical Brightener Compensation (OBC) Module User Guide, X-Rite [E-text type]. (2012). http://www.xrite.com/documents/literature/en/OBC_User_Guide_en.pdf [51] Argyll Color Management system Home Page, Fluorescent Whitener Additive Compensation (FWA Compensation) [E-text type]. (2012). http://www.argyllcms. com/doc/FWA.html [52] Fairchild, M. D. (1993). Chromatic Adaptation in Hardcopy/Soft-copy comparisons. Proc. SPIE 1912, Color Hard Copy and Graphic Arts II, 14–61. [53] Fairchild, M. D. (2005). Color Appearance Models (Second Edition), Massachusetts: Addison-Wesley, 158–159. [54] Schläpfer, K. (2002). Farbmetrik in der grafishen Industrie, Dritte Auflage. UGRA, 61. [55] Thiry, M. C., (2004). Turn on the light: The importance of lighting for textiles in a retail environment. AATCC Review 4, 34. [56] Xu, H., Luo, M. R., Rigg, B. (2003). Evaluation of daylight simulators: Part 1: Colorimetric and spectral variations. Coloration Technology 119, 59–69.

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[57] Maroney, N., Fairchild, M. D., Hunt, R. W. G., Li, C., Luo, M. R., Newman, T. (2002). The CIECAM02 color appearance model, Proc. IS & T/SID 10th Color Imaging Conference, 24–25. [58] Bračko, S., Šolar, A., Forte Tavčer, P., Simončič, B. (2009). Color constancy of vart prints on cotton fabric. Coloration Technology 125, 222–227. [59] Fahlcrantz, C. (2005). On the Evaluation of Print Mottle [doctoral thesis]. Stockholm, 40–45. [60] Sadovnikov, A., Lensu, L., Kamarainen, J., Kalviainen, H. (2005). Quantified and Perceived Unevenness of Solid Printed Areas. Progress in Pattern Recognition, Image Analysis and Applications: Lecture Notes in Computer Science 3773, 710–719. [61] Fahlcrantz, C., Johansson, P. A. (2004). Comperison of diffrent print mottle evaluation models. Proceedings of the Technical Association of the Graphic Arts, 511–525. [62] ISO/IEC 13660:2001. Information technology – Office equipment – Measurement of image quality attributes for hardcopy output – Binary monochrome text and graphic images, 1–27. [63] Dubé, M., Mairesse, F., Boisvert, J., Voisin, Y. (2005). Wavelet Analysis of Print Mottle. IEEE Transactions On Image Processing, 1-8. [64] Hladnik, A., Debeljak, M., Gregor-Svetec, D. (2010). Assessment of paper surface topography and print mottling by texture analysis. ImageJ User and Developer Conference, 150–155. [65] ISO 12647-8:2012. Graphic technology – Process control for the production of halftone color separations, proof and production prints – Part 8: Validation print processes working directly from digital data, 1–16. [66] BS EN ISO 105-B02:1999. Textiles - Tests for color fastness. Color fastness to artificial light: Xenon arc fading lamp test, 1–26. [67] ISO 105-B04:1994. Textiles - Tests for color fastness - Part B04: Color fastness to artificial weathering: Xenon arc fading lamp test, 1–8.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 4

INKJET PRINTED PHOTO-RESPONSIVE TEXTILES FOR CONVENTIONAL AND HIGH-TECH APPLICATIONS Shah M. Reduwan Billah* Department of Chemistry, Durham University, Durham, UK and The School of Textiles and Design, Heriot-Watt University, Galashiels, UK

ABSTRACT Inkjet printing technology, a modern non-impact printing technique, is in the process of revolutionizing the whole printing industry, including textile printing, for producing almost any print design on textiles within a very short time. It provides inkjet printing a cutting edge over other conventional printing techniques. Photo-responsive inkjet printed textiles have many applications, some of which include, fashion and design, selfindicating alert systems, anti-counterfeit, security and brand protection. Both photochromic dispersed and photochromic acid dyes can be used to formulate inkjet inks to produce photo-responsive inks for inkjet printing on different types of textiles (for example, cotton, wool, silk, nylon) for potential conventional and high-technology applications. Formulation of inkjet inks using functional dyes, such as, photochromic dyes needs proper care for producing jettable inks which can retain functional behaviour for a considerable period along with other desired properties (for instance, high print quality and robust technical performances of printed textiles). In addition, the porosity of the substrate plays a significant role on the absorption or penetration behaviour of an inkjet ink or more simply regulates its spreading on a substrate thus controlling inkjet printed image quality and the technical performances of an ink to some extent. As a result, it is necessary to control a number of influencing factors to produce desired high quality printed responsive substrates with good technical performances for various applications. This chapter briefly point out some of these issues along with the applications of inkjet printed textiles for a variety of conventional and high-tech applications.

*

Dr. Shah M. Reduwan Billah, 7 Laurel Grove, Galashiels TD1 2LA, Scotland, UK, E-mail: reduwan. [email protected] or [email protected].

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Keywords: Inkjet printing, photo-responsive, printed-textile, conventional and high-tech applications.

INTRODUCTION Inkjet printing, a non-contact printing technology, allows deposition of ink droplets on various substrates, such as, textiles, paper, leather, ceramic, glass and also on many other substrates for different purposes [1-7]. It is capable to meet the market demand for producing samples and product within a very short time compared to screen printing technology and also suitable for mass customisation along with the scope of adaptation to unlimited design possibilities with respect to repeat size and colour range. Inkjet printing techniques can also be used for the digital dyeing of textiles using a very innovative technique where the colorants and related additives can be applied on the substrates in the form of a jettable ink disposing through the inkjet print head which is commonly used for inkjet printing technology. Inkjet printing techniques are increasingly gaining the momentum to produce very high quality printed substrates using a wide variety of materials, including, conventional dyes, functional dyes, pigments to meet the demand for a wide variety of coloured substrates for their different applications. Photochromic dyes are classed as functional dyes which usually change the colour from a colourless state to a coloured state when exposed to UV light or sunlight and the inks produced using these dyes also retain the same functional character to impart this unique colour change behaviour to inkjet printed substrates making them suitable for a huge range of applications. For a better understanding on the nature of photo-responsive inkjet printed textiles which is the main concern of this chapter it is important to briefly discuss different aspects of inkjet printing technology and also to analyse its features which made it so important as a technique to draw very high attention both in academia and in industry to replace conventional printing techniques with this technique.

A Brief Historical Overview on Inkjet Printing The idea of inkjet printing goes back to the eighteenth century when Abbé Nollet published his experiments where he analysed the effect of static electricity on a stream of droplets in 1749 [8]. After almost a century later, in 1833, Felix Savart found that an acoustic energy could be used to break up a laminar flow-jet into a train of droplets and Joseph Plateau investigated the formation of liquid jets from nozzles in 1856 which in turns forms the basis of modern day inkjet printing technology [9]. However, it was only between 1858 and 1867 when Lord Kelvin at first developed inkjet like recording device for recording signal of the Atlantic Cable [10]. The Belgian physicist Joseph Plateau (in 1856) and the English physicist Lord Rayleigh (in 1878) studied the break-up of liquid streams and are, therefore, considered as the founders of modern inkjet printing technology [11]. After these different pieces of theoretical work at different times, the first actual form of a continuous inkjet printing device was patented by Elmqivist of Siemens-Elma in 1951 [12]. Then after a relative short period of time there was significant development in the field of inkjet printing technology. In 1965, M. Naiman at first patented thermal inkjet where he

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developed a sudden stream printer [13] and Richard G. Sweet patented device for direct writing signal using fluid droplet recorder [14]. In 1972, Steven I. Zoltan of Clevite Corporation, USA patented a squeeze mode piezoelectric inkjet print head for pulsed droplet ejecting system [15]. After that in 1973 Nils Gustaf Erick Stemme of Sweden patented bend mode piezoelectric inkjet print head which he used it for writing on paper with coloured liquid using the device and also stated the detail mechanism of writing system [16]. In 1976, Sears et al., patented certain method and apparatus for recording with writing fluids and drop projection systems [17]. In 1984, Stuart D. Howkins of Exxon Research and Engineering, USA patented push mode piezoelectric inkjet print head and explained the detail operating principles of a push mode piezoelectric print head [18]. Since then there is a huge upsurge in the development in the field of inkjet as a micro-disposal technique also as a technique for inkjet printing on textiles. Figure 1 shows a brief history of different stages of development in inkjet technology in the form of a chart presentation.

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SI NCETHENTHEREARESI GNI FI CANTDEVELOPMENTSI NTHEFI ELDOFI NKJ ETPRI NTI NGTECHNOLOGY

Figure 1. Brief presentation of different stages of development in inkjet technology.

History of Inkjet Printers for Textile Printing Introducing colour in our surrounding environments and also into our life styles involves a huge variety of arts, sciences, technologies, businesses and industries- where textile printing for producing lucrative colourful design enjoys a significant importance. The findings during different archaeological excavations to explore the nature of civilization in ancient Egypt bear

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the hallmarks of textile printing which used to be carried out using curved wooden printing blocks [19]. In Europe textile printing industry flourished in a much later date which is evidenced by the discovery of first crafted textile printing samples in 15th century. During 18th century there was a remarkable growth in textile printing particularly in the UK reaching at its zenith just before the First World War which trend faced a gradual decline after the war and this decline continued at a higher speed even after the Second World War [20]. The introduction of new fibres and also new colorants (such as, reactive and disperse dyes) contributed for a significant development in textile printing during the second half of the 20th century [21]. However, it is very interesting to observe that textile printing saw a significant competition between different techniques at the last few decades of 20th century. For example, screen printing, especially with rotary screens, has continued to replace roller printing and during this period new machinery with level of sophisticated control was introduced into the printing industry [22]. A precise alignment of screens using digitally controlled electromechanical systems is a notable achievement of this time which at present controls around 80% of all printed textiles which are produced by using flat o rotary screens [23, 24].

Inkjet Printing of Textiles Textile dyeing and printing industry is in the verge of new digital era where digital solutions are increasingly playing an important role as the intensity in competition between the level of versatility and flexibility available in different printing processes are intensified. Digital printing and analogue printing use different type of techniques for representing data and methods during print reproduction. In the analogue systems if the computer is used it is used to make a variation in continuous phenomena such as voltage or pressure during the transmission of print data, however, in the digital printing systems digital signals are transmitted using computers which completely rely on discontinuous pattern transmission using discrete amount of electricity or light for data communication [25]. In usual terms digital printing covers a range of technologies including, inkjet printing, thermography, electrophotography, electrostatic printing, ionography and magnetography. In all these cases digital data may be used to produce images. Inkjet printing technique has the highest potential compared to these other techniques for textile applications [26]. Table 1 demonstrates a brief historical review on the significant development on the direct inkjet printing of textiles from 1975 till 2004 and after that period the inkjet printing of textiles has reached to maturity stage in a number of areas which is beyond the scope of this current chapter. It is important to note that relative contemporary developments from different companies also contributed to the direct inkjet printing of textiles, some of which are, development of Fast Jet single pass print head of Inca Digital, M class piezo MEMS and water tolerant piezoelectric print head from Spectra, Xaar 1001 series print heads, Picojet 256 all stainless piezoelectric print heads from Picojet and also the improvement of pigmented binder-less inkjet inks by BASF have profound impacts on the total development process. Additionally, developments in the areas of sublimation ink and sublimation transfer printing techniques have significant contributions on the indirect digital printing of textiles. Some of the most important developments are – (a) Roy DeVries sublimation transfer printing method in 1974, (b) Donal Hare T-shirt decoration method in 1978, (c) inkjet sublimation method by

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Crompton and Knowles in 1982, (d) RPL-QLT inkjet sublimation method in 1988, (e) Saw grass patent on sublimation ink in 1991, (f) development of Fotoware-Canon inkjet transfer paper in 1994 and (g) soft link method by Hanes in 1999 [27]. Table 1. A brief historical overview on the significant developments on the direct inkjet printing of textiles Year 1975 1976 1990 1993 1996 1997 1998 2001 2002 2003

2004

Significant developments Milliken-Millitron carpet printer Zimmer-Carpet printer Seiren-Parallel processing Embleme-Water UV direct T-shirt Perfecta/Zund-Flatbed Rhome Revolution-Direct T-shirt Encad and Mimaki-Textile proofing L&P-UV-curable textiles and Dupont Artisti 3210 Mimaki-GP 0604 Mimaki TX 3, DupontArtisti 2020, L&P UV-cure dye, Robustelli Mona Lisa, Reggiani DReAM, Zimmer Chromotex USSPI Fast T-Jet & USSPI Fast T-Jet Jombo, Kornit 930 and Kornit 931

Inkjet Printers for Textiles Inkjet printing systems are used different areas of textile printing, some of the most widely used areas are – fashion accessories, sports and swimwear, home textiles (e.g., curtains, sheets, towels, table settings, furniture upholstery), flags and banners, t-shirts and specialties, automation and transportation upholstery, architectural textiles, medical textiles (e.g., trans-dermal dosing) and also in some types of technical textiles. Some of the most notable inkjet printers used for digital textile printings are – Colorspan Display Maker XII, Mimaki TX2 and TX3, Dupont Artisti 2020, Legget & Platt UV-dye, Robustelli Mona Lisa, Reggiani DReAM, Zimmer Chromotex and Imaje-Osiris. For direct T-shirt printing different types of inkjet printers are used, some of which are – Mimaki (e.g., Mimaki GP-1810, Mimaki GP – 604) and Kornit (e.g., Kornit 930, Kornit 931) printers. Digital inkjet printing of textiles can be divided into different categories, such as wide format direct, wide format indirect, single pass printing and inkjet T-shirt printers [27, 28].

Inkjet Print Head Technologies All inkjet technologies are basically precise micro-disposal techniques where digitally controlled the fluid droplets (e.g., the inks) are ejected from the print head onto a substrate. Various techniques can be used for a digital control on the fluid droplet ejection from the print head to the substrates which are sometimes used as a basis for the classification of inkjet

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print heads. For example, continuous inkjet printing technique or drop-on-demand inkjet printing technique are two mostly used terms for a broader classification of industrial inkjet printing technology (although there are variants within each class). The print head that uses continuous inkjet technology ejects drops continuously (Figure 3) where the drops are either directed to the substrate or to a collector for recirculation and reuse. On the other hand, the print head which uses drop on demand type inkjet printing technology ejects drops only when required (Figure 4). A brief classification of inkjet print heads are shown in Figure 2. Continous inkjet print heads are of two type in terms of the use of inks – continuous inkjet print heads which uses aqueous inkjet inks (such as, Kodak, Versamark) and continuous inkjet print heads which uses solvent or UV curable inks (such as, Danaher, Dover, Domino, ITW, Mathews). In this same sense, drop-on-demand print heads can be divided into different classes- (a) thermal inkjet print heads which only use aqueous inks (e.g., Hewlett-Packard, Cannon, Lexmark, Kodak), (b) piezoelectric print heads which use all types of inks (e.g., Epson, Dimatix, Xaar, Richoh, Konica-Minolta, Toshiba Tec, Panasonic) and (c) valvejet print heads which mainly uses solvent based inks, however, they can be used for all types of inks (e.g., VideoJet, Imaje, Crayon, Loveshaw, Kortho, Foxjet, Miliken, Zimmer, Danaher, Dover, Domino, ITW, Mathews). However, based on deflection mode continuous inkjet print heads can be divided into two categories – (a) binary (such as, Stork, Scitex, Iris, Siemens, Domino, Kodak, Versamark) and (b) multi-deflection (such as, VideoJet, Danaher, Imaje, Dover, Linx, Willet). Based on printed head technologies, piezoelectric print heads are of five types, they are – push mode (e.g., Ricoh, Trident, Brother, Epson), bend mode (e.g., Sharp, Epson, Xerox, PicoJet, Dimatix Samba & M-class, Kyocera), squeeze mode (e.g., Siemens, Gould), shear wall shear mode (e.g., Xaar, Konica, Minolta, Toshiba Tec, Seiko II, Brother, Kodak, Microfab) and shear mode (e.g., Dimatix) [27, 28].

Figure 2. A schematic representation of the classification of the inkjet print heads.

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Continuous Inkjet (CIJ) Printing Technique Continuous Inkjet printing is an amateur micro-disposal technique popularly used for marking and coding of products and packages. In a CIJ disposal technique, a pump directs fluid from a reservoir to small nozzles that eject a continuous stream of drops at high frequency (in the range of roughly 50 kHz to 175 kHz) using a vibrating piezo crystal. In addition, the drops are charged using an electrostatic field which are then allowed to pass through a deflection field to determine landing position of the charged the drops while at the same time the unprinted drops are collected and returned to the reservoir for reuse. The high drop frequency of continuous inkjet micro-disposal system makes this technique suitable for a direct translation into a very high speed printing system as evidenced by such applications as the date coding of beverage cans using continuous inkjet printing technique. It also shows very high drop velocity which allows micro-disposal at relatively (compared to other inkjet technologies) large distances from the print head to the substrate for useful in industrial environments. CIJ shows advantage over other inkjet technologies in its ability to use inks based on volatile solvents that allow rapid drying and aiding in adhesion on different substrates. However, CIJ shows relatively low print resolution but requires very high maintenance and environmentally not friendly due to the use of volatile solvent-based fluids which need to be charged for printing.

Figure 3. A schematic representation of a continuous inkjet printing system.

In principle, the continuous inkjet printers apply a pressure wave pattern to an orifice in order to break a continuous liquid jet into droplets of equal size and spacing. During the formation of droplets they are selectively charged and the stream of drops is passed through an electric field to deflect the charged droplets. According to the nature of the printer either the charged or uncharged drops are used for image generation while the unused drops are collected for recirculation. Based on the mechanism of image generation, the continuous inkjet printers may be of different types, such as, (a) the binary or multiple deflection, (b)

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hertz, and (c) microdot types. The continuous printers are mostly used in industrial marking processes and also in the field of graphic arts. These printers usually generate a smaller drop size, a high drop velocity, and a higher drop generation rate (up to 1 MHz) compared to other inkjet printers. However, they are expensive and difficult to control the satellite drop formation. Figure 3 illustrates a schematic diagram of a continuous inkjet printing system [29, 30].

Drop-on-Demand Inkjet (DOD) Printing Technique In broad terms it refers to an inkjet technology which allows the micro-disposal of inkjet inks (in the form of droplets) when required using pressure pulse. In addition, DOD print heads are classified in different sub-categories based on the technique which is used to generate this pressure pulse and these are – thermal, piezo and electrostatic. Besides these print heads, MEMS print heads are also often merged into this drop-on-demand type of print heads which are invariably still based on either piezo or thermal inkjet technology. In a drop on demand type inkjet print head, it uses a vacuum method to control drops and eject only when the drops are in demand. It applies a negative pressure in the print head to keep the ink inside until a local pressure wave at the nozzle is generated which can eject a droplet. DOD inkjet print heads are more advanced compared to continuous inkjet print heads as they are free from some requirements which are highly required in the continuous print heads, such as, starting up and shutting down, complicated charging, deflection hardware and also the need for an ink recirculation unit. Different pieces of work for producing inkjet printed high performance photo-responsive surfaces reported in this chapter has widely used piezoelectric inkjet print head (DOD Xaar Omnidot 760) so this chapter will briefly cover different aspects of piezoelectric printing technology along with other print head technologies [31, 32].

Thermal Inkjet Technology In a thermal inkjet system, drops are generated from a rapid heating of a resistive element (of the print head) in a small chamber containing the ink. During the heating of the resistive element temperature rises very fast (such as, from 350°C to 400°C) that causes a vaporisation of a thin film of ink above the heater for a rapid creation of a bubble that in turns creates a pressure pulse to force the ink (in the form of a droplet) through the nozzle. When the drop is ejected it leaves a void in the ink chamber which is subsequently replaced and filled by the ink in preparation for the creation of the next drop for a continuation of this droplet formation (in Figure 4A, illustrates a thermal inkjet print head). Thermal inkjet print heads are comparatively cheaper and have the potential in producing very small drop sizes along with higher nozzle density suitable for compact devices. However, the print head must have to withstand the effects of ultra-high local temperature which is usually used to vaporise the ink for the creation of ink droplet in the form of the bubble. Thermal inkjet inks are usually based on aqueous systems and the ink formulation needs significant level of accuracy; otherwise, there are chances to form a hard coating on the resistive element which in turns limits the efficiency of the print head causing a total failure in

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long term. This type of print head is not suitable to dispose most of functional inks because the high temperature often has very high detrimental effect on the functionality [33, 34].

Principle of Operation for a Piezoelectric Print Head A piezoelectric print head uses a piezoelectric element (such as, lead zirconate titanate or PZT) to modulate a pressure based deformation on the ink flow for the physical displacement of the ink droplet by the way of sending the electrical impulse. For printing an electrical impulse is sent to a piezoelectric element of the print head to cause physical displacement by way of changing the elongation or bends of the piezoelectric element. This physical displacement creates a volumetric change in the nozzle chamber to produce a pressure wave to push the droplet through the nozzle orifice. Figure 4 shows a schematic representation of different print heads – (A) thermal, (B) piezoelectric and (C) electrostatic. Piezoelectric print heads have comparably higher manufacturing costs although they have a long operation life. This high manufacturing cost is one of the main limitations of the piezoelectric print heads which categorically hinders the miniaturisation of the nozzles. In addition, piezoelectric print heads are also sensitive to the air bubbles trapped in the nozzles which also limits their printing qualities. It is an important requirement for the inks to be used the piezoelectric print heads that the ink must remain incompressible in order to maintain a controllable propagation of mechanically generated pressure waves in the nozzle chamber. Air bubbles in the nozzle disturb this condition and de-gassing operation should be carried out to remove the air or dissolved gases before actual printing. It is commonly used technique to purge a considerable amount of ink through the print head before printing in order for ensuring the total removal the air or bubbles to produce high quality printing images or high quality disposal of inks to a desired substrate [35, 36]. Piezoelectric drop-on-demand inkjet printers are usually used in graphic designs, textile printing, commercial printing, industrial and digital fabrications and also in biomedical applications. Thermal piezoelectric print heads are normally used as desktop printers and also used in graphics, commercial and biomedical printings. Electrostatic drop-on-demand print heads mostly used in the printing on beverage cans while valve jet printers most got their applications for carpet printing, coating, marking and coding. In addition, continuous inkjet print heads are widely used in proofing, marking, coding and sometimes also in textile printing.

Figure 4. A schematic representation of different print heads – (A) thermal, (B) piezoelectric and (C) electrostatic.

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Inkjet printing techniques can also be used for graphic designs which have been used in a wide variety of fields some of which include – textile printing, coding and marking, carpeting, office inkjet printing, addressing direct mails, proofing, CAD, wide format graphics (for billboards and signage), flags, T-shirts, wall covering, floor covering, ceramics, photo finishing, food decorations, packaging, and also other types of commercial printings [27, 28].

Choice of Technology and the Selection of Inkjet Print Heads Inkjet printing technology as a micro-disposal technique has a wide range of applications in different fields, including in electronics, photovoltaic, electronic displays, 3D additive manufacturing, chemical formulations, tissue engineering, high-throughput screening, biomedical applications. However, during the selection of an inkjet print head for a particular application needs rigorous study on the different aspects of the inkjet print head, available facilities, properly defined objectives of the project where the print head to be used, nature of the substrates, nature of the inks to be used, technical performance, the market, costs and related many other fundamentals issues. For example, during the selection of print heads proper care and advices from different manufactures and others involved in the supply chain is instrumental because one particular type does not necessarily meet or even suitable for all desired applications. Briefly, some important characters of a print head needs careful consideration (during matching it to different applications) include, (a) single-pass throughput, (b) firing frequency, (c) fluid firing viscosity range, (d) types of fluids the print head can tolerate (e.g., effective pH range for aqueous inks where print head can be operated), (e) drop velocity, (f) native dpi (depth per inch) of printed image, (g) nature of crosstalk, (h) print line length, (i) nozzle diameter, (j) nozzle pitch, (k) drop size, (l) drop firing straightness, (m) greyscale capability, (n) drop through distance, (o) nature of the heater (in the case of thermal inkjet print head and (p) maximum operating temperature [28,37-39]. There are different elements in inkjet technology which virtually control the whole system, some of the main elements include – (a) the nature of a print head, (b) firmware, driver, RIP (raster image processing) and image generation software, (c) print controller electronics, (d) print head monitoring and maintenance, (e) print head and/or substrate movement, (f) substrate transport and handling, (g) the nature of an ink or a fluid, (h) the ink delivery system, (i) colour control, (j) nature of pre-treatment or post treatment on the substrate, (k) curing, fixing and drying processes, (l) the system integration and (m) tailoring and tuning components to meet specific requirements. [40, 41]. Some recently introduced printers for textile application includes, Durst Kappa (Ricoh Gen4), MS LaRio (Kyocera Kj4B), Konica Minolta Nassenger Pro 1000 (KM 1024 – 4 lines for 256 nozzoles), SPG Prints (Stork), La Meccanica (Kyocera KJ4B), Kornit Allegro (Dimatrix Nova AAA), D-gen Teleios Grande (Ricoh Gen4L), Shima Seiki new SIP flat bed (Ricoh Gen 4L), AnaJetmPower (Ricoh Gen4). [27, 28].

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Table 2. Types of inkjet inks Different types of inks Division based on solvent or and the method Different types of inks Aqueous solution, dispersion or micro-emulsion Non-aqueous inks Oil based or solvent based Phase change inks Liquid to solid, liquid to gel Reactive inks UV curable inks Division based on the colorants used in the ink formulation Dye based inks Acid, Reactive, Direct, Disperse, Vat, Sulphur, Solvent Pigment based inks Inorganic pigments (e.g., Carbon Black), and organic pigment based Polymer based inks Aqueous, Non-aqueous, Polymer blend based

Different Types of Inkjet Inks There are different types of inkjet inks and a brief division is shown in Table 2 and the inkjet print heads which suitable to certain types of inkjet inks are shown in Table 3. Table 3. A brief presentation of different inkjet print heads suitable for specific ink classes Print head model Oil Xaar 1001 √ Trident 256Jet √ Epson TFP √ HP X2 √ Richo Gen 4 √ Fujifilm Dimatix PQ-512/15 √ Fujifilm Dimatix Scan PAQ QS-10 √ Fujifilm Dimatix QS-256/10 √ Fujifilm Dimatix Samba √ Panasonic 600X600 √ Kyocera KJ4A √ Kyocera KJ4B √

x √ √ x √ x √ √ √ √ √ √

Different types of inks Water Solvent √ √ √/ x x √ √ √ √ x x x x

UV-cure √ √ x √ √ √ √ √ √ √ x √

DESIGN AND DEVELOPMENT OF INKS AND TYPICAL INK COMPONENTS The ink and the print head are the two vital components of the inkjet printing system (in exception to the nature of the substrates which have significant importance), because even they are improved individually to an outstanding level, it is finally the cooperation of both, which defines the printing performance. This section focuses on the challenges for designing

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and developing inkjet inks. The composition of the inks is not trivial and the inks must fulfil several essential requirements to be jettable also to produce high quality prints.

Design Requirements of Inkjet Inks Sometimes specific requirements for certain print heads exert challenges in the design and development of particular classes of inkjet ink formulations. These requirements define the nature of inkjet inks, some of the important features are – intrinsic characteristics of the inks, ink performance in the printers and interaction of the ink with print media. Since all of these requirements are intricately related to each other so during designing the ink a compromise between these categories is important. The intrinsic ink characteristics are basically the physicochemical properties of an ink particularly relating to the ink composition. Other important properties which need rigorous considerations include, viscosity, surface tension, pH, conductivity, purity of the components, drop velocity, dye solubility, visible spectrum, density (specific gravity), solid content, and stability of the inks as well as health, safety, and environmental considerations. As some these properties are more specifically related to the print head technology (such as, the type or model of the print head) so these properties must be optimised to meet the specific operation range of the print head used for the printing purpose. Jettability and drop placement accuracy of the inkjet print head depend on the interaction of inks with the print head and its components. It also important to note that nature of ink plays a vital role in terms of technical performance which is defined by the level of interactions between the inks and the substrates. A primary consideration is the ink must be compatible with the printer print head and should not cause any corrosion to the metallic parts, softening or swelling of the organic parts along and any type of contaminations. Inks should be free from chemical reactions, biological or fungal growth, particle agglomeration or precipitation or foaming must during the operation and storage. The ejected inkjet drops should be of identical volume and velocity. The drop break off length should be uniform without any satellite or secondary droplet formations. The ink should be resistant to any pH changes, decomposition and evaporation. The ink should neither clog the orifice nor wet the face plate. The ink droplets should show desired criteria when the printed on the substrates to achieve desired print quality. It is expected that the ink drops should reveal proper wetting and spreading on the substrate and dry reasonably quickly. When printing is carried out nonporous media (such as glass) the surface energy of the substrate and the surface tension of the ink are most likely to define the spreading and the dot size. However, during the printing on porous substrates (such as, a textile substrate), the ink vehicle usually wets the surface and penetrates into it to set the correct dot size to provide a printed image. It is also expected that during penetration and evaporation, errors like bleeding, feathering, mottling, or line banding should not occur. Additionally, the printed patterns should have high print quality and high technical performances. A quality inkjet ink is usually designed considering all the above mentioned points [42, 43].

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REQUIREMENTS FOR DIFFERENT INKJET PRINTING TECHNOLOGIES Different inkjet print heads uses different techniques to jet the inkjet inks onto different substrates. Inkjet inks are required to meet certain criteria (such as, physical and chemical requirements) to be jetted from a particular type of inkjet print head. So, in order for such inks or fluid compositions to be deposed from a certain type of print head the compositions may be formulated to meet the characteristics as specified in Table 4.

Rheological and Other Requirements for a Good Jettable Fluid The nature of inkjet fluid is of immense importance which controlled the quality and performances of both printed images as well as the productivity and printing performances of the inkjet print heads. Different selected properties of the inkjet fluid is briefly summarised here. Table 4. Jet fluid property requirements for specific print head technologies Property

Drop on demand (DOD) Thermal (TIJ) Piezo Valvejet

Viscosity (cP) (at operating 1-4+/- 0.25*b temp*a) Surface tension(dynes/cm) 30-50 Conductivity (uS/cm) 0

2-15+/-0.25-0.5*b 2-20 25-45 0

25-50 0

Salt content Chlorides (ppm) Particle size limit (um) pH % solids(residual) Stable to shear rate of (s-1) Dot diameter (um) Droplet volume (pico-litre)

Cd2+ >Zn2+ [12]. The maximum uptake capacity and efficiency of metal ions removal from the ternary mixture was obtained for the sample L5. Nevertheless, it can be noted that sorption capacity of all tested samples is proportional to the amount of functional groups (see Table 3). This suggests that amount of hemp fibers acidic functional groups have dominant influence on the metal ions biosorption, since they act as an active cites for adsorption. Beside the amount and accessibility of functional groups, the process of biosorption is also influenced by their surface distribution i.e., surface homogeneity [41].

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Figure 5. Total heavy metals uptake capacity of unmodified and modified hemp fibers.

For the better understanding of biosorption process, sorption equilibrium data were treated with Langmuir and Freundlich adsorption isotherms. In order to calculate isotherm parameters, the linear regression analysis was the most commonly used method. However, linearization of such data distorts the experimental error, and the suitability of isotherm models to describe experimental data, is determined only on the marginal differences between correlation coefficients. Therefore, the non-linear form of Langmuir and Freundlich adsorption isotherms were used for isotherm parameters calculation, and the model which is best supported by experimental data is selected by model selection criteria e.g., Akaike information criterion (AIC). AIC is able to answer the question: which model is better for mathematical description of experimental data. On the bases of the results presented in Table 7 we can conclude that shorter time of modification, favor higher values of adsorption capacity and greater homogeneous distribution of active sites for adsorption on the surface of hemp fiber. For all tested samples values of 1/n were less than unity which indicates that the biosorption of zinc on short hemp fibers is a chemical process. This also suggests that biosorption of zinc is predominantly occur through the ion exchange reaction on the functional groups. Adsorption kinetic data obtained using zinc ions as a model of heavy metal ion were analyzed by pseudo-first and pseudo-second order kinetic models, and the best fitting model is chosen using Akaike information criterion [41]. In order to determine the rate-controlling

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step in the overall process of biosorption, kinetic data were examined by intraparticle diffusion model. The values of the equilibrium amount of zinc adsorbed calculated by pseudo-first and pseudo-second order models, are compared with the experimental data (Table 8.). The calculated values were fitted with the experimental data by minimizing the squared magnitude of the residuals of the amount of zinc adsorbed. The optimal model parameters: qe.cal and k1 for the pseudo-first, and qe.cal and k2 for the pseudo-second order models, obtained by this fitting procedure, have enabled the best comparison with the experimental data. The values of the model parameters, Akaike information criterion and the standard deviation are shown in Table 8. These results show that biosorption of zinc ions on all tested short hemp fiber samples predominantly follows the pseudo-second order kinetic model indicating that adsorption/binding of zinc ions on hemp fibers is mediated by chemical forces rather than physical forces of attraction. Table 7. Corrected Akaike information criterion, standard deviation and Langmuir and Freundlich isotherm parameters for zinc ions adsorption on unmodified and modified hemp fibers samples Sample C L5 L60 H5 H45

Langmuir Q0 (mg/g) 8.0 8.3 7.1 8.1 7.4

b (l/mg) 0.200 0.164 0.322 0.226 0.231

AICc 3.317 6.474 -2.166 5.169 4.109

std 0.135 0.365 0.053 0.333 0.254

Freundlich 1/n Kf 0.390 2.100 0.470 1.606 0.331 2.300 0.420 2.101 0.381 2.046

AICc 5.487 6.995 5.679 6.085 3.362

std 0.253 0.328 0.3228 0.393 0.211

Table 8. Corrected Akaike information criterion, standard deviation and kinetic parameters obtained by pseudo-first order and the pseudo-second order kinetic models for zinc ions adsorption on unmodified and modified hemp fibers samples, for initial zinc ion concentration of 0.1 mmol/l Sample C H5 H45 L5 L60

Pseudo-first order k1, (min-1) qe. cal, (mg/ g) 0.30 2.210 0.20 2.500 0.21 2.378 0.28 2.431 0.30 2.353

AICc -1.352 1.281 1.051 -0.141 -0.206

std 0.147 0.265 0.257 0.190 0.181

Pseudo-second order k2, (min-1) qe. cal, (mg /g) 0.51 2.195 0.40 2.479 0.38 2.400 0.42 2.453 0.55 2.350

AICc -8.336 -5.168 -8.308 -4.548 -6.027

std 0.027 0.054 0.026 0.057 0.029

qe. exp, (mg /g) 2.193 2.454 2.393 2.505 2.444

In order to investigate the diffusion mechanism during the biosorption process, experimental data was tested by the intraparticle diffusion model. Figure 6 shows the plots of qt versus t1/2 for sample H5 and for zinc initial concentrations of 0.1 and 0.2 mmol/dm3.

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Figure 6. Intraparticle diffusion plots of the zinc ions onto sample H5 at various initial zinc ions concentration.

The initial stage, addressed to external surface adsorption is quite fast, which is expected in the well shaken system. The second step is assigned to moderate intraparticle diffusion while final slow step corresponds to the equilibrium adsorption process, where the intraparticle diffusion starts to slow down due to the extremely low solute concentration in solution. The rates of adsorption observed at different stages of the process indicated that the adsorption rate was initially very fast and then slowed down as time progressed. Obtained multi-linearity in the intraparticle diffusion curves and the fact that the second and the third linear part of the curves did not pass through the origin, suggests that the intraparticle diffusion is not the only rate-controlling step in the overall adsorption process. As the external mass transport is much faster than the diffusion of heavy metal ions through the fibers, the adsorption rate mainly depends on the diffusion of metal ions through the porous structure of hemp fibers and adsorption at interior active sites. In order to describe the mechanism of adsorption and ion transport from water solution through the hemp fibers, mathematical model has been developed [42] and used for modeling the heavy metal ions adsorption on hemp fibers.

(CD

MATHEMATICAL MODELING OF HEAVY METAL IONS , ZN2+AND PB2+) BIOSORPTION BY CHEMICALLY MODIFIED SHORT HEMP FIBERS

2+

Mathematical model that describes phenomena of different ions (Pb2+, Cd2+ and Zn2+) transport through the porous fiber matrices was developed to determine the profile of heavy metal ion concentration in fibers and optimize the biosorption of heavy metal ions by short hemp fibers. Since the hemp fibers sample L5 showed the highest efficiency in heavy metals removal [12], the mathematical model was developed based on the adsorption results obtained for this fiber sample.

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Mathematical model, formulated for the phenomenological description of the biosorption of metal ions from the aqueous solution by the fibers, is based on the second Fick’s low, and represents the modification of the model developed by Medovic et al. [59]. Diffusion process into the fibers was approximated as mass transport process in the very long cylindrical body with radius R. The model of biosorption process describes the change of metal ions concentration in swollen fibers. The last one is due to the fact that the fiber swelling process is much faster than the biosorption of the ions based on our experimental observation. Maximum swelling of fiber sample L5 was attained already after less than 5 min while the highest sorption efficiency for all the three ions from mixture was attained after 60 min [12]. The experimental data of ion concentrations in solution are introduced into the model in order to: (1) determine the effective diffusion coefficient for metal ions within the fibers and (2) predict the profiles of heavy metal ion concentration within the fibers. Balance equation of metal ion concentration change in the fiber is:

1   CF r , t   CF r , t  r  Deff  r  r  t r 

(6)

where:

CF r, t  is ion concentration difference, i.e., C F r, t   C F eq  C F r, t  , C F r, t  is local ion concentration, CF eq is the equilibrium ion concentration, Deff is effective diffusion coefficient of ions in fibers. Deff corresponds to the Stokes-Einsteind diffusion coefficient for the diluted systems (the single ion solutions). In the case of the concentrated system (the aqueous ion mixture) it represents the temporally averaged collective diffusion coefficient. Balance equation of metal ion concentration change in the solution is:

VS

CS t   CF r , t     Deff   t r  

Peff r R

where:

CS r, t  is ion concentration difference, i.e., C S t   C S t   CSeq ,

CS t  is ion concentration in the solution,

(7)

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C S eq is the equilibrium ion concentration in the solution,

VS is volume of the solution, Peff is the effective interface between fibers and the solution, i.e.,

Peff 

2VF ( R is the radius of already swollen fiber, V F is total volume of the already R

swollen fibers). The boundary conditions for sorption of metal ions from the solution to the fibers are: 1) At t  0 , the initial concentration of metal ion in the solution is CS 0  CS 0 . 2) At t  0 , the initial concentration of metal ion in the fibers for r  R is

C F R, 0  C S 0 .

3) At every t the concentration of metal ion in the fibers for r  R is equal to

C F R, t    t  C S t  , where parameter  t  represents the effectiveness of

sorption. 4) The initial value of parameter

 is  0  1 based on the condition (1).

5) At t  t eq (where the equilibrium time for sorption of metal ions was t eq  60 min

 

the equilibrium concentration of metal ion in solution is C S t eq  C S eq .

 

6) At t  t eq the equilibrium concentration of metal ion in fibers was C F t eq  C F eq (where

C F eq 

the

C

S0

equilibrium

 C Seq  VS VF

ion

concentration

in

fibers

is

equal

to

).

Model balance equation, Eq. (6) is solved analytically by Fourier’s dividing of the variables and using Bessel functions. The general solution of Eq. (6) determines the profile of the metal ion concentration within the fibers. It is expressed as:

CF r, t   CF eq  e  t C1 J 0 ra   C2 N 0 ra  2

(8)

Where:

J 0 ra and N 0 ra  are the Bessel functions, while the parameter a is equal to a

2 Deff

,

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Deff is the effective diffusion coefficient of metal ions through the fibers,

2 is the specific rate of changes of metal ions concentration. Only the Bessel function J 0 ra  



1  ra    2 k 0 k!  2 

2k

has the exact value for r  0 equal

to J 0 0  1 . On that base, we formulate the particular solution of Eq. (6) as:

 ra 2 ra 4 ra 6  2 C F r , t   C F eq  e  t C1 1     4 64 2304  

(9)

where C1 is the constant which is determined starting from the boundary condition (2) and Eq. (9). The value of C1 is expressed as:

C1 

C Feq  C S 0

(10)

Ra 2  Ra 4  Ra 6 1 4

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After introducing Eq. (10) into Eq. (9) for r  R we obtain:

C F R, t   C F eq  C Feq  C S 0  e   t 2

(11)

The temporal change of the ion concentration in the solution is expressed from Eq. (11) and the boundary condition (3) as:

C S t    t 

1

The parameter

 C F eq  C Feq  C S 0  e  t  2

(12)

 t  is expressed in accordance with the boundary condition (4). It is

formulated as:

C Feq  C Feq  C S 0  e   t 2

 t  



C S 0  C S 0  C Seq  1  e  t 2



(13)

After introducing Eq. (13) into Eq. (12), following relationship for the concentration of metal ions in the solution is expressed:

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

C S t   C S 0  C S 0  C Seq  1  e   t 2



(14)

Eq. (9) is in the accordance with the boundary conditions 1 and 6. After introducing Eqs. (9), (10) and (12) into Eq. (7) we obtain:

R R 3a 2 R 5a 4   VS C S 0  C Feq  2 16 384  2 4 Peff C Feq  C S 0  Ra   Ra   Ra 6 1 4 64 384

(15)

Effective diffusion coefficient is obtained from Eq. (15) for all experimental conditions using iterative procedure. The procedure is expressed by introducing the error function from Eq. (15) as:

R R 3a 2 R 5a 4   VS C S 0  C Feq  2 16 384   a   2 4 Peff C Feq  C S 0    Ra 6 Ra  Ra  1   4 64 384

(16)

The optimal value of diffusion coefficient is calculated from the condition

2  a  / a aeff  0 such that Deff  2 . a a eff

Mathematical model enables the estimation of metal ion effective diffusion coefficient value and the prediction of the change of the metal ion concentration in the fiber as the function of time and fiber radial distance (profiles of metal ions concentration in fiber). The model prediction values of ion concentration in solution are calculated from Eq. (14). The predicted values are fitted with the experimental data by non-linear least-squares regression, minimizing the squared magnitude of the residuals of the heavy metal ion concentrations in solution. The experimental data and model prediction of Pb2+ ion concentration in single ion solution, the initial ion concentration 0.1 mmol/L, are shown in Figure 7. The similar agreement between experimental data and model prediction of ion concentration in solution for Zn2+ and Cd2+ in the single ion solutions and for all three ions in the ternary mixture was obtained (data not shown here). The optimal model parameter 2 obtained by this fitting procedure that enables the best agreement with the experimental data is given in Table 9. The values of the model parameter 2 are introduced into Eq. (15) in order to estimate the corresponding values of the effective diffusion coefficients. The effective diffusion coefficients are calculated using the iterative procedure described by Eq. (16) and given in Table 9. Additionally, the equilibrium ion concentrations in fibers (CFeq) obtained as a model prediction are shown in Table 9.

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Figure 7. The change of Pb2+ ion concentration in single ion solution during the biosorption obtained by experiment and by mathematical model.

Table 9. Value for effective diffusion coefficient (De), specific rate of changes the concentration of metal ions (2) and equilibrium ion concentration in fibers (CFeq) for Cd2+, Pb2+ and Zn2+ ions in the single ion solutions and ternary mixture of ions Metal ion Cd2+ Zn2+ Pb2+

Single ion solution Deffx1012 2 2 (m /s) (min -1) 10.10 0.179 10.80 0.228 22.80 0.419

CFeqx10-3 (mmol/m3) 16.87 16.35 16.00

Ternary mixture of ions Deffx1012 2 2 (m /s) (min -1) 9.40 0.131 9.45 0.199 9.71 0.205

CFeqx10-3 (mmol/m3) 14.10 12.90 16.00

Both, specific rate of changes the concentration of metal ions (2) and effective diffusion coefficient (Deff) in the single ion solution have the highest value for the lead ions. The effective diffusion coefficient value is affected by thickness of the metal ions solvation layer in aqueous solution, ion-ion (same and different species of ion) and ion-fiber interactions, the surface microporosity and oxidized hemp fibers structure. In the aqueous solution metal ions are surrounded by solvation layer, whose thickness affects the ion transport through the solution. Ions with smaller radius have thicker solvation layer [60], therefore their transport toward the biosorbent surface is slower. Consequently, the diffusion coefficient of these ions is smaller. Also, in the single ion solution initial concentration of metal ions is low enough that mutual ion interaction can be neglected, so the ions keep the solvation layer when entering the fibers. Considering fact that the dimension and share of the interfibrillar spaces in the fiber structure is much higher than the dimension and share of micropores, microcavities and microcracks, further transport of ions through the fiber can be approximated with the transport through the interfibrillar spaces. The interfibrillar spaces are filled with a solution so it can be assumed that the ions keep almost unchanged salvation layer during the transport. Therefore, the ion transport through the fiber and effective diffusion coefficient is affected by

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thickness of the solvation layer. Lead ions that have larger radius compared to cadmium and zinc, and thinner solvation layer, need the shorter time to reach the hemp fibers surface. This is in agreement with the highest value for the lead ion diffusion coefficient in the infinite diluted solution (D0(Pb2+)=10.00x10-10 m2/s, D0(Cd2+)=7.19x10-10 m2/s, D0(Zn2+)=7.10x10-10 m2/s), obtained from the literature [61,62]. In the case of ternary mixture lead ion also has the highest effective diffusion coefficient, but in this case the values of Deff are similar for all three examined ions. Though the initial concentration of each metal ion was the same as in the single ion solution, there were a three times more particles. This is the reason for an intensive collision between the same and different type of ions, during the transport of these ions through the solution and fiber. As a consequence of the mutual interactions, ions lose solvation layer and change the path of transport. Mechanism of ions transport was partially changed compared to the single ion solution, and now it mostly depends from the efficiency of collision. Lead ions have the highest effective diffusion coefficient in both cases. Therefore, lead ions faster reach the surface of the hemp fiber then other two ions, and have a priority of deposition in micropores and microcracks of fibers and penetration into interfibrillar space in fibers structure. Sorbed lead ions can represent the steric obstruction for sorption of other ions. In the next step of mathematical modeling, calculated values of effective diffusion coefficient are introduced into Eq. (9) to determine concentration profiles of heavy metal ions in fiber: for the single-ion solutions and for the mixture of all three ions in solutions. The profiles of zinc ion concentrations in fibers are shown in Figure 8. The similar trend of ion concentration in fibers was obtained for lead and cadmium ions [42]. Effectiveness of sorption (model parameter α), given by Eq (13), could be explained as the measure of biosorption efficiency in regard to increased ion concentration in fibers (Figure 9).

Figure 8. Profile of Zn2+ ions concentration in the fibers depending on time of biosorption for the single ion solution and ternary mixture.

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Figure 9. The dependence between the effectiveness and time of sorption for the single ion solution and ternary mixture.

The biosorption of metal ions depends on: (1) the transport phenomena within the fibers and (2) the resistance effects which arise as the result of the electrostatic interactions between ions within the fibers. The effectiveness of sorption (α(t)) represents the influence of both processes. The effectiveness of sorption (α(t)) is primarily influenced by the transport of ions within the fibers in first 15 min (regime I). However, the resistance of the further transport of metal ions within fibers increases with the increase of the ion concentration in fibers. The resistance of the transport of metal ions within the fibers dominantly influences the biosorption in next 45 min (regime II). During the regime I effectiveness of sorption is higher for the lead ions then for cadmium and zinc, in both single ion solution and in mixture of ions. In the single ion solution the effectiveness of sorption is changed in regime II in favor to the cadmium and zinc ions. On the other hand, effectiveness of sorption value retained the same order for all three ions (Pb2+>Cd2+>Zn2+) in the mixture during the both regime. The effectiveness of sorption of Cd2+ and Zn2+ ions is higher for the single ion solution then for the mixture of ions, while for Pb2+ ion is the similar in both cases. As it is explained earlier [12], in the competitive condition (mixture of ions) short hemp fibers have a best affinity towards lead ions. Therefore, effectiveness of sorption for lead ions will have the similar value in both single ion solution and in the mixture of ions. In the same time, the effectiveness of sorption for Cd2+ and Zn2+ will decrease in the mixture of ions. Proposed mathematical model provides a better insight into phenomena of different ions transport through porous fiber matrices. Consequently, this model may be considered useful in the optimization of the complex process of biosorption. This is from great importance in the case of using short hemp fibers as filter material for removing the heavy metal ions from polluted water.

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HEMP FIBERS WASTE AS A PRECURSOR FOR CARBON MATERIALS Carbon materials with high surface area and pore volumes can be prepared from a variety of carbonaceous materials such as coal, coconut shell, wood, agricultural or industrial wastes. In the recent years, there is a growing interest in utilization of the low-cost and abundantly available waste materials and biomass as precursors for the preparation of carbon materials [63]. The usage of the waste materials represents a special way of recycling and producing useful products. At the same time the cost of waste disposal are minimized. Additionally, carbon sorbents obtained from waste can be used for water purification by removal of specific pollutants, like dyes [64-66], heavy metals [67-69], pesticides [70,71] and phenols [72]. The possibility of using different type of biomass has already been tested for production of the carbon materials [63,65,72-80]. Among other biomass types, Reed and Williams [81] have used hemp fibers for obtaining activated carbon. Hemp fiber is a lignocellulosic material that contains celluloses, hemicelluloses and lignin which are rich in carbon, and therefore presents a good precursor for carbon materials production.

CARBONIZATION OF CELLULOSIC MATERIALS Celluloses based carbon materials are obtained by controlled thermal decomposition of celluloses in the inert atmosphere and undergoes through the two phases. During the pyrolysis of celluloses, that represents the first phase and ends around 400 oC, the large amount of different compounds (CO, CO2, H2O and resinous products) are released. Therefore the weight loss is very high and obtained carbonaceous material contains 60 – 70 % of carbon. Carbonization represents the second phase with the ending temperatures over the 900 oC. During the carbonization the defect graphitic structure is formed and the carbon content is increased over the 90 %. Although the full mechanism of carbonization of cellulose is not understood completely, a summary of some of the chemical aspects of the process given by Bacon and Tang [82] is shown in Figure 10. The pyrolysis of cellulose is controlled mainly by two predominant reactions, dehydration and depolymerization (cleavage). Physical desorption of water is the first processes during pyrolisys, and take place between 25 and 150 oC, followed by dehydration of the cellulosic unit which continues between 150 and 240 oC. The dehydration reaction stabilizes the cellulose structure: during the dehydration, elimination of the hydroxyl groups results in double bonds, conjugated double bonds, and subsequently, in an aromatic structure. The polymeric structure is basically retained through dehydration and at this temperature range weight loss is usually limited to the evaporation of water. Degradation of native cellulose fibers starts at 200 oC and ends around 380 oC, under inert atmosphere. Although the physicochemical processes taking place during the transformation of cellulose into carbon are complex, it is certain that depolymerisation of the macromolecular chains produces a variety of oxygenated compounds. This leads to the major mass loss of the solid residue through the production of volatile substances. Based on the molecular stoichiometry (C6H10O5)n the theoretical carbon yield of carbonization process of cellulose structure is 44.4 %. However, the actual yield is only between 10 and 30 %. During

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the depolymerisation of the macromolecular chains, the carbon content is decreased due to releasing of carbon monoxide (CO) and carbon dioxide (CO2), aldehydes, organic acids and tars [83].

Figure 10. Mechanism of celluloses controlled thermal decomposition, proposed by Bacon and Tang [82].

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Carbonization is the second step of controlled thermal decomposition of celluloses and represents the conversion of depolymerized structure into graphite-like layers through the repolymerization. Depolymerization to monosaccharide derivatives occurs through the thermal cleavage of the glycosidic linkage and ether bonds which is followed by decrease in degree of polymerization. These derivates are re-polymerized by forming condensed, aromatic structures and releasing gases containing non-carbon atoms (O, H). Subsequently, in the temperature range of 400 – 900 oC, the carbonaceous residue is converted into a more ordered carbon structure. The heat treatment up to 900 oC, under an inert atmosphere, leads to formation of semi-ordered carbonaceous structures. Further heating, above 900 oC, initiate graphitization, and generally amorphous carbonaceous structures converts to a turbostratic carbon structure containing graphene layers. A remarkable feature is that the carbon structure formed via pyrolysis retains some memory of the starting structure through the entire process [83]. Additionally, characteristics of obtained carbon materials depend of the carbon precursor structure and parameters of carbonization process [13].

THE INFLUENCE OF PREPARATION PROCESS PARAMETERS ON THE CARBONIZED HEMP FIBERS SURFACE CHARACTERISTICS Chemical modification of short hemp fibers prior to carbonization was used to examine the influence of carbon precursor chemical structure and morphology on carbonized material characteristics. The amount of hemp fibers structural components, especially lignin, hemicelluloses and cellulose, may affect surface characteristics of carbonized materials, especially specific surface area and amount and nature of surface functional groups [84]. In order to obtain a row material with different characteristics, short hemp fibers were chemically modified as it is described in the literature [12]. The progressive removal of the hemicelluloses was brought by treating the fibers with 17.5 % NaOH solution, while the lignin was progressively removed by treating hemp fibers with 0.7 % NaClO2. The samples obtained by chemical modification along with the original (as received) hemp fiber were then carbonized at 1000 oC under constant nitrogen flow (150 cm3/min), with the heating rate of 5 oC/min. The isothermal time at maximum carbonization temperature was 30 min. After carbonization, five samples denoted Ch1, ChL5, ChL60, ChH5 and ChH45 (as it is shown on the Figure 11), were obtained [13]. The changes in both chemical and structural properties of the hemp fibers incurred as a result of alkali and oxidative chemical treatment are already explained in this Chapter. After carbonization all samples retain fibrous structure of the precursor fibers. Compared to the carbonized hemp fibers obtained from unmodified fibers (Ch1, Figure 12a), the carbonized hemp fibers modified prior to the carbonization (ChL5, ChL60 and ChH5, Figure 12b, 12c and 12d)) are characterized by visible surface fibrillation. In the case of sample ChH45 (Figure 12e) the fibrillation is even more pronounced. The amount of lignin, hemicelluloses and cellulose in the carbon precursor affects the specific surface area of carbonized materials [84]. Lignin has been found to be effective in creating pores, as evident from the work by Kennedy et al. [85]. Furthermore, the BET surface area was found to be highest for the carbon materials obtained from carbon precursors with highest lignin content [81]. In view of that, short hemp fiber modified by removing the

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lignin, after carbonization gave samples ChL5 and ChL60 with lower specific surface area (Table 10) [13].

Figure 11. The scheme of carbonized hemp fibers production.

Figure 12. SEM photographs of carbonized hemp fibers: a) Ch1, b) ChL5, c) ChL60, d) ChH5 and e) ChH45.

Table 10. Specific surface area and amounts of CO and CO2 evolving surface oxygen groups of carbonized short hemp fibers samples Sample Ch1 ChL5 ChL60 ChH5 ChH45

SBET (m2/g) 518.5 428.6 388.6 425.9 573.5

CO evolving groups (mmol/g) 1.718 2.641 4.364 3.513 2.054

CO2 evolving groups (mmol/g) 2.192 0.812 1.851 1.119 0.613

CO + CO2 (mmol/g) 3.910 3.453 6.215 4.632 2.667

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During the alkali treatment of origin short hemp fibers, the crystal structure of cellulose, named as cellulose I (Cell I), is transformed in to cellulose II (Cell II) [31,32]. The polymorphic transformation of Cell I to Cell II depends on alkali concentration and the time of treatment [33]. In the chemical treatment used for obtaining the carbon precursor for sample ChH45 the concentration of NaOH and the time of treatment was high enough to provide appropriate conditions for this polymorphic transformation. This transformation of cellulose I in to more reactive cellulose II is probably the reason for high specific surface area of sample ChH45 [13]. Surface oxygen complexes on carbon materials can be quantified by temperatureprogrammed desorption (TPD), as they decompose upon heating by releasing CO and CO2. TPD peaks of CO and CO2 at different temperatures are related to the bond strength of the specific oxygen groups. Thus, the position of the peak maximum at a defined temperature corresponds to a specific oxygen complex at the surface. For example, CO2 is released by decomposition of carboxylic groups at 373–673 K or lactone groups at 463–923 K. Both CO and CO2 peaks originate from the decomposition of carboxylic anhydrides in the temperature range of 623–900 K. Phenols, ethers, carbonyls and quinones give rise to CO at 973–1253 K [86-89]. The quantities of CO and CO2 released during the TPD experiments correspond to the total amount of oxygen groups present at the carbonized hemp fibers samples surface (Table 10). For all samples modified prior to carbonization amount of CO evolving groups increase while amount of CO2 evolving groups decrease compared to sample Ch1. It is interesting that sample ChL60 has the highest amount of surface oxygen groups and sample ChH45 the lowest, which are totally opposite to the values of their specific surface area. Also, the extension of the oxidation treatment time leads to the increased amount of the surface oxygen groups, while the extension of alkali treatment time leads to the reduced amounts of the functional groups.

Figure 13. The scheme of activated hemp fibers production.

Specific surface area and the amount of surface oxygen groups can be increased by activation of carbon material surface [13,86]. Activation of carbonized hemp fibers using different amounts of potassium hydroxide, as activating agent, is schematically presented in

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Figure 13. During the activation process, decomposition of KOH molecules is followed by gasification process under high temperature: 2KOH → K2O+H2O H2O+C → CO+H2 Stronger activation, i.e., increased ratio of KOH, open up the porous structure and increases specific surface area up to 673 m2/g for sample ACh1 and 2192m2/g for sample ACh2 [13].

Figure 14. TPD spectra of carbonized short hemp fibers samples: (a) CO and (b) CO2 desorption profile.

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Potassium hydroxide activation increases the amount of both CO and CO2 evolving groups with increased amount of KOH used. TPD profiles of CO and CO2 evolution for all tested samples are shown in Figure 14. The TPD spectra of CO2 desorption profiles of all tested samples show an intensive peak at relatively high temperature (from 890 K to 1073 K). For the sample ACh2 this peak is most intensive and shifted to the higher temperatures. It can be noted that activation process as well as the increased amount of activating agent increase the intensity of the peak and shifts it to the higher temperature, which suggests the stabilization of surface oxygen groups. For all tested samples, CO desorption profiles have a maximum at the temperature which coincides with the maximum in CO2 desorption profile indicating the existence of anhydride groups, which decompose upon heating by releasing both CO and CO2. The increase of this peak area, with increased amount of KOH used for activation, suggest that high amount of anhydride groups on the surface of activated hemp fibers samples is probably consequence of the KOH activation process [86].

CARBONIZED AND ACTIVATED HEMP FIBERS APPLICATION AS SORBENT MATERIALS The possibility of producing carbon materials with high specific surface areas, microporous structure, high adsorption capacity and degree of surface reactivity brings the variety of application for these materials. The carbonaceous materials have been proved to be effective sorbents for removal of metal ions as well as their complexes. Their large sorption capacity is linked to well develop internal pore structures, a large specific surface area, and the presence of a wide spectrum of surface functional groups [87]. In the past decade, there is a growing interest in using different type of biomass for production of carbon materials [68,69,90], as a low cost and ecologically acceptable alternative to activated carbon. Carbonized hemp fibers obtained by carbonization of origin and chemically modified waste hemp fibers was used as an efficient, low-cost sorbent for heavy metals removal. Sorption properties of carbonized hemp fiber samples tested through the heavy metal ions adsorption are presented in Figure 15. The increase of the heavy metal ions initial concentration leads to the increase of the adsorbed equilibrium amount. For the initial concentration of 50 mg/dm3 all samples obtained by chemical modification of carbon precursor have similar sorption capacity, which are considerably higher compared to the sample obtained by carbonization of unmodified precursor (Ch1). With increasing the initial concentration up to 100 mg/dm3, the sample Ch1 shows the lowest sorption capacity for lead ions, while its sorption capacities toward cadmium and zinc ions have comparable values. Also, obtained results (Figure 15) suggest that changes in carbon precursor morphology, caused by chemical treatment, affect the sorption process and sorption capacity of examined samples.

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Figure 15. Sorption capacity of carbonized hemp fiber toward a) Cd2+, b) Pb2+ and c) Zn2+.

In order to connect sorption process of heavy metal ions with structural parameters of carbonized hemp fibers (CHF), mathematical model previously developed for prediction of heavy metals biosorption, and described in this Chapter, was upgraded. For this purpose adsorption of lead ions, which is proved to be the most concurrent ion during the adsorption from the mixture of heavy metal ions [91], was used. Since, transport of ions depends on ion concentration in water solution and structure of fibers, model consideration included two successive steps: analysis of ion transport from water solution through CHF and characterization of CHF structure. For ion transport analysis, developed model was upgraded [92] by introducing the damping coefficient that quantifies the influence of fibers morphology and surface porosity on ion transport, while ion transport through the porous matrices is characterized by the effective diffusion coefficient. Additionally, structure of carbonized hemp is described by: the pore volume as function of pore diameter, the porosity and the average tortuosity. Effective diffusion coefficient, damping coefficient and the lead ion concentration profile within the carbonized hemp fibers, obtained as results of proposed mathematical model, give the insight in the mechanism and the rate of adsorption process, while average tortuosity connected the sorbent structure and ions transport through the sorbent. Figure 16 shows the correlation between model prediction and experimental data obtained for lead ions concentration within the sample Ch1.

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Figure 16. Correlation between model prediction and experimental data obtained for lead ions concentration within the sample Ch1.

As it was shown in Figure 16, model prediction is well fitted with the experimental data for the initial concentration up to 200 mg/dm3. With further increase of initial ion concentration in solution data obtained by model prediction and experiment starts to differ, but remaining in good correlation. A good agreement between model prediction for both structural and ion transport model parameters and the experimental data, indicates that the proposed mathematical model can be successfully used for optimization of heavy metal ions adsorption process. Different carbon materials have been widely used as sorbents in the solid phase extraction (SPE) which is an efficient and economical sample preparation technique for preconcentation of the target analyte. This method has been previously applied to the determination of many pesticides in natural water and crops due to its substantial advantages such as providing higher concentration factors, decreasing sample preparation time, reducing costs, and requiring less solvent [93,94]. Following the standard SPE procedure, carbonized and activated hemp fibers described previously in this chapter were used as a sorbent in the solid-phase extraction for pesticide analysis in water samples. Extracts, obtained after SPE procedure, were analyzed by liquid chromatography–tandem mass spectrometry technique. The pesticides belonging to the different chemical classes as triazine (atrazine, simazine, propazine), neonicotinoid (imidocloprid, acetamiprid, thiamethoxam), carbamate (carbofuran, methomyl), organophosphate (monocrotophos, dimethoate, malathion, acephate), hydroxyanilide (fenhexamid), diacylhydrazine (tebufenozide) and phenylurea (linuron) were chosen. The method recoveries obtained using carbonized hemp fibers as a sorbent in SPE procedure is presented in Table 11 and Figure 17.

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Table 11. Recoveries of selected pesticides obtained using different carbonized hemp fibers as SPE cartridges

Pesticide Thiamethoxam Monocrotophos Imidocloprid Acetamiprid Tebufenozide Fenhexamid *

Ch1 ChL5 Recovery (%) (RSD (%)) 62.9 (0) 93.1 (8) 14.3 (11) 57.2 (17) 64.2 (7) 88.8 (19) 61.9 (14) 105.8 (12) 61.4 (10) 95.3 (1) 40.4 (13) 71.1 (0)

ChL60

ChH5

ChH45

90.7 (13) 73.9 (0) 95.2 (7) 87.6 (15) 100.7 (15) 84.3 (0)

89.5 (5) 37.8 (20) 95.2 (7) 89.4 (0) 91.7 (12) 62.5 (3)

91.9 (2) 70.7 (10) 85.3 (7) 96.0 (18) 86.2 (1) 81.8 (13)

RSD – relative standard deviation.

Sample Ch1 could not be used as a sorbent for SPE cartridges due to low recoveries (under 70 %). Carbonized hemp fibers modified prior to the carbonization can be used for preconcentration of few pesticides: thiamethoxam, imidocloprid, acetamiprid, tebufenozide and fenhexamid. Additionally, samples ChL60 and ChH45 can be used for preconcentration of monocrotophos. Activated hemp fibers sample ACh1 can be used for preconcentration of all examined pesticides except for methomyl, imidocloprid, linuron and fenhexamide (Figure 17). Activated sample ACh2, can be used for all examined pesticides except for acephate, methomyl, linuron and fenhexamide. Recoveries obtained for activated samples are comparable with those obtained for commercial cartridges [13]. In the case of acephate, dimethoate, simazine, carbofuran, propazine, malation and tebufenozide recoveries obtained by activated hemp fibers was even better than those obtained with commercial cartridges.

Figure 17. Recoveries of selected pesticides obtained using activated hemp fibers as SPE cartridges.

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Comparing the results obtained in the SPE experiments with the surface properties and morphology of the carbonized and activated samples, it can be noted that the best SPE efficiency was achieved with activated hemp fibers samples with the highest specific surface area and the amount of surface oxygen groups.

CONCLUSION The research summarized in this chapter represents an attempt to explain the influence of chemical modification on hemp fibers structure and consequently on their properties. Hemicelluloses and lignin removal, induced by oxidative and alkaline treatment, affects the fiber structure and improves the fiber properties that are of great importance for their usage for clothing, working and protection textile materials. The influence of hemp fiber chemical composition on their heavy metal ions sorption potential, were assessed by evaluating the water and metal ions uptake capacities of differently modified hemp fibers. The process of heavy metal ions biosorption on short hemp fibers was clarified by mathematical model development. Proposed mathematical model provides a better insight into phenomena of different ions transport through porous fiber matrices, and possibility of optimization of the complex process of biosorption. Also, chemical modification of hemp fibers, prior to carbonization, affects the specific surface area, amount of surface oxygen groups and morphology of carbonized hemp fibers. Furthermore, activation of carbonized materials with potassium hydroxide improves sorption properties of carbonized hemp fibers by increasing the specific surface area (up to 2192 m2/g) and amount of surface oxygen groups. Good sorption properties of short hemp fibers, obtained as the waste material from textile industry, and therefore their very low price in comparison with commercial sorbents highly recommends their use for purification of wastewater. On the other hand, short hemp fibers represent an attractive low cost precursor for carbon material production. Due to the good adsorption properties toward heavy metals and pesticides, carbonized and activated hemp fibers were successfully used as a sorbent for the purification of water polluted with pesticides and heavy metals. Also, activated hemp fiber sorbent used for analyte preconcentration in the solid-phase extraction procedure for pesticide analysis in water samples, showed even higher efficiency in pesticides preconcentration than expensive commercial cartridges.

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In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 17

TEXTILES USING ELECTRONIC APPLICATIONS Marica Starešinič, Andrej Javoršek and Dejana Javoršek University of Ljubljana, Faculty of Natural Sciences and Engineering, Ljubljana, Slovenia

ABSTRACT Textiles, from fibers to fabric, with integrated special electronics are more and more used as special materials in newly developed smart clothing. Simple systems are based on electronic elements integrated in pockets and connected with soft wires, while in more developed systems, conductive fibers are used to connect sensors, processors, LED lighting, photovoltaic cells, communication elements and more. Hybrid systems, with permanently integrated electronics, are developed with the elements that are washable and can be used in extreme weather conditions. Different microcontrollers (ATMEL ATmega, ATtiny etc.) used in the products of wearable electronics – LilyPad Arduino, are already available. These textiles can be used as protective clothing due to their material properties for heat, fire, increased visibility and UV protection. For such a protection, electronic sensors can be integrated in combination with integrated batteries and photovoltaic cells that generate electricity, which is stored in batteries. Special fibers can generate power when in motion or when exposed to light and this can be used for the power or reversed, to light the integrated OLED lights. Such textiles can be used in all kinds of activities in different terrain and weather conditions as sports and free time activities as well as in different accidents, natural or transportation, to save lives. These technologies are also used in medicinal applications, when the clothing with integrated sensors can measure patient’s conditions and transmit the data to doctors. In this chapter, textile applications with integrated electronic elements are presented on several examples. The safety vest that was presented at the LOPE-C conference in Frankfurt, with integrated photovoltaic cells and LED lights, can be used in conditions for better visibility on roads and in the case of accidents. Another example is textiles with integrated microcontrollers in the combination with different sensors, e.g., temperature or light, as well as LED lights, which enable numerous combinations of their usage, for protection or decoration, or simply for the color/lighting effect. The integration of a

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Email: [email protected].

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Marica Starešinič, Andrej Javoršek and Dejana Javoršek custom made printed circuit board and designed program for a different action of LED is represented. The research shows that the knowledge from various fields, e.g., textiles, chemistry, electronics and programming, can lead to the creation of textile applications with electronic elements.

Keywords: Wearable electronics, LED light, microcontroller, printed circuit boards

INTRODUCTION Smart textiles, from fibers to fabrics, with integrated special electronics are nowadays used to develop smart clothing. In this paper, some examples for future designs and development are presented, as well as the safety vest that was presented at the LOPE-C conference in Frankfurt with integrated photovoltaic cells and LED lights. Smart textiles are, by definition, textiles which respond to the changes in the environment as a result of mechanical, thermal, chemical or electromagnetic influences [1]. Interactive textiles [2] represent textiles that have built-in into their structure the elements to control (sensors, switches, communication components, batteries). Most commonly, these elements control the health care functions (pulse, temperature, blood sugar etc), enable communication or represent the security and entertainment systems, as well as they allow the power supply thereof. The development of textiles with electronic components can be subdivided into: –

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Simple systems: electronic components are incorporated into pockets sewn-in or attached over soft cables and should be removed before cleaning, e.g., LED lighting devices; Hybrid systems: the elements are a part of permanent fabrics, woven or embroidered, using conductive yarns; Complete integration: the elements are integrated, using the fibers with special properties that act as electronic textiles (sensors etc).

The functions [3] of textiles using electronic applications are: – Passive functions: as a result of material properties, they can sense the environment (sensors); – Active functions: as a result of installed sensors, they can act to the environment – actuators, and can work to supply energy (work actively to changes in temperature hot/cold), for protection (inflatable elements for protection against impact, missiles), protection from water – floating clothing, increased active visibility, communication – a cry for help, protection from hazardous substances, chemicals, gas, alarm and protection against radiation, measurement of vital signals (pulse, temperature etc), integrated antennas for communication and embedded components for the photovoltaic generation of electricity for the operation – independent of batteries.

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Embedded components that measure the heart function and enable monitoring of the user throughout the day, the data being transferred to a medical institution, are already used for medical purposes. After the surgery, patients wear clothing with integrated elements of control, thus allowing the movement and they avoid the pain for the installation of measurement probes for their medical condition control. For communication [4], the developed elements can be washed and are a part of the clothing, where they operate as touch screens (touch-pad), are flexible, lightweight, durable and allow interactivity. Smart textiles, which include safety clothing, are materials that allow the installation of a variety of technologies, e.g., various electronic components, in clothing. Such fabrics permit the perception of the environment and thus the adaptation to different conditions. The main functions enabled in smart textiles are integrated sensors [5] that measure vital functions (medical textiles), enable communication, processing and storage of data, acquisition and transmission of energy (including PCM materials – Phase Change Materials) [6]. Electronic components can be fitted directly into textile fibers, e.g., conductive materials and conductive textile fibers, diodes, transistors and photovoltaic fibers. Current electronic components prepared on a silicon base are not flexible whereas the new elements developed on the base of organic polymers are. The fibers that are made from materials which convert light into electricity or electricity is the result of the fiber movement [7] enable the production of electricity. The energy is stored in batteries and when necessary, it powers the built-in OLED lighting. At MIT (Massachusetts Institute of Technology), dyes have been developed for the print of solar cells [8] on different materials, including textiles.

USE OF SMART TEXTILES Smart textile [9] products have been used in various fields, as smart textiles SFIT – Smart Fabrics and Interactive Textiles, as wearable technology (wearable tech), and as interactive textiles. The areas of application range from the clothing for personal protection, e.g., work clothes for special environments, for the protection of the health of workers and for the protection in extreme sports in a variety of environments (hot, cold, wet, dry etc). Smart textiles are intended for everyday use, heated/cooled clothing, for entertainment (clubs, concerts, public events) and special effects with fashionable elements such as built-in lighting, changing colors, as well as for communication. Many of these technologies are being used or planned for use for the elderly who need active assistance or protection in everyday life (control and communication – garments with wearable physiological sensors) in order to reduce the costs of care and treatment. The research is conducted in the areas of direct installation in the clothing, enabling easy maintenance (washing) and increased generation of energy or lower consumption to operate. Energy can be produced on the basis of photovoltaic cells that can be a part of the garment – as a fashion accessory or using piezo crystals, based on the movement of MEMS (MicroElectronic Mechanical Systems). It also works in the field of storage and use of heat energy that is released in the movement – walking user. For all these cases of energy generation, it is

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necessary to develop more storage options to be able to use printed batteries that are smaller and can be incorporated into products. All of the above results in increased consumption and increased amount of post-consumer textile waste. Development can take place in the direction of one time use – large quantities of waste, or multiple uses – problems of maintenance, but less waste. The ecology [10] of smart textiles is still at the beginning, which means that there is still a lot of work to be done and the need for deciding whether to use better and more expensive organic materials or recycled towards the development of smart textiles. Of course, these problems are also the opportunity for smaller companies which could focus on the development and manufacture of tailor-made eco-smart clothes. This could lead to the development of products with high added value, with added knowledge and the use of novel developed materials. In today’s world, when electronics become a part of clothing, with embedded microcontrollers and variety of sensors (e.g., temperature or light) and LED lighting, endless combinations for use in both protective and decorative purposes are allowed. Microcontrollers that can be washed, which is their major advantage, allow various connections between the LED elements that can be programmed for any application, which is extremely important for the use in textiles. On the market, there are different microcontrollers (e.g., ATMEL ATmega, ATtiny etc) which can be used in the products of wearable electronics, e.g., LilyPad Arduino [11]. By using these microcontrollers, different applications can be developed, with custom made circuits with arbitrary shape and at reduced price. In our research, the design of printed circuit boards and programs for different behaviors of LED lighting (gradual or simultaneous switched LED lighting) was performed [12]. The final product represents a warning-decorative LED light arrow that lights up differently. The research showed that the knowledge in the field of textiles, chemistry, electronics and programming contributes to the manufacture of high quality applications that in addition to textile components also includes the elements of electronics.

EXAMPLES OF SMART TEXTILES PLED Dress Clothes are changing every day, not only on the basis of fashion trends, but also to follow the research in the field of technology, new materials and innovations from other fields. Predicting the future has never been easy, people have predicted flying cars, peace, a diseasefree world etc – which has not (yet) happened, while nobody foresaw the use of mobile phones, 3D printed food and invisible clothes. At fashion events, we can see clothing equipped with the LED technology and micromotors that change dimensions and act as a light show. Chalayan [13] presented hightech dresses that transform on the body and translated them into wearable, commercially viable pieces. The models, when walking, activated the application at the collar and the fabric unraveled to reveal an entirely different look. Figure 1 shows the clothes illuminated by LED lights, which is interesting from the design point of view.

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Figure 1. Dress with integrated PLED (Polymeric Light Emitting Diode) (Source: Museum of Science and Industry in Chicago, online: http://www.crunchwear.com/cute-circuit-galaxy-led-dress). Cute Circuit Galaxy LED Dress.

Figure 2. Schematic drawing of photovoltaic fiber.

Figure 3. Photovoltaic fibers [17] and single fiber [18].

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Figure 4. Printing dress and detail of keyboard.

For the production of such garments, fabrics with special properties are necessary, e.g., photovoltaic fibers [14], which act as photovoltaic cells for generating electrical energy. Figure 2 shows a scheme of such fibers. Fibers can under the influence of light, wind or rain generate electric potential energy and act as a hybrid photovoltaic-piezoelectric device. Hybrid films are constructed by depositing an organic photovoltaic cell on a commercial PVDF film, while hybrid fibers are developed by depositing an organic solar cell on a piezoelectric [15] polymer fiber. When the hybrid film/fiber is subjected to mechanical vibrations from the wind, rain or tide, the piezoelectric part produces an electrical voltage that is converted to a constant DC voltage by a rectifier. The photovoltaic part of the hybrid film produces constant DC voltage from the solar energy. Electrical energy can then either be used online or stored in a battery. These materials are now available as an energy harvesting device for the use in various e-textile [16] applications. Materials can be fitted on textiles as added materials on the surface or integrated as a part of the material itself, e.g., photovoltaic fiber [19]. An interesting example of this technology is the printed dress which acts as a screen “Printing Dress” [20]. The dress integrates different technologies. It consists of three main parts of the upper corset and a skirt. The corset has fitted four elements LilyPad Arduino 11, a USB port for connecting to a laptop computer, keyboard, a built-in corset and wires to connect. The skirt is made up of a material with incorporated aluminum wires and hangs over the projector which projects images directly onto the skirt. Each time the user presses a key, it communicates with the processor to display the animation typewritten text on the skirt. In Figure 4, the dress [21] is presented. The dress is presented as a prototype of the concept and application of printed electronics in the clothing purposes. The experience will contribute to the creation and development of smart clothing. Nowadays, the dress can be used as a tool to communicate or tweet.

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Safety Vest In the more and more changing climate on the planet, we have to be able to work and travel in the most challenging situations. The weather pattern can change very fast from hot to cold, from draught to floods, so there is a need for the clothing to protect us. The advances in new textiles and printed electronics on flexible substrates can together offer some interesting possibilities. The OE-A association (Organic Electronic Association, Germany), organizer of LOPE-C, presented an international competition for student projects in order to present the possibilities of using printed electronics, they offered a set of elements that had to be assembled in working demonstrator. Safety clothing – the safety vest presented in Figure 5, with printed solar cells on the back and LED lights was developed at our department. The generated energy was stored in the built-in battery and when necessary, the LED lights that are on the back can be used. The basic concept (cf. Figure 6) is to use polymer solar cells to generate the power that is stored in the built-in batteries and used for better visibility on the roads or in nature. The polymer solar cells (Konarka), batteries and LED (Light Emitting Diode) lights are linked by the special built-in softwire, the switch, battery and operation button being in the pocket. In the sunlight, solar cells convert light into electricity, the energy is stored in the batteries and when it gets dark, the LED lights, which are integrated on the back, give light. Previous applications based on reflection, in our case the LED, give light in the dark. LED lights are semiconductor diodes that emit light under the influence of electricity. Photovoltaic cells are the elements that unlike LED lights emit electricity when under light. Unlike past examples of safety clothing that acted on the principle of reflective elements [22] embedded in clothing, our safety vest in Figure 5 has built-in LED lights that are powered by photovoltaic cells. Figure 7 presents the details of the links which are located in the inner side. The basic elements consist of polymer photovoltaic solar cells, LED lighting and batteries. The safety vest represents the beginning of the research in the field of clothing and the added value represented by the elements of printed electronics. Photovoltaic polymer cells printed on a flexible substrate are suitable for the use on textile substrates.

Figure 5. Safety vest on model of conference LOPE-C 2011.

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Figure 6. Basic concept and developed model.

Figure 7. Integration of polymer photovoltaic solar cells, LED lighting and batteries.

Figure 8. Power plastic photovoltaic cells.

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Decorative Arrow with Custom Made Printed Circuit Board In addition to the development of high-tech fabrics for the manufacture of sports clothing [23], it is always possible to achieve better sports results with the incorporation of different elements into fibers and fabrics, which is becoming more and more popular. Some of these elements are microcapsules. Back in the early 1980s, NASA developed the technology for embedding microencapsulated phase change materials into textiles for their temperature control [24], [25]. In the printing and graphic arts industry, the microcapsules are used for pharmaceutical and medical purposes, in cosmetic and food industries, for agricultural products, as well as in the chemical, textile and construction industries, biotechnology, photography, electronics and waste management [26, 27, 28]. In addition to the microcapsules integrated into fibers, there can be different electronic elements, interlacing for the protective or decorative purposes. Electronic components can be fitted directly into textile fibers (hybrid systems) or integrated in pockets connected via flexible cables, e.g., batteries connected to LED lights (simple systems) [29]. Different integrated sensors can be used for a variety of medical purposes, e.g., for the control of respiration or the measurement of respiratory signals [30]. One study presented the usage of sensors and a printed circuit board embedded in textiles, which enables the detection of the changes in the basic life functions for infants, e.g., breathing and heart rate [31], while another study improved the integration of sensors and electronics into textiles enabling the control of the ECG combined with wireless communication [32]. Ultrasonic sensors in combination with a printed circuit board in textiles can be used to detect the obstacles in helping people with impaired vision [33]. The sensors are small, use little power, can be installed internally and can be washed. Embedded microcontrollers, in combination with a variety of sensors (e.g., temperature or light sensors) and LED lighting, can be programmed and used for any purpose. Their advantage lies in the fact that they can be washed, which is for the use in textile applications extremely important. On the market, there are different microcontrollers available (e.g., ATMEL ATmega, ATtiny etc), which are used in the products of wearable electronics such as LilyPad Arduino 11. LilyPad Arduino was designed and developed by Leah Buechley in collaboration with the company SparkFun Electronics. Wearable electronics LilyPad consist of different components (LED light, processor board, light sensor etc). LilyPad electronics are well suited for prototypes and unique design products, while their size (processor board is approx. 50 mm in diameter and approx. 3 mm in thickness) and price make them unsuitable for the mass production or very small items. Some researchers design their own printed circuit boards, while others use LilyPad Arduino microcontrollers, e.g., for an immediate determination of the pH value of the sweat that is excreted in sporting activities. In that case, Arduino controls the operation of LED lights that change color according to the measured pH value of the sweat [34, 35]. The advantage of self-made decorative-protective applications is that they are made as a separate element which can be integrated into various garments or fashion accessories, that they are affordable, and their size and purpose is adjusted to the application. Another example of our work presents a design of wearable electronics that consists of LED lights, a processor, circuit board and custom written program for different behaviors of these LED lights (gradually or simultaneously switched LED lights). The final product represents a warning-decorative arrow shaped with LED lights that light up differently.

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Figure 9. Printing template of circuit board.

Figure 10. Printed circuit board.

Figure 11. Insertion of electronic components a) side view, b) back view.

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Figure 12. Soldering.

For that case, a printed circuit board was designed using the program EAGLE (Easily Applicable Graphical Summary Layout Editor) from CadSoft, in which we made a printed circuit diagram which represents the logical symbols and signs of electronic components and their connections. In Figure 9, the printing template of the circuit board is represented. The manufacturing of a printed circuit board (cf. Figure 10) was followed by the drilling of holes for the insertion of electronic components (cf. Figure 11) and solder (cf. Figure 12) electronic components into the pre-prepared printed circuit board. The software that is run by a microcontroller was designed in the C programming language in the program Arduino 11 1.0 and is shown in Table 1. Figure 13 presents the operation of LED lights for the final application – warning-decorative arrow. The presented program code allows a gradual or simultaneous ignition of LED lights. In Figure 14, the final product is presented. The advantages of our applications are that they still present the most inexpensive option of the relevant microcontroller – in our case ATtiny13 – and a precise adjustment for the desired final product with a manufactured printed circuit board is allowed. The presented application (cf. Figure 14) can be used for various purposes, e.g.: – – – –

for clothing (sportswear, roller skaters and cyclists on the road, for sports activities in low-light conditions, as well as for clothing for entertainment in nightclubs), for fashion accessories (brooch, add-on bag), for warning safety margin for pets on walk and for marking and identification of luggage when traveling.

Possible uses depend only on the imagination of the users. The advantage of the application is in the fact that it can be washed, which is especially for sportswear of extreme importance and it is only necessary to remove the battery before washing. Due to the battery, such products are not suitable for use under water, whereas if the application is well protected with waterproof elements, it can be used in the case of water sports, or in other extreme wet conditions.

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Marica Starešinič, Andrej Javoršek and Dejana Javoršek Table 1. C program code for microcontroller #include uint32_t GUT = 0; uint32_t STEP_DELAY=0; uint8_t U=0; void setup() { DDRB = 0b00011111; // all ports on the controller are output PORTB=0x00; // when initialized all ports turned off } void loop() { GUT=millis(); // assignment of system time if(GUT-STEP_DELAY>300){ // delay for 300 ms before next step if (U < 5){ // during first five steps turn on the port with corresponding number PORTB |= _BV(U); U++; // increase step } else if(U == 5){ // in step 5 PORTB = 0x00; // turn off all ports U++; // increase step } else if(U == 6){ // in step 6 PORTB=0xff; // turn on all ports U++; // increase step } else if(U == 7){ PORTB = 0x00; // turn off all ports U++; // increase step } else if(U == 8){ PORTB=0xff; // turn on all ports U++; // increase step } else if(U == 9){ PORTB = 0x00; // turn off all ports U++; // increase step } else if(U == 10){ PORTB = 0b00010001; // turn on first and fifth port U++; // increase step } else if(U == 11){

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PORTB = 0b00011011; // turn on first, second, fourth and fifth port U++; // increase step } else if(U == 12){ PORTB = 0xff; // turn on all ports U++; // increase step } else{ PORTB = 0x00; // in the last step turn off all ports U=0; // reset step to the firs one } STEP_DELAY=GUT; // set the time of step delay } }

Figure 13. Operation of warning-decorative arrow; a)–f) turning on additional two LED lights at the same time in five steps; A) and C) all LED lights are turned off; B), D) and F) all LED lights are turned on; E) gradually turning on four LED lights (two from front and two from back).

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Figure 14. Warning-decorative arrow.

In our case, we used only LED lights as the integral part of the application, while for other applications, a variety of sensors can be used. Examples are the sensors for sensing different lighting conditions in the environment or temperature sensors, force sensors, flex sensors etc.

CONCLUSION Clothes are changing every day, not only due to fashion trends, but also to follow the research in the field of technology, new materials and innovations. Predicting the future has never been easy, people have predicted flying cars, peace in the world without diseases etc – which has not (yet) happened, while nobody foresaw the use of mobile phones, 3D printed food and invisible clothes. At fashion events, clothing equipped with the LED technology and micromotors that transform dimensions and act as a light show are nowadays presented. Some of the materials shrink under the influence of temperature; consequently, when our surroundings get warmer, we no longer need to turn up the sleeves, since they roll up themselves. Development takes place in the direction of specific materials that can be cut with ordinary tools, and can protect against electromagnetic and infrared radiation. For medical purposes, the materials containing nanocapsules with colors that burst in the presence of infection with bacteria have been developed and with the use of UV light, doctors can quickly check for the presence of infection, as clothes change color. Furthermore, textile products are being developed that can detect the presence of infection on the skin which has been burned faster than enabled by the standard tests, which is especially important in the therapy for children. For safety purposes, the presented safety vest can be used in difficult conditions as it has integrated power-lighting system (photovoltaic cells-batteries-lights), hence making the user independent. The designed printed circuit board in combination with LED lights can be shaped into decorative-protective applications of different sizes with an optional LED lights effect, e.g., special lighting effects.

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For the production of these quality applications, in addition to textile components with integrated electronics items, we must combine the knowledge of textiles, chemicals, electronics, programming and ultimately, of ecology. The research in this area is opening up new possibilities for the development of new products in combination with the technologies in various fields.

REFERENCES [1] [2] [3]

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Smart textiles –Textile glossary e-text type. (2012). http://www.textileglossary. com/terms/smart-textiles.html. Interactive textiles – Textile glossary e-text type. (2012). http://www.systex.org /content/definition-smart-textiles. Zhang, X. & Tao, X. (2001). Smart textiles: Passive smart, June (2001) 45–49, Smart textiles: Active smart, July (2001) 49–52, Smart textiles: Very smart, August (2001), 35–37, Textile Asia. Sungmee, P. & Sundaresan, J. (2003). Smart Textiles: Wearable Electronic Systems. MRS Bulletin, 28, 585–591. Huang, C. T., Tang, C. F., Lee, M. C. & Chang, S. H. (2008). Parametric design of yarn-based piezoresistive sensors for smart textiles, Sensors and Actuators, 148 (1), 10– 15. Van Langenhove, L., & Hertleer, C. (2003). Smart Clothing : a new life. Proceedings of INTEDEC 2003. Heriot-Watt University. Elias, S. (2011). A hybrid photovoltaic-piezoelectric device, e-text type. http://www.printedelectronicsworld.com/articles/a-hybrid-photovoltaic-piezoelectricdevice-00003565.asp. Barr, M. C., Rowehl J. A., Lunt, R. R., Xu, J., Wang, A., Boyce, C. M., Im, S. G., Bulović, V. & Gleason, K. K. (2011). Direct Monolithic Integration of Organic Photovoltaic Circuits on Unmodified paper, Advanced Materials, e-text type. http://onlinelibrary.wiley.com/doi/10.1002/adma.201101263/pdf. White Paper on Smart Garments, e-text type. (2011).http://www.ohmatex.dk/pdfer /whitepaper_smart_textiles.pdf. Köhler, A. R., Hilty, L. M. & Bakker, C. (2011). Prospective Impacts of Electronic Textiles on Recycling and Disposal. Journal of Industrial Ecology, 15 (4), 496–511. LilyPad, e-text type. (2013). http://lilypadarduino.org. Javorsek, D., Staresinic, M. & Javorsek, A. (2012). Use of microcontroller with custom made printed circuit board for textile applications. Tekstilec, 55 (4), 296–301. WATCH: Hussein Chalayan’s Incredible transforming Dress; e-text type. (2013). http://www.styleite.com/runway/hussein-chalayan-transforming-dresses-fall-2013. Bedeloglu, A. C., Demir, A., Bozkurt, Y. & Sariciftci, N. S. (2010). A Photovoltaic Fiber Design for Smart Textiles. Textile Research Journal, 80 (11), 1065–1074. A hybrid photovoltaic-piezoelectic device, e-text type. (2013). http://www. printedelectronicsworld.com/articles/a-hybrid-photovoltaic-piezoelectric-device00003565.asp?sessionid=1.

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[16] Hadimani, R. L., Bayramol, D. V., Sion, N., Shah, T., Qian, L., Shi, S. & Siores, E. (2013). Continuous production of piezoelectric PVDF fibre for e-textile applications. Smart Materials and Structures, 22 (7), 075017. [17] Szondy, D. (2012). New type of optical fiber could be used in photovoltaic fabric, etext type. http://www.gizmag.com/solar-cell-fabric/25367. [18] Lee, M. R., Eckert, R. D., Forberich, K., Dennler, G., Brabec, C. J., Gaudiana, R. A. (2009). Solar power wires based on organic photovoltaic materials. Science, 324, 232. [19] Krebs, F. C. (2006). Fabrication and processing of polymer solar cells: A review of printing and coating techniques. Solar Energy Materials & Solar Cells, 90, 1058–1067. [20] The Printing Dress, Microsoft Research, e-text type. (2012). http://research. microsoft.com/pubs145919/Theprintingdress.pdf. [21] Small, S. M., Roseway, A. (2012). The printing dress: You are what you tweet, Microsoft corporation, e-text type. http://research.microsoft.com/pubs/149519/the_ printing_dress.pdf http://hlt.media.mit.edu/publications/buechley_DIS_10.pdf. [22] Safety Smart Gear, e-text type. (2011). http://www.safetysmartgear.com. [23] Nusser, M. & Senner, V. (2010). High-tech textiles in competition sports. Procedia Engineering 2 (2), 2845–2850. [24] Mondal, S. (2008). Phase change materials for smart textiles – An overview. Applied Thermal Engineering, 28 (11–12), 1536–1550. [25] Nelson, G. (2001). Microencapsulation in textile finishing. Review of Progress in Coloration, 31(1) 57, 64. [26] Staresinic, M., Šumiga, B. & Boh, B. (2011). Microencapsulation for textile applications and use of SEM image analysis for visualisation of microcapsules. Tekstilec, 54 (4/6), 80–103. [27] Fanger, G. O. (1974). Microencapsulation: A brief history and introduction. Vandegaer J. E. (Ed.), Microencapsulation – processes and applications, Plenum Press, New York, London, 1–20. [28] Boh, B., Knez, E. & Staresinic, M. (2005). Microencapsulation of higher hydrocarbon phase change materials by in situ polymerization. J. Microencapsulation, 22, 715–735. [29] Staresinic, M. (2011). Izdelava prototipa varnostnega oblačila “Safety Vest”. Tekstilec 54 (10–12), 238–244. [30] Huang, C. T., Tang, C. F., Lee, M. C. & Chang, S. H. (2008). Parametric design of yarn-based piezoresistive sensors for smart textiles. Sensors and Actuators A: Physical, 148 (1), 10–15. [31] Jourand, P., De Clercq, H. & Puers, R. (2010). Robust monitoring of vital signs integrated in textile. Sensors and Actuators A: Physical, 161 (1–2), 288–296. [32] Coosemans, J., Hermans, B. & Puers, R. (2006). Integrating wireless ECG monitoring in textiles, Sensors and Actuators A: Physical, (130–131), 48–53. [33] Bahadir, S. K. (2012). Wearable obstacle detection system fully integrated to textile structures for visually impaired people, Sensors and Actuators A: Physical, (179), 297– 311. [34] Benito-Lopez, F., Coyle, S., Byrne, R., Smeaton, A., O’Connor, N. E. & Diamond, D. (2009). Pump Less Wearable Microfluidic Device for Real Time pH Sweat Monitoring, Procedia Chemistry, (1), 1103–1106.

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[35] Curto, V. F., Coyle, S., Byrne, R., Diamond, D. & Benito-Lopez, F. (2011). Real-Time Sweat Analysis: Concept and Development of an Autonomous Wearable Micro-Fluidic Platform. Procedia Engineering, 25, 1561–1564.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 18

TEXTILES FOR CARDIAC CARE Narayanan Gokarneshan, Palaniappan P. Gopalakrishnan, Venkatachalam Rajendran and Dharmarajan Anita Rachel NIFT TEA College of knitwear fashion, Tirupur, India

ABSTRACT This chapter highlights the developments in textile materials used for cardiac care. Blood flow has been analyzed through a polyester vascular prosthesis. Woven bifurcated vascular prosthesis has been developed that has good biocompatibility. The mechanical behavior of knitted vascular graft has been analyzed. Weaving technique has been developed for making small diameter blood vessels that are found very useful in cardiovascular surgeries. A fabric prosthesis has been manufactured that is expected to respect haemo-dynamics, with a central opening, and that is associated with good fatigue resistance for long-term durability. Research has been focused to study the long term fatigue behavior of woven polyester fabrics of different yarns and construction factors to find whether they are suitable for heart valve replacement. Recent developments have focused on developing a stent that minimizes the occurrence of retenosis (blocking of artery). Weft knits have found suitability as stents for arterial implants, and have proved to be more advantageous than their metallic counterparts.

Keywords: Artery, Hemodynamic, Grafts, Prosthesis, Stent

1. INTRODUCTION The textile materials have found varied technical applications and medical textiles is one such emerging area. This chapter specifically focuses on the technological advances with regard to development of textiles for cardiology purpose. A good deal of research has been reported over the past decade and this has revolutionized the surgical procedures in cardiac care. Experimental studies on blood flow have enabled to design better artificial textile 

E-mail: [email protected].

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prosthesis. Bifurcated prosthesis has been woven adopting 3D weaving technique, and the prosthesis so woven is found to be versatile in its function. The underlying technology has been highlighted. Textile implants have saved millions of people, but they are not yet perfect because of the complexity of arterial biology and textile mechanics. Biocompatibility has been achieved but the problems of compliance and resistance to the blood flow remain. Textile vascular prosthesis made of polyester have been used in crimped form and these exhibit better mechanical properties and resist deformation, and thereby show promise. Technology has been developed for weaving small diameter blood vessels that would render vascular surgery successful. Grafts of desired size can be engineered and their properties predicted. A textile heart valve manufacturing process has been developed, consisting of forming a fabric tube in a concentric way. The process minimizes fabric deformation, especially in the zones that will experience the greatest stress when the valve is functioning. This work already shows that the textile material can be used to manufacture a tricuspid heart valve with performance that is close to that expected for such kinds of replacement prostheses. Recent research trends indicate that one can use to develop criteria for designing a fabric most highly suited for use in heart valve application.

2. ANALYSIS OF BLOOD FLOW IN POLYESTER PROSTHESIS 2.1. Review of the Earlier Prostheses Types During the earlier days progress in vascular surgery has been closely linked to the use of synthetic woven and knitted prostheses. Textile vascular prostheses made of Polyethyleneterapthalate (PET), which was porous, had been used as substitutes. This permitted good clinical performance with regard to satisfactory tissue ingrowths and biostability. The first generation of textile prostheses consisted of hand sewn woven structures. Such devices exhibited practical difficulties after implantation due to lack of compression resistance and tendency to kink. Thus crimping (imparting waviness) was suggested to give the grafts radial resistance and longitudinal compliance. The crimping had been obtained by fixation of an “accordion” pleat deformation, permitting easier implantation of prosthesis and allowing the surgeon to control the longitudinal tension. Crimping also improved the resistance of the prosthesis to kinking when crossing the knee and, also to external compression. The graft was tunnelised subcutaneously.

2.2. The Analysis Method Blood flow has been analyzed in impregnated polyester prostheses commonly used in vascular surgery [1]. Gelatin and collagen are generally used to make the prosthesis impermeable. Experimental investigations have been carried out to assess the impact of their crimping on the flow. Flow velocity profiles measured with a laser doppler anemometer reveal that crimping yields to decrease in flow velocity, particularly near the surface of the prosthesis.

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This has been followed by a numerical simulation of the blood flow in vascular prosthesis using specific computer code, which adopts finite element method. The flow has been investigated in both stationary and pulsatile cases, considering the most crucial physical parameters of the blood namely, relative density and viscosity. In literature, haemodynamics has been widely associated with pathological effects related to the vascular wall [2, 3].

2.3. Discussions and Findings of the Study Experimental measurements and numerical simulations of the blood flow in textile prostheses characterized by the wavy form of their wall under steady and pulsatile regimes have revealed the presence of two distinct zones: an undisturbed central zone that preserves the properties of the Poiseuille flow, and a disturbed zone near the wall characterized by recirculation of the fluid inside crimping associated with very low velocities and shear stress. These perturbations linked to the crimping lead to a braking of the flow detected in the experimental and numerical studies. From all haemodynamic factors, wall shear rate is the most frequently cited parameter affecting the pathobiology of arterial walls [4, 5]. The low shear stress observed in wall crimping can explain the deposit of particles and excessive cell development, which might affect prostheses. Thrombosis, the formation of clots in sanguine vessels from blood constituents, is induced by the wall alteration linked to the slowing of the sanguine current. The zones near crimping could facilitate the adherence of platelets to the wall, releasing the coagulation in the prosthesis. In this area, multiplication of endothelial cells can be explained by the low shear stresses in crimping zones. This mechanical factor can also be responsible for the haemolysis phenomenon characterized by red cell destruction under high shear rates. Several researchers, e.g., Siegel el al. [6], Blustein et al. [7], Siouffi [8], Stergiopulosel al [9] have used laser doppler anemometry, ultrasonic anemometry, or magnetic resonance imaging to measure arterial flow velocity. They attempted to study the impact of particular shapes of artery walls, like stenosis or aneurysm, on flow properties. They agree about the implication of those shapes for decreased downstream shear stress and associate the deposit of particles causing thrombosis to low shear stress. The in-vitro study led by Moore and Ku [10] on unsteady flow in a blown glass abdominal aorta model observed by magnetic resonance imaging shows that at the end of the cardiac pulsation, although the debit remains positive, low negative velocities are recorded in zones close to the wall. They have established a correlation between low shear stress measured in the anterior wall of the aorta and the progression of atherosclerosis and hyperplasia. The numerical analysis of steady and pulsatile blood flows in a vascular prosthesis have been studied. The design of textile artificial vessels requires knowledge of prosthesis flow properties, especially near the wall. These data are of great interest to manufacturers of prostheses who model the architecture of the implant as a function of local mechanical causes of physiological and physic-pathological processes. Quantitative and qualitative studies of flow fields could provide solutions for some pathology linked to haemodynamic factors in prostheses. The low wall shear stress observed in the crimping area can explain some problems that could affect prosthesis, such as particle deposit and cell wall development.

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Further work will add additional realism to blood flow-simulation. The next factor to be considered is wall motion under arterial pressure. A specific computer code presents a module solving Napier-Stokes equations for deformable mesh, which can be used for simulations in moving wall flow fields.

3. WOVEN BIFURCATED PROSTHESIS Three-dimensional fabrics have recently entered the medical field. Their specific area of application is in the weaving of vascular prosthesis. Vascular prostheses are surgically implantable materials. They are used to replace the defective blood vessels in patients so as to improve blood circulation. Conventional types of prosthesis were made from air corps parachute cloth, vignon sailcloth and other types of clothing materials. Materials such as nylon, teflon, orlon, stainless steel, glass and dacron polyester fiber have been found to be highly suitable for the manufacture of prosthesis. These materials were found to be significantly stable with regard to resistance towards degradation, and were not adversely affected by other factors [11]. Dacron polyester, which has bio-compatibility and high tensile strength, is being used over a period of time as suture thread or artificial ligaments [12–14].

3.1. Comparison of Woven and Knitted Grafts Vascular grafts are manufactured on a very small scale as woven and knitted grafts, and also as Velour and Gore Tex. Knitted grafts may be of warp or weft knitted types [15]. Velour is a fabric made from textured yarns, wherein the filaments are exposed on either or both sides of the velour grafts. The woven grafts have been used earlier. Gore Tex grafts are made of polytetrafluoroethylene and molded as one single piece. Woven grafts have a good bursting strength and resistance to fatigue. They can be woven compact enough to make them least permeable to water and blood. They are manufactured as seamless tubes on special tape looms with shuttles. Knitted grafts are comparatively more porous than woven grafts. In the case of grafts with weft-knitted structures, the mobility of yarn is higher in the course direction than in the wale direction. This is a drawback since it leads to increase in diameter with time. Such a problem ultimately leads to rupture of the graft. Hence, weft-knitted structures are not preferred in the manufacture of grafts. Conversely, warp-knitted fabrics are highly versatile since they can imitate woven- or weft-knitted fabrics with regard to mechanical performance. Also, they are dimensionally stable comparatively and show higher compliance in the course direction than in the wale direction. Woven grafts are manufactured on tape looms with shuttle, specially designed for vascular prosthesis. The grafts are made as tubes without seams. Single jersey grafts are manufactured on flat knitting machines with very fine gauge and specifically designed for producing grafts. Tubular warp-knitted structures are produced on warp knitting machines equipped with two needle bars.

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3.2. Manufacturing Technology A prototype of a manually operated loom has been developed, which is suitable for weaving of straight as well as bifurcated vascular prosthesis [15]. It is based upon the principle of 3D weaving. A separate warp yarn selection device is incorporated. The main trunk of the bifurcated prosthesis has been woven as a tubular structure using weft from the same pirn. The filling yarn is inserted in the top layer of the warp shed and then the bottom layer of the warp shed. The bifurcated branches are more difficult to make as they are individually woven. The warp sheet is split into two layers so as to weave a tubular structure. Both the layers of warp sheet are manually wound around a warp beam. After string up, the warp yarns are passed through the dents of the reed and then wound onto the cloth roll. The two branches of the bifurcated prosthesis are woven by using two weft pirns in succession. For weaving one branch of the prosthesis, the weft from a pirn is passed from the selvedge to the centre of the top layer of warp shed and then inserted from the centre of the bottom layer of warp shed to the same selvedge. The second branch is woven by repeating the operation with the second weft pirn. It is to be noted that the weft yarns do not cross the entire width of the warp shed. This requires special selection of heald frames. Hence, the warp sheets have been divided longitudinally into two equal sections. Each half of the warp sheet corresponding to one branch of the prosthesis has been selected with a special heald frame group. Eight heald frames have been used for weaving. Each of the heald frame can be placed in three different positions, namely, higher, middle and lower positions.

Figure 1. Flow chart indicating weaving of prosthesis main trunk.

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The middle position is used for weaving the branches. The two branches of the prosthesis have been woven simultaneously. The first filling yarn is inserted successively in the top layer and then the bottom layer warp sheds of the right branch and the second filling yarn is inserted in the top layer and bottom layer warp sheds of the left branch.

Figure 2. Flow chart indicating weaving cycle of prosthesis branches.

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During the first selection, the odd numbered warp threads are lifted, and during the second selection, the even numbered warp threads are lifted. The woven bifurcated prosthesis thus has the following technical particulars:      

Type of material – Texturised dacron polyester yarns (circular cross-section). Linear density – warp and weft – 16 tex (34 fibres per yarn cross-section). Number of yarns per warp sheet – 160 (for right branch).160 (for left branch). Reed particulars – 20 dents/cm. 4 ends/dent – 2 yarns for top warp sheet. 2 yarns for bottom warp sheet.

Dacron polyester yarn has been found suitable as it has sufficient resistance to be woven without ruptures. Mechanical treatments comprising of compaction and crimping and also thermal finishing treatments impart the desired tubular shape to the prosthesis. The weaving of the branches of the bifurcated prosthesis requires special heald frames so as to enable selection of the two sections of the warp sheets individually. The heald frames have been set in the intermediate position and the filling yarn has been inserted manually to the middle of the warp sheet so as to perform this special weaving. Such an arrangement is not found on existing looms weaving narrow width fabrics. The 3D weaving machine could also be utilized for the manufacture of thick ribbons consisting of two bonded fabrics and being used as artificial knee ligaments. The same material as used for the vascular prosthesis, namely, biocompatible polyester can be used. In this case, the heald frame selection requires some modification and also the yarn linear density and the density of reed have to be changed.

5. ANALYSIS OF MECHANICAL BEHAVIOR OF PROSTHESIS Graft implantation is a common surgical procedure in the management of patients having severe blood circulation difficulties. Textile technology has provided several solutions for vascular surgery and a large number of textile vascular prostheses have been implanted in patients to revascularize downstream from diseased or injured arteries. Since 1954, the date of the first transplant on man, textile implants have saved millions of people, but they are not yet perfect because of the complexity of arterial biology and textile mechanics. Biocompatibility has been achieved but the problems of compliance and resistance to the blood flow remain. In previous studies [16, 17], correlations between flow nature and pathologies in prostheses such as progression of atherosclerosis, thrombosis and hyperplasia, have been established. The first generation of cardiovascular textile prostheses made of hand-sewn woven structures demonstrated some difficulties after implantation because of lack of compressionnal resistance and a tendency to kink. Today, crimped textile implants made of polyester share the market with those molded in one single piece of PTFE. In comparison with the flat shape of molded grafts, the crimping of textile vascular prostheses showed several mechanical advantages. In fact, crimping was achieved by fixation of an “accordian” pleat deformation permitting the surgeon to control the longitudinal tension and improving the resistance to kinking. Furthermore, knitted and woven structures showed better aptitude for sutures than molded ones. For these reasons, textile implants are exclusively used in particular sites

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needing long grafts with satisfactory bending properties such as femoral bypass at the knee level. The mechanical behavior of vascular prostheses under steady and pulsatile flow has been investigated. First, a theoretical model of the deformation based on elasticity hypotheses has been established and a test system simulating blood flow conditions has been built. This test system was linked to an image-processing device permitting the measurement of prosthesis wall displacements. In the literature, the mechanical properties of biological arteries have been widely investigated. Most studies [18-20] consider that arterial tissue is a perfectly elastic material whereas studies concerning the mechanical behavior of textile vascular prostheses appear to be extremely rare. Under steady and pulsatile flow the prosthesis was bent and its axis remained in the same vertical x-y plane of prosthesis deformation under flow pressure. The image processing provided the coordinates of all points belonging to the graft boundaries and permitted the determination of vertical displacement of the mid-point of the prosthesis lower boundary. Vertical displacements in steady flow conditions, and the evolution of theoretical and experimental values at different pressure levels, corresponding to a flow variation between 0 and 60 mL s-1, have been tested. The experimental results showed that vertical deformation remained constant between p = 10 and p = 30 mm mercury and increased with pressure elsewhere. The theoretical model predicted linear behavior for the vertical displacement. The Dialine® II prosthesis tested showed complex displacements of the boundaries under pulsatile conditions. This deformation was essentially characterized by prosthesis bending associated with a low horizontal de- formation evolution of textile graft bending during a cardiac pulse. The vertical displacement of the mid-point in the lower boundary of the prosthesis under pressure and vertical displacements in pulsatile flow conditions have been studied. These show a periodic deformation of the textile graft having the same frequency as the pressure wave. The highest vertical displacements were obtained during the pressureincreasing period (systole). This deformation shows a sudden and rapid drop at the beginning of the pressure-decreasing period (diastole). The pressure variation obtained with the pulsatile flow system and measured with the image processing device shows that the system correctly simulates the physiological flow. The pressure curves obtained have the same shape as physiological pressure curves measured for the human body and described by Westerhof et al. [19] and Womersly [20]. This flow system made it possible to see that the textile vascular prosthesis bends under flow pressure. This bending, which has never been observed with natural or molded grafts, is certainly due to the crimping of the textile prosthesis. The theoretical and experimental results show some divergences probably due to the elasticity hypotheses considered as the developed theoretical model was based on describing textile prosthesis bending under flow pressure on them. This elastic behavior was broadly suggested by natural blood-vessel deformation, cited in the literature [17, 20, 21]. Several studies concerning arterial mechanics showed that pressure inside natural grafts only induces augmentation of the diameter of the elastic natural artery. The complex behavior of the textile prosthesis seems to be linked to the viscoelastic character of the knitted fabric. An investigation of the instantaneous elasticity and relaxation module recommended by Hofer et al. [22] would lead to better results. The experimental results show the influence of the pulsed character of unsteady flow on the graft deformation. Indeed, in the case of steady flow, the vertical displacement evolves almost proportionally to the flow and pressure inside the prosthesis. In the case of pulsatile

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flow, the prosthesis bends in a periodic manner but not according to pressure evolution. During the cardiac pulse, the graft bends almost permanently. It returns to its linear position when pressure drops and bends again during that quarter of the cycle. Pulsatile flow evidently generates a complex mechanical behavior of the knitted graft in which linearity between pressure and deformation is not observed. This confirms the inadequacy of the elasticity hypotheses selected in the case of steady flow. The prosthesis behavior seems to be viscoelastic at higher stresses and elastic at low stresses because of the crimped shape of the graft walls.

6. WEAVING TECHNIQUE OF SMALL BLOOD VESSELS For success in vascular surgery involving small-diameter (< 6 mm) vessels, a graft must closely match the internal diameter of the host artery and have desired high elasticity, porosity and transverse compliance. Thus although arterial grafts have gained acceptance in larger-caliber (> 6 mm) applications, where the requirements are flexible, a vein from the body continues to be preferred for small-vessel repair. An attempt has been made to develop an understanding of the material and the construction factors that affect the values of a woven tube's diameter, pore size, elastic recovery and transverse compliance [23-25]. This information is largely absent in literature. By varying yarn size and fabric structure, seamless tubes (1.5–7 mm diameter) were constructed. These were heat set for circular shapes and characterized for size, geometry and radial elasticity. Property–structure correlation models have been presented. Grafts of desired size can be engineered and their properties predicted. A number of factors are to be considered in the design of the blood vessels. These are a) b) c) d) e)

Determination of the graft dimensions Determination of the optimum heat setting conditions for the grafts Determination of the pore size of the grafts Determination of the compliance in grafts Determination of the elastic recovery properties of grafts

The factors that affect the graft internal diameter are a) b) c) d) e)

Denting order Number of warps Yarn size Denting order x number of warps Yarn size x denting order

The factors that affect the pore size of the graft are a) Denting order b) Pick density c) Yarn size

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7. TEXTILE HEART VALVE PROSTHESIS 7.1. Manufacture and Performance Evaluation Following the first attempt by Hufnagel [26] in 1952 to replace a faulty human valve with a mechanical prosthesis, a large variety of artificial valves have been developed. There are currently two types of prosthesis that fit the surgeons’ needs. Mechanical prostheses with tilting disks (mono- or bileaflet) have shown good durability [27] but require long-term anticoagulant medication for the patient because of the high risk of thrombo-embolism. Biological valves (porcine valves or valves obtained from bovine pericardial tissue) respect the haemodynamics of humans with a central opening, carrying less thrombo-embolic risk, and in general do not require anticoagulation. Their durability (~10 years) is nevertheless limited [28] due to tissue degeneration and accelerated calcification, especially in young patients. The development of non-invasive surgical techniques [29, 30] (which are less traumatic for the patient) requires flexible material that is less fragile than biological tissue to prevent valve leaflets from rupturing when folded in a catheter. In this case, fabric seems to be particularly adaptable because of both its resistance and flexibility. A fabric prosthesis has been manufactured that is expected to respect haemodynamics, with a central opening, and that is associated with good fatigue resistance for long-term durability. At the same time, textile materials have very low bending stiffness due to the discontinuity of the fabric and yarn structure (essential for good fatigue resistance and thereby durability of the valve leaflets during the cyclic opening and closing phases), and good orthotropical traction stiffness (essential for bearing the diastolic membrane stress under the closing pressure). At the same time, the non-smooth surface of the material, when manufactured with controlled porosity, should allow limited tissue in growth, making the prosthesis completely biocompatible. The fabric material used is PET, which has been used extensively for vascular grafts and has been demonstrated to be well tolerated in the bloodstream. The prosthesis is manufactured using a forming process that will limit yarn deformation and optimize flow tightness through adapted forming geometry.

7.1a. Testing and Analysis To test the prototype in vitro, a sewing ring (also realized with fabric) is adapted to the formed valve. In the closed position, the three cusps come together to ensure proper floodtightness. In the open position, flexibility of the cusps allows flow to push them aside with low flow resistance. Free-edge curvature inverts easily during this process. Static Regurgitation As fabric has a more porous structure compared with biological material, leakage across the textile prototype in the closed position is higher than in the bio-prosthesis. Compared with a mechanical valve, the difference is not as relevant because the required functioning tolerance on the mechanical valve also partly induces leakage of the device. Changing the

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parameters of the fabric used (saturation index and yarn structure) could reduce porosity and consequently leakage. However, from a biological point of view, tissue in growth on the fabric scaffold can be expected once the valve is implanted in its biological environment. Porosity of the material should therefore naturally decrease.

Dynamic Regurgitation Dynamic regurgitation is higher for the fabric valve than for the reference valves used. However, the closing volume (14%), corresponding indirectly to the time the valve needs to close, is not far from that obtained with a biological valve (8%). It represents the largest part of the whole dynamic regurgitation and it should be easy to reduce this value by using a fabric with lower bending rigidity. The lower the material bending rigidity, the easier will be the valve cusps movement from the closed to the open position. Valve closing time will thereby be reduced. A plain weave fabric made up of microfilaments yarns and with a reduced saturation index would be the best adapted material concerning this aspect. It should be possible to reach at least the performances of the mechanical valve that do meet the physiological requirements. Pressure drop across the valve, when comparing the fabric prototype with a mechanical valve, did not show significant difference, although the fabric valve is characterized with a central opening geometry offering no flow resistance. This is due to the roughness of the cusp’s fabric surface which induces a pressure drop at the flow–material interface. In contrast, the smoothness of the biological tissue causes a reduced pressure drop with the biological prosthesis. However, the tissue in growth that will occur on the fabric scaffold, once implanted, should transform the initially rough surface into a smooth surface. Pressure drop values will therefore decrease.

7.2. Fabric Construction and Durability The rapid development and success of percutaneous vascular surgery over the last two decades [31], with the now common stent graft implantation, make this non-invasive technique attractive today even for heart valve replacement [32]. Research has been focused to study the long term fatigue behavior of woven polyester fabrics of different yarn and construction factors to find whether they are suitable for heart valve replacement. A heart valve undergoes a combination of flexural and tensile stress during operation. A fabric having lower flexural resistance can be expected to have a longer working life. Textiles are unique materials in that they have low weight, high tensile strength, and high flexibility. The latter is what makes them comfortable as apparel products. These properties in textiles are primarily due to bonding between the chains in fibers and no direct bonding between fibers in the yarn and between yarns in the fabric. Fibers in yarns and yarns in a fabric can slip when flexed. Among the fibers available, one that has been used most extensively in implants (arterial and stent grafts, for example) is polyester. It is biocompatible and resistant to degradation when in contact with body fluids [33, 34]. Polyester fabric has already been shown to be able to behave dynamically like a valve in vitro [35–37]. Tests were however only performed over a short period of time. When an assembly is bent, the resistance to bending will be governed by the combined bending rigidity of the individual elements and the frictional forces between the elements that resist

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slippage between them [38–39]. The role of friction or cohesion between the elements of an assembly is not well detailed in the literature [41, 42]. For textile heart valve development, in which extensive cyclic flexing must occur, inter-filament cohesion becomes a central issue. At each valve cycle, the valve leaflet’s material undergoes flexure and tension stress. The leaflet tension force, borne by the filaments, will generate radial yarn-to-yarn and filament-tofilament forces due to the cohesion of the fabric structure. At the contact zones, these radial forces will generate friction forces. During the flexure of the leaflet, these friction forces will consequently need to be overcome before the required flexing will occur. The energy associated with that movement will be dissipated at the contact zone where the phenomenon occurs. Cyclic flexing, therefore, leads to an increase in the energy that is dissipated, which may cause damage to the surfaces in contact after a period of time. Even if the overall (global) stiffness of fabrics is low, repeated cycling of textile heart valve prosthesis at heart pulse rate may still lead to filament damage or rupture. A detailed assessment of these effects will help to predict a material’s durability when used as a heart valve. In order to find which fabric construction factors will provide the suitable structure for the application, the effects of yarn and fabric construction on the long term cyclic bending of fabrics, have been investigated. Fabric strips of 5 mm width and of different yarn and fabric structures have been subjected to combined flexure and tensile fatigue generated by cyclically pulsating water flow. The test samples were taken out periodically from the dynamic tester and characterized for change in their bending stiffness. As flexing of the specimen involved only small strains which were well below a fiber’s elastic yield strain, the inherent elastic stiffness of specimen was assumed to remain constant. Any change in bending stiffness was then assumed to be a result of a change.

8. WEFT KNITS AS CARDIAC STENTS Weft knits are used as stents in arterial implant. Stents have been used in treating coronary arterial diseases. The stents could be implanted through a catheter to compress the plaque and open the artery lumen for efficient flow of blood after the implant. The stent needs to be flexible so as to enable it to be carried to the place in the artery where the injury is located [42]. The stent should keep the artery open by allowing flow of blood and it should also be elastic so that it may accompany contraction and expansion of the arteries as the heart beats. The radial expansion force is the resistance of the stent to collapsing during expansion [43]. This is a determining factor of the capacity of the stent to keep the adequate artery geometry for the blood to flow. The structural design and the type of material determine the radial elasticity and the flexibility of the stent. Another important property of the stent is its fluoroscopic visibility, which enables its exact detection on the harmed area of the artery. This is related to the material used to make the stent and to its dimensions. Stainless steel has a low fluoroscopic visibility, while tantalum has a good fluoroscopic visibility owing to its radio-opacity. If the stent is too small, its fluoroscopic visibility is also poor. Yet another aspect to be considered is that the stent should be able to be sterilized so as to avoid being contaminated by bacteria. A textile stent should necessarily have lengthwise flexibility, high radial expansion force, high elastic

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recovery after radial expansion, resistance to corrosion, good fluoroscopic visibility, and high biocompatibility. Invariably, biocompatibility becomes a necessary criterion for a stent for its effective use [44, 45]. The performance of a stent will depend on its interaction with the human cells and fluids. Recent developments have focused on developing a stent that minimizes the occurrence of restenosis (blocking of artery). The problem is common with metallic stents and could be improved by applying textile materials over the metallic stent or by the application of special substances over the metallic structure. Polyester is generally used in covering metallic stents. In other cases, the metallic stent is impregnated with anti blood clotting substances. Researchers have proved that occurrence of restenosis may be reduced by covering metallic stents with textile fibers, and this has paved way for the development of the 100% textile stent. Modern day stents are textile materials that could be designed with improved properties over the metallic ones. Both knitted and braided textile stents could be easily compressed, resulting in blocking of artery and thus lead to heart attack, or other problems such as stent migration etc. [46]. The flexibility of a stent is one of the most important characteristics, as without this property it may not be possible to reach the harmed part of the artery. However, to obtain the ideal flexibility of the stent, the radial compression force may be compromised. This latter property refers to the resistance to collapse when the stent expands and is the stents capability to maintain the lumen geometry. Another critical property of the stent is its biocompatibility which has to be very high to minimize the risk of thrombosis or a neo-intimate proliferative response. Recent studies have focused on development of 100%textile stents to replace commercially available metal and hybrid ones [47]. Polypropylene fiber has been found to be suitable owing to its economical cost as well as compatibility in physical properties. It is effective, readily available, versatile, and cheap. The use of monofilament will enable a greater stiffness and better results when the stent is subjected to compression, tensile, and bending forces as these will be directly borne by the yarn.

MECHANICAL PROPERTIES Studies on the radial compression tests for both knitted and braided fabrics have revealed that the best results have been obtained for the braided fabrics with a marginal increase for those heat-set at 140oC. It has been observed that as the fabric cover increases the resilience of the structures also increases [48] Studies on bending tests at 90oC for both knitted and braided samples have shown that the best results have been obtained for the braided fabrics with the effect of the heat-setting temperature producing small and unclear differences. It has been observed that resilience of the structures increases with the fabric cover. Studies on tensile tests for the knitted fabrics have shown that the structures produced with the thicker yarn have a greater stiffness. For the same yarn diameter, the shorter loop length resulted in the stiffer structure. The braided structures produced with the thicker yarn have a greater stiffness. For the same yarn diameter, the higher the braid angle the stiffer is the structure. The braided structures were considerably stiffer than the knitted structures and therefore performed better.

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Overall, the braided structures had better mechanical properties, that is, higher stiffness, than the knitted ones and this was due to their structure being made up of straight yarns rather than loops. The tightness of the construction increased the stiffness in all cases as more fiber per unit area is available to resist the loads. It has been observed that as the yarn diameter increased, the thickness of the fabrics (stent wall) also increased. This may explain the increase in the stiffness of the stents with yarn diameter due to an increase in the thickness of the stent wall.

CONCLUSION Polyester prosthesis used in vascular surgery has been crimped and analyzed for blood flow. The effect of crimping on the blood flow has been measured. Experimental studies have revealed that there are two zones of flow- one is the undisturbed central zone and the other is the disturbed zone at the vascular wall caused due to crimping. A weaving technique has been developed to manufacture bifurcated vascular prosthesis. Dacron polyester has been used owing to its biocompatibility. Studies on the mechanical behavior of crimped polyester prosthesis indicate that the behavior seems to be visco-elastic at higher stresses and elastic at low stresses because of the crimped shape of the graft walls. Yarn size and fabric structure have been varied to produce seamless tubes ranging between 1.5 – 7 mm in diameter. These were heat set for circular shapes and characterized for size, geometry and radial elasticity. Property–structure correlation models have been presented. Grafts of desired size can be engineered and their properties predicted. A fabric prosthesis has been manufactured that is expected to respect haemodynamics, with a central opening, and that is associated with good fatigue resistance for long-term durability.

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Saber Ben, A., Bernard, D., Sameer, A., Nabil, C.(2001), Blood flow in a polyester textile vascular prosthesis: Experimental and numerical study, Text. Res. J. 71(2), 178183. Budwig, R., Elger, D., Hooper, H., Slippy, J. (1993), Steady flow in abdominal aortic aneurysm models. J. Biomech. Engg. 115(4A), 418-423. Fatemi, R. S., and Rittgers, S. E. (1994), Derivation of shear rates from near-wall LDA measurements under steady and pulsatile flow conditions. J. Biomech. Engg., 116(3), 361-368. Lei, M., Kleinstreur, C., Truskey, G. A. (1997), Hemodynamic simulations and computer-aided designs of graft-artery junctions. J. Biomech. Eng. 119, 343-348. Sigel, J. M, Markou, C. P., Ku, D. N., Hanson, S. R.(1994), A scaling law for wall shear rate through an arterial stenosis. Biomech. Eng. 116(4)446-451. Bluestein, D., Niu, L., Shoephoerster, R. T., Dewanjee, M. K.(1996), Steady flow in an aneurysm model: Correlation between fluid dynamics and blood platelet deposition. J. Biomech. Eng.118, 280-286.

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Sioufri. M. (1988). Analyse des Effects Instationnairessur les Car-acteYistiques de l'Ecoulement En Avald'un Rdtrecissement Locale de Section. Doctoral thesis, Universite d'Aix-Mar-seille II, France, 12. Stergiopulos, N., Yung, D. F., Rogge, T. R. (1969), Computer simulation of arterial flow with applications to arterial and aortic stenoses, J. Biomechanics, 25(12), 1477-1488. Moore, J. E., Ku, D. N.(1997). Pulsatile velocity measurements in a model of the human abdominal aorta under simulated exercise and postprandial conditions. J. Biomech. Eng. 116(1), 107-111. Pourdehyemi, B. (1986), Vascular Grafts: Textile structure and their performances, Text. Prog. 15, 1-34. Kieffer, E. (1988), Arterial replacement: Principles and applications, AERCV editions. Paris, 68-69. Ben Abdessalem, S., Durand, B., Akesbi, S., Chakfe, N., Lemagnen, J. F.,(1999), Influence of crimping textile polyester vascular prosthesis on the fliud flow kinetics, Eur. J. Vasc. Endovasc. Surg. 18(5), 375-380. Rajendran, S., Anand, S.C (2002), Developments in medical textiles, Text. Prog.1-42. Ben Abdessalem, S., Mokhtar, B., Chakfe, N (2006), A new concept of three dimensional weaving of bifurcated vascular prosthesis, Indian J. Fib. Text. Res. 31(4)., 573-578. Ben Abdessalem, S., Durand, B., Akesbi, S., Chakfe´, N. (2001), Blood Flow in a Polyester Textile Vascular Prosthesis: Experimental and Numerical Study, Textile Res. J. 71(2), 178. Ballyk, P. D., Walsh, C., Butnay, J., Ojha, M.(1998), Compliance mismatch may promote graft artery intimate hyperplasia by altering suture line stresses. J. Biomech. 31, 229-237. Fung, Y. C., Liu, S. Q.(1993), Elementary mechanics of the endothelium of blood vessels. J. Biomech. Engg., 115(1), 1-12. Westerhof, N., Bosman, F., Cornelis, J., Noordergraaf, A.(1969), Analog studies of human systemic arterial tree, J. Biomech.2, 121-143. Womersley, J. R. (1957), Oscillatory Flow in Arteries: The constrained elastic tube as a model of arterial flow and pulse transmission, Phys. Med. Biol. 2, 178-185. Durand, B., Dieval, F., Lemagnen, J. F., Chakfe, N., (2001), Approche du Comportement DesMate´riauxSouples, in “Acquisitions Nouvellessurles Biomate´riauxVascu-laires” ESVB Mulhouse Conference, December. Hofer, M., Rappitsch, G., Perktold, K., Trubel, W., Schima, H.(1996), Numerical study of wall mechanics and fluid dynamics in end-to-side anastomoses and correlation to intimal hyperplasia. J. Biomech. 29(10), 1297-1308. Moghe A. K., Gupta B. S. (2008), ‘Small-diameter blood vessels by weaving: Proto typing & Modeling. J. Text. Inst, 99(5), 467. Cribier, A., Eltchaninoff, H., Tron, C., Bauer, F., Agatiello, C., Sebagh, L., Bash, A., Nusimovici, D., Litzler, P. Y., Bessou, J. P., Leon, M. B. (2004), Early experience with percutaneous trans catheter implantation of heart valve prosthesis for the treatment of end-stage inoperable patients with calcific aortic stenosis, J. Am. Coll. Cardiol, 43(4), 698-703. Cribier, A., Eltchaninoff, H., Tron, C., Bauer, F., Bash, A., Leon, M. B., Borenstein, N., Derumeaux, G., Anselme, E., Laborde, F. (2002), Percutaneous trans-catheter

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N. Gokarneshan, P. P. Gopalakrishnan, V. Rajendran et al. implantation of an aortic valve prosthesis for calcific aortic stenosis: First human description. Circulation, 106(24), 3006-3008. Hufnagel, C.A. (1951), Aortic plastic valvular prosthesis, Bull. Georgetown Univ. Med. Cent. 5, 128-130. International Organization for Standardization (2013), Cardiovascular implants Cardiac valve prostheses – Part 3: Heart valve substitutes implanted by trans-catheter techniques, ISO 5840-5843. Oxenham, H., Bloomfield, P.(2003), A twenty year comparison of mechanical heart valve with porcine bioprosthesis, Heart and education in heart, 89(7), 715-721. Sigwart, U., Puel, J., Mirkovitch, V., Joffre, F., Kappenberger, L.(1987), Intravascular stents to prevent occlusion and restenosis after trans-luminal angioplasty, N. Engl. J. Med. 316(12),701-706. Henry, M., Klonaris, C., Amor, M., Henry, I., Tzetanov, K.(2005), State of Art: Which stent for which lesion in peripheral interventions. Text. Heart Inst. J., 27(2), 119-126. Cribier, A., Eltchaninoff, H., Bash, A., Borenstein, N., Tron, C., Bauer, F., Derumeaux, G., Anselme, F., Laborde, F., Leon, M. B.(2002), Percutaneous trans-catheter implantation of an aortic valve prosthesis for calcific aortic stenosis: First human case description. Circulation, 106(24), 3006-3008. Van Damme, H., Deprez, M., Creemers, E., Limet, R. (2005), Intrinsic structural failure of polyester (Dacron) vascular grafts: A general review, Acta Chir. Belg.105(3), 249255. Von Recum, A., Jane, E.(1998), Handbook of biomaterials evaluation: Scientific, technical, and clinical testing of implant materials, 2nd Edition. CRC Press 1-915. Heim, F., Durand, B., Kretz, J. G., Chakfe, N.(2003), Method for producing an aortic or mitral heart valve prosthesis and resulting aortic or mitral heart valve, WO03/090645. Heim, F., Durand, B., Chakfe, N.(2008), Textile Heart Valve Prosthesis: Manufacturing process and prototype performances, Text. Res. J., 78(12), 1124-1131. Heim, F., Durand, B., Chakfe, N.(2006), Textile heart valve prosthesis: Influence of the fabric parameters on its hydrodynamic performances in vitro. Res. J. Textile Apparel, 58, 75-86. Backer, S. (1952), Mechanics of bent yarn, Text. Res. J. 22, 668-681. Grosberg, P.(1966), The mechanical properties of woven fabrics, Part II: The bending of woven fabric, Text. Res. J.36(3), 205-211. Platt, M. M., Klein, W. G., Hamburger, W. J.(1959), Mechanics and elastic performances of textile materials: Part XIV: Some aspects of bending rigidity of single yarns, Text. Res. J. 29 (8), 611-627. Skelton, J. (1974), Frictional effects in fibrous assemblies, Text. Res. J. 44, 716-722. Skelton, J., Schoppee, M.M. (1976), Frictional damping in multi-component assemblies, Text. Res. J. 46, 661-667. Owen, J. D., Livesey, R.G.(1964), Cloth stiffness and hysteresis in bending, J. Text. Inst., 55, 516-530. Palmaz, J. C. (1992), Cardiovasc. Interv. Radiol. 15(5), 279-284. Roubin, G. S, Pinkerton, C. A., Gianturco- Roubin, (1992), Stent: Development and investigation, Coronary Stents, 79-99.

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[44] Anand, S. C., Kennedy, J. F., Mirafbat, M., Rajendran, S. (Eds) (2005). Implantable devices- An overview, Medical textiles and biomaterials for health care, Cambridge, Woodhead,329-334. [45] De Arjuo, M., Fangueiro, R., Hong, H. (2001), Technical textiles: Materials of the new millennium, Braga Williams/DGI 329-336. [46] Irsale, S., Adanur, S.(2006), Design and characterization of polymeric stents, J. Ind. Text., 35(3), 189-199. [47] De Arjuo, M., Freitas, A., D. P., Zu, W. W., Fangueiro, R. M. E. (2010), Development of weft knitted and braided polypropylene stents for arterial implants, J. Text. Inst. 101(12),1027-1034. [48] Benson Dexter, H. (1998), Development of textile reinforced composites for air craft structures, 4thinternational symposium for textile composites, Japan, 5.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 19

EFFECT OF CLOTHING MATERIALS ON THERMOREGULATORY RESPONSES OF THE HUMAN BODY P. Kandha Vadivu* Department of Fashion Technology, PSG College of Technology, Coimbatore, India

ABSTRACT The human body continuously generates heat by its metabolic processes. The heat is lost from the surface of the body by convection, radiation, evaporation and perspiration. In a steady-state situation, the heat produced by the body is balanced by the heat lost to the environment by maintaining the body core temperature around a small range between 36 °C and 38 °C. Clothing is used outside the skin to extend the body’s range of thermoregulatory control and reduce the metabolic heat by thermo regulation. Clothing has a large part to play in the maintenance of heat balance, as it modifies the heat loss from the skin’s surface and at the same time has the secondary effect of altering the moisture loss from the skin. The properties of clothing materials critically influence the comfort and performance of the wearer in different weather conditions. Heat transfer through a textile assembly or a fabric system is a complex process, involving conduction, radiation and convection across the fabric system, consisting of fabric and air layers. This study discusses the thermoregulatory process of the human body, the thermal comfort properties of fabrics and the effect of clothing material on the thermoregulatory process of human body in different weather conditions.

1. INTRODUCTION Comfort may be defined as ‘a pleasant state of physiological, psychological and physical harmony between a human being and the environment. Physiological comfort is related to the *

Corresponding author: E-mail: [email protected].

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human body’s ability to maintain life, psychological comfort to the mind withstanding the effect of the external environment on the body [1]. Thermo physiological comfort is defined as the attainment of a comfortable thermal and wetness state; it involves transport of heat and moisture through a fabric. For getting thermo physiological comfort the clothing should have suitable thermal insulation properties as well as sufficient permeability to water vapour and / or sufficient level of ventilation [2]. Comfort involves thermal and non-thermal components and it is related to wear situations such as working, non-critical and critical conditions [3]. Comfort is related to complex interactions between the fabric, climatic, physiological and psychological variables. A person feels comfortable in a particular climatic condition if his energy production and energy exchange with environment are evenly balanced so that heating or cooling of the body is within tolerable limits. A core body temperature of approximately 37 °C is required by an individual for his well being. Hence, the body temperature is the most critical factor in deciding comfort. Heat is gained by the body from the sun or intermediate source of energy, by internal metabolism, by physical exercise or activity, or by involuntary contractions of skeletal muscles in shivering [4]. The heat transport to the environment is achieved through a dry flux (conduction, convection and radiation) and a latent flux produced by perspiration. The first flux depends on the insulation property of clothing while the second one depends on its moisture transport properties. The body vapour must have the opportunity to pass immediately from the skin to the outer surface of the clothing. Heat loss by conduction, convection or radiation, depends partly on the temperature gradient between the skin and the environment and this gradient is modified by varying the skin temperature. Excessive heat may be dissipated rapidly by vapourization of body water and the clothing system that hinders the free evaporation to any appreciable extent will thus be uncomfortable. On the other hand, undesirable heat loss can be prevented by increasing the thermal resistance of the barrier between the body and its environment and a fabric with low resistance will again result in discomfort to the wearer [4]. So it is clear that clothing is a key to body comfort and it should essentially help the wearer in his / her effort and not to give additional physical and heat stress.

2. MECHANISM OF THERMAL REGULATION OF HUMAN BODY The metabolic heat generated by a human body differs based on the physical activity. A base level of metabolism has been defined as the metabolism of a seated person resting quietly and for a man of typical height and surface area, the metabolic rate is about 100W. To normalize among people of different sizes, metabolism is typically expressed in per unit skin surface area. A specialized unit, the ‘met’ has been defined in terms of multiples of basal metabolism: one met is equal to 58.15 w/m². A sleeping person has the rate of 0.7 met, and reclining awake is 0.8 met. Office work (a mostly seated activity but one that involves occasionally moving about) is 1.2 met: Walking slowly (0.9 m/s or 2 mph) is 2 met, moderate walking (1.2 m/s or 2.7 mph) is 2.6 met, and fast walking is 3.8 met and jogging 8 to 12 met. In terms of energy, a sleeping person has the rate of 40.71 w/m², and reclining awake is 46.52 w/m², Office work is 69.78 w/m² [5].

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The body’s heat loss is through radiation, convection, conduction, evaporation and through respiration. In a neutral environment, where the body has no need to take thermo regulatory action to preserve its balance, evaporation provides about 12% of total heat loss and sensible heat loss provides 88%. In general, the heat transfer by conduction through the soles of the feet or to a chair is small, around 3%. In normal indoor environments with still air, the convective and radiation heat transfer are about equal. In the outdoors, wind strongly affects convective heat loss or gain and radiation can also cause large losses and gains. Sweating is important for heat regulation, and it is also a major source of water absolute loss. There are two types of water loss: insensible perspiration and sweating. Insensible perspiration loss from the skin cannot be eliminated. Daily loss is about 400 ml in an adult and the respective heat loss is 238 kcal. The heat loss can be quite significant because there is a loss of 0.58 kcal for every ml of water evaporated. The maximum rate of sweating is up to 5 ml/min or 2000 ml/hr in an acclimatized adult. This rate cannot be sustained, but losses up to 25% of total body water is possible under severe stress and could be fatal. There is always a constant amount of trans-epidermal loss of water vapour directly diffused through the skin resulting in heat loss by insensible evaporation. In addition the breathing cycle involves humidifying exhaled air producing another evaporative heat loss. The transversal moisture diffusion is about 100 to 150 ml per day per m² of skin surface representing a heat loss of 6% as great as the evaporation from a fully wetted surface. The respiratory portion of the body’s total heat loss is estimated to be 12% depending on the metabolic rate. Clothing is used outside the skin to extend the body’s range of thermoregulatory control and reduce the metabolic heat by thermo regulation. It reduces sensible heat transfer, while in most cases, it permits evaporated moisture to escape. Bed clothes are a form of clothing used for sleeping, because the metabolic rate during sleep is lower than the basal rate and the body‘s skin temperature tends to be higher during sleep, bed clothes typically have a higher insulation value than clothing.

3. MECHANISM OF HEAT TRANSFER To understand the thermal properties of the textile system, it is necessary to assess the contributions of the various heat-transfer mechanisms that may be operative. These mechanisms are conduction, convection and thermal radiation for dry heat transfer [6,7]

3.1. Conduction Fibers and air intermingle together in any textile yarns and fabrics hence the fabrics are neither homogeneous nor isotropic. However, with the preposition that the average heattransfer properties of fabrics are to be measured and calculated through the theoretical and practical work, it is reasonable to assume that a fabric is a homogeneous and isotropic material in heat transfer. In addition, since thickness of a fabric is substantially smaller than the fabric width and length in normal clothing situations, it is also feasible to consider the heat transfer through a fabric is a one-dimensional problem. Under such assumptions, the

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transient heat-transfer process through the insulating material is described as in Equation (3.1) [8].

T   2T  . t cp x 2 Where,

T t λ ρ c x

(3.1)

temperature (°K); time (s); conductivity (W m -1 K -1 ); mass density (kg m -1 ); specific heat (W S kg -1 K -1 ); and direction of heat transfer.

3.2. Convection As one of the basic heat-transfer mechanisms, convection involves the transport of energy by means of the motion of the heat-transfer medium, in this case the air surrounding the human body. When cold air moves past a warm body, it sweeps away warm air adjacent to the body and replaces it with cold air. It has been found that there is no convection inside clothing insulation even with a very low density [9]. In the finite element analysis, the convective heat transfer will be set as a boundary condition. The heat flux due to convection can be expressed as follows [10].

q  h(Tr  Tx )

(3.2)

heat flux (W m -2 ); h film coefficient (W m -2 K -1 ); TΓ out surface temperature of the fabric (°K); and T∞ temperature of the ambient atmosphere (°K).

Where, q

3.3. Radiation The heat loss carried out by radiation from a clad human body to the environment is a situation where the clad human body as the heat source is enveloped by the environment. In this case, the heat flux by radiation at the outer surface of the textile assembly is governed by the following equations (3.3) and (3.4) [6]. q    (Tr4  Tx4 ) 

Where, q

y  h( Tr  Tx )   ( Tr4  Tx4 ) n

heat flux (W m -2 );

(3.3) (3.4)

Effect of Clothing Materials on Thermoregulatory Responses ... σ ε h TΓ T∞ λ

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Stefan-Boltzmann constant which is 5.6703×10-8 W m-2 K-4 emissivity of the surface. film coefficient (W m -2 K -1 ); out surface temperature of the fabric (°K); and temperature of the ambient atmosphere (°K). conductivity (W m -1 K -1 ).

4. MEASUREMENT OF CONDUCTIVE, CONVECTIVE, RADIATIVE AND EVAPORATIVE HEAT TRANSFER OF HUMAN BODY In order to clarify the heat transfer area involved in convective heat exchange for the human body, which is required for calculating heat exchange between the human body and the environment, Yoshihito Kurazumia et al. (2004) [11] calculated the total body surface area of six healthy subjects and the non convective heat transfer area and floor and chair contact areas for the various body positions. The effective thermal convection area factor for nine common body positions such as standing, sitting in a chair, sitting in the seiza position, sitting cross-legged, sitting sideways, sitting with both knees erect, sitting with a leg out, and the lateral and supine positions are measured. The results showed that the effective thermal convection area factor for the naked whole body in the standing position was 0.942, when sitting in a chair 0.860, when sitting in a chair, excluding the chair contact area 0.918, in the seiza sitting position 0.818, in the cross-legged sitting position 0.843, in the sideways sitting position 0.855, in the both-knees-erect sitting position 0.887, in the leg-out sitting position 0.906, in the lateral position 0.877 and the supine position 0.844. For all body positions, the effective thermal convection area factor was greater than the effective thermal radiation area factor, but smaller than the total body surface area. Kurazumia et al. (2008) [12] scrutinized the convective and radiative heat transfer coefficients of the human body, while focusing on the convective heat transfer area of the human body. Thermal sensors, directly measuring the total heat flux and radiative heat flux, were employed. The mannequin was placed in seven postures. The regression equations for the convective heat transfer coefficients (hc [W/ (m2 K)]) for natural convection, driven by the difference between the mean skin temperatures corrected using the convective heat transfer area and the air temperature, are given below: Standing (exposed to atmosphere) Standing (floor contact) Chair Sitting (exposed to atmosphere) Chair Sitting (contact with seat, chair back and floor) Cross-Legged Sitting (floor contact) Legs-out Sitting (floor contact) Supine (floor contact)

hc = 1.007∆T 0:406 hc = 1.183∆T0:347 hc = 1.175∆T0:351 hc = 1.222∆T 0:299 hc = 1.271∆T 0:355 hc =1.002∆T 0:409 hc = 0:881∆T 0:368

where hc is the convective heat transfer coefficient [W/(m2 K)], and ∆T the difference between mean skin temperature corrected using convective heat transfer area and air temperature [K].

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Richard et al. (1997) [13] analyzed the convective and radiative heat transfer coefficients for individual human body segments and found that the radiative heat transfer coefficient measured for the whole-body was 4.5 W/(m2 K) for both the seated and standing cases, closely matching the generally accepted whole-body value of 4.7 W/(m2 K). Similarly, the whole-body natural convection coefficient for the manikin fell within the mid-range of previously published values at 3.4 and 3.3 W/(m2 K) when standing and seated respectively. In the forced convective regime, heat transfer coefficients were higher for hands, feet and peripheral limbs compared to the central torso region. The ASHRAE Handbook of Fundamentals (1993) has indicated a linearized radiative heat transfer coefficient hr=4.7 W/m2 per K which has been widely accepted as a reasonable whole-body estimate for general purposes [14]. Jones (1998) [15] addressed the need to include the radiation non-uniformity commonly found in indoor environments in body heat loss calculations. Extensive research has been carried out to evaluate the sweating rate. In 1998, Toshio Ohhashi et al. [16] reviewed the methods of human perspiration evaluation. In 1986, Kraning and his co-operator [17] reported a new forced-evaporation-type skin capsule for measuring local sweat gland activity in humans. Shamsuddiny and Togawa (1998) [18] reported a method of continuous monitoring of sweating in which deion solution was perfused at a constant flow rate through a chamber attached to the skin surface.

5. EFFECT OF CLOTHING ON THERMAL COMFORT Clothing has a large part to play in the maintenance of heat balance as it modifies the heat loss from the skin surface and at the same time has the secondary effect of altering the moisture loss from the skin. However, no one clothing system is suitable for all occasions. A clothing system which is suitable for one climate may not be suitable for another climate. Good thermal insulation properties are needed in clothing and textiles used in cold climates. The thermal insulation depends on a number of factors, viz, thickness and number of layers, drape, fiber density, flexibility of layers and adequacy of closures. The thermal insulation value of clothing when it is worn is not just dependent on the insulation value of each individual garment but on the whole outfit as the air gaps between the layers of clothing can add considerably to the total thermal insulation value. This assumes that the gaps are not so large that air movement can take place within them, leading to heat loss by convection. Because of this limitation the closeness of fit of a garment has a great influence on its insulation value as well as the fabric from which it is constructed. The resistance that a fabric offers to the movement of heat through it is of critical importance to its thermal comfort.

6. THERMAL COMFORT PROPERTIES OF FABRICS Thermal properties of textile materials especially thermal conductivity have always been the major concern when the comfort properties of clothing are concerned. The properties of clothing materials critically influence the comfort and performance of the wearer. Clothing is not just a passive cover for the skin. It interacts with and modifies the heat regulating function of the skin and its effects are modified by the environment. Thermal conductivity and thermal

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insulation or thermal resistances and thermal absorptivity are few measures of thermal comfort.

6.1. Thermal Conductivity The ability of a fabric to conduct heat through it is of critical importance to its thermal comfort. Thermal conductivity is a property of materials used to describe the thermal transfer behavior of the heat flow through a fabric due to a combination of conduction and radiation where the convection within a fabric is negligible. The conduction loss can be determined by the thickness of the fabric and its thermal conductivity. As defined by ASTM, thermal conductivity is the time rate of unidirectional heat transfer per unit distance, per unit difference of temperature of the planes. Another relevant concept is thermal conductance (C), also defined by ASTM as the time rate of heat flux through a unit area of a body induced by unit temperature difference between the body surfaces. Normally thermal conductivity can be expressed in equation 6.1

k

Q/ A  T / L

(6.1)

Where Q is the amount of heat passing through a cross-section A, causing a temperature difference ∆T, over a distance of ∆L. Q/A is therefore the heat flux which is causing the thermal gradient. The measurement of thermal conductivity, therefore, always involves the measurement of the heat flux and temperature difference. The difficulty of the measurement is always associated with the heat flux measurement. Guarded hot plate, as described in ISO 8302, is a widely used and versatile method for measuring the thermal conductivity of textiles. Another widely used simple method is directly using a heat flow meter as described in ASTM C 518.

6.2. Thermal Insulation Thermal insulation property of the fabric refers to the ability to resist the transmission of heat by all modes. It can also be defined as effectiveness of a fabric in maintaining the normal temperature of the body under equilibrium conditions. The most important thermal property in most of the apparels is the insulation against heat flow, which is measured by thermal resistance. It is defined as the ratio between temperature difference between the two faces and heat flux. The thermal resistance, R and thermal conductivity, K are related as follows, R = d /K

(6.2)

Where d is the thickness of the material. Since K is roughly constant for different fabrics, hence thermal resistance is approximately proportional to fabric thickness. Thermal insulation value is higher in case of silk fabric compared to cotton fabric. It is due to openness of knit

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structure of silk fabric. Silk fiber contains higher thermal insulation value as it has lower thermal conductivity (50 mw/m/k) than cotton (71 mw/m/k). In studying the thermal insulation properties of garments during wear, it is reported that thermal resistance to transfer of heat from the body to the surrounding air is the sum of three parameters: (i) the thermal resistance to transfer heat from the surface of the material, (ii) the thermal resistance of the clothing material and (iii) the thermal resistance of the air interlayer. It is obvious that heat transfer through a fabric is a complex phenomenon affected by many factors. The three major factors in normal fabrics appear to be thickness, enclosed still air and external air movement. Out of which, the entrapped air is the most significant factor in determining thermal insulation. There are "microlayers" (those between contacting surfaces of the materials) and "macrolayers" (between non-contacting surfaces) of air enclosed within an assembly and an increase of either of these can increase thermal insulation. However, the characteristics of fiber, yarns, fabrics and garment assemblies have also a major contribution towards thermal comfort. Most textile fibers are poor conductors of heat, but air conducts even less heat. If air is confined in small spaces, then convection is also minimized, and the air is ‘dead’. The higher the volume of dead air within a textile structure, the lower the thermal transmittance, therefore, the better the insulation value of the textile material [19].

7. FACTORS AFFECTING CLOTHING COMFORT Thermal wear comfort is mainly related to the sensations involving temperature and moisture. This factor responds mainly with the thermal receptors in the skin and relates to the transfer properties of clothing such as heat transfer, moisture transfer and air permeability. Clothing protects cold or heat to maintain body thermal comfort throughout the full range of human activity. Various types of tactile moisture and thermal interactions between the clothing material and the human skin determine the comfort level of a person at a given environmental condition while engaged in specific activity. The fabric type and its blend composition, the tactile and thermal insulation behavior of the fabric assembly and the moisture management capabilities of the clothing can affect the comfort [20]. A number of properties of fibers, yarns, fabrics and garments are significantly related to comfort and must be taken into account in producing suitable apparel items. However, suitable fabrics from the comfort point of view must be developed by textile technologists by proper selection of fiber content, yarn and fabric construction techniques and finishing treatments as they influence physiological comfort level through thermal retention or transmission, moisture vapour permeability, water resistance, static charge build-up, UV protection etc., Quality of fabrics for clothing depends to a great extent on aesthetic performance, comfort related properties and wear related properties [21]. Of the various properties affecting comfort, fiber type, fineness, cross – sectional shape, crimp, length and surface properties are extremely important. Fabric structure includes yarn linear densities, sett, weave, crimp levels and can influence such critical fabric properties as cover, thickness, bulk density, mechanical and surface behavior which have direct relation with fabric comfort. Finishes which affect the properties of the fabrics and appearance can

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also significantly change the performance of a fabric in clothing. Fabric properties, together with the garment design and size influences the various garment properties [21]. For getting thermo physiological comfort, the clothing should have suitable thermal conducting properties as well as sufficient permeability to water vapour and / or sufficient level of ventilation [2]. The textile structures can be developed to enhance the clothing comfort by focusing principally on the thermal and mechanical properties [4]. There is general agreement that the movement of heat and water vapour through clothing are probably the most important factors in clothing comfort, and Rees [22] describes the temperature regulation of the body in order to define the system in which comfort must be maintained. Hollies (1977) [23] stresses the importance of ‘contact comfort’ in dealing with a clothing system.

8. HEAT TRANSFER THROUGH TEXTILES In the case of clothing, the body temperature is nearly always higher than the temperature of the surrounding environment, so the normal direction of heat transfer is from the warm body to the outside environment. Of course, in particularly hot climates, the reverse is true. When the surrounding environment is colder than the body, resistance to heat transfer increases as the volume of dead air in the clothing increases, and more heat is kept near the body. As long as the air within a fabric or fabric assembly is so called ‘dead’ air, it provides good resistance to heat transfer. However, as the volume of air space increases, the likelihood of air movement, or convection, increases. When convection occurs, it is usually the dominant mode of heat transfer, overpowering any effects of reduced conduction of heat [19]. Heat transfer through a textile assembly or a fabric system is a complex process, involving conduction, radiation and convection. The combined heat transfer across the fabric system, consisting of fabric and air layers, is not simply the sum of what each mechanism would do in the absence of the others. The three heat transfer mechanisms work together to determine the characteristics of the overall heat transfer process. Heat transfer refers to the transfer of heat energy from one environment to another. Heat transfer occurs whenever a temperature difference (∆T) exists between the two environments; heat moves from the warmer surface or area to the cooler surface or area. Heat transfer will continue until the two areas attain same temperature (at equilibrium). The rate at which heat is transferred depends on ∆ T as well as any resistance imposed between the two environments. For people, this means that if the ambient temperature is lower than the body temperature (37° C), heat will flow from the body to the surrounding area. If the ambient temperature is higher than the body, heat will flow the other way and the body will become warmer. Clothing can provide resistance to heat transfer in either direction by serving as insulation between the two environments [19]. For clothing textiles, heat transfer is a complicated transient process. Generated from the body, heat transfers through the air gap between skin and fabric, then through the fabric system, to the outer surface of the fabric system. During this process, conduction, convection and radiation are all involved, may be to different extent, in determining the total heat loss.

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8.1. Effect of Fiber Properties on Heat Transfer Because various fibers differ little in thermal transmittance behavior, fiber physical structure more than chemical make-up affects the overall insulation capacity of a fabric and the thermal comfort of the user or wearer. Fibers have a high surface to volume ratio; thus there are many small spaces for dead air within a fibrous structure. In those spaces, there is little thermal transmittance because air is a very poor conductor of heat; and there is little radiation because although air is transparent to radiation, fibers are not [19]. Some fibers have physical characteristics that enhance this effect of air insulation. For example, wool is a good fiber for insulation because its natural crimp maintains a high volume of dead air. Likewise, manufactured fibers are often given a degree of crimp or surface irregularity that increases thermal resistance. In addition, hollow fibers that inherently entrap air are produced specifically for end-uses in cold weather apparel. Finally, fiber size is consideration in insulation effectiveness. Finer fabrics have more surface area, which results in more dead air space between fibers. An example is the effective use of micro-fibers in coats for use in cold climates [19].

8.2. Effect of Fabric Structure on Heat Transfer Fabric construction also influences thermal insulation. Knitted fabrics generally have a soft hand and higher heat-retaining properties compared with that of woven fabrics of a specific thickness or weight. Knits usually will entrap more air than woven fabrics, although the tightness of the weave or knit is a factor as well. In addition to the openness of the structure, other fabric characteristics are influential in thermal insulation. Pile or napped constructions are often good for cold weather because the yarns or fibers perpendicular to the surface provide numerous spaces for dead air. This effect is maximized when such fabrics are worn with the napped or pile surface next to the body, or when they are covered with another layer. Otherwise, the protruding fibers in the nap structure may conduct heat away from the body [19]. Fabric thickness is of primary importance and is usually considered to be the single more important variable in determining thermal insulation and hence thermal comfort. A thicker fabric provides more air space and, therefore, more resistance to heat transfer that a thin fabric. However, there is a limit for the thickness of the fabric. It must also be lightweight enough to be worn comfortably and, therefore, the ratio of thickness to weight is important [19].

8.3. Heat Transfer through Multilayered Structures Several textile properties affect the thermal resistance or insulation effectiveness of a fabric or a layered assembly of fabrics. An important consideration is the amount of air space contained within a textile structure. Air has low thermal transmittance and high thermal resistance. Most textile fibers are poor conductors of heat, but air conducts even less heat. If air is confined in small spaces, then convection is also minimized, and the air is ‘dead’. The

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higher the volume of dead air within a textile structure, the lower the thermal transmittance, therefore, the better the insulation value of the textile material [19]. Voinov and Karlina (1972) [24] suggested that in clothing assemblies that include air layers, the thermal resistance of the air layer varies in a complex manner with the clothing thickness; they used their results to postulate that better use of the insulating ability of air layers could be made by suitable clothing structure design. Weiner and Shah (1969) [25] however, made attempts to isolate the factors of thickness and weight, and found that for a fixed weight, thermal insulation increases with thickness, whereas the property decreases with increased weight if the thickness is maintained constant. Karlina, with various co-workers (1971) [26] distinguishes microlayers (those between contacting surfaces of the materials) and macrolayers (between non-contacting surfaces) of air enclosed within an assembly and then shows that an increase in either of these can increase thermal insulation. Fonseca (1970) [27] claims that the thermal characteristics of a clothing assembly are governed decisively by the properties of outer layer and that any interior layers merely occupy a part of the still-air layer; their presence therefore merely serves to prevent a decrease in the size of the still-air layer by collapse of the outer garments onto the body. Kawabata and Akagi (1977) [28] found a close correlation between the feeling of warmth on first touching a fabric and the maximum absorption rate of heat flow as measured physically. Markus Weder et al. [29] used Neutron radiography to study moisture transport in textiles for the first time. Clothing systems composed of layers with differing water transport properties were studied to demonstrate the feasibility of using the technique. The results were compared to the weights of the individual layers and the results of the three measurement approaches agree with respect to layer wise moisture distribution in the different textile combinations, and the radiography data provide a lateral visualization of the distributions.

9. CONTROL OF HEAT TRANSFER IN TEXTILES For effective use of textiles to enhance or control heat transfer, one must first identify the primary mode of heat transfer and then select textiles that will modify or enhance that particular mode. Textured, thick, bulky fabrics, and fabrics used in multiple layers reduce conduction. Tightly woven fabrics and designs that restrict air movement control heat transfer by convection. Finally, fabrics with smooth reflective surfaces influence heat transfer by radiation [19]. Peirce and Rees (1946) [30] pointed out that at the outer surface of the clothing exposed to the air; heat is lost by means of both convection and radiation. Farnworth (1983) [31]presented a theoretical treatment of heat transfer through a bed of fibers considering conduction and radiation and reported that no detectable convective heat transfer took place inside the fiber bed. In a more recent study, Mohammade et al.(2003) [32] presented a theoretical equation of the combined thermal conductive, convective, and radioactive heat flow through heterogeneous multi-layer fibrous materials. Dul’nev and Muratova (1968) [33] discussed heat transfer processes in fibrous materials and derived formulae from which effective thermal conductivity can be calculated from thermal, geometrical, and volumetric parameters of the components. Mitu and Potoran (1971) [34] used a formula derived by earlier workers for calculating the thermal resistance of

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clothing to determine a series of values of this property that represent acceptable comfort limits for the human body when engaged in lying, sitting, walking, running and other such activities. As long as the air within a fabric or fabric assembly is so called ‘dead’ air, it provides good resistance to heat transfer. However, as the volume of air space increases, the likelihood of air movement, or convection, increases. When convection occurs, it is usually the dominant mode of heat transfer, overpowering any effects of reduced conduction of heat [19]. Fibers have a high surface to volume ratio; thus there are many small spaces for dead air within a fibrous structure. In those spaces, there is little thermal transmittance because air is a very poor conductor of heat; and there is little radiation because although air is transparent to radiation, fibers are not [19]. Heat transfer through a textile assembly consisting of fabric and air layers can be calculated based on a theoretical model capable of dealing with conductive, convective and radioactive heat transfer. The size of the air gaps has a significant influence on the heat transfer. The balance heat flux drops by 40 per cent when the air gap increases from 2 to 10 mm. The influence of the air gap tends to become smaller as the air gap is further increased. The number of fabric layers in the textile assembly has a noted influence; more so when the ambient temperature is lower [35].

10. MEASUREMENT OF CLOTHING COMFORT USING THERMAL MANIKIN Since the first one segment copper thermal manikin in the world was made for the US army in the early 1940s, more than 100 different thermal manikins have been employed for research and product development worldwide. Holmer [36] reviewed thermal manikin development history and summarized the milestones. Interest in using thermal manikins in research and measurement standards is steadily growing and several international testing standards have been developed in the field of the thermal comfort evaluation. To date, thermal sweating manikins are widely used in large scale textiles and clothing research laboratories all over the world for analyzing the thermal interface of the human body and its environment. Normally, the thermal manikin is made from metal or fabric e.g., copper, plastic or water / windproof fabric with an independent controllable heating/sweating subsystem, data measurement and analyzing subsystems. With the development of computer and computation technologies, visual realization models have become more and more important and are now widely applied in the field of thermal comfort estimation. Li et al. [37] developed a computer based model for studies of heat moisture transfer in clothing systems. Buxton et al. in the UK are also developing a similar model that allows the use of human body data from whole body scanners and motion patterns derived from real recordings.

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11. MEASUREMENT OF CLOTHING COMFORT USING THERMAL / SWEATING PLATE The thermal/sweating plate has been used for years to determine the thermal and moisture resistance properties of fabrics. The applications and description of sweating hot plates can be found in Goldman [38] and Holmer et al. [39]. There are several types of skin model employed in clothing comfort research. Firstly, Kawabata [28] reported the application of hot plate technology for the measurement of fabric warm and cool feelings. The thermal lab is only used to evaluate the warm or cool feeling produced upon touching a fabric. Thermal conductivity is measured in the steady state. A damp paper was put on the hot plate to stimulate human skin. A representative sweating hot plate is described in the Farnworth’s paper [31]. This sweating hot plate is designed to maintain a constant surface temperature of 35ºC and consists of a circular shaped inner plate, a guard ring plate and a base plate. The sides of the inner plate are separated from the guard ring plate by a 1 mm air gap and the bottom of the inner plate is separated from the base plate by 50mm of foam insulation. The guard ring plate and the base plate prevent heat flow away from the inner plate in the lateral and downward directions, respectively. Electrical heaters, connected to DC power supplies, are used to maintain the inner plate at a constant temperature of 35oC, which is determined by a thermistor. All three plates are located inside a heated box to eliminate further heat flow away from the inner plate in any direction other than that upward from the plate surface. Typical structure and detailed description of a sweating hot plate can be found in ISO 119021993(E).

CONCLUSION The properties of clothing materials critically influence the comfort and performance of the wearer. Clothing is not just a passive cover for the skin, it interacts with and modifies the heat regulating function of the skin and its effects are modified by the environment. The combined effects of the properties of clothing materials and wind on the physiological parameters of human wearers are the critical factors to be considered in designing functional clothing and are going to be the niche area of research in future.

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Slater, K. (1977). Comfort Properties of Textiles. Textile progress, 9, 1-91. Jeffries, R. (2005). Functional Aspects of High performance clothing. Book of Abstracts, Fashion the future, British Textile Technology Group, Shirley Publication, 126-128. Fourt, L. and Hollies, N.R.S. (1970). Clothing: Comfort and Function. Marcel Dekker Inc., New York, USA Bhat, P. & Bhonde, H. U. (2006). Comfortable clothing for Defence Personnel. Asian Text. J. 73-77.

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[24] [25]

P. Kandha Vadivu Butera, F. M. (1998). Principles of thermal comfort. Renew. Sust. Ener. Rev., 2(1-2), 39-66. Gagge, A. O., Buston, A. C. & Bazett, H. C. (1941). A Practical system of units for the description of heat exchange of Man with his environment. Science, 94, 428-430. Rohsenow, W. M. & Hartnett, J. P. (1973). Handbook of Heat Transfer, McGRAQHALL Book, New York. Yang. S. M. & Tao., W. Q. (1999). Heat Transfer. Higher Education Press, Beijing. Peirce, F. T. & Rees, W. H. (1946). The transmission of heat through textile fabrics, Part II. J. Text. Inst., 37, 181-204. Incropera, F. P. & DeWitt, D. P. (2002). Fundamentals of Heat Transfer, 5th ed. Wiley, Somerset, NJ. Kurazumi, Y., Tsuchikawa, T., Matsubara, N. & Horikoshi, T. (2004). Convective heat transfer area of the human body. Eur. J. Appl. Physio., 93, 273-285. Kurazumia, Y., Tsuchikawab, T., Ishiia, J., Fukagawaas, K., Yamatoc, Y. & Matsubara, N. (2008). Radiative and convective heat transfer coefficients of the human body in natural convection. Building and Environment, 43, 2142-2153. Richard, J., Dear, D., Arens, E., Hui, Z. & Oguro, M. (1997). Convective and radiative heat transfer coefficients for individual human body segments. Int. J. Biometeorol., 40, 141-156. Fanger, P. O. (1977). Local Discomfort to the Human Body caused by Non-Uniform Thermal Environments. Ann. Occup. Hyg., 20(3), 285-291. Jones, B. W. (1998). Radiant heat transfer between the human body and its surroundings. ASHRAE Transactions, 104(2), 1340-1350. Ohhashi, T., Sakaguchi, M. & Tsuda, T. (1998). Human perspiration measurement. Physiological Measurement, 19, 44. Kraning K. K. & Gonzalez, R. R. (1991). Physiological consequences of intermittent exercise during compensable and uncompensable heat stress. J. Appl. Physiol., 71(6), 2138-2145. Shamsuddin A. K. M & Tatsuo, Togawa. (1998). Continuous monitoring of sweating by electrical conductivity measurement. Physiological Measurement, 19(3), 375. Collier, B. J. & Epps, H. H. (1999). Textile Testing and analysis. Prentice-Hall Inc., New Jersey, U.S.A. Kothari, V. K. (2006). Thermophysiological comfort characteristics and blended yarn woven fabrics. Indian J. of Fib.Text. Res., 31(1), 179-186. Kothari, V. K. (2004). Fabric comfort. Proc. of the seminar on comfort in textiles, IIT Delhi, New Delhi, India, Rees, W. H. (1972). Materials and Clothing in Health and Disease-The Biophysics of Clothing Material, Lewis Pub., London. Hollies, N. R. S. & Goldman, R. F. (1977). Clothing comfort: Interaction of thermal, Ventilation construction and Assessment Factors. Michigan, Ann Arbor Science publishers Inc. ann harbor, USA. Voinov, Y. F. & Karlina K. V. (1972). Assessment of the Thermal Resistance of clothing. DRIC translation, 2920. Weiner, L. I. &Shah, J. (1969). Insulating Characteristics of Battings. Text. Chem. Color., 1, 301-306.

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[26] Karlina, E. V. & Tretyakova, L. I. (1971). Investigation of the Effect of Macro-Layers of Air on the Thermal Insulation Properties of Clothing Assemblies. Teknolngiva, Legrol Drom., 2, 98-102. [27] Fonseca, C. F. &Breckenridge,J. R. (1965). Wind Penetration Through Fabric Systems, Text. Res. J., 35, 95-103. [28] Kawabata, S. & Akagi, Y. (1977). The Standardization and Analysis of Hand Evaluation. Text. Mach. Soc. Japan, 3, T13. [29] Weder, M., Brühwiler, P. A. & Herzig, U. (2004). Neutron Radiography Measurements of Moisture Distribution in Multilayer Clothing Systems. Text. Res. J., 749s(8),695700. [30] Peirce, F. T. & Rees, W. (1946). The transmission of heat through textile fabrics, Part II. J. Text. Inst., 37, 181-204. [31] Farnworth, B. (1983). Mechanisms of heat transfer through clothing insulation, Text. Res. J., 53, 717-725. [32] Mohammade, M. & Banks-Lee, P. (2003). Determining effective thermal conductivity of multilayered nonwoven fabric. Text. Res. J., 73, 802-808. [33] Dul’nev, G. N. & Muratova. (1968). Thermal Conductivity of Fibrous Systems, J. Eng. Phys. Thermo physics, 14(1), 15-18. [34] Mitu, S. & Potoran, I., (1971). Fundamentals of Textile Clothing Technology. Bul. Inst. polytech. Iasi, 17(1-4), 61. [35] Sun, Y., Chen, X., Cheng, Z. & Feng, X. (2010). Study of heat transfer through layers of textiles using finite element method. Int. J. Clothing Sci. Technol., 22(2/3), 161. [36] Holmer, I. (2004). Thermal manikin history and application. Eur. J. Appl. Physiol., 92(6), 614-618. [37] Li, Y. & Holcombe, B. V. (1998). Mathematical Simulation of Heat and Moisture Transfer in a Human-Clothing-Environment System. Text. Res. J.,68(6), 389-397. [38] Goldman, R. F. (1981). Evaluating the Effects of Clothing on the Wearer. Bioeng. Thermal Physiol. Comfort, 41-55. [39] Holmér, I. & Elnäs, S. (1981). Physiological evaluation of resistance to evaporative heat transfer by clothing. Ergonomics, 24, 63–74.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 20

DESIGNING OF JUTE–BASED THERMAL INSULATING MATERIALS AND THEIR PROPERTIES Sanjoy Debnath National Institute of Research on Jute and Allied Fibre Technology, Indian Council of Agricultural Research, Kolkata, West Bengal, India

ABSTRACT Among the different natural fibres, jute is less expensive, annually renewable and commercially available fibre compared to other fibre crops. Jute is mostly cultivated in India and Bangladesh. This fibre is being popularly used as packaging material, hessian and carpet backing for over a century. After introduction of man-made fibres in the1950s, the market of such traditional products made out of jute has been almost replaced by the synthetic fibres due to their low cost and high production speed. As far as thermal insulating material is concerned, wool-based material either from natural wool or artificial fibres like acrylic is thought about but seldom jute/jute-blended materials. However, in the present chapter, effort has been made on diversification of jute usage, specifically, as thermal insulating material. To upgrade its thermal insulation properties, the suitable modifications done to the fibre/yarn structures, have been discussed here. Also, the structural design of weaving using jute-based yarns and the design parameters involving in designing of suitable warm garments from jute-based materials have been discussed. The measurement of thermal insulating property and its factors affecting its insulating property have also been covered. Besides, important area like nonwoven fabrics mostly used as industrial material, its design towards development of jute-based thermal insulating material has also been focused in this chapter.

Keywords: Blending of fibres, Chemical treatment, Jute fibre, Polyester fibre, Polypropylene fibre, Thermal insulation, Warm fabrics



E-mail: [email protected]; [email protected].

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INTRODUCTION Among the different fibre crops, jute is one of the oldest cultivated fibre crops in India. India is the highest producer of jute in the world, and is mostly cultivated in the eastern part of the country. It is the cheapest fibre crop available commercially in bulk quantities so jute fibre is being technically used extensively over the centuries. For example it is used as, packaging material, carpet backing, hessian as industrial applications. It is also used for reinforcement of rural mud houses, thermal insulating material for domestic animals like cattle, pet dogs etc. As far as the properties of jute fibre are concerned, it has both desirable and undesirable ones. Basically, this fibre has mesh like structure which provides better coverage, good tensile strength, toughness and durability. Due to its less extension at break, it ensures dimensional stability. The natural colour of the fibre renders it an ethnic value, which ensure its use as a material for various handicrafts and artefacts. Unlike any other fibres, the drawbacks of jute fibre crop are high surface roughness and prickliness, low extension at break and coarseness which restricts its use in textile garment. Keeping this in view warm clothes has been designed and developed using jute-based fibres and yarns. Thermal insulation is one of the essential properties for any warm fabrics [1]. Judicious modifications of the fibre/yarn structure is one of the important aspect as far as its development as thermal insulating material is concerned. The thermal insulation related properties mainly depends on the availability of amount of air pores in the textile structure. Air trapped in fabric pores, makes the fabrics act as thermal insulating media [2].

CLASSIFICATION OF WARM CLOTHS Structurally, the warm fabrics can be classified into different categories viz., knitted, woven, nonwoven and composite (more than one structure of fabric or combination of structures). Also, as per the usage of the warm cloths, it can differentiated as wearable textile and non-wearable textiles. Under the wearable textile the applications may be shawl, jacket, blazer, muffler, sweater, pullover etc. on the other side the non-wearable textiles include blanket, carpet, floor coverings, curtains, industrial insulation etc.

DESIGNING OF WARM FABRICS The basic structures like woven and knitted, require yarn as prerequisite material for designing of warm fabrics. However, in-case of nonwoven structures, instead of yarn, it may be directly from fibre, where modifications in fibre or fabric stages are needed to achieve desire properties for warm fabrics [3]. In case of woven and knitted structures modifications during yarn forming or fabric manufacturing stages or modifications of both the stages are essential to develop jute based warm fabrics. Bulking of yarn is prerequisite for designing of warm fabrics either from weaving or knitted structures [4]. Following process describes about the bulking methods used to achieve considerable bulk in the yarn structure of woven or knitted fabric.

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WOOLLENISATION OF JUTE As wool fibre is sourced from animal, fibre has limitation of production and also costly compared to jute fibre. However, jute fibre does not have any crimp or scale as found in case of wool fibre. Because of presence of these scales/crimps in wool fibre, the fibres do not come close to each other in the fabric or yarn structure and as a result more void occurs in the structure. The static air gets trapped in the void and acts as thermal insulating medium and hence any material made out of wool seems to have higher thermal insulation. Woollenisation is basically an alkaline treatment [5] and it is also called as chemical texturizing process of jute. This process produces wool like crimp [6, 7, 8, 9] and thus increases available air space. Breaking elongation increases after this treatment due to formation of crimp/lateral expansion of the yarn. In this process, jute is treated with the NaOH solution and it is found that 18% NaOH solution gives optimum result for the Woolenization [10]. Alkaline treatment removes significant amount of the hemicellulose and small quantity of soluble lignin present in the jute structure and as a result fall in strength of the jute has been observed. Several attempts were also made to recover NaOH after this delignification process, from the spent liquor. Woollenisation process introduces several changes in properties of the jute fibre. Accordingly, yarn properties after woollenisation treatment also changes significantly compared to un-treated yarn [11]. After this process, the surface of the yarn becomes rough, and exaggerated further when bleached. Because of these reasons, fully woollenised jute yarn is not solely appropriate for preparation of warm garments like shawl/wrappers, sweaters etc. However to improve the surface feel and softness of the yarn, different chemical softeners such as Velan PF and Sopamine OC, has been used. Further, to increase the water repellence different silicone treatment is needed. The introduction of the silicone treatment gives a semipermanent water repellence property and it withstands laundering fairly well.

WOOLLENISED JUTE AND WOOL BLENDED YARN Woollenised jute can be well mixed with natural wool at 50:50 ratio [1]. We can produce coarse yarn in woollen/worsted systems. Other than the wool fibre, other natural or synthetic fibres such as cotton or polypropylene (PP) can be blended with woollenised jute to produce different unconventional high value products [5]. Bleaching of blended yarn produced from woollenised jute and wool can be done with 0.75 vol H2O2 solution for 2 hours at 80oC [5]. Twelve different shades were obtained by dyeing of woollenised jute blended yarn; both bleached and unbleached woollenised jutes were used and they were mixed with wool at the ratio of 35:65 [6, 12, 13].

WOOLLENISED JUTE AND POLYPROPYLENE BLENDED YARN In several studies, different fibers were blended with the woollenised jute. One the fibres that is often mixed with woollenised jute is Polypropylene (PP). The blend ratio of 80:20 (Jute: PP) is used to produce yarn and it is found that incorporation of PP to the blend gives a higher bulk with stretch. It also facilitates the preferential migration to the surface of the yarn.

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Woollenised jute and PP blended yarn have higher bulk in comparison to the yarn which is produced from Indian Chokla wool. However, this wool yarn shows higher breaking elongation and uniformity of diameter. The Tenacity of textured Jute:PP blended yarn is higher than the wool yarn (Indian Chokla Wool), though at the time of woollenisation the tenacity of the jute component drops significantly [1]. It is also found that wet/dry tenacity ratio is higher in jute: PP blended textured yarns than the wool yarn [14, 15, 16].

WOOLLENISED JUTE-POLYESTER, JUTE-HOLLOW POLYESTER AND JUTE-ACRYLIC BLENDED KNITTING YARN Rotor spun short staple jute-polyester blended yarns were texturized and compared with conventional apron draft jute spun texturized yarn by Ghosh and Samanta, 1997 [17]. It was found that 70:30 of jute and polyester blended rotor spun yarn showed the optimum result. Sinha and Basu, 2001 [18] used jute-shrinkable acrylic fibre to develop bulked knitted yarn. They used a simple technique to develop bulk in the raw jute-acrylic blended yarn. The bulk in the raw yarn can be developed by boiling the yarn in water for 15-30 min or steaming treatment. Study was also conducted on effect of sodium hydroxide on jute-acrylic blended yarn spun in DREF spinning system [19]. They studied the effect of treatment time, concentration and blend proportion on yarn bulk, strength, extension and packing of juteacrylic blended DREF spun yarns. Jute and hollow polyester fibre (80:20) blended fine yarn (130 tex) has been developed [20]. These yarns was further plied and made into 2-ply and 3-ply yarns. Woollenisation treatment was done for 2-ply and 3-ply blended yarns. Further, bleaching and dyeing was also conducted. The yarn shrinkage and weight loss properties have been studied at every stage and compared with the untreated yarn. Also, other physical properties viz., tenacity, breaking strain, diameter, coefficient of friction, specific work of rupture, bulk density have been studied and compared with the similar woollen and acrylic commercial yarns. This study (Debnath et al. 2007a) established that jute-hollow polyester blended yarn has higher bulk over similar commercial yarns due to low yarn packing [20]. The 3-ply jutehollow polyester blended bulked yarn has better bulk, regularity (cv %), extensibility, pliability and work of rupture than those of 2-ply yarn. The tenacity of 3-ply blended bulked yarn deteriorates after 18% (w/w) NaOH chemical treatment while breaking extension remarkably increases (Figure 1). However the percentage coefficient of variation of both tenacity and breaking extension decreases after bleaching and dyeing. This yarn shows almost similar tenacity with lower extension compared to wool yarn (Figure 2). The lowest specific work of rupture is observed in the 3-ply blended bulked yarn. This 3-ply blended bulked yarn also shows lower coefficient of friction than wool yarn (Table 2). The specific flexural rigidity of jute-hollow polyester blended yarns are lower than woollen yarn but comparatively higher than acrylic yarns.

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Table 1. Yarn shrinkage and weight loss behaviour of 80:20 jute-polyester (hollow) blended bulked yarn [20] Chemical Processes Bleaching Dyeing

2-Ply blended yarn Shrinkage (%) Weight loss (%) 10 15.37 10 18.01

3-Ply blended yarn Shrinkage (%) Weight loss (%) 12.5 14.27 12.5 16.74

Table 2. Comparison of 80:20 jute-Polyester (hollow) bulk yarn with acrylic and wool commercial yarns [20] Properties 3-ply acrylic Linear density (tex) Diameter (mm) Packing factor Packing factor C.V.% Bulk density (g/cm3) Tenacity (cN/tex) Tenacity C.V.% Breaking strain (%) Breaking strain C.V.% Specific work of rupture (mJ/tex-m) Coefficient of friction of yarn () Specific flexural rigidity (mN-mm2/tex2 X 10-4)

Commercial yarns 4-ply acrylic

4-ply wool

3-Ply dyed jute-hollow polyester yarn

170 1.19 0.128 15.46 0.153 7.44 7.01 37.35 9.83

290 1.71 0.106 11.56 0.126 9.10 6.55 45.42 11.57

300 1.35 0.161 11.61 0.210 4.00 10.12 18.01 16.73

370 1.85 0.094 16.14 0.138 3.84 9.09 8.6 7.83

16.85

14.00

4.47

1.27

0.81

0.80

0.90

0.84

9.57

5.20

23.20

11.98

Figure 1. Stress strain behaviour of jute-hollow polyester blended yarns [20].

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Figure 2. Comparison of stress strain behaviour of jute-hollow polyester blended yarn with acrylic and wool yarns [20].

BLANKET AND CARPET PRODUCTS FROM WOOLLENISED JUTE AND POLYPROPYLENE BLENDED YARN Different products have been developed out of woollenised jute and polypropylene fibre blends, some of them are listed below: CAPLON Blanket – Main advantages of this blanket over wool blanket is higher Strength, moth resistance, and good thermal insulation properties. Carpet – Different kinds of carpets that can be produced from the woollenised jute: PP blended yarns are Chenile, hand knitted, tufted and woven carpets. Chenile carpets – These kind of carpets can be produced by doubling the woollenised pile yarn and varying the length of pile. Main advantage of this kind of carpet is that, pile yarns do not easily come out from the carpet body. Hand knitted carpets – This kind of carpets shows a similar tuft withdrawal force and recovery from compression properties to wool carpets and its properties are superior than carpets which are produced from the polypropylene. Tufted carpets – Tufted carpets have also been developed from woollenised-Jute/PP blended yarn. They showed better performance because of high strength and uniformity of the yarns. Woven carpets – Woven carpets are also known as Wilton and Tapestry carpets. Main advantages of this kind of carpets are fly generation and fibre shredding are almost absent at the time of production. The yarn breakage during production are also less. It gives a better stretch property which enhance the formation of proper piles with less tension, and this piles show better results to the seat and grip than jute pile yarns [16, 20].

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Blanket from Woollenised Jute and Hollow Polyester Blended Fibre Traditionally, one of the application of wool is well known to all of us for use in making blanket. However, due to limited production of this natural fibre, nowadays synthetic fibres like acrylic, polyester etc. are also being used in the area of blanket making. It is found that, jute is still the most cheapest textile fibre available in some part of the world. Hence the product made out of this cheap fibre will reduce the cost of production. The jute and hollow polyester (PET) fibre were blended homogeneously in the ratio of 80:20 in first drawing machine of jute spinning system [4]. The final blended yarns were spun in jute slip draft spinning machine to achieve the yarn linear density of 276 tex (8 lbs/spy). These yarns are directly used in warp direction during weaving. Further, these same yarns were plied into two ply and twisted to obtained linear density of 552 tex (16 lbs/spy). This 2 ply is use as weft yarn during weaving of blanket. Both these warp and weft yarns were chemically texturized separately using standard procedure [10] and further dyed in dark shade (Figure 3). The yarns were finished as per standard method to obtain melange effect. Jute-hollow polyester (80:20) blended yarns were used to weave into fabric (2/2 twill) with 276 tex (8 lbs/spy) single yarn in weft direction (18-20 picks/inch). In warp direction, 276 tex (8 lbs/spy) 2-ply yarn (9-10 ends/inch) was used [22]. Normally, it is recommended that a reed width of more than 78“ is essential for weaving of blanket fabric, considering the loom stage shrinkage. It has been found from the literature that 80:20 jute-PET blended blanket and 100% woollen blanket are having thermal insulation values (TIV) of 0.78 tog and 0.86 tog respectively [23]. Performance and cost wise jutehollow polyester (80:20) blended raised blanket and 90:10 raised blanket is lower (Rs.295/-) compared to commercial woollen (Rs.450/-) and acrylic (Rs.825/-) blankets [23].

Figure 3. Blanket from chemically texturized jute-hollow polyester blended yarns.

SPINNING OF JUTE-BASED BLENDED FINE YARN FOR WARM CLOTHS In case of apparels, wherein person has to wear it or wrap it around the body it is essential to have the fabrics as light as possible. The final weight of the fabric for the aforesaid purpose has to be reduced, so very fine yarn of 122 tex has been developed using jute spinning system. The polyester (hollow) fibre of 6 denier, 110 mm is used to develop the

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yarn for the warm cloth weaving. Jute-hollow fibre blended yarn has higher bulk density compared to other blended yarns [24, 25]. The conventional jute spinning system is used to produce blended yarn. The blended yarn of jute and polyester (hollow) fibre was successfully spun from drawing stage of blending processes. The raw jute of TD-3 was used for development of overall blended samples. The conventional jute batching oil was used before piling for 48 hours. The blended yarn samples were produced both with 70:30 and 80:20 jute:polyester fibres [26]. These samples produced from spinning was of 122 tex with 6 t.p.i. (twist per inch), ‘Z’ twist. All these blended yarn samples were spun suitably in apron draft spinning system over slip draft spinning system.

WEAVING OF SHAWL FABRIC FROM VERY FINE YARN AND CHARACTERISATION The jute-blended yarn was used as weft yarn and commercial cotton yarn of 5.9 tex (100s Ne) as warp yarn for development of the shawl fabric. Handloom weaving machine [27] with jacquard attachment (at least 100 hooks) and handloom preparatory machinery were used to weave these fabrics. Plain and twill (3/1) are the two basic designs used to weave the fabrics. For body and border of the shawl separate jacquard weaves were used. Ornamentation was done with introduction of extra weft yarns [28] (commercial polyester-viscose of 14.7 tex or 40s Ne two ply) at the jacquard design areas on the fabric. Few samples were also developed using localised dyeing in the warp yarn, giving a Kotkee look (tie-dye) to the fabric. Attempt was also made to develop fabric with combination of plain and twill weave (Figure 4). The developed shawl fabrics were characterised and compared with the commercial (khadi) cotton and acrylic shawls. The fabric weight, fabric thickness, fabric cover factor, thermal insulation value (tog) and flexural rigidity are the various properties that have been studied using standard testing methods [29]. The thermal insulation value was studied using the instrument developed by NIRJAFT [30, 31] where the test is non-destructive in nature.

Figure 4. Shawl from jute-polyester blended and cotton yarns.

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507

The fabric weight increases with the increase in pick density for both the plain and twill weaves [2]. The fabric weight is between 147 and 160 g/m2 for commercial fabrics under consideration. However, the fabric weight of the developed fabric ranges between 169 and 263 g/m2. Both the thickness and thermal resistance values of the developed jute blended fabric samples are closer to that of cotton/acrylic commercial shawl fabrics. The cloth cover factor was also higher compared to commercial shawl fabrics (cotton/acrylic). The flexural rigidity in warp direction of the developed fabrics is comparatively lower than the cotton/acrylic fabrics due to use of very fine cotton yarn in warp direction (5.9 tex). Jute has higher rigidity due to its coarseness, so when it is used in the weft direction of the jute blended fabric, a tremendous increase in flexural rigidity in weft direction is observed in the developed fabrics. It also increases with the increase in pick density of the fabric. Few fabrics were developed where slit film were used alternately in weft direction along with jute-polyester blended yarn. The fabric weight is between 147 and 160 g/m2 for commercial fabrics under consideration. However, the fabric weight of the developed lightweight shawl fabrics ranges between 136 and 162 g/m2. The thickness values of the developed shawls are closer to cotton shawls but lower than acrylic shawls. Cover factor values of the developed shawls are between 17 and 20 (which, is between the cover factor values of commercial acrylic and cotton shawls). The thermal resistance values of the developed jute blended fabric samples are 19% higher compared to acrylic and 66% higher compared to cotton commercial shawl fabrics [32]. These developed shawl fabrics are moreor-less equally porous compared to commercial shawls under consideration as per as the sectional air permeability is concerned. The tenacity and breaking extension behaviour of the developed jute blended shawls and compared with the commercial cotton and acrylic shawls both in warp and weft directions. The tenacity values of the jute-blended shawls are closer to that of cotton shawls and lower than acrylic shawls in warp direction. However, in weft direction, tenacity is little higher than cotton and closer to acrylic shawls. Breaking extension values of the developed shawls are much lesser than acrylic or cotton shawls both in warp and weft directions of the fabric samples [31]. The effect of washing (after five-repeated detergent washing) on tensile and air permeability property of jute-polyester and cotton blended shawls and compared with their original values (before washing). This study reveals though there is little drop in tenacity after wash in warp direction (cotton yarns) but no change have been found in weft direction (jutepolyester blended yarns). Little improvement in extension have been observed in weft direction. There is a fall in flexural rigidity values in warp direction and an increase in trend was found in weft direction after washing treatment. A significant drop in sectional air permeability was observed after washing of the developed shawl samples [31].

Jacket from Jute-Based Yarn and Evaluation Jackets have been developed using handloom to weave winter fabric. Three different types of jute-polyester and cotton blended jacket fabrics have been developed. Handloom jacquard has been used to introduce design in the fabric during weaving. The jute-blended yarn and commercial cotton yarn were used alternately as weft and commercial cotton yarn of 5.9 tex (100s Ne) was used as warp for development of the jacket fabric of 136 g/m2. For

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other two fabrics, in warp direction, cotton yarns were dyed in dark blue shade. In weft direction alternate use of cotton and jute-blended yarn improves the fabric appearance and other physical properties (Figure 5).

Figure 5. Jacket from jute-based jacket fabric.

The fabric weight and thermal insulation values were measured for the developed fabrics and compared with the commercial (khadi) cotton and acrylic jacket fabrics. The developed jacket fabric shows 30 % and 62 % higher thermal insulation value compared to commercial acrylic and cotton jacket fabrics respectively. This developed fabric is also 8 % and 17 % lighter in weight compared to commercial acrylic and cotton jacket fabrics respectively. The fabric thickness of the developed jute based fabric is 47% and 19% lower compared to commercial acrylic and cotton jacket fabrics respectively [32]. Alternate use of jute-polyester and cotton yarn in weft direction has been used to improve the aesthetic and physical properties of developed fabrics. Other four different types of jackets have been tailored using these developed jacket fabrics. Other than zip, buttons and sewing yarn, all these developed jackets comprise of three basic materials: a) jacket fabric; b) lamination material and c) lining material. In one case the lining material for developed jacket used as acrylic fabric and rest of the cases polyester lining material have been used. Out of all these jackets, one reversible jacket has been developed using developed jacket fabric. Weight, thermal insulation and thickness properties of the developed jute-blended jackets have been evaluated and compared with commercial jacket (Oswal make). It is found that overall the thermal insulation of the developed jackets are higher than commercial jackets (Anonymous, 2008). The thermal insulation of jackets can be lower or higher depending on the constructional design of the jacket fabric and lining material of the jacket. The weight of the jackets depend on the design of the jacket fabric and jacket type. Thickness values of all developed jackets except those of reversible ones, are lower than commercial jacket (Oswal

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make). Apart from these no dimensional changes of jackets have been observed after one cold water detergent wash.

Thermal Insulation Behaviour of Jute-Based Nonwoven Fabrics Different types of parallel laid and random laid needle punched and adhesive bonded nonwoven fabrics were prepared using blending of different fibre materials (polypropylene, acrylic, jute, woollenised jute, jute caddis, cotton, wool, ramie, pineapple leaf fibres etc.). Two types of blending methods were used such as sandwich and homogeneous. Sandwich blending of polypropylene or acrylic with woollenised jute shows better thermal insulation compare to homogeneous blended materials as found by Debnath et al., 1987 [3]. They also found that nonwoven prepared out of woollenised jute-wool (2:1), woollenised jute-acrylic (2:1) and woollenised jute-pineapple leaf fibre (2:1) have better thermal insulation property. Air permeability and thermal conductivity of jute needle-punched nonwoven fabrics have been studied by Sengupta et al., 1985 [33] and found that jute needle punched nonwoven has poor in heat transmission. Further, Box and Behnken factorial design [34] was used to design and development of needle-punched nonwoven fabrics made from jute and polypropylene blends to study the effect of fabric weight, needling density and blend proportion on thickness, thermal resistance, specific thermal resistance, air permeability and sectional air permeability. Polypropylene fibre of 0.44 tex fineness, 80 mm length and jute fibres of Tossa-4 grade were used to develop the jute-polypropylene blended needle-punched nonwoven [35]. Some of the important properties of these jute and polypropylene fibres are presented in the Table 3. Table 3. Properties of jute and polypropylene fibres [35] Property Fibre fineness, tex Density, g/cm3 Moisture regain at 65% RH, % Tensile strength, cN/tex Breaking elongation, %

Jute 2.08 1.45 12.5 30.1 1.55

Polypropylene 0.44 0.92 0.05 34.5 54.13

PREPARATION OF JUTE-POLYPROPYLENE BLENDED THERMAL INSULATION NONWOVEN FABRICS The jute reeds were opened in a roller and clearer card, which produces almost mesh-free stapled fibre. The woollenised jute and polypropylene fibres were hand opened separately and then blended using three different blend proportions (Table 4). The proportion of woollenised jute fibres taken is 2% higher than the blends showcased in Table 4 considering droppings of jute component [35] in the card and subsequent processes to maintain target blend in the output material. The blended materials were thoroughly opened by passing them through one carding passage.

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Table 4. Actual and coded values for three independent variables and the experimental design [35] Levels of variables Fabric code

X1 level

Coded

Actual

Coded

Actual

Coded

Actual

1

–1

250

–1

150

0

60 : 40

2

–1

250

1

350

0

60 : 40

3

1

450

–1

150

0

60 : 40

4

1

450

1

350

0

60 : 40

5

–1

250

0

250

–1

40 : 60

6

–1

250

0

250

1

80 : 20

7

1

450

0

250

–1

40 : 60

8

1

450

0

250

1

80 : 20

9

0

350

–1

150

–1

40 : 60

10

0

350

–1

150

1

80 : 20

11

0

350

1

350

–1

40 : 60

12

0

350

1

350

1

80 : 20

13

0

350

0

250

0

60 : 40

14

0

350

0

250

0

60 : 40

15

0

350

0

250

0

60 : 40

X2 level

X3 level

X1 – Fabric weight, g/m2; X2 – Needling density, punches/cm2; and X3 – Blend ratio (polypropylene: woollenised jute).

The blended fibres were then fed to the lattice of the roller and clearer card at a uniform and predetermined rate so that a web of 50 g/m2 can be achieved. The fibrous web coming out from the card was fed to feed lattice of cross-lapper, and cross-laid webs were produced with cross-lapping angle of 20. The web was then fed to the needling zone. The required needling density was obtained by adjusting the throughput speed [36]. As per the fabric weight (g/m2) requirement, certain number of webs were taken and passed through the needling zone of the machine for a number of times, depending upon the punch density required. A punch density of 50 punches/cm2 was applied on each passage of the webs reversing the face of the web alternatively [36]. The fabric samples were produced as per the coded and actual levels of three variables (Table 4). The depth of needle penetration was kept constant at 11 mm. For all webs, 15  18  36  R/SP, 3½  ¼  9 needles were used.

Evaluation of Thermal Insulation and Resistance The thermal insulation and resistance can be tested by using appropriate thermal insulation and resistance tester. The conventional Marsh method and guarded two plate

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method are more popular methods of measuring thermal insulation behaviour of textile fabrics. The thermal resistance (TRs) of jute-polypropylene blended needle-punched nonwoven fabrics was measured using guarded two-plate thermal resistance instrument [30]. This instrument [30,31,35] (Figure 6) is based on a microprocessor and provides automatic results of thermal resistance value. The area of the test specimen used is 706.85 cm2 (diameter 30 cm). The test is non-destructive and process of preparation of sample is free from human error. TRs of each fabric sample was measured randomly at five different places under a pressure of 0.3352 kPa. Average of five readings was considered and the coefficient of variation of readings was  2%. Specific thermal resistance (STRs) value was used to compare the thermal resistance of different fabric samples. STRs values of all the samples were determined using the following equation [35, 31]: STRs 

TRs T0

(1)

where STRs is the specific thermal resistance in K m/W; TRs, the thermal resistance value of fabric in K m2/W; and T0, the mean thickness in meter at 1.55 kPa pressure of the fabric sample.

Figure 6. NIRJAFT thermal resistance instrument.

EFFECT OF FABRIC WEIGHT, NEEDLING DENSITY AND BLEND PROPORTION OF JUTE-POLYPROPYLENE BLENDED NEEDLE-PUNCHED NONWOVEN ON THERMAL RESISTANCE It is found that the thermal resistance increases with the increase in fabric weight [35]. This can be supported by the existence of significant (p < 0.05000) positive correlation (r =

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0.82) between fabric weight and thermal resistance, as observed from the correlation matrix (Table 3). With the increase in fabric weight, thermal resistance increases more prominently at lower needling density (150 punches/cm2), but its effect is negligible at higher needling density (350 punches/cm2). However, at 40% and 60% jute content levels, the effect of fabric weight on thermal resistance is almost similar at all needling densities between 150 punches/cm2 and 350 punches/cm2. The highest thermal resistance of 8.5  10–2 K m2/W has been obtained at 430 g/m2 fabric weight and 150 punches/cm2 needling density for 40% jute content level [34]. With the increase in fabric weight, the number of fibres per unit area of the fabric increases. This causes increases in fabric thickness and also amount of pores in the fabric structure, causing increase in thermal resistance. However, with the increase in needling density, thermal resistance decreases because the fabric structure tends towards higher degree of consolidation and hence reduces amount of pores in the structure. This can also be supported by significant (p < 0.05000) negative correlation which exists between needling density and thermal resistance (r = – 0.67), as observed from the correlation matrix (Table 5). Thermal resistance = 4.0520833 – 0.0114167X1 – 0.0007917X2 + 0.0558333X3 0.0000079X12 – 0.0000104X22 – 0.0021979X32 + 0.0000250X1X2 – 0.0002125X1X3 – 0.0001X2X3 (R=0.9002; F9,5=15.04) ...

(2)

Table 5. Correlation matrix of variables Variables

FW

N

J%

T

TRs

STRs

AP

SAP

FW N J% T TRs

1.00 0.00 – 0.00 0.05 0.51

– 1.00 0.00 – 0.49 * – 0.67

– 0.00 0.00 1.00 – 0.39 – 0.26

0.50 – 0.49 – 0.39 1.00 0.82*

0.51 – 0.67* – 0.26 0.82* 1.00

0.28 – 0.61* – 0.02 0.29 0.78*

– 0.93* – 0.11 – 0.19 – 0.36 – 0.37

– 0.75* – 0.33 – 0.43 0.08 – 0.02

* 1.00 – 0.22 – 0.11 – 0.02 0.29 0.78* – 0.61 * * AP – 0.93 – 0.11 – 0.19 – 0.36 – 0.37 – 0.22 1.00 0.89 * * SAP – 0.75 – 0.33 – 0.43 0.08 – 0.02 – 0.11 0.89 1.00 FW – Fabric weight, g/m2; N – Needling density, punches/cm2; J% – Jute proportion, T0 – Fabric thickness, cm; TRs – Thermal resistance  10–2, K m2/W; STRs – Specific thermal resistance, K m/W; AP – Air permeability, cm3/cm2/s; SAP – Sectional air permeability, cm3/s/cm. * Correlations are significant at p < 0.05000.

STRs

0.28

EFFECT OF FABRIC WEIGHT, NEEDLING DENSITY AND BLEND PROPORTION OF JUTE-POLYPROPYLENE BLENDED NEEDLE-PUNCHED NONWOVEN ON SPECIFIC THERMAL RESISTANCE This study show the effect of fabric weight and needling density on specific thermal resistance at the jute content levels of 20%, 40% and 60% respectively (Figure 7). It is found that the specific thermal resistance decreases with the increase in needling density, irrespective of the blend composition in jute-polypropylene blend [35]. Also, a significant (p

Designing of Jute–Based Thermal Insulating Materials and Their Properties

513

< 0.05000) negative correlation (r = – 0.61) has been found between needling density and specific thermal resistance, as observed from the correlation matrix (Table 5). This is due to the formation of consolidated structure with the increase in needling density. The number of fibres per unit area increases with the increase in fabric weight. This generates more air pockets per unit thickness of the fabric apart from better entanglement, resulting in increase of specific thermal resistance. The specific thermal resistance value initially increases up to 375 g/m2 fabric weight and thereafter it decreases, with the increase in fabric weight at 40% jute content and higher needling density (350 punches/cm2) levels [35] as observed form Figure 7a. The similar phenomenon has also been observed at higher jute content level (60%) but the decrease in trend of specific thermal resistance occurs at lower fabric weight (325 g/m2) as obtained from Figure 7b.

Figure 7. Effect of fabric weight and needling density on specific thermal resistance at (a) 20% jute, (b) 40% jute and (c) 60% jute content levels [26].

Jute can easily form consolidated structure due to its poor resilience compared to polypropylene fibre. Hence, at higher needling density and jute content levels, the fabric consolidation initially improves and beyond certain fabric weight (325 g/m2) the bulkiness increases. With the increase in fabric weight, more number of fibres will be available to the

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needle barb during needling. Beyond certain level (325 g/m2) of fabric weight, the increasing amount of fibres at the same needling density and needle barb is insufficient to form better entanglement, resulting in poor consolidation. Hence, at higher jute content level (60%), the fabric consolidation occurs at lower level of fabric weight (325 g/m2) as found from Figure 7c, compared to that at 40% jute content level [35, 36]. However, highest specific thermal resistance of 20.6 K m/W is observed at 150 punches/cm2 needling density and 400-450 g/m2 fabric weight for 40% jute content in jute-polypropylene blended needle-punched nonwoven (Figure 7a, 7b and 7c). Specific thermal resistance= – 2.3122917 + 0.0612292X1 – 0.0160917X2 + 0.5955833X3 – 0.0000490X12 + 0.0000452X22 –0.0056073X32 – 0.0000365X1X2  0.0002725X1X3 – 0.0002163X2X3 (R=0.9327; F9,5=7.69) ...

(3)

MEASUREMENT OF THERMAL INSULATION VALUE AND COMPARATIVE STUDY OF DIFFERENT JUTE BASED MATERIALS Paul and Mukhopadhyay, 1977 used a simple method to measure the thermal insulation value of different textile materials based on jute and cotton fibres [37]. The methods which are commonly used for measurement of thermal insulation value are the disc method, the constant temperature method and cooling method. Out of these three methods, cooling method is the simplest compared to other two methods. In this method of measurement of thermal insulation, a hot body is wrapped with the fabric and its rate of cooling is measured. The outer side of the fabric is exposed to air. In this experiment, the time taken by a hot body covered with the fabric sample (tc) and without the sample (tu) to cool through a particular temperature range under identical atmospheric conditions. To measure the thermal insulation with this method, a brass cylinder (45 cm length, 5 cm external diameter and 2 mm thickness) closed at one end with a cork was filled with distilled water heated to about 50C. The mouth of the cylinder was closed with a cork through which a thermometer was inserted. To simulate the actual condition, a wire mesh has been wrapped on the surface of the cylinder to obtain a clearance of 2 mm between fabric sample and brass cylinder. A rectangular specimen of the fabric was used to cover the entire outer surface of the brass tube. The length-wise edges of the specimen were made to touch each other closely avoiding overlapping and kept in position by using cello-tape over the joint running parallel to the length of the cylinder. The experiment was started when the temperature of the water was exactly 48C. A stop watch was used to find the time taken for the temperature fall at every 1C. A cooling curve was drawn from these data and the time taken to cool from 48C to 38C was found. The thermal insulation value (TIV) was calculated by Marsh method is as follows [37, 38]:



TIV = 1 



tc    100 tu 

(4)

Designing of Jute–Based Thermal Insulating Materials and Their Properties

515

where, (tc) is time taken by the covered body to cool through a certain temperature range and (tu) is time taken by the uncovered body to cool through the same temperature range. They found that thermal insulation value is related to the thickness of the fabric, the basis weight(fabric weight) and the number of layers of the fabric [37]. The intra fabric air aspces and inter space between fabric and body are also important. The thermal insulation value of the fabric is greater when a non-conducting mesh (polythene) is present between the cylinder and fabric instead of conducting metal mesh in the same position. Increase in any of these factors increases the thermal insulation value significantly. There has been marginal effect on thermal insulation value with varying fabric nature.

CONCLUSION It is concluded that the thermal insulation of the warm fabric increases significantly after chemical treatment. The blending with synthetic fibres like acrylic, polypropylene, polyester improves the thermal insulation apart from appearance. With the change in structural design of the garment/jacket, the thermal insulation varies widely. Overall, knitting yarn, warm fabric, warm garments, blankets etc. can be developed from jute-based materials effectively. These materials are comparable with commercially available similar material out of synthetic/wool. It has been established that the thermal insulation value is directly proportional to the thickness of the fabric, the fabric weight and the number of layers of the fabric present irrespective to the woven/nonwoven and raw material used to develop the fabric. The air spaces within the fabric and between the body and fabric are also influence the thermal insulation of the fabric. The thermal insulation value of the fabric is greater when a nonconducting mesh (polythene) is present between the cylinder and fabric, instead of conducting metal mesh in the same position. With regards to the nonwoven material, it has been observed that thermal resistance and thickness increase but air permeability and sectional air permeability decrease significantly with the increase in fabric weight at all levels of jute contents. The influence of fabric weight on thickness is more prominent at 40% and 60% jute content levels than at 20% jute content level. Both thermal resistance and specific thermal resistance decrease with the increase in needling density as supported by significant (p < 0.05000) negative correlations r = – 0.67 and r = – 0.61 respectively. The highest values of thermal resistance and specific thermal resistance of 8.5  10–2 K m2/W and 20.6 K m/W respectively are found at 150 punches/cm2 needling density and 430 g/m2 fabric weight for 40% jute content level. Cluster analysis reveals that the thickness and thermal resistance form a cluster and specific thermal resistance being sub-cluster depends on them. Thickness, thermal resistance and specific thermal resistance as dependent variables together form a cluster influenced by jute percentage as an independent variable. Sectional air permeability among the dependent variables are highly influenced by fabric weight (Euclidean distance ~ 560) which is a different cluster identity. This study is useful to develop thermal insulating material for industrial applications from jute-polypropylene blended needle-punched nonwoven.

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REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

[15]

[16]

[17] [18] [19]

Singh, U. S., Bhattacharya, G.K., Bagchi, N.N., Debnath, S. (2004). Comparative Study of Woollen Blanket and Jute-Wool Blanket. Textile Trends 47, 9, 27-28. Anonymous. (2008a). Annual report 2007-2008, National Institute of Research on Jute & Applied Fibre Technology, ICAR, 12, Regent Park, Kolkata, India, pp. 33. Debnath, C.R., Bhowmick, B.B., Ghosh, S.K., Das, P.K. (1987). Thermal insulation behaviour of some nonwovens. Textile Trends 30, 5, 45-49. Anonymous. (2006). Annual report 2005-2006, National Institute of Research on Jute & Applied Fibre Technology, ICAR, 12, Regent Park, Kolkata, India, 69-70. Anonymous. (1981). Annual report, Jute Technological Research Laboratories, ICAR, 12, Regent Park, Kolkata, India. Chakravarty, A.C. (1962). Crimp produce in jute fibre by treatment with solution of sodium hydroxide. Textile Research Journal 32, 6, 525-526. Chakravarty, A.C. (1963). Woolenization of jute: some physical aspect, Jute Bulletin 26(1), 16-17. Ganguly, P.K., Sao, K.P., Ambally, C. (1985b). Crimp in alkaline treated jute, Effect of treatment time. Textile Research Journal 55(4), 253-254. Sao, K.P., Jain, A.K.(1995). Mercerization and crimp formation in jute. Indian Journal of Fibre and Textile Research 20(4), 185-191. Saha, P.K., Chatterjee, K.K., Sarkar, P.B. (1961). Woollenised Jute as Wool Substitute. Indian Central Jute Committee Monogram. Ganguly, P. K., Sao, K.P. (1985a). Effect of treatment time on swelling of jute. Textile Research Journal 55(6), 376-377. Sao, K.P., Jain, A.K., Anantha Krishanan, S.R. (1983). A comparative study of the Woollenised jute fibres of several strains. Textile Trends 26, 7, 47-49. Sao, K. P., Jain, A. K. (1984). On Crimp measurement in alkali treated jute. Journal of Textile Association (India) 46, 155-159. Gupta, N.P., Bhattacharyya, G.K. (1984). Performance of yarns and blankets from chemically treated jute-polypropylene blends. Indian Journal of Textile Research 9(4), 160-163. Gupta, N.P., Mazumdar, A., Bhattacharyya, G.K., Sur, D., Roy, D. (1982). Chemically texturizing jute and jute-polypropylene bleached yarns. Textile Research Journal 52(11), 694-702. Sinha, A.K., Mathew, M.D., Roy, D. (1988). Properties of jute polypropylene blended yarns texturised by sodium hydroxide solution. Indian Journal of Textile Research 13(1), 26-30. Ghosh, P., Samanta, A.K. (1997). Chemical Texturing or bulking of rotor-spun jute/polyester fibre blended yarns. Journal of Textile Institute 88( 3), 209-231. Sinha, A.K., Basu G. (2001). Studies on Physical Property of jute-acrylic bulked yarn. Indian Journal of Fibre and Textile Research 26, 268-272. Chaudhury, A., Basu, G. (1998). Studies on the properties of DREF spun acrylic yarn. Indian Journal of Fibre and Textile Research 23(3), 8-12.

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[20] Debnath, S., Sengupta, S., Singh, U.S. (2007a). Properties of Jute and Hollow-polyester Blended Bulked Yarn. Journal of The Institution of Engineers (India): Textile Engineering 87(2), 11-15. [21] Sinha, A.K., Gupta, N.P. (1986). Performance of texturized jute blended carpet. Indian journal of Textile Research 11(1), 35–37. [22] Debnath, S., Bhattacharya, G.K., Singh, U.S. (2009). A blanket from jute-hollow polyester blended bulk yarn and method of preparing the same. Indian Patent Application No. 1102/KOL/2009, August 28. [23] Anonymous. (2008b). Annual report 2007-2008, National Institute of Research on Jute & Applied Fibre Technology, ICAR, 12, Regent Park, Kolkata, India, pp. 76-83. [24] Singh, U.S., Debnath, S., Naskar, R.B., Bhattacharya, G.K. (2006). Studies on Properties of Jute-Viscose Blended Yarn. Textile Trends 49(2), 45-46. [25] Debnath, S., Sengupta, S., Singh, U.S. (2007b). Comparative Study on the Physical Properties of Jute, Jute-viscose and Jute-polyester (hollow) Blended Yarns. Journal of The Institution of Engineers (India): Textile Engineering 88(1), 5-9. [26] Debnath, S., Sengupta, S. (2009). Effect of linear density, twist and blend proportion on some physical properties of jute and hollow polyester blended yarn. Indian Journal of Fibre & Textile Research 34(1), 11-19. [27] Sengupta, S., Debnath, S., Bhattacharyya, G.K. (2008). Development of handloom for jute based diversified fabrics modifying traditional cotton handloom. Indian Journal of Traditional Knowledge 7(1), 204-207. [28] Sengupta, S., Debnath, S., (2010). A new approach for jute industry to produce fancy blended yarn for upholstery. Journal of Scientific & Industrial Research 69(12), 961965. [29] Sengupta, S., Debnath, S. (2012). Studies on Jute-based ternary blended yarn. Indian Journal of Fibre & Textile Research, 37 3, 217-223. [30] Roy, G., Naskar, M., Ghosh, S.N. (2009). Development of Digital Thermal Insulation Value Tester for Jute Products. Indian Journal of Fibre and Textile Research 34(1), 3640. [31] Debnath, S., Madhusoothanan, M. (2010). Thermal insulation, compression and air permeability of polyester needle-punched nonwoven. Indian Journal of Fibre & Textile Research 35(1), 38-44. [32] Debnath, S., Sengupta, S., Singh, U.S. (2008). A method for producing jute-hollow polyester blended yarn, union fabric of said yarn and method of preparing said union fabric and shawl from the said yarn. Indian Patent Application No. 1187/KOL/2008, July 09. [33] Sengupta, A.K., Sinha, A. K., Debnath, C.R. (1985). Needle-punched non-woven jute floor coverings: Part III – Air permeability and thermal conductivity. Indian Journal of Fibre & Textile Research 10(4), 147-151. [34] Box, G.E.P., Behnken, D.W. (1960). Some New three level designs for the study of quantitative variables. Technometric, 2, 455-475. [35] Debnath, S., Madhusoothanan, M. (2011). Thermal resistance and air permeability of jute-polypropylene blended needle-punched nonwoven. Indian Journal of Fibre & Textile Research, 36(2), 122-131.

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[36] Debnath, S., Madhusoothanan, M. (2012). Compression creep behaviour of jutepolypropylene blended needle-punched nonwoven. Textile Research Journal, 82(20), 2097-2108. [37] Paul, N.G., Mukhopadhyay, M. (1977). Thermal insulation values of jute fabrics and its blends with other fibres, Indian Journal of Textile Research 2(3), 88-91. [38] Marsh, M.C. (1931). The thermal insulation properties of fabrics. Journal of Textile Institute 22(4), T245-273.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 21

EFFECTS OF RING FLANGE TYPE, TRAVELER WEIGHT AND COATING ON COTTON YARN PROPERTIES Muhammet Uzun1,2, and Ismail Usta2 1

Institute for Materials Research and Innovation, University of Bolton, Deane Road, UK 2 Department of Textile Engineering, Faculty of Technology, Marmara University, Goztepe, Istanbul, Turkey

ABSTRACT Ring spinning is the most important and effective staple yarn production process. A ring spinning machine consists of a variety of parts of which rings and travellers are the dominant elements. This experimental study has highlighted that the ring flanges and the ring travellers have an effect on the properties of 100% cotton yarn. The interaction between the yarn quality and the spinning elements has been analysed. Ne 40/1 cotton yarns were produced by using both flange 1 and flange 2 rings, half round (dr) and flat (f) profile of ring travellers with four different traveller masses and five different traveller coatings. 80 copses of yarn were produced by using different process combinations. The yarn properties were tested in terms of yarn count, yarn twist, irregularity, yarn hairiness, strength, elongation, spinning tension and balloon angle. As a result, yarn twist and count decreased with increasing spinning tension. Spinning tension in Flange 1 was greater than spinning tension in Flange 2. Increasing the spinning tension improved the following yarn properties; yarn hairiness and yarn twist. The properties of the yarns produced with Flange 2 show better properties than the yarns produced with Flange 1. Increase in ring traveller weight also improved the yarn properties.

Keywords: Cotton yarn, Ring spinning, Flange, Traveller, Hairiness, Yarn irregularity



Email: [email protected] and [email protected].

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Muhammet Uzun and Ismail Usta

INTRODUCTION The main advantages of spinning technology are high productivity, improved yarn characteristics and special twist-imparting mechanism. In recent years, new yarn spinning systems have been designed such as open-end rotor, friction, Sirospun®, Vortex and compact spinning. Despite the emergence of new spinning technologies, conventional ring spinning still remains the most used. This process accounts for 80% of the total staple yarn production due to its superior yarn properties and wide range of yarn productions. The ring spinning and traveller system are illustrated in Figure 1 [1-5]. The spinning tension is one of the critical ring spinning parameters which depends entirely on the ring and the traveller. Some studies aimed to determine the perfect balanced spinning geometry yet there is still room for improvement to produce yarns with optimum characteristics. During the production of yarn with ring spinning, the machine parameters must be taken into consideration. These are traveller weight, traveller and ring geometry, traveller and ring coating, ring position and traveller drive angle to the ring. An ideal combination for production would be: higher traveller speed (which means higher productivity), lower working temperature between ring flange and traveller, extended ring and traveller usage time, better yarn quality (which means less hairiness), reduction of end breaks which has negative effect on productivity, and also avoidance of yarn tension peaks [6-11]. The main conclusion from the previous ring traveller studies show that yarn hairiness can be reduced by using optimum traveller weights. It has also been observed that yarn hairiness strongly depends on mean fibre position, with an inward shifting of the packing density leading to low yarn hairiness [5]. The intervals of helix profiles decreased as the twist increased, the yarn twist value can affect the mean fibre position and hairiness [12,13]. The main aim of this work is to utilise the ring flanges and travellers for the yarn quality in terms of hairiness, twist, breaking strength and irregularity. For this purpose, 80 different combinations were employed to produce yarns. The yarn characteristics were determined by using standard test methods. The tests aimed to establish the impact of the machine parts on the quality of cotton yarns. The results were conducted in an attempt to analyse the optimum production parameters.

Figure 1. Ring and traveller system.

521

Effects of Ring Flange Type …

MATERIALS AND METHODS Materials The cotton fibre specifications are shown in Table 1. The cotton roving was provided by Marmaris Iplik Co., Kahramanmaras, Turkey. The roving count was 655tex (Ne0.91) and irregularity values of 4.8 CV%. Table 1. Cotton fibre specifications

Cotton fibre

Linear Density (dtex) 1.7

Mean length (mm) 28.1

Tenacity (cN/tex) 17.5

Breaking elongation (%) 4.9

The ring flanges and travellers were obtained from Temak Textile Machinery Accessories Industry and Trade Co., Istanbul, Turkey. The ring flange 1 is 3.2mm wide and flange 2 is 4.1mm wide. C type traveller with half round (dr) and flat (f) profiles with five different coating types of blacknic (oxidized), bluenic (oxidized), micronic (nickel plated), silvernic (silver plated) and superpolish (special polished) and four different traveller weights of 35mg, 40mg, 45mg and 50mg were used in this study.

Methods Yarn Production The yarns were produced using a conventional laboratory-type ring spinning machine, SUESSEN-Ringspinntester, the machine specifications are given in Table 2. The 15tex (Ne40) yarns were produced with αtex40 (αe 4.2) twist level and spindle speed 10000rpm. The yarn production was carried out in a conditioned laboratory at 65 % RH and 200C atmosphere. Table 2. Ring machine component specifications Specifications Size in mm Machine size 650×1960×1000 Drafting rollers 28 Front drafting zone 45 Main drafting zone 42 F1-Flange 1 and F2- Flange 2.

Specifications Spindle length Tube length Ring diameter Flange widths

Size in mm 210 260 50 (F1) 3.2 and (F2) 4.1

The Yarn Physical Properties The produced yarn samples were tested individually and analysed to provide a comprehensive understanding of their yarn count, yarn twist, irregularity, yarn hairiness, strength, elongation, spinning tension and balloon angle. Whole yarn production and tests were carried out under standard atmosphere condition (200C±2 and 65%±2 RH) [14].

522

Muhammet Uzun and Ismail Usta a) Yarn counts: The yarn counts were determined in accordance with TS 244 EN ISO 2060: 1999. The yarn samples were prepared in 100m lengths for each yarn types and their masses were weighed by using OHAUS balance and the results were calculated in Ne. b) Yarn twist: The twists were assessed in accordance with TS 247 EN ISO 2061: 1999, by using James H. Heal twist counter equipment. c) Yarn tensile properties: The breaking strength (cN) and elongation (%) properties of yarns were determined using Instron 4411 with test parameters of 500 mm gauge length, 10 cN pre-tension, 5 kg load cell with a test speed of 500mm/min [15,16]. d) Yarn irregularity: The irregularity of yarns were characterised by using Uster Tester I equipment, in accordance with DIN 53817 [17]. The yarn properties obtained were irregularity CV%, thin places (-50%), thick places (+50%) and neps (+200%) for one km of yarn. e) Yarn spinning tension: The aim of this test is to study the influence of the traveller weight on yarn properties. The tension of yarn spinning was determined between the end of the drafting system and yarn guide during the production process. The measurement was performed by using Schmidt ZF2 [18,19]. f) Yarn hairiness: The yarn hairiness was determined by using Shirley Yarn Hairiness Tester. This equipment can detect over 3mm hairs in the yarn surface over a chosen period (5 to 40 seconds). g) Balloon angle: The yarn ballooning angles were photographed during the yarn production by using a Kodak digital camera. From these pictures the angle values were calculated manually [19].

RESULTS AND DISCUSSION The Yarn Physical Properties a) Yarn Counts The yarn counts in Ne are given in Figure 2. It can be observed that the counts are affected by the weight of travellers. The yarns thinned when the traveller’s weights were 50 mg, for all the coatings. The differences were less than Ne 0.5. It has been found that the yarns which were produced by flange 1 were slightly thinner than those produced using flange 2. In general, the yarn counts ranged from Ne 38.46 to Ne 41.12. b) Yarn Twist The number of twists per meter is affected by yarn production tension. The yarn twist number produced with flange 1 was slightly higher than flange 2, but the differences were insignificant (Figure 3). In this study, the highest twist number was found to be 1034.8 T/m, which was produced by using flange 2 and 50 mg traveller weight. The effect of profile of the travellers on yarn twist was analysed and it was observed that the flange 2 yarns with dr profile traveller had more twists than flange 1 with dr and f profile travellers, and also flange 2 with f profile traveller.

523

Effects of Ring Flange Type …

Yarn Count, Ne

F1-50 F1-45 F1-40 F1-35 F2-50 F2-45 F2-40 F2-35

Traveller profile and coating type Figure 2. Yarn counts (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2). F1-50 F1-45 F1-40 F1-35

Twist, T/m

F2-50 F2-45 F2-40 F2-35

Traveller profile and coating type Figure 3. Yarn twists (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

The lowest twist number was for the f type profile. The weight level of the travellers had a significant effect on the yarn twist for flange 1. When the yarns were produced with heavier travellers, the twist values increased. The traveller coating’s effect on the yarn twist were not statistically significant.

c) Yarn Breaking Strength and Elongation The yarn breaking strength is directly dependent on the number of twists per meter in the yarn. The strength will increase with increasing twist value. The flange 2 yarn breaking strengths’ were higher than flange 1’s breaking strength. Significant differences were observed (50 cN) (Figure 4). The highest breaking strength value was demonstrated by flange 2 with 50 mg traveller mass. The traveller profile cross-section also affects the strength and f profile had higher breaking strength than dr profile. The yarn which was produced by a superpolish coating and f profile had superior breaking strength compared to other flangecoating-profile combinations. In general, increased traveller weights increases the yarn strength.

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Figure 4. Yarn breaking strength (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

Due to the difference in twist, elongation values of flange 2 were found to be higher than flange 1. The elongations of the yarns were affected by the coating and weight in a variable way. There was no constant interaction between the coatings and traveller weights. The breaking elongation ranged from 3.5% to 5.5% (Figure 5). The traveller profiles did not have a decisive influence on the breaking elongation of yarns. However, flange 2 dr profile did have the highest elongation value which is about 5.5%.

d) Yarn Irregularity In general, CV% values of the flange 2 had lower yarn unevenness than flange 1. Flange 1’s unevenness was CV% 11 and flange 2’s unevenness was CV% 8. The coatings were found to be significantly important in terms of yarn unevenness (Figure 6). Blacnic and micronic coatings had less unevenness compared to bluenic, silvernic and superpolish. Only superpolish had less unevenness with flange 2 and f profile. Increased traveller weights decreased the yarn unevenness. The minimum unevenness values were observed for flange 2 ring and dr profile traveller with black and micronic coatings.

Elongation, %

F150 F145 F140 F135

Traveller profile and coating type Figure 5. Yarn elongation (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

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Effects of Ring Flange Type …

Irregularity, CV%

F150 F145 F140 F135

Traveller profile and coating type Figure 6. Yarn irregularity (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

The yarn neps decreased with increase in traveller mass. The number of neps in the yarn varies between flanges. Another important finding of this assay was the effect of traveller profile. f type traveller had significantly higher number of neps than dr type traveller. There are no significant differences between the traveller coatings.

e) Yarn Spinning Tension Yarn spinning tension is one of the important spinning parameters which can directly affect the quality of yarn. Previous studies on the interaction between the traveller weights and the spinning tension has confirmed that when the mass of traveller increase, the spinning tension also increases [6, 18, and 19]. The results from this study confirm the hypothesis (Figure 7). The traveller with 50 mg weights had the highest spinning tension for all the coating types. Flange 2 had slightly higher spinning tension compared to flange 1 in some coatings. The spinning tension differences between coatings are not significantly important.

Spinning tension, cN

F150 F145 F140 F135 F250

Traveller profile and coating type Figure 7. Spinning tension (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

f) Yarn Hairiness In the case of yarn hairiness, the hairiness decreased when the traveller weights were increased. It is observed that the yarns which were produced by using flange 2 had lower hairiness value than those produced using flange 1. dr profile traveller caused less hairiness when used with flange 1. The f profile traveller was effective when used in conjunction with

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flange 2. The coating types did not affect the yarn hairiness significantly. The hairiness ranged from 30 to 70 H/m (Figure 8).

Hairiness, H/m

F150 F145 F140 F135 F250

Traveller profile and coating type

Balloo angle, degree

Figure 8. Yarn hairiness (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

F150 F145 F140 F135

Traveller profile and coating type

Figure 9. Balloon angle (dr: Half round, f: Flat, F1: Flange 1, F2: Flange 2).

g) Balloon Angle It was found from the statistical analyses that the balloon angle decreased with increased traveller weight. Figure 9 shows the relationship between the traveller weight and the spinning balloon angles. In this study, the angle of the spinning balloon decreases when the travellers with an increase in weight was due to the increase in tension values. In general, most types of coatings produced with flange 1 had higher balloon angle than flange 2.

Statistical Analysis Variance analysis has been applied to check whether the results obtained are important statistically. The tests of significance were made at 95% and 99% confidence limits. Yarn properties were investigated by two-way variance analysis depending on the traveller weight and coating type. All the analysis results are given in Table 3.

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Effects of Ring Flange Type … Table 3. Variance analysis of yarn properties with different traveller weight and coating

Properties Yarn count

Variation Sources Traveller weight Traveller coating

Flange 1 Traveller profile dr f α0.05 α0.01 α0.05 α0.01 ns ns ns ns ns ns ns ns

Traveller weight ns Traveller coating ns Yarn Traveller weight ns strength Traveller coating s Traveller weight s Elongation Traveller coating s Traveller weight s Irregularity Traveller coating s Spinning Traveller weight s tension Traveller coating s Traveller weight ns Hairiness Traveller coating s Balloon Traveller weight s angle Traveller coating s s – significant, and ns – not significant. Yarn Twist

ns ns ns s s s ns ns s s ns s s s

ns ns ns ns ns ns ns ns s s ns ns s s

ns ns ns ns ns ns ns ns s s ns ns s s

Flange 2 Traveller profile dr f α0.05 α0.01 α0.05 α0.01 ns ns ns ns ns ns s s ns ns ns ns ns ns ns s s s s s ns s

ns ns ns ns ns ns ns s s s s s ns ns

s ns ns s s ns ns s s s ns ns s ns

s ns ns ns ns ns ns s s s ns ns s ns

When Table 3 is examined, it can be clearly seen that traveller weight and coating have an important effect on spinning tension in both significance levels. Balloon angle effect from traveller weight and coating is important in flange 1 in both significance levels. Traveller weight has not important effect on yarn count and yarn strength. Also traveller coating has not important effect on yarn twist. Except flange 2 with f profile, traveller coating has not important effect on yarn count. Except flange 2 with f profile, traveller weight has not important effect on yarn twist. Traveller coating has an important effect in flange 1 with dr profile. Yarn elongation effect from traveller weight and coating is important in flange 1 with dr profile. Traveller coating has an important effect on yarn irregularity in flange 2 with dr and f profiles. Yarn hairiness effect from traveller coating is important in dr profile with both flange 1 and flange 2.

CONCLUSION In order to define the relationship between the physical properties of the yarn and the production process, it is considered that the usage of flange 2 has some advantages over flange 1. In this study demonstrated that the traveller weight and yarn spinning tension are important production parameters. From the results and discussion of this study it can be concluded that the yarns produced with flange 1 are slightly finer than flange 2, yet for most of the yarn this was not found to be of a significant level. It was significant only for f profile travellers. Except flange 2 with f profile, the traveller coatings did not have any important effect on the yarn counts.

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The observed twist values of flange 1 and flange 2 were very similar. The highest twist number(T/m) was found in the yarn that was manufactured by using flange 2 with a traveller weight of 50 mg. Traveller profile had a variable effect on the yarn twist. Flange 2 with dr profile traveller had higher twists in general. When the traveller weight was increased, the twist value also increases. In general, flange 2’s breaking strengths were more than flange 1’s breaking strength, and the differences were of a significant level (50 cN). The highest breaking value was demonstrated by flange 2 ring and 50 mg travellers. The yarn which was produced using the superpolish coated f profile traveller had superior breaking strength compared to the other combinations. Yarn elongation was affected by the coating and weight in a variety of ways. The traveller profiles did not have a decisive influence on the yarn elongation behaviour. For most of the combinations, flange 2 had much lower yarn irregularity than flange 1. Flange 1’s irregularity was 11 CV% and flange 2’s irregularity was 8 CV%. The coatings had a considerable effect on the yarn irregularity. The yarn spinning tension of this study was found to be similar to the previous studies. When the traveller weight increased, the spinning tension increases. Flange 2 had slightly higher spinning tension compared to flange 1. The coatings have important affect in the spinning tension. The yarn hairiness decreased with increased traveller weight and yarns produced using flange 2 had less hairiness than those produced using flange 1. The balloon angle changed with traveller weight changes, higher the traveller weight lower the lower angle.

ACKNOWLEDGMENTS The authors are thankful to Marmaris Iplik Co., Kahramanmaras, Turkey and Temak Textile Machinery Accessories Industry and Trade Co., Istanbul, Turkey for their support during this research.

REFERENCES [1] [2] [3] [4] [5]

Johnson, T.F.N. (1996). World fiber demand 1890-2050 by main fiber type. Man Made Fiber Year Book (CFI), 31-37. Mourad, K., Ethridge. D. (2004). A Qualitative Approach to Estimating Cotton Spinnability Limits. Textile Research Journal, 74(7), 611-616. Krifa, M., Ethridge, M.D. (2006). Compact Spinning Effect on Cotton Yarn Quality: Interactions with Fiber Characteristics. Textile Research Journal, 76(5), 388-399. Demir, A., Torun, A. (2003). Tekstilde Üretim Yöntemleri. İ.T.Ü., 75-92. Huh, Y., Kim, Y.R., Oxenham W., (2002). Analyzing Structural and Physical Properties of Ring, Rotor, and Friction Spun Yarns. Textile Research Journal, 72(2), 156-163.

Effects of Ring Flange Type … [6] [7]

[8]

[9] [10] [11] [12] [13] [14] [15]

[16] [17] [18] [19]

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Usta, İ., Canoglu, S. (2002). Influence of Ring Traveller Weight and Coating on Hairiness of Acrylic Yarns. Fibres & Textiles in Eastern Europe, 39, 20-24. Barella, A., Manich, A.M. (1988). The Influence of the Spinning Process Yarn Lineer Density and Fibre Properties on the Hairiness of Ring Spun and Rotor Spun Cotton Yarns. The Journal of the Textile Institute, 79/2, 189-197. Viswanathan, G., Munshi, V.G., Ukidve, A.V., Chandran K. (1989). A Critical Evaluation of the Relationship Between Fiber Quality Parameters and Hairiness of Cotton Yarns. Textile Research Journal, 59/11, 707-710. Subramanian, V., Mohamed, A.P. (1991). A Study of Double-rove Yarn Hairiness in the Short-staple-spinning Sector. The Journal of the Textile Institute, 82/3, 333-339. Sonntag, E. (1995). Analysis of the Forces Generated During the Clipping of Travellers onto Rings. Textile Research Journal, 65, 178-184. http://www.textiletechnology.co.cc/spinning/Rings-and-Travellers-4.htm Morton, W.E. (1956). The Arrangement of Fibres in Single Yarns. Textile Research Journal, 26, 325-331. Hearle, W.S., Gupta, B.S. (1965). Migration of Fibres in Yarns. Part III: A Study of Migration in a Staple Fibre Rayon Yarn. Textile Research Journal, 35, 788-795. ASTM (D-1776-90), “Standard Practice for Conditioning Textiles for Testing. American Society for Testing and Materials, West Conshohocken, PA, 483-446. Uzun, M., Patel, I. (2010). Mechanical properties of ultrasonic washed organic and traditional cotton yarns. Journal of Achievements in Materials and Manufacturing Engineering, 43/2, 608-612. TS EN ISO 2062: 2010. DIN 53817-1, (1981). “Testing of Textiles; Determination of Unevenness of Slivers and Yarns” Deutsches Institut Für Normung. Demir, A., (1990). İplik Gerginliğinin Önem ve Ölçümü, Bölüm 3: İplik Ölçümlerinin Uygulamaları. Tekstil & Teknik, 94-99. Usta, I. (2008). Effect of Balloon Angle on the Hairiness and other Yarn Properties of Polyester Ring Spun Yarn. Fibres&Textiles in Eastenr Europe, 70, 40-47.

In: Textiles: History, Properties and Performance … Editor: Md. Ibrahim H. Mondal

ISBN: 978-1-63117-262-5 © 2014 Nova Science Publishers, Inc.

Chapter 22

OPTICAL FIBER EXAMINATION BY CONFOCAL LASER SCANNING MICROSCOPY Andrea Ehrmann Niederrhein University of Applied Sciences, Faculty of Textile and Clothing Technology, Moenchengladbach, Germany

ABSTRACT Confocal laser scanning microscopy (CLSM) is a microscopy technique which can be used to obtain high-resolution optical pictures. By acquiring images from a series of depth layers using a focused laser beam, a computer program can be used to reconstruct a three-dimensional picture of a sample surface. This technique is on the one hand similar to a scanning electron microscope (SEM); on the other hand, a CLSM needs no introduction of samples into a vacuum chamber. The lateral resolution of a CLSM of about 150 nm is most often sufficient to examine textile fibers, e.g., to distinguish between different natural and man-made fibers as well as between different natural fibers. This chapter will give an introduction into the technique of confocal laser scanning microscopy and depict optical differences between several textile fibers, enabling a nondestructive examination of natural and chemical fibers.

INTRODUCTION The resolution of optical microscopes is limited by the wavelengths of the visible light spectrum, resulting in maximal resolutions of around 1 micron (i.e., 0.001 mm). Scanning electron microscopes (SEM) can have resolutions in the order of 1 nm (0.001 micron); however, they mostly require some sample preparation, such as sputtering a thin conductive film on the surface, and samples are normally introduced into a vacuum chamber for measurement. 

Corresponding author: Andrea Ehrmann. Niederrhein University of Applied Sciences, Faculty of Textile and Clothing Technology, Webschulstr. 31, 41065 Moenchengladbach, Germany. E-mail: andrea-ehrmann@gmx. de.

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For non-invasive examination of samples which require a higher resolution than possible in optical microscopes, but should be measured without pretreatment (especially valid for biological samples), a confocal laser scanning microscope can be the ideal solution. The method of confocal laser scanning microscopy (CLSM) was patented by Marvin Minsky, who needed to make real-time microscopic pictures of living systems, in 1961 [1]. It tries to overcome the resolution limits of wide-field optical microscopy and additionally enables “seeing” through semi-transparent sample parts into defined depths. After the first confocal microscope built by Egger and Petran in the late 1960s, the development of CLSMs was supported by advances in laser and computer technology, until in the late 1980s the first commercial instruments became available [2]. The principle setup of confocal laser scanning microscopes is depicted in Figure 1. A coherent laser beam is emitted through a pinhole and a lens onto a sample surface. The reflected beams can only pass the second pinhole if both pinholes are in conjugate planes, i.e., confocal. This leads to elimination of out-of-focus signals (dotted line in Figure 1) as well as of stray light. Refocusing of the microscope’s objective results in a new plane of the sample under examination being confocal with the pinhole planes and thus becoming visible in the photo-detector. In contrast, a sample examined by optical wide-field microscopy is evenly lit in all focal planes, leading to a large unfocused background in the camera or photo-detector of a digital microscope or in the user’s eye for an analog microscope, respectively. While a usual optical microscope’s lateral resolution can be calculated due to the Rayleigh criterion as ropt = 0.6  / NA (with the light wavelength  and the numerical aperture of the objective lens NA), experimental investigations of CLSMs show that this value is reduced to rCLSM = 0.4  / NA in confocal microscopes. With ultraviolet laser light (e.g., 408 nm wavelength [3]) and numerical apertures next to 1 (e.g., 0.95 for the highest-resolution objectives [3]), resolutions of 170 nm are possible.

After [1], modified. Figure 1. Principal sketch of a confocal microscope.

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While the confocal technique can significantly enhance the optical resolution by deleting undesirable light from other focal planes, the elimination of large parts of the light by the pinhole also results in longer measurement times. For each experiment, resolution and exposure time have to be balanced according to the demands of the respective analysis. Scanning the sample happens via the scan head which rasterizes the scans and collects the signals from the sample in a CCD camera or a photomultiplier. The scan head contains inputs from the laser sources by a fiber optic coupler, normally followed by a beam expander leading to the laser beam filling the complete objective rear aperture, dichromatic mirrors, a scanning system for x- and y-direction, variable pinhole apertures to generate the confocal image, and a light detector [2]. Beam scanning can happen via two different techniques: Most CLSMs use single-beam scanning, working with a pair of computer-controlled galvanometer mirrors which let the laser beam scan the sample in a raster pattern. However, if faster scanning rates are desired for real-time videos of living systems, a spinning Nipkow disk with an array of pinholes and micro-lenses can be used instead. In these multiple-beam systems, arc-discharge lamps can replace the laser to reduce possible damage of the sample. Such microscopes can capture complete images with an array detector, such as a CCD camera. The aperture in front of the detector can contain pinholes of different diameters in a rotating disk, allowing for adjustment of the focal plane thickness by the pinhole size. The illumination spot on the sample, which is in the order of magnitude of 0.1 to 1 micron, is defined by the numerical aperture of the objective [2]. Some CLSMs use a white light source additional to a short-wavelength (ultraviolet) laser. While the laser light creates a high-resolution grayscale picture, as described above, the white light produces a colored picture with lower resolution, showing the real colors of the observed object. Superposing both pictures results in a high-resolution colored picture [3]. Other CLSMs allow for fluorescence pictures of biological samples. For this purpose, multi-wavelength laser systems for ultraviolet, visible, and near-infrared spectral regions, enhanced interference filters and sensitive low-noise wide-band detectors are of special interest [2]. The software packages belonging to a commercial CLSM are normally able to generate three-dimensional views of the sample under investigation, including the possibility of measuring the depth of sample features or depicting the surface roughness by false color representation.

EXPERIMENTAL Several natural and chemical fibers used in the textile industry have been examined by CLSM, giving rise to differences in the surface structure, allowing for differentiation between natural and chemical fibers, on the one hand, but also between different kinds of wool etc. Sometimes, the results of chemical or physical treatment are also visible, which is shown here exemplarily by a chemical treatment of hemp and a laser-treated polyester fiber. All microscopic images in this chapter have been taken with the microscope VK-9700 by Keyence.

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Figure 2. Overview on VK-9700 by Keyence (left panel); objectives with 20 x, 50 x, and 100 x magnification (right panel).

Figure 2 (left panel) gives an overview on the CLSM system used for the microscopic pictures in this chapter. The display on the left side shows the results of the measurements performed with the laser head and the objective system on the right side. The objectives (Figure 2, right panel) can be rotated to change the magnification and can be completely exchanged. Figure 3 shows the software front panel which is used to setup the CLSM. Firstly, the software is switched to “Camera” to search the height area in which parts of the picture are sharp. This area defines the measurement range, set by the values for the upper and lower position of the motor stages. An auto gain allows for taking photographs which are neither too dark nor too bright. The Z pitch defines the steps for the movement of the laser head relative to the sample. The duration of taking one photograph can vary between a few seconds (for rather flat samples, high Z pitch and low resolution) and ten or twenty minutes for rough samples, low Z pitch and high resolution. A special feature of the VK-9700 by Keyence is the possibility to superpose the laser intensity with a color picture with lower resolution, which adds real colors to the sharp laser intensity picture. Most images in this chapter have been taken using an objective with 50 x magnification, corresponding to a nominal magnification (on a 15’’ display) of 1000 x. That means each microscopic picture (besides Figure 4) in this chapter shows an area of 202 m x 270 m. These values can be extended to a magnification of 15 x / 3000 x by changing the objective. Additionally, an optical zoom can add up to 6 x magnification, resulting in a maximum nominal magnification of 18,000 x. Opposite to a digital zoom, this optical zoom does not decrease the resolution, but can really add more information. Since the optical zoom is not connected with a change of the lenses, it can be very helpful, especially for investigations of fibers which may be touched during a rotation of the objective system. For comparison, Figure 4 depicts microscopic images of wool fibers with nominal magnifications of 1000 x (left panel) and 3000 x (right panel). The typical scales on the fibers are clearly visible in both pictures.

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Figure 3. The software used to control the CLSM allows for several adjustments, dependent on the respective sample to be examined.

Figure 4. Wool fibers, microscopic images with nominal magnifications of 1000 x (left panel) and 3000 x (right panel).

Since the working distance for the objective with highest magnification is only ~ 0.2 mm, fiber examinations can be performed more easily with a lower resolution. As Figure 4 shows, it is often sufficient to work with a nominal magnification of 1000 x; otherwise, the optical zoom can be used to enlarge the magnification.

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Figure 5. Report with line measurement of the height of the wool scales.

Nevertheless, higher resolutions can be very helpful for more exact measurements, e.g., of the height of the scales on wool fibers. In Figure 5, a line measurement of this scale height is depicted, performed on the microscopic image shown in Figure 4 (right panel). The precision of measurements in lateral direction (i.e., in the sample plane) is defined by the resolution of the microscopic image, while for measurements in z-direction (i.e., perpendicular to the sample plane) the Z pitch also influences the possible measurement precision. Depending on the desired accuracy in distance measurements, it might be supportive to enhance the magnification and / or the Z pitch, the latter resulting in more images taken in different heights and correspondingly longer measurement times. After this short introduction into the technique of CLSM, the next sub-chapters will give an overview of different natural and man-made fibers and possibilities of differentiation between them.

ANIMAL FIBERS Animal fibers, e.g., wool, silk, cashmere wool, mohair, angora, but also not commercially used hair of dog, cat, wild pig etc. or feathers, consist mostly of proteins. In mass production, sheep wool and silk are used most often, but alpaca or mohair are also quite common.

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Figure 6. Undercoat (short hair lying underneath the longer outer hair) of dog (left panel) and guard hair (hair on top) of wild pig (right panel). The magnification is identical for both pictures.

Differences in the fiber structure and surface (length, thickness, crimp, scale) define the properties of the yarns and textiles produced from these fibers. Thus, microscopic pictures can be a tool to distinguish between different animal fibers – not only between, e.g., silk and wool, but also between different sorts of sheep wool. In Figure 6, undercoat of a dog and guard hair of a wild pig are shown. Compared with the wool fibers in Figure 4 (left panel), both sorts of hair have a larger diameter. The scale structure of the dog undercoat differs significantly from sheep wool, the latter having larger, higher and more clearly defined scales. The wild pig guard hair, however, shows a significantly larger diameter, with several well-defined scales positioned side by side on the surface, opposite to sheep wool which mostly shows one or two scales on one circumference. Apparently, distinguishing between different animals is possible with CLSM, if a reference database is available. But can confocal microscopy also help in differentiating between, e.g., the wool of different sheep? One of the properties which can often be used to distinguish between different fibers is the fiber diameter. In Figure 7, microscopic images of the wool of a mountain sheep and a Texel sheep are shown, both photographs taken with the same magnification. The difference in the diameters of both sorts of wool is obvious. Additionally, the forms and dimensions of the scales can support differentiation between both types of wool. While the mountain sheep wool has irregular scales, partly forming “spikes” and having similar heights and widths (left panel), the Texel sheep wool shows more rounded scales which are mostly less high than wide (right panel). Moreover, the Texel sheep wool shows several dot-like “hills”, additional to the scale structure (right panel), which is significantly less pronounced in the picture of the mountain sheep wool. Such sub-structures, however, must be treated carefully, since they might arise from contaminations with other materials – since the CLSM is not element-sensitive, only the color of such features can give a hint about their nature. The final decision whether small structures are a basic part of a certain sort of fiber, or if some impurities become visible in the CLSM pictures, is often up to the experimentalist’s experience. A simpler, but also more common question deals with fiber blends. Especially for financial reasons, fiber blends may be declared incorrectly. Figure 8 shows microscopic pictures of a fabric which has been declared to consist of 100 % finest wool.

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Figure 7. Wool of mountain sheep (left panel) and Texel sheep (right panel), microscopic images both taken at a nominal magnification of 1000 x.

Figure 8. Fine wool fibers (left panel) and unexpected addition of synthetic fibers (right panel).

While parts of the fabric do indeed consist of wool (left panel), additional synthetic fibers can be found in the textile (right panel), which can clearly be identified by their flat surfaces without any scale structures. In this way, microscopic images can even help to identify possible imitations of fabrics made of valuable fibers, such as cashmere or pashmina, a mixture of cashmere and silk [4].

PLANT FIBERS Plant fibers can be bast fibers extracted from field crops, which are typically harvested after one season of growing, opposite to trees which can be harvested continuously. Thus, plant fibers often have to be stored for long times before they can be used in pulp mills. Among the bast fibers, hemp, flax / linen, jute, nettles, ramie etc. can be found. Cotton, bamboo, sisal and other fibers, however, are produced from leaf, fruit, and other fibers of plants besides the stem-skin bast fibers. Plant fibers are based on cellulose which is often bound by lignin, a material which can be found in the cell walls between cellulose, hemicelluloses, and pectin. Some synthetic fibers are also based on cellulose fibers, such as Lyocell, rayon or bamboo.

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All bast fibers have a similar appearance, different from the typical scale structures of animal fibers. Hemp fibers (Figure 9, left panel) are connected by pectin to form fiber bundles. The single fibers become visible here due to biological and chemical treatment which dissolves the pectin bonds. The transverse thickenings can be attributed to mechanical load during growth or during digestion [5, 6]. Mechanical digestion separates the fibers from the wooden parts. Flax fibers (Figure 9, right panel) have been used for clothing production for tens of thousands years until in the nineteenth century cotton became more popular. The fiber is quite straight and smooth, soft and flexible, although less elastic than cotton. The chemical procedure of retting the flax and the mechanical breaking, scotching, and heckling processes separate the fibers from the inner wooden part of the stem and remove the straw from the fibers. Figure 9 (right panel) shows a single fiber (smooth, shiny fiber in the middle of the picture) between fiber bundles. The optical appearance of both types of bast fibers, as can be seen in Figure 9, is thus strongly dependent on the physical and chemical treatment prior to taking the CLSM pictures. While the fibers can clearly be identified as types of bast fibers, optical differentiation between them can be difficult, depending on the amount of digestion. Complete fiber bundles, still containing the original amount of pectin and straw, can be hard to identify, as visible in Figure 9, comparing the pectin-surrounded fiber bundles in both images. If the single fibers are visible, then the irregularly formed hemp fibers can, e.g., be distinguished from the polygonal flax fibers. Cotton fibers, consisting nearly completely of cellulose, grow in a capsule around the seeds of cotton plants. Nowadays cotton is the most often used natural fiber for clothing. Opposite to bast fibers (Figure 9), cotton fibers have a characteristic flatoval cross-section form which allows for differentiation from the triangular cross-section of silk as well as from the smooth, even synthetic fibers.

CELLULOSE FIBERS Synthetic fibers are normally produced by extrusion of the respective materials through spinnerets into the air where the thread is formed. They can be subdivided into cellulose fibers, polymer fibers, mineral, metallic and other fibers.

Figure 9. Microscopic images of hemp fibers (left panel) and flax fibers (right panel).

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Figure 10. CLSM image of cotton fibers.

Figure 11. Lyocell (left panel) and alginate (right panel) fibers as examples for regenerated cellulose fibers.

Manufactured cellulose fibers are extruded from a pulp of regenerated or pure cellulose. Rayon (viscose), including modal and Lyocell fibers, are quite common. Other man-made fibers from cellulose are, e.g., bamboo fibers or alginate, produced from seaweed. Lyocell fibers (Figure 11, left panel) are, opposite to other viscose fibers, normally quite smooth, with a roughly round cross-cut. The longitudinal grooves which are typical for viscose fibers are not visible in Lyocell [7, 8]. The smooth, even alginate fibers (Figure 11, right panel) are often used as wound dressing, since they swell during gelatinization due to the moisture in the wound, thus completely filling even very deep wounds with nearly inaccessible areas. Due to the spinning process from a pulp, synthetic cellulose fibers can normally not be distinguished, although some cross-sections and surface structures can be typical for certain materials.

POLYMER FIBERS Opposite to synthetic cellulose fibers, polymer fibers are produced from synthetic chemical materials.

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Amongst them, materials like polyester, polyamide, polyolefin fibers or acrylic fibers can be found as well as aromatic polyamides (aramids) or polyethylene with partly extremely long chains, resulting in ultra-high-molecular-weight polyethylene (UHMWPE) fibers with very special physical properties, such as very low elasticity and friction combined with very high abrasion resistance. Polyester (PES) (Figure 12) belongs to the polycondensation fibers which are based on monomers reacting step-wise to dimers, trimers, and longer and longer oligomers, losing small molecules as by-products. Polyester fibers normally have a round cross-section and a flat, smooth surface; however, the structure can be influenced by the form of the spinneret and chemical treatments. Other polyconcensation fibers are polyamides or polyurethanes. Aliphatic polyamide 6 (PA 6) fibers are depicted in Figure 13 (left panel), aromatic polyamide (aramide) fibers are shown in Figure 13 (right panel). Both look very similar to each other and to the PES fibers in Figure 12. Chain-growth polymerization fibers, e.g., polypropylene, polyethylene, or polyvinyl chloride, are based on unsaturated monomer molecules adding on the active position of a growing polymer chain without producing by-products with low molecular weight.

Figure 12. Microscopic image of polyester fibers.

Figure 13. CLSM pictures of polyamide 6 (left panel) and aramide fibers (right panel).

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Figure 14. Polyacrylonitrile (PAN) fibers (left panel) and UHMWPE fiber “Dyneema” produced by DSM, Netherlands (right panel).

PAN (polyacrylonitrile) fibers (Figure 14, left panel) as well as the UHMWPE fiber Dyneema (Figure 14, right panel) show structured surfaces, the PAN fibers additionally a not round cross-section. However, these properties depend on the form of the spinnerets and thus cannot be used for a differentiation between different types of fibers [8]. Nevertheless, the fibril structure visible in the Dyneema fibers is a typical feature due to the special spinning process. The loose fibril in Figure 14 (right panel) is the result of an improper rewinding process.

METALLIC FIBERS Pure metal fibers are mostly round, since they are drawn step-wise through smaller and smaller spinnerets. Figure 15 shows stainless steel filaments from a pure stainless steel yarn. Opposite to optical examinations by eye, the typical metallic brilliance is not visible here, due to the auto gain function of the microscope which avoids too bright picture parts. On the surface, fine longitudinal marks are visible, less pronounced than in the Dyneema fiber (Figure 14, right panel), but also continuous, unlike the structure of the PAN fiber depicted in Figure 14 (left panel). Although the surface structure of the metal filaments seems to be unique, compared with the other figures in this chapter, care must be taken due to the possible influences of the spinnerets and physical / chemical treatments of metal and other fibers.

PHYSICAL AND CHEMICAL TREATMENTS OF FIBERS Opposite to pure metal fibers, partly metalized fibers can be recognized easily in CLSM images. Figure 16 (left panel) shows fibers of a Shieldex yarn, consisting of pure PES and silver coated fibers, the fine silver layer being partly destroyed by several washing cycles. Here, the rougher surface structure, compared to pure polyester, and the metallic glittering on the coated fibers clearly indicate a metallic coating on parts of the fibers. Another way of physical treatment of PES fibers is exposition to a pulsed excimer laser. The results are shown in Figure 16 (right panel).

Optical Fiber Examination by Confocal Laser Scanning Microscopy

543

The lateral ripples are produced by the sudden heating and cooling due to the intense laser pulses. In the middle of the image, several tipped-over ripples can be identified, additional to a part of one fiber which has apparently been shaded from the laser light, thus still presenting a flat surface without ripples. For the detection of such structures, a CLSM is ideally suited, while a simple optical microscope can only give a rough idea of these laserproduced surface structures without more detailed information. In some cases, the influence of chemical treatment of fibers is also visible in CLSM. Figure 17 show hemp fibers treated by hammer mill, without (left panel) and with (right panel) chemical after-treatment, i.e., digestion of the fibers by chemical retting in, e.g., sulfuric acid. Comparing both pictures, the vanishing of the pectin in the fiber bundle apparently leads to dissolving of the fibers which become singularly visible. It should be mentioned, however, that other chemical treatments, nano-coatings, etc., are normally not visible in a confocal laser scanning microscope, since the resolution is not sufficient to identify nano-scale features.

Figure 15. Stainless steel filaments, recorded by CLSM.

Figure 16. Shieldex yarn, produced by Statex, Bremen, Germany (left panel) and laser treated PES fibers (right panel).

544

Andrea Ehrmann

Figure 17. Hemp fibers treated by hammer mill only (left panel) and additionally treated chemically (right panel).

Figure 18. Wool fibers with insufficient measurement range (left panel) and Lyocell fibers with only one part of the possible measurement range (right panel).

CHANCES AND PROBLEMS While especially natural fibers and physical treatments of fibers can often be identified by CLSM, the technique possibilities are nevertheless limited. Especially the basic principle of confocal laser scanning microscopy, i.e., scanning only in well-defined distances to the objective, may be problematic. Figure 18 depicts an image of wool fibers (left panel) for which an insufficient measurement range has been chosen, leading to black areas inside the fibers where the surface was not positioned between upper and lower limit of the measurement range. While such a problem is evident and can thus be corrected in a new picture with extended limits, it is also possible to completely miss some fibers. Comparing Figure 18 (right panel) with Figure 11 (left panel), both pictures clearly show the same area of the same yarn; however, in Figure 18 (right panel), some fibers are missing due to a wrong limit in the measurement range. The shading effects, caused by higher fibers which are missed in this way can nevertheless influence the appearance of the depicted fibers which might cause additional interpretation problems.

Optical Fiber Examination by Confocal Laser Scanning Microscopy

545

CONCLUSION Similar to an SEM, a CLSM is not able to distinguish between all sorts of synthetic fibers which often look identical, independent of their chemical composition. However, confocal laser scanning microscopy is a powerful tool for optical examination of fibers, combining some of the advantages of optical light microscopy and scanning electron microscopy. For most fibers, the resolution of a CLSM is sufficient to analyze the surface structures which can be used to identify the type of fiber.

REFERENCES [1] [2]

[3] [4]

[5] [6] [7]

[8]

Minsky, M. (1961). Microscopy Apparatus. US Pat. 3,013,467. Claxton, N. S., Fellers, T. J., Davidson, M. W. (2013). Laser scanning confocal microscopy. Olympus website. 1-37. Available at: http://www.olympusfluoview.com/ theory/LSCMIntro.pdf. Instruction book of VK9700K, Keyence. Tillmanns, A., Korger, M., Weber, M. O. (2012). Konfokale LaserscanningMikroskopie – Zerstörungsfreie Faseruntersuchung. forward textile technologies 4, 4647. Thygesen, L. G., Hoffmeyer, P. (2005). Image analysis for the quantification of dislocations in hemp fibres. Ind. Crop Prod. 21, 173-184. Wang, H. M., Wang, X. (2005). Surface morphologies and internal fine structures of bast fibers. Fiber Polym. 6(1), 6-12. Abu-Rous, M., Ingolic, E., Schuster, K. C. (2006). Visualisation of the nano-structure of Tencel® (Lyocell) and other cellulosics as an approach to explaining functional and wellness properties in textiles. Lenzinger Berichte 85, 31-37. Kleinhansl, E., Mavely, J. (1986). Denkendorfer Fasertafel 1986; Textilpraxis Int., Leinfelden-Echterdingen, GE.

INDEX # 20th century, 84, 201, 268, 319 21st century, 16

A A(H1N1), 384 abatement, 311 abrasion, 23, 25, 41, 42, 43, 44, 48, 218, 343, 345, 375, 383, 386, 389, 541 abrasion resistance, 218, 375, 541 abrasion test, 383, 386 absorption spectra, 104, 177, 181, 183, 184, 185, 194, 200 absorption spectroscopy, 177, 321 abstraction, 176 access, 5, 195, 314, 356, 372 accessibility, 5, 129, 130, 140, 141, 148, 149, 268, 401, 411, 413, 419 accordion, 466 accounting, 113 acetic acid, 99, 123, 136, 137, 138, 140, 155, 179, 406 acetic acid content, 138, 140 acetone, 139, 140, 148, 149, 151, 179, 238 acetonitrile, 208 acetyl content, 138, 139, 140 acetylation, 136, 137, 139, 140, 141, 155, 404 acidic, 116, 177, 178, 179, 375, 412, 419 acidic functional groups, 412, 419 acidity, 217 acrylate, 155, 365 acrylic fibers, 165, 541 acrylic resin, 242, 321, 345 acrylics, 98, 100, 157, 159 acrylonitrile, 154, 217 activated carbon, 397, 430, 436, 444, 445

activation energy, 112 active site, 295, 420, 422 active smart textiles, 240 active thermal insulation effect, 242 active transport, 199 active type, 190 actuation, 244 actuators, 188, 189, 239, 241, 245, 250, 448 AD, 264, 266, 270, 276, 337 adaptation(s), 67, 68, 69, 82, 188, 400, 449 additives, 79, 82, 102, 109, 116, 208, 210, 220, 365 adhesion, 87, 101, 196, 249, 250, 256, 277, 283, 306, 313, 343, 362, 363 adhesion properties, 101, 196, 256 adhesives, 124, 344, 352 adjustment, 457, 533 adsorption, 115, 155, 280, 307, 351, 400, 412, 415, 419, 420, 421, 422, 436, 437, 438, 440, 441, 443, 444, 445 adsorption isotherms, 420 adsorption properties, 155, 400, 440 advancement(s), 188, 274, 415 adverse conditions, 320 adverse environmental effects, 294 aesthetic, 1, 21, 22, 24, 192, 244, 339, 490, 508 aesthetic finishing process, 21 aesthetic satisfaction, 192 aesthetics, 3, 191 AFM, 305, 306 Ag-agglomeration process, 301 agar, 296, 300 Ag-clusters, 277, 279, 282, 286, 306 Ag-disinfection performance, 289 age, 8, 9, 13, 322 aged textiles, 316, 336 aggregation, 113, 184, 292 Ag-hospital textiles, 289 Ag-nanoparticulate films, 278 Ag-nitrides, 278

548

Index

Ag-polyester fibers, 285 agriculture, 362 Ag-sputtered films, 277 Ag-textile surfaces, 278 air permeability, 384, 490, 507, 509, 512, 515, 517 air pollutants, 100 air temperature, 487 Akaike information criterion, 420, 421 alcohols, 98, 217, 328 aldehyde functionalities, 406 aldehydes, 370, 431 algae, 289 alginate, 350, 351, 383, 384, 385, 389, 395, 540 alginate chains, 384 alginate fibers, 540 algorithm, 61, 65 alkali-clearing property, 165 alkaline treatment, 324, 404, 407, 408, 412, 440, 501 alkyl methacrylates, 122 allergenic effect, 400, 403 allergic responses, 370 alters, 249 amine(s), 77, 154, 159, 165, 168, 173, 361, 372, 375 amine group, 361 amino, 23, 34, 43, 55, 78, 158, 164, 165, 166, 169, 170, 171, 172, 177, 179, 184, 185, 205, 236, 238, 373, 374, 375 amino acid(s), 23, 34, 43 amino groups, 158, 373, 374, 375 aminoazobenzene derivatives, 159 aminosilicone softener, 374, 375 ammonia, 99, 280 ammonium, 165, 167, 182, 218, 374 amorphous regions, 326, 329, 333, 401, 410, 413 amylase, 23 amylopectin, 23 anaerobic conditions, 271 anatase, 314 anatomy, 17 aneurysm, 467, 478 angioplasty, 480 angora, 536 anhydroglucose units, 405 aniline, 165, 172, 173, 176, 235, 236 ANOVA, 384, 387, 388, 391, 395 ANOVA analysis, 388 Anthraquinone, 159, 160 Anthraquinone derivatives, 159 Anthraquinone disperse dyes, 160 anthraquinone dyes, 159 anti-back staining agent, 28 antibacterial activity, 278, 301, 313, 314, 365 antibacterial surfaces, 278, 288

anticoagulant, 474 anticoagulation, 474 anti-counterfeit, vii, 81, 103, 118, 210 antimicrobial agents, 310, 365, 384 antimicrobial nanoparticulate films, 289 antimicrobial properties, 362, 403 antique, 2, 8 aorta, 467, 479 aortic stenosis, 479, 480 aortic valve, 480 apparel, 3, 8, 19, 20, 21, 22, 23, 24, 25, 26, 31, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 46, 47, 48, 49, 136, 191, 211, 227, 243, 246, 367, 368, 390, 475, 490, 492 apparel industry(ies), 20, 21, 22, 23, 367 apparel manufacturers, 21, 22 apparel products, 475 apron draft spinning system, 506 aptitude, 471 aqueous solutions, 34, 177, 412, 413, 441, 443, 444 arabinofuranose units, 402 arc-discharge lamps, 533 archaeological excavations, 83 archaeological sites, 316 archaeological textiles, 274, 275, 276, 317, 336 archaeologists, 259, 260, 269, 270, 271, 272, 273, 274 archaeology, 269, 274, 276, 339 aromatic diazo compound, 163 aromatic polyamide, 541 aromatic rings, 207, 214 arteries, 471, 476 artery, 465, 467, 472, 473, 476, 477, 478, 479 artificial fibres, 278, 499 artificial textile prosthesis, 466 aryl azo pyridone dyes, 162, 185 aseptic, 400 aseptic properties, 400 Asia, 441, 442, 461 assessment, 31, 79, 181, 182, 227, 338, 476 atherosclerosis, 467, 471 atmosphere, 12, 278, 286, 290, 292, 301, 303, 306, 430, 432, 486, 487, 521 atmospheric pressure, 280, 441 atomic absorption spectroscopy, 321 atomic force, 305, 306 atoms, 108, 262, 263, 279, 283, 285, 286, 289, 297, 310, 375, 377, 432 ATP, 206 attachment, 77, 239, 254, 265, 506 attenuated total reflection FTIR spectroscopy, 321, 324 attractiveness, 5, 6

Index attribution, 324 Austria, 264 authentication, 107, 117, 195, 209, 210 authenticity, 4, 9, 10, 11, 13 automation, 85 avoidance, 520 awareness, 5, 10, 12, 20, 22, 270, 271 azo colorants, 157, 159, 162, 163, 179 azo compounds, 157, 159, 166 azo coupling, 163 azo dyes, vii, 157, 159, 163, 164, 165, 167, 170, 175, 176, 177, 179, 180, 181, 182, 183, 184, 185 azo groups, 159, 179, 197 azo pigments, 167 azobenzene, 105, 159, 197, 208 azobenzothiazoles, 162 azo-hydrazone equilibrium, 158 Azo-hydrazone tautomerism, 157, 179 azopyrazolone, 162 azopyridones, 162 azothiophenes, 162 azulenes, 197, 203

B backlash, 3 bacteria, 23, 165, 263, 277, 278, 279, 280, 283, 285, 289, 290, 291, 295, 296, 300, 305, 306, 310, 311, 313, 384, 395, 418, 460, 476 bacteria inactivation, 277, 297 bacteria respiratory enzyme, 278 bacterial cell wall membrane, 297 bacterial colonies, 296 bactericide surfaces, 290, 292 balloon angle, 519, 521, 526, 528 bamboo fibers, 540 ban, 400 band gap, 223 Bangladesh, viii, ix, xii, 19, 20, 26, 48, 49, 123, 124, 136, 153, 154, 499 baroque, 316 barriers, 22, 116, 314 base, 11, 13, 56, 61, 124, 129, 158, 168, 179, 185, 190, 212, 216, 227, 234, 241, 242, 251, 264, 363, 365, 369, 372, 406, 411, 425, 449, 461, 462, 484, 495, 499 basic dyes, 103, 165 bast fibers, 400, 441, 538, 539, 545 bath exhaustion, 343, 345 bathochromic effect, 176 baths, 76, 349 batteries, 210, 240, 252, 447, 448, 449, 450, 453, 454, 455, 460

549

beams, 166, 532 BED, 352 bedding, 243, 246 behaviors, 450, 455 Beijing, 496 Belgium, 121 bending, 19, 25, 31, 36, 51, 240, 247, 250, 253, 254, 328, 386, 390, 472, 474, 475, 477, 480 bending length, 19, 31, 36, 51, 386, 390 bending rigidity, 25, 475, 480 beneficial effect, 278 benefits, 5, 6, 16, 242, 253, 371 benzene, 176, 179, 235, 406, 419 benzene ring cleavage, 406, 419 benzodifurane, 159 beverages, 352 bias, 275 Bifurcated prosthesis, 466 bifurcated vascular prosthesis, 465, 469, 478, 479 bing, 351 biochemistry, 188 biocidal action, 263 biocidal properties, 263, 264 biocidal surfaces, 278, 384 biocompatibility, 278, 292, 299, 362, 465, 466, 471, 477, 478 biodegradability, 362, 403 biodegradable enzymes, 23 biodeterioration, 317, 320, 321, 337 biofinishing cotton, 47 biological samples, 532, 533 biological systems, 194 biomass, 399, 418, 430, 436, 441, 445 biomaterials, 54, 189, 480, 481 biomedical applications, 89, 90, 205, 292, 312, 351, 384 biomimetic systems, 219 biomimetics, 240 biomonitoring, 227 bioprocessing, 240 biosorbents, 399, 401, 418 biosorption capacities, 419 biostatic properties, 373, 381 biostoning denim, 47 biosynthesis, 50 biotechnology, 188, 240, 350, 455 biotic, 337 bisphenol, 217 blankets, 505, 515, 516 bleach wash, 20, 21 bleach washing process, 21 bleaching, 125, 353, 384, 406, 414, 502 bleeding, 59, 92

550 blends, 54, 164, 226, 249, 351, 442, 504, 509, 516, 518, 537 blood, 448, 465, 467, 468, 471, 472, 473, 476, 477, 478, 479 blood circulation, 468, 471 blood clot, 477 blood clotting substances, 477 blood constituents, 467 blood flow, 465, 467, 468, 471, 478 blood vessels, 465, 466, 468, 473, 479 bloodstream, 474 bluenic, 521, 524 body core temperature, 483 body fluid, 475 body temperature, 210, 211, 244, 384, 484, 491 Boltzmann constant, 487 bonding, 177, 230, 280, 329, 358, 404, 418, 475 bonds, 35, 268, 280, 289, 306, 317, 322, 323, 328, 329, 331, 332, 362, 368, 402, 430, 432, 539 bone(s), 246, 264 boric acid, 147, 217, 381 bounds, 414 boutique-style shops, 12 braided edge, 271 braided structure, 477, 478 braids, 136 brain, 241 branching, 401 brand image, 12, 13 brand name, 6, 9 brand protection, vii, 81, 107, 117, 118, 194, 209, 210 brass, 248, 514 breakdown, 159, 268, 317 breaking elongation, 56, 330, 334, 502, 524 breaking extension, 387, 388, 502, 507 breaking force, 30, 33, 51, 56 breaking strengths, 523, 528 breaking stress, 330, 334 breathing, 370, 455, 485 brilliant yellows, 161 Britain, 4 brittleness, 249, 333 brushing action, 24 bulk coloration, 171 bundle cross-section, 409 burial environment, 262, 264, 273, 274 buried contemporary materials, 318 burn, 310, 311 businesses, 7, 14, 55, 83 butadiene, 246 buttons, 11, 508 buyer(s), 20, 25

Index by-products, 445, 541

C Ca2+, 314 cables, 448, 455 CAD, 90 cadmium, 428, 429, 436, 444, 445 calamitic molecules, 215 calcification, 474 calcium, 94, 259, 321, 442 caliber, 473 calibration, 286 calorimetry, 361 camera, 55, 195, 522, 532, 533 candidates, 107, 224 cane sugar, 154 capillary, 408, 413, 414, 415, 416, 417, 419, 443 capsule, 488, 539 carbon, 152, 163, 201, 233, 234, 241, 248, 249, 262, 264, 294, 313, 377, 397, 399, 401, 404, 405, 407, 430, 432, 434, 436, 438, 440, 444, 445 carbon atoms, 377, 432 carbon dioxide, 263, 431 carbon materials, 399, 401, 430, 432, 434, 436, 438, 445 carbon monoxide, 431 carbon nanotubes, 233, 234, 249, 445 carbon precursor chemical structure, 432 carbon skeleton of the cellulose backbone, 405 carbonaceous materials, 430, 436 carbon-carbon bond cleavage, 405 carbon–carbon linkages, 404, 407 carbonization, 399, 400, 430, 432, 433, 434, 436, 439, 440 carbonized hemp fibers, 400, 432, 433, 434, 437, 438, 439, 440, 441 carbonyl groups, 329, 358, 418 carboxyl, 280, 294, 384, 405, 411 carboxylic acid(s), 356, 357, 358, 360, 362, 365, 373, 375, 379, 381, 382, 402, 405 carboxylic groups, 371, 405, 434 carboxymethyl cellulose, 123, 124, 125, 153, 154, 155 carboxymethylation, 124, 125, 129, 130 carcinogenic amines, 159 cardiac care, viii, 465 cardiac pulse, 472, 473 cardiovascular surgeries, 465 cardiovascular textile prostheses, 471 carsolchromic, 246 case study(ies), 265, 266, 271, 272, 310 cashmere, 536, 538

Index cashmere wool, 536 catalysis, 192, 231, 263, 313 catalyst, 27, 177, 263, 302, 357, 358, 362, 363, 364, 372, 375, 377, 378, 381 catalytic activity, 301 catalytic domain, 23 catalytic properties, 445 catheter, 474, 476, 479, 480 cation, 405 cationic agent printed cotton, 54 cattle, 500 CBD, 23 C-C, 150, 294, 406 cell development, 467 cell killing, 279, 311 cell phones, 250 cell surface, 361 cell wall components, 412 cellulase, 19, 20, 21, 23, 24, 25, 27, 33, 34, 35, 36, 37, 38, 39, 40, 41, 43, 44, 46, 47, 48, 49, 50, 51, 52, 340 cellulase enzyme, 19, 20, 21, 23, 27, 33, 36, 46, 47, 48, 49, 50 cellulose acetate, 123, 124, 136, 141, 153, 155, 157, 158, 159, 160 cellulose chains, 43, 323, 326, 329, 355, 367, 368, 369, 371, 372, 373, 375, 401 cellulose crystallinity, 323, 324 cellulose derivatives, vii cellulose fibers, 355, 404, 442, 443, 445, 538, 539, 540 cellulose fibre, 211, 323, 397 cellulose I, 340, 404, 434, 442 cellulose II, 404, 434 cellulose macromolecules, 324, 330 cellulose microfibrils, 401, 403, 408 cellulose molecules, 360, 375, 403, 404 cellulose nitrate, 123, 124, 145, 152, 153, 155, 156 cellulose-binding domain, 23 cellulosic, 23, 24, 49, 51, 123, 124, 125, 136, 145, 153, 170, 263, 264, 266, 267, 273, 276, 318, 319, 321, 322, 326, 331, 336, 337, 340, 341, 355, 356, 360, 361, 363, 367, 371, 372, 377, 380, 381, 397, 401, 405, 430, 441 cellulosic derivatives, 123, 124 cellulosic textiles, 337, 367, 372 cellulosic wastes, 123, 153 cellumonas fimi, 23 cell-wall membrane, 300 Central Europe, 265 ceramic, 82, 93, 95, 245, 261 cesium, 199 CFI, 528

551

chain branching, 401 chain scission, 317 challenges, 11, 20, 55, 91, 92, 104, 276 changed appearance, 317 charge density, 418 charge transfer sites, 296 charity shops, 4 charm, 3 chemical characteristics, 76, 124, 133, 405, 416 chemical damage, 317 chemical fibers, viii, 400, 531, 533 chemical interaction, 99 chemical modification, 400, 407, 411, 432, 436, 440, 441, 443 chemical phenylpropane units, 402 chemical processing steps, 19 chemical properties, 104, 195, 340, 378 chemical reactions, 92, 377 chemical softeners, 501 chemical stability, 344 chemical structures, 335, 377 chemical texturizing process of jute, 501 chemical treatments, 31, 404, 405, 406, 411, 541, 542, 543 chemicals, vii, 20, 21, 22, 23, 25, 26, 28, 47, 48, 54, 55, 76, 78, 362, 365, 369, 371, 377, 384, 400, 441, 448, 461 CHF, 437 Chicago, 15, 17, 451 children, 188, 211, 460 China, 56 chiral molecules, 210 chirality, 207 chitin, 361 chitosan, 55, 78, 350, 351, 362, 365, 378, 443 Chitosan, 350, 361, 365 chlorine, 20, 24, 356, 406 chlorine bleach, 20, 24 chloroform, 179 cholesteric liquid crystal, 210 cholesterol, 210 Christianity, 320 chromatic adaptation-transformed values, 69 chromatography, 321, 438, 446 chromic materials, 193, 239, 240, 246, 247, 252 chromium, 167, 182 chromophore, 196, 215, 216 chromophoric azo group, 157, 159 circulation, 93, 468, 471 cities, 7, 264, 275 civilization, 83 clarity, 210 classes, vii, 86, 91, 92, 105, 107, 115, 158, 218, 438

552

Index

classification, 15, 85, 86, 158, 192, 193, 211, 220 cleaning, 21, 288, 310, 311, 312, 384, 406, 448 cleavage, 106, 107, 184, 405, 406, 419, 430, 432 climate(s), 244, 453, 488, 491, 492 clinical performance, 466 clinical trials, 250 Clostridium difficile, 384, 396 clothing materials, 400, 468, 483, 488, 495 clothing structure design, 493 clusters, 7, 277, 278, 279, 280, 282, 285, 306 CMC, 69, 79, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 139, 144, 145, 147, 153, 154, 374, 375 CO2, 430, 431, 433, 434, 435, 436 coal, 400, 430 coatings, 122, 136, 154, 188, 220, 232, 248, 249, 256, 283, 289, 295, 313, 314, 519, 522, 524, 525, 526, 527, 528, 543 cobalt, 221, 234 coding, 87, 89, 90 coefficient of capillary diffusion, 416 coefficient of friction, 502 coefficient of variation, 409, 414, 502, 511 coffee, 444 collaboration, viii, 188, 259, 260, 269, 271, 272, 273, 274, 455 collagen, 466 colleges, vii collisions, 280 colloidal suspension, 280 colonisation, 317 colonization, 279, 338 color constancy, 67, 68 color difference equations, 56 color fastness determinations, 286 color fields, 63 color filters, 157, 163, 179, 180, 182 color gamut, 55, 59, 62, 63, 64, 66, 67 color inconstancy index, 53, 54, 56, 67, 68, 69, 70, 76, 79 color management, vii, 53, 54, 55, 58, 59, 61, 65, 66, 79 color management application, vii, 53 color patches, 59, 60, 63, 65, 67 color patterns, 53, 55, 65, 74 color photography, 157, 159 color prints, 53, 54 color profiles, 53, 55, 56, 58, 61, 63, 65, 76 color stabilization, 58 color tone, 54 color transformations, 66 colorimetric matching, 65 colorimetrically transforms in-gamut colors, 67

colour change, 82, 99, 103, 104, 106, 108, 109, 113, 115, 117, 121, 190, 192, 193, 194, 195, 196, 197, 198, 199, 203, 209, 210, 211, 212, 213, 214, 216, 217, 218, 219, 220, 221, 222, 224, 229 Colour Index, 158, 159 combined effect, 495 comfortable garments, 367 comfortness, 36 commercial, 23, 49, 89, 90, 103, 106, 122, 159, 177, 188, 195, 245, 250, 289, 343, 345, 346, 400, 439, 440, 452, 502, 503, 505, 506, 507, 508, 532, 533 commercial colorants, 159 commercial fabrics, 507 communication, 6, 12, 13, 14, 84, 201, 229, 239, 250, 251, 252, 253, 260, 274, 447, 448, 449, 455 communication technologies, 252 community(ies), 12, 337, 338 compact spinning, 520 compaction, 471 comparative analysis, 311 compatibility, 98, 468, 477 compensation, 65 competition, 2, 5, 11, 84, 453, 462 competitive advantage, 5, 10, 17, 190 competitive conditions, 419 competitors, 5, 6 complex interactions, 484 complexity, 2, 71, 402, 419, 466, 471 compliance, 466, 468, 471, 473 composite materials, 145, 188, 399 composites, 189, 226, 240, 248, 249, 256, 303, 402, 441, 442, 481 composition, 19, 27, 91, 92, 97, 99, 100, 102, 145, 155, 181, 210, 222, 286, 295, 322, 325, 344, 345, 350, 382, 399, 401, 403, 404, 407, 409, 410, 411, 412, 414, 415, 416, 419, 440, 441, 490, 512, 545 compounds, 55, 78, 105, 107, 157, 158, 159, 161, 163, 166, 170, 171, 176, 183, 200, 205, 208, 211, 213, 214, 215, 216, 221, 230, 247, 249, 355, 361, 369, 370, 371, 372, 406, 430, 444 compressibility, 25 compression, 466, 477, 504, 517 compression resistance, 466 computation, 250, 494 computer, 55, 84, 188, 452, 467, 468, 478, 494, 531, 532, 533 computer program, 531 computer technology, 532 computer-aided design, 478 computer-controlled galvanometer mirrors, 533 computing, 188, 227 condensation, 167, 212 conditioning, 30, 33, 51, 255

Index conductance, 489 conducting polymer composites, 256 conduction, 222, 223, 278, 282, 305, 483, 484, 485, 489, 491, 493, 494 conductive fibers, 239, 248, 249, 253, 447 conductive materials, 239, 240, 248, 254, 449 conductive smart textiles, 250 conductive textiles, 248, 249, 250, 257 conductive threads, 253, 254 conductivity, 92, 94, 98, 195, 219, 222, 233, 248, 249, 250, 254, 357, 383, 384, 386, 390, 391, 392, 394, 486, 487, 488, 489, 490, 493, 495, 496, 497, 509, 517 conductor(s), 211, 219, 247, 249, 254, 490, 492, 494 conference, 51, 255, 364, 447, 448, 453 confidence limits, 526 confocal laser scanning microscopy, 531, 532, 544, 545 confocal magnetron-sputtering systems, 292 conformity, 3 Congo, 236 Congress, 119, 364 conjugate planes, 532 conjugated double bond, 430 conjugated electrochromic polymers, 224 conjugation, 106, 193, 202, 212, 214, 215 consciousness, 190 conservation, 145, 259, 260, 268, 269, 270, 271, 272, 273, 274, 276, 316, 320, 325, 336, 338, 341 conservation process, 270 conserving, 260, 275, 276, 316 consolidation, 268, 273, 512, 513 constant ink composition, 100 constituent materials, 270 constituents, 2, 321, 402, 467 Constitution, 119 construction, 118, 242, 245, 270, 386, 455, 465, 473, 475, 476, 478, 490, 492, 496 consumers, 3, 4, 8, 9, 10, 11, 12, 13, 14, 21, 22, 25, 191 consumption, 2, 3, 14, 449, 450 contact time, 302, 309, 418, 419 contactless printing, 166 containers, 12, 266 contaminate historical textiles, 336 contamination, 289, 290, 315, 337, 339, 384, 396 contemporary costumes, 271 continuous inkjet printing technique, 85, 87, 94 continuous washing cycles, 349 controversial, 400 convection, 127, 483, 484, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 496 conventional dyes, 82

553

conventional pad–mangle systems, 242 conventional ring spinning, 520 conventional textile materials, 384 convergence, 188, 239 COOH, 177, 411, 412 cooking, 352 cooling, 216, 241, 242, 244, 245, 289, 484, 514, 543 cooling process, 242 cooperation, 91 coordination, 211, 234 copolymer(s), 143, 150, 153, 235, 246, 255, 350, 365, 378 copolymerisation, 220 copolymerization, 154, 155 copper, 208, 231, 232, 248, 249, 259, 262, 263, 264, 266, 267, 268, 273, 276, 313, 383, 384, 385, 387, 388, 389, 390, 391, 393, 394, 395, 396, 444, 445, 494 copper alginate, 384, 389 copper sulphate, 383, 385, 395 copper volumes, 390 correlation(s), 71, 74, 176, 303, 409, 420, 437, 438, 467, 471, 473, 478, 479, 493, 512, 515 correlation coefficient, 420 correlation matrix, 512, 513 corrosion, 92, 94, 98, 99, 249, 262, 263, 264, 274, 275, 477 cortex, 332 cosmetic(s), 124, 157, 159, 195, 210, 344, 377, 455 cost, 76, 89, 101, 118, 123, 124, 136, 159, 221, 344, 356, 373, 399, 401, 430, 436, 440, 443, 477, 499, 505 cost effectiveness, 159 cotton and acrylic jacket fabrics, 508 cotton commercial shawl fabrics, 507 cotton fabrics, 24, 49, 50, 51, 54, 63, 129, 134, 136, 312, 347, 348, 352, 353, 356, 361, 362, 363, 364, 365, 367, 368, 370, 377, 378, 379, 380, 381 cotton fiber, 24, 55, 136, 144, 153, 154, 313, 346, 348, 349, 362, 365, 377, 539, 540 cotton linters, 124, 154 cotton textiles, 268, 282, 367, 370, 371, 375 cotton twill fabric, 21 cotton/acrylic commercial shawl fabrics, 507 cough, 370 country of origin, 6 coupling reaction, 163, 170, 179 covalent bond, 358 covalent chemical bond, 76 covering, 90, 322, 368, 387, 477 CPU, 252 crabs, 361 cracks, 44, 326, 413

554

Index

creatinine, 155 creativity, 3 creep, 518 crimped textile implants, 471 critical fabric properties, 490 critical ring spinning, 520 crop, 444, 500 crop residue, 444 crops, 438, 499, 500, 538 cross-contamination, 384, 396 crosslinking, 333, 355, 356, 357, 358, 360, 361, 362, 363, 364, 365, 367, 369, 370, 371, 372, 373, 374, 375, 377, 378, 379, 380, 381, 382 crown, 197, 199, 208, 230, 231 crystal structure, 434, 442 crystalline, 24, 155, 215, 232, 263, 268, 279, 323, 324, 329, 357, 368, 384, 401, 404, 412, 414, 442 crystalline structure, 279, 357, 384, 404 crystalline supermolecular structure, 401 crystallinity, 112, 268, 323, 324, 325, 328, 329, 330, 334, 336, 340, 408, 412, 414 crystallinity index, 324, 340, 414 crystallization, 241 crystallographic Ag-clusters, 285 crystals, 24, 193, 210, 215, 233, 247, 279, 285, 289, 449 Cuba, 351 cultivation, 268 cultural heritage, 316, 317, 337 cultural property, 260 culture, x, 2, 4, 8, 259, 260, 270, 272, 274, 295, 300, 351 cure, 85, 91, 100, 364, 372 curing process, 77, 102, 356, 379 currency, 20 current limit, 226 customer service, 6, 11, 14 customers, 8, 9, 10, 11, 12, 13, 14, 20, 22 cuticle, 332 CV, 521, 522, 524, 528 CVD, 289, 313 cyanamide, 362 cyanide, 205 cycles, 115, 196, 204, 230, 250, 289, 297, 305, 346, 348, 349, 363, 542 cycling, 22, 292, 476 cyclodextrins, 231, 377, 382 cyclohexanone, 179 cysteine, 333 cysteine residues, 333 cytotoxicity, 278, 292, 303, 305 Czech Republic, 386, 387, 397

D dacron, 468, 471 damping, 245, 437, 480 damping coefficient, 437 danger, 251, 336 darker-grey metallic Ag-color, 292 data analysis, 7 data communication, 84 data processing, 251 data set, 387, 391 data transfer, 252, 253 database, 537 DC-magnetron sputtering, 277, 283, 286, 312 decay, 112, 315, 337, 341 decolouration, 112, 113, 114 decomposition, 92, 116, 176, 200, 268, 300, 305, 317, 340, 361, 365, 430, 431, 432, 434, 435, 445 decomposition temperature, 176 decontamination, 337 deconvolution, 290 decoration(s), 84, 90, 100, 210, 316, 447 decorative-protective applications, 455, 460 decoupling, 128 defects, 289 defence, 191, 397 deficiency, 249 deflate, 348 deformation, 89, 253, 329, 334, 368, 390, 466, 471, 472, 474 degradation, 24, 37, 43, 44, 116, 155, 177, 184, 196, 263, 264, 313, 317, 319, 320, 331, 337, 338, 339, 340, 341, 357, 372, 377, 405, 406, 407, 468, 475 degradation process, 320 degree of fiber swelling, 412 degree of lattice transformation, 404 degree of polymerisation, 329 degree of substitution, 123, 124, 126, 129, 136, 138, 139, 147, 148, 153 degree of swelling, 404, 412 Degussa, 177 dehydration, 211, 430 delignification process, 501 denim, vii, 8, 11, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 397 denim apparel, 19, 20, 21, 22, 23, 24, 25, 26, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48 denim designs, 22, 23, 25 denim ready-made apparels, vii, 19, 20, 25, 47 denim trousers, 19, 28, 29 Denmark, 274

Index dependent variable, 515 depolymerisation, 323, 326, 328, 329, 330, 333, 334, 336, 430 depolymerization, 404, 430 deposition, 82, 94, 136, 145, 153, 249, 253, 254, 279, 283, 286, 288, 289, 290, 292, 297, 298, 302, 311, 314, 345, 353, 428, 478 deposition rate, 286, 297, 298 deposits, 279, 286 depth, 31, 32, 90, 190, 389, 510, 531, 533 derivatives, vii, 23, 49, 123, 124, 136, 155, 159, 161, 164, 165, 168, 177, 181, 182, 183, 184, 185, 200, 202, 204, 205, 207, 208, 210, 216, 220, 230, 232, 234, 365, 372, 378, 381, 382, 402, 406, 432, 442 design, vii, 9, 20, 21, 22, 49, 50, 81, 82, 83, 92, 107, 117, 118, 119, 191, 194, 209, 210, 226, 227, 228, 239, 242, 247, 250, 251, 305, 381, 450, 455, 461, 462, 465, 467, 473, 476, 491, 493, 499, 506, 507, 508, 509, 510, 515 design and fashion apparel, 20 designers, 3, 4, 9, 15, 20, 21, 22, 25, 55, 78, 191 designing of warm fabrics, 500 desizing, 23, 28 desizing agent, 28 desorption, 377, 430, 434, 435, 436, 445 desorption of water, 430 destruction, 264, 271, 305, 397, 467 detectable, 104, 493 detection, 297, 455, 462, 476, 543 detection system, 462 detergent, 21, 28, 507, 509 detergents, 55, 63 detrimental effects, 262 developed countries, 344 developed fabrics, 507, 508 developed jacket fabric, 508 deviation, 421, 439 diabetic wound dressing, 289 diarylethenes, 107, 111, 115, 194, 197, 199, 201, 208 diastole, 472 diastolic membrane stress, 474 diazo compounds, 163 diazo printing, 157, 159 diazonium salts, 163, 164, 170, 177, 179 diazotization, 163, 170, 171 diazotized aromatic amines, 168 dichromatic mirrors, 533 dielectric constant, 105, 195 differential scanning, 361 differential scanning calorimetry, 361 diffraction, 155, 193, 285

555

diffusion, 158, 184, 221, 282, 295, 306, 386, 416, 417, 421, 422, 423, 425, 426, 427, 428, 437, 444, 485 digestion, 539, 543 digital cameras, 250 digital dyeing, 82, 103 digital microscope, 532 digital printing, vii, 53, 54, 55, 61, 77, 79, 84, 100, 120, 250 digital technologies, 118 digital textile printing, 53, 54, 55, 58, 66, 78, 85 diketone keto esters, 167 dimensional stability, 20, 49, 54, 355, 500 dimensions, 8, 233, 263, 272, 285, 376, 386, 404, 450, 460, 473, 476, 537 dimethyl sulfoxide, 128, 139, 147, 155 dimethylformamide, 176, 178, 184 diodes, 189, 449, 453 diphenyldiazene, 159 dipoles, 306 direct mail, 90 dirndl skirts, 10 disabled patients, 188 disazo pyridone compound, 171 disazo reactive dyes, 183 discomfort, 252, 484 discontinuity, 474 discriminant analysis, 341 diseases, 460, 476 disinfectant, 279, 384 disinfectant reactivity, 279 disinfected properly, 384 disinfection, 278, 279, 288, 289, 303, 311, 314 disorientation of the fibrils, 409, 412, 417 disoriented fibrillar network, 409 disperse dyes, 84, 103, 116, 121, 122, 157, 158, 159, 160, 161, 162, 163, 164, 165, 179, 181, 182, 184, 229 dispersing metallic particles, 248 dispersion, 91, 94, 99, 158, 181 displacement, 89, 254, 472 dissociation, 5, 185, 195 distillation, 139 distilled water, 31, 123, 126, 128, 137, 146, 385, 514 distribution, 4, 5, 16, 52, 70, 112, 113, 155, 295, 345, 419, 420, 493 diverse core materials, 344 diversification, viii, 499 diversification of jute, viii, 499 diversity, 315, 336 DMF, 176 DNA, 54, 77, 234, 278, 305 DNA damage, 278, 305

556

Index

doctors, 447, 460 dogs, 500 DOI, 381 domestic animals, 500 domestic washing, 348, 349 donors, 217 doping, 222, 224, 296 doppler, 466, 467 dosing, 85 double bonds, 430 downstream shear stress, 467 draft, 53, 56, 58, 59, 502, 505, 506 draught, 453 drawing, 416, 451, 505, 506 dressings, 384 drop-on-demand inkjet printing technique, 86 DRS, 296, 303 drug carriers, 350 drug delivery, 192, 199, 209, 350 drug release, 188, 199, 205 drugs, 157, 159, 344 drying, 29, 30, 87, 90, 98, 100, 128, 343, 345, 346, 350, 351, 403 DSM, 352 durability, 21, 39, 54, 121, 191, 221, 250, 343, 344, 345, 346, 349, 353, 362, 363, 365, 370, 371, 465, 474, 476, 478, 500 durable fragrances, vii, 344 durable press, 355, 356, 362, 363, 364, 367, 368, 372, 377, 378, 379, 380 durable press finishing, 356, 362, 363, 367, 372, 377, 378, 379, 380 dye manufacturing companies, 158 dyeing, 34, 49, 51, 82, 84, 103, 122, 158, 160, 164, 165, 166, 170, 172, 174, 176, 179, 181, 182, 183, 184, 192, 195, 196, 200, 204, 218, 220, 242, 381, 384, 396, 414, 501, 502, 506 dyeing characteristics, 158, 183

E Eastern Europe, 10, 256, 353, 397, 529 easy care finishing, 367, 377 easy-ironing clothes, 368 eco-fashion, 25 ecology, 450, 461 economic downturn, 4 economical cost, 477 economics, 162 eczema, 370 editors, 122, 154, 228, 229 education, 480 educational background, 269

egg, 396 Egypt, 83, 268, 337 Egyptian mummies, 338 elaboration, 252 elasticity, 95, 192, 245, 401, 403, 472, 473, 476, 478, 541 elasticity hypotheses, 472, 473 election, 469 electric charge, 410 electric current, 220 electric field, 87, 94, 244, 280 electrical conductivity, 248, 496 electrical properties, 249, 250, 256, 403 electricity, 82, 84, 119, 246, 401, 403, 447, 448, 449, 453 electrochemical reaction, 263 electrochromic dye, 103 electrochromic materials, 219, 220, 221, 224, 234 electrochromic switches, 187, 190, 194, 208 electrochromic textile production, 219, 224 electrodes, 201, 219, 227 electrolyte, 98, 220, 221, 235 electromagnetic, 192, 194, 280, 448, 460 electromagnetic influences, 448 electron diffraction, 155 electron microscopy, 44, 45, 285, 299, 303, 304, 316, 321, 322, 326, 327, 332, 341, 343, 345, 346, 545 electron-accepting group, 177, 179 electron-donating substituents, 177, 179, 229 electronic and photonic textiles, 190 electronic devices, 251, 254, 344 electronic materials, 54 electronic smart textile, 239, 252, 254 electronic structure, 195, 203 electronics, vii, viii, 54, 90, 96, 188, 189, 226, 227, 230, 240, 247, 249, 250, 256, 447, 448, 450, 452, 453, 455, 461 electrophotographic (, 55 electrospinning, 220 electrostatic properties, 400 elementary fibers, 408 elongation, 25, 30, 51, 56, 89, 132, 142, 150, 330, 334, 409, 501, 502, 509, 519, 521, 522, 524, 527, 528 e-marketing, 12 embedding microencapsulated phase change materials, 455 embolism, 474 emergency, 64, 188 emerging markets, 10 emission, 193, 194, 195, 243, 295 empirical studies, 6 employees, 11

Index employment, 273 emulsions, 351 encapsulate, 264 encapsulated nanoparticles, 344 encapsulation, 189, 344, 351 encouragement, viii endangered, 320, 325 endorsements, 5 endothelial cells, 467 endothelium, 479 energy, 82, 92, 100, 112, 122, 158, 162, 190, 193, 198, 202, 214, 222, 223, 224, 230, 239, 241, 245, 251, 279, 280, 285, 301, 306, 308, 309, 383, 384, 385, 387, 388, 390, 392, 394, 395, 396, 444, 448, 449, 452, 453, 476, 484, 486, 491 energy constraint, 239 energy density, 241 energy supply, 251 energy transfer, 122, 193, 230, 241 enforcement, 250 engineering, 54, 77, 90, 188, 191, 210, 227, 239, 240, 245 England, 28, 29, 120, 124, 136, 145, 255, 276 entangled fibers, 399, 401, 418 entangled hemp fibers, 399, 401 entanglements, 245 entrapment, 98, 418 entrepreneurs, 7, 16 environmental change, 189, 245 environmental conditions, 103, 115, 117, 189, 190, 209, 271, 273, 278, 315, 320, 321 environmental effects, 294 environmental factors, 263 environmental impact, 441, 443 environmental influences, 368 environmental issues, 9 environmental pollution, 124 environmental protection, 240 environmental stimuli, 190, 192, 193, 214 environmental warning system, 117, 209 environmentally friendly clothes, 399 environments, vii, 83, 87, 109, 196, 240, 244, 260, 264, 268, 274, 321, 336, 449, 485, 488, 491 enzymatic action, 23 enzymatic degradation, 24, 377 enzymatic hydrolysis, 24, 41, 401 enzymatic process, 20, 24 enzyme(s), 19, 20, 21, 22, 23, 24, 26, 27, 28, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 117, 180, 192, 209, 278, 317, 338, 341, 403, 441 enzyme wash, 19, 20, 21, 22, 23, 26, 27, 28, 33, 34, 35, 37, 38, 39, 40, 41, 42, 44, 47, 48

557

enzyme washing process, 21, 22, 23 epidemic, 396 epidermis, 352 equilibrium, 158, 177, 178, 179, 212, 280, 414, 415, 416, 420, 421, 422, 423, 424, 426, 427, 436, 489, 491 equilibrium adsorption process, 422 equilibrium ion concentration, 423, 424, 426, 427 equipment, 24, 80, 100, 252, 522 ergonomics, 191 Escherichia coli, 384 estate sales, 4 ester, 30, 132, 134, 143, 150, 153, 163, 171, 173, 236, 356, 357, 358, 362, 363, 364, 365, 372, 379, 380 ester bonds, 362 etching, 254 e-textile applications, 462 e-textile fabric, 254 ethanol, 97, 98, 123, 124, 125, 129, 138, 145, 168, 178 etherification, 125, 129, 130, 131, 132, 154 ethers, 197, 217, 231, 434 ethical awareness, 10 ethical issues, 13 ethics, 276 ethyl alcohol, 124 ethylcellulose, 362, 365 ethylene, 164, 214, 246, 255, 350 ethylene glycol, 350 ethylene oxide, 255 EU, 226 Europe, 3, 10, 84, 180, 256, 265, 316, 353, 397, 529 evaporation, 92, 100, 295, 430, 483, 484, 485, 488 evaporative heat loss, 387, 395, 485 evenness, 401, 403 everyday life, 124, 136, 145, 260, 449 evidence, 7, 134, 143, 150, 260, 263, 270, 271, 272, 275, 283, 294 evolution, 2, 33, 42, 77, 260, 436, 472, 473 examinations, 535, 542 excavated textiles, 259, 260, 270, 271, 273, 274 excavation project, 270, 271 excavations, 83, 265, 271 excitation, 107, 116, 222, 224 execution, 66 exercise, 479, 484, 496 exertion, 244 expensive organic materials, 450 experimental condition, 426 experimental design, 510 expertise, 5, 9, 10, 12, 14, 113

558

Index

exposure, 74, 75, 76, 99, 104, 112, 113, 114, 115, 194, 196, 197, 205, 206, 218, 250, 322, 337, 340, 533 extension at break, 500 external compression, 466 external environment, 190, 484 external influences, 323 external surface adsorption, 422 extinction, 157, 159, 162, 280 extraction, 128, 247, 400, 438, 440, 441, 446 extrusion, 211, 218, 220, 241, 352, 539

F fabric antibacterial kinetics, 280 fabric based circuits, 253 fabric construction factors, 476 fabric cover factor, 506 fabric deformation, 466 fabric dimensional properties, 385 fabric prosthesis, 465, 474, 478 fabric scaffold, 475 fabric thickness, 386, 391, 392, 489, 506, 508, 512 fabric weight, 19, 31, 34, 35, 36, 37, 39, 41, 345, 506, 507, 508, 509, 510, 511, 512, 513, 515 fabrication, 54, 77, 253 Fabrication, 119, 462 family members, 11 fashion, vii, x, xiii, xiv, xv, 1, 2, 3, 4, 7, 8, 9, 10, 12, 13, 15, 16, 18, 20, 21, 22, 23, 25, 49, 50, 63, 81, 85, 107, 117, 118, 119, 136, 187, 192, 209, 225, 234, 240, 247, 250, 367, 449, 450, 455, 457, 460, 465 fashion aspects, 367 fashion consumer, 1, 2, 7 fashion effects, 21 fashion industry, 2, 3, 4, 63 fashion trends, 3, 4, 8, 10, 20, 23, 450, 460 fastness properties, 104, 157, 163, 165, 168, 175 fat, 418 fatigue resistance, 106, 196, 200, 253, 465, 474, 478 fatty acids, 217 feelings, 495 fiber bundles, 409, 414, 415, 539 fiber content, 490 fiber crystalline phase, 414 fiber diameter, 406, 409, 414, 537 fiber movement, 449 fiber optic coupler, 533 fibre compositions, 319 fibre identification, 266 fibre position, 520

fibrillation, 331, 405, 406, 408, 411, 413, 417, 419, 432 fibrils, 24, 35, 44, 47, 332, 336, 402, 406, 408, 409, 412, 417 field crops, 538 filament, 249, 476 film thickness, 286 films, 101, 112, 123, 127, 128, 132, 136, 139, 145, 150, 155, 221, 224, 233, 234, 235, 253, 254, 277, 278, 283, 285, 286, 288, 289, 290, 292, 294, 297, 298, 301, 305, 306, 313, 314, 452 filters, 157, 163, 179, 180, 182, 195, 533 filtration, 94, 127 financial, 17, 180, 310, 537 financial support, 310 fineness, 24, 56, 401, 403, 407, 409, 490, 509 finishing, 19, 20, 21, 25, 48, 49, 58, 90, 344, 352, 353, 356, 361, 362, 363, 365, 367, 369, 371, 372, 373, 377, 378, 379, 380, 381, 382, 384, 386, 394, 462, 471, 490 finishing material, 386 finite element method, 467, 497 Finland, 256 fire fighting, 250 fire-retardant fabrics, 384 first aid, 240, 273 first generation, 240, 466, 471 fish, 351 fish oil, 351 fishing, 246 fitness, 250 fixation, 55, 78, 100, 377, 381, 466, 471 flame, 240, 356, 360, 361, 363, 364, 365 flame protection, 240 flammability, 243, 361, 373 flavor, 344 flavour, 351, 352, 353 flax, 266, 268, 320, 321, 322, 323, 324, 325, 337, 400, 410, 441, 443, 538, 539 flax fiber, 443, 539 flex, 460 flexibility, 19, 31, 55, 84, 191, 216, 240, 243, 248, 249, 253, 402, 409, 410, 474, 475, 476, 477, 488 flexible circuit boards, 253 flexible display techniques, 188 flexural rigidity, 51, 383, 384, 386, 390, 396, 502, 503, 506, 507 floating clothing, 448 floods, 453 flora, 339 flow field, 467, 468 flow properties, 94, 467 flowers, 218

559

Index fluctuations, 241 fluid, 83, 85, 87, 90, 93, 94, 95, 96, 97, 98, 99, 118, 195, 414, 467, 478, 479 fluorescence, 19, 32, 33, 46, 47, 192, 202, 204, 205, 301, 533 fluorescence microscope, 19, 32, 33, 46 fluorescent brighteners, 64, 161 fluorescent lights, 67 fluorescent sensor, 204 fluorotriazine groups, 172 focal plane thickness, 533 food, 18, 54, 90, 124, 210, 344, 351, 362, 450, 455, 460 food decorating, 54 food products, 124 foods, 157, 159, 351 footwear, 104, 242, 243 force, 30, 33, 51, 56, 88, 96, 193, 305, 306, 308, 460, 476, 477, 504 forced-evaporation-type skin capsule, 488 formal suit, 8 formaldehyde, 345, 356, 362, 363, 364, 365, 369, 370, 371, 378, 379, 380 formaldehyde-based chemicals, 369 formaldehyde-free easy care agents, 370 formation, 82, 87, 88, 94, 98, 132, 141, 153, 155, 195, 213, 222, 239, 245, 254, 263, 276, 278, 279, 280, 285, 289, 290, 308, 333, 356, 357, 358, 361, 362, 368, 371, 372, 380, 404, 406, 408, 419, 432, 467, 472, 501, 504, 513, 516 formula, 32, 127, 395, 493 Fourier transform infrared spectroscopy, 316, 340 fragmentary painted clay-covered basketry, 270 fragments, 261, 264, 265, 272, 275 fragrance microcapsule, 344, 345 France, 10, 51, 479 free radicals, 233, 357, 375 free volume, 112, 113 free world, 450 freedom, 108, 390 freezing, 102, 244, 272, 351 friction, 25, 35, 245, 283, 346, 476, 502, 503, 520, 541 frictional washing, 347 fruits, 446 FTIR, 123, 128, 132, 133, 134, 139, 142, 143, 145, 147, 150, 151, 153, 274, 321, 322, 323, 324, 326, 328, 329, 330, 332, 333, 334, 337, 339, 340, 341, 357, 358, 363, 364, 380, 397 FTIR spectroscopy, 321, 323, 324, 326, 339, 341, 380 fulgides, 107, 194, 197, 199, 201, 202, 230 fulgimides, 107, 197, 202

functional dyes, 81, 82, 103, 104, 118 functional inkjet ink, 98, 103 functionalized smart textiles, 239 fundamental weave, 385 funding, 153 fungal colonisation, 317 fungal contaminations, 316 fungal growth, 92, 283, 316, 320, 321, 322, 323, 330 fungal infection(s), 320, 321, 322, 324, 325, 336 fungal proteolytic activities, 333 fungal species, 315, 317, 325, 326, 331, 332, 333, 334, 336 fungal spores, 320 fungi, 23, 50, 289, 315, 316, 317, 318, 320, 321, 323, 326, 329, 330, 331, 332, 334, 336, 338, 340, 341 fungus, 326, 340 furan, 202 furnishings, vii, 316 fusion, 191, 242, 276 fusion technology, 191

G galactoglucomannans, 402 Galaxy, 451 garage sales, 4 garment industries, 20, 124 gasification, 435 gasification process, 435 gel, 91, 122, 128, 132, 139, 142, 147, 150, 235, 277, 278, 362, 375, 384 gel content, 132, 139, 142, 147, 150 gelation, 350 genus, 320 geometry, 58, 116, 208, 211, 297, 473, 474, 475, 476, 477, 478, 520 Georgia, 319 Germany, ix, xi, xiv, 28, 99, 124, 227, 228, 255, 256, 257, 295, 310, 313, 346, 367, 387, 453, 531, 543 germination, 317 gland, 488 glass transition, 245 glass transition temperature, 245 glass transition temperature polymers, 245 glasses, 195, 232 global awareness, 22 global brands, 2 Global Positioning System, 241 glucose, 20, 23, 199, 328, 329, 377 glucoside, 401 glue, 242 glycerol, 98, 441 glycol, 98, 350

560

Index

glycoside, 322, 323, 328, 329 glycosidic bonds, 402 glycosidic linkages, 401 GPS, 241, 250 grades, 123, 124, 153 graduate students, viii graft implantation, 475 graft polymerization, 139, 147 grafting, 124, 127, 132, 134, 141, 143, 149, 150, 362, 382 grafting efficiency, 127, 141, 149 grafts radial resistance, 466 grain size, 306 graphite, 432 grass, 85 gravimetric analysis, 360, 361 gravity, 92, 414, 416 gravure printing, 242 Great Britain, 4 Greece, v, x, xii, xiv, 259, 260, 261, 262, 265, 266, 268, 269, 273, 274, 276 green chemistry, 22 growing polymer chain, 541 growth, 2, 18, 84, 92, 99, 264, 272, 278, 281, 283, 285, 295, 296, 316, 317, 320, 321, 322, 323, 326, 330, 331, 336, 361, 400, 402, 415, 440, 474, 475, 539, 541 guidance, 270, 272 guidelines, 320

H haemodynamics, 467, 474, 478 haemolysis phenomenon, 467 hair, 339, 341, 536, 537 hairiness, viii, 519, 520, 521, 522, 525, 526, 527, 528 hallucinogenic properties, 400 halochromic, 218 halogenation, 184 hand sewn woven structures, 466 handloom preparatory machinery, 506 hardwoods, 402 harmony, 483 harvesting, 103, 452 hazardous substances, 448 hazards, 101, 370 HCC, 323, 329 headache, 370 healing, 310 health, 92, 101, 187, 188, 190, 199, 225, 227, 240, 250, 252, 253, 278, 279, 356, 448, 449, 481 health care, 187, 199, 225, 250, 252, 278, 448, 481 health information, 240

health status, 240, 252 heart attack, 477 heart rate, 240, 455 heart valve application, 466 heart valve replacement, 465, 475 heat loss, 246, 384, 387, 395, 483, 484, 485, 486, 488, 491 heat release, 242 heat resistance, 158, 163, 171, 180, 289 heat resistance surfaces, 289 heat transfer, 158, 393, 485, 486, 487, 488, 489, 490, 491, 492, 493, 494, 496, 497 heat transfer coefficients, 487, 488, 496 heat transfer printing, 158 heating rate, 432 heat-retaining properties, 492 heat-setting temperature, 477 heat-storage capacity, 242 heat-transfer mechanisms, 485, 486 heavier travellers, 523 heavy metal biosorbents, 399, 401 heavy metal ions biosorption, 399, 440 heavy metal ions solution, 418 heavy metals, 400, 420, 422, 430, 436, 437, 440, 443 height, 324, 414, 415, 416, 484, 534, 536 helix profiles, 520 hemicellulose(s), 321, 323, 329, 399, 401, 402, 403, 404, 405, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 430, 432, 441, 442, 443, 501, 538 hemp fiber chemical composition, 399, 417, 440 hemp fiber surface, 411, 413, 417, 419 heterocyclic components, 159, 162, 184 heterogeneity, 56, 112 heterogenous chemical composition, 399, 401 hexane, 176, 197 high energy disperse dyes, 158 high fat, 200 high performance fabrics and garments, 241 high performance photo-responsive surfaces, 88 high strength, 34, 40, 43, 48, 504 high value-added products, 384 high-density imperfections, 289 higher molar mass dyes, 158 high-pressure liquid chromatography, 321 high-resolution optical pictures, 531 high-tech dresses, 450 high-technology applications, 81, 103, 118 historical and archaeological textile objects, 318 historical overview, 85 historical textiles, 317, 318, 320, 321, 322, 325, 335, 336, 337, 339

561

Index history, 9, 10, 13, 83, 210, 233, 270, 272, 315, 321, 322, 335, 462, 494, 497 homeland security, 250 homogeneity, 113, 419 Hong Kong, 28 hormones, 344 host, 192, 199, 271, 473 hot-melt inks, 157, 173, 179, 183 House, 255, 312 HPLC analysis, 266 hub, 187 hue, 59, 65 human, viii, 21, 67, 71, 191, 209, 226, 243, 251, 260, 278, 279, 292, 310, 316, 339, 356, 368, 377, 387, 472, 474, 477, 479, 480, 483, 484, 486, 487, 488, 490, 494, 495, 496, 511 human activity, 490 human body, viii, 191, 243, 368, 472, 483, 484, 486, 487, 488, 494, 496 human health, 356 human perspiration, 488 human skin, 209, 377, 387, 490, 495 human visual system, 71 Humicola insolens, 23 humid wound-pads, 279 humidity, 54, 74, 104, 112, 118, 219, 244, 250, 283, 285, 315, 317, 320, 324, 326, 336, 377, 384, 403, 410, 411 humidity sensor, 54 Hunter, 182, 442 hunting, 12 hybrid, 77, 113, 118, 122, 234, 255, 452, 455, 461, 477 hybrid film/fiber, 452 hydazone tautomers, 179 hydrazone, 157, 177, 178, 179, 185 hydrocarbons, 217 hydrochromic, 247 hydro-extractor, 28 hydrogels, 205, 206, 219, 351 hydrogen, 22, 124, 125, 136, 163, 169, 170, 172, 176, 177, 178, 212, 218, 230, 232, 306, 323, 329, 358, 368, 375, 401, 404, 414, 418 hydrogen abstraction, 176 hydrogen bonds, 306, 323, 368 hydrogen peroxide, 22, 124, 125, 136 hydrogen peroxides, 22 hydrolysis, 24, 33, 34, 35, 38, 39, 41, 43, 44, 48, 51, 123, 139, 140, 263, 317, 323, 329, 338, 375, 401 hydrolytic degradation, 319, 340 hydrophilic gel, 384 hydrophilicity, 311 hydrophobic fibers, 157, 158, 164, 165, 181

hydrophobic lignin network, 403 hydrophobic synthetic fibers, 164 hydrophobicity, 95, 307, 308 hydroxide, 123, 124, 125, 126, 400, 404, 406, 410, 417, 434, 436, 440, 445, 502, 516 hydroxyl, 129, 130, 134, 141, 148, 152, 158, 172, 179, 355, 356, 357, 358, 362, 368, 371, 372, 373, 375, 377, 401, 402, 404, 405, 406, 430 hydroxyl groups, 130, 134, 141, 149, 152, 355, 358, 362, 368, 371, 372, 373, 377, 401, 405, 406, 430 hygiene, 396 hygroscopicity, 400 hyperplasia, 467, 471, 479 hyphae, 317, 318, 322, 329 hyphal penetration, 317 hypochlorite bleaches, 22 hypothermia, 244 hypothesis, 525 hypsochromic shifts, 176 hysteresis, 480

I ICC, 54, 55, 58, 59, 61, 63, 64 ideal, 109, 240, 241, 397, 477, 520, 532 identification, 147, 189, 211, 266, 268, 283, 341, 457 identity, 5, 316, 515 illumination, 56, 65, 67, 69, 75, 76, 533 image analysis, 462 image generation software, 90 image makers, 3 imagination, 457 imitation, 5 immersion, 31, 33, 52, 128, 147 immobilization, 145, 442 implantable materials, 468 implants, 188, 279, 313, 465, 466, 471, 475, 480, 481 impregnation, 263, 283, 343, 345, 346 improvements, vii, 101, 103, 250 impurities, 99, 136, 289, 401, 403, 406, 537 in vitro, 350, 474, 475, 480 in vivo, 279 incandescent light, 67, 69 incidence, 285, 313 income, 1 incompatibility, 98 increased competition, 2 incubation, 316, 326, 327, 328, 329, 331, 333, 334, 336 incubation period, 316 incubation time, 329, 334, 336 independent variable, 510, 515

562

Index

India, x, xiii, xiv, xv, 28, 124, 136, 145, 268, 396, 465, 483, 496, 499, 500, 516, 517 indigo dye, 23, 25, 27, 35, 49 individuality, 2 individuals, 10 inducible enzyme, 23 induction, 50, 246 inductively coupled plasma mass spectrometry, 321 industrial environments, 87 industrial wastes, 430 industries, 20, 22, 23, 24, 47, 54, 83, 123, 124, 136, 153, 455 industry, vii, 1, 2, 3, 4, 20, 21, 22, 23, 24, 47, 49, 50, 55, 63, 65, 81, 82, 84, 102, 120, 124, 136, 145, 154, 188, 190, 210, 246, 343, 344, 352, 353, 356, 361, 367, 399, 401, 440, 455, 517, 533 infants, 250, 455 infection, 320, 324, 325, 331, 336, 460 information technology, 188, 240 infrared spectroscopy, 316, 340, 341, 379 ingredients, 94, 99 inhibition, 121, 281, 338, 367 inhibitor, 97, 99 inhomogeneity, 71, 74, 76 inhumation burials, 259, 261, 265, 266, 268, 273 initial state, 109 injury, 240, 476 ink droplet, 82, 88, 89, 92, 95, 98 ink formulations, 92, 95, 97, 98, 99, 106, 108, 109, 112, 116 inkjet disposing fluids, 97 inkjet inks, 64, 81, 84, 86, 88, 91, 92, 94, 98, 99, 100, 101, 102, 103, 104, 105, 109, 111, 115, 117, 118, 121 inkjet inks formulations humectants, 98 inkjet nozzles, 94 inkjet printed image, 81, 103, 118 Inkjet printed photo-responsive textiles, 197, 229 inkjet printed substrates, 82, 104, 111, 113, 115, 116, 117 inkjet printing, 54, 55, 61, 64, 71, 76, 77, 78, 81, 82, 84, 85, 86, 87, 88, 90, 91, 94, 95, 98, 100, 101, 103, 104, 105, 108, 111, 115, 118, 119, 120, 166, 192, 195, 220 inkjet printing technology, 54, 82, 86, 95, 103, 104, 120 inoculation, 316, 326, 330, 331, 334 insect repellents, 344 insertion, 190, 247, 457 inspections, 316 institutions, 316, 317, 320, 321, 322, 324, 335, 336, 337 Instron, 386, 522

insulating material, 486, 499, 500, 515 insulation, 242, 243, 246, 251, 254, 386, 397, 484, 485, 486, 488, 489, 490, 491, 492, 493, 495, 497, 499, 500, 501, 504, 505, 506, 508, 509, 510, 514, 515, 516, 517, 518 insulin, 443 integration, 90, 100, 104, 118, 188, 190, 210, 226, 228, 234, 248, 350, 447, 448, 455 intelligent coating/membranes, 240 intense laser pulses, 543 interactive textiles, 249, 449 interface, 247, 251, 253, 283, 424, 475, 494 interfacial capillary forces, 414 interfacial charge transfer, 278, 297, 301, 305, 306, 308, 309, 314 interfacial charge transfer mechanism, 297 interference, 193, 533 interfibrillar regions, 412 interfibrillar spaces, 427 inter-filament cohesion, 476 interlacing, 247, 455 intermolecular interactions, 113, 334 international competition, 453 interventive action, 271 intramolecular bonding, 329 intraparticle diffusion model, 421 intrinsic ink characteristics, 92 intrinsic viscosity, 126, 127, 130, 131 invertebrates, 264, 275 investment, 4, 289 inward diffusion, 295 iodine, 351, 413, 414 iodine sorption, 413, 414 iodine sorption values, 413 ion exchange mechanism, 384 ion transport, 422, 427, 437, 438 ion-exchange, 443 ion-fiber interactions, 427 ionic crosslinking, 374, 377, 381 ionization, 283, 404, 410, 418 ionochromic dye, 103 IPO, 440 IR spectra, 177 IR spectroscopy, 341, 380 Iran, ix, 239 iridium, 220, 221 iron, 262, 264, 267, 268, 273, 313, 351 irradiation, 103, 105, 106, 107, 108, 109, 110, 111, 114, 115, 117, 167, 180, 194, 196, 197, 199, 200, 206, 207, 278, 280, 288, 289, 292, 293, 294, 295, 300, 301, 305, 306, 309, 313, 317, 337, 357, 364, 376, 381 IR-spectra, 128

563

Index Islam, viii, 154 isomerization, 105, 208 isomers, 112, 113, 194 isotherms, 420 isotope, 185 issues, 7, 9, 10, 13, 81, 90, 98, 101, 104, 195, 225, 239, 251, 260, 288 Italy, 256

J jacket fabric, 507, 508 jacquard weaves, 506 Japan, 32, 44, 46, 49, 56, 121, 127, 128, 129, 226, 228, 280, 311, 481, 497 jettable inks, 81, 118 Jordan, 270, 276 jute fibre, 500, 501, 509, 516 jute spinning system, 505 jute-acrylic blended yarn, 502 jute-based materials, viii, 499, 515 jute-blended yarn, 506, 507 jute-hollow polyester blended yarns, 502, 503, 505 jute-polyester blended yarns, 502, 507 jute-polypropylene blended needle-punched nonwoven fabrics, 511 jute-shrinkable acrylic fibre, 502 juxtaposition of vintage, 3

K K+, 221, 296, 297, 300, 314 KBr, 128, 132 keratin, 333, 341 keratin oxidation, 333 ketones, 217 kidney, 346, 348, 349 kill, 165 kinetic model, 112, 420, 421, 444 kinetic parameters, 421 kinetics, 24, 112, 113, 114, 176, 184, 263, 277, 278, 279, 280, 283, 284, 287, 290, 292, 295, 297, 301, 303, 305, 306, 341, 415, 444, 479 knees, 487 knitted fabrics, 397, 468, 477 knitted rag, 124, 125, 126, 128, 129, 130, 132, 133, 136, 137, 138, 139, 141, 143, 145, 146, 148, 149, 150, 153 knitted structure, 468, 477, 500 knitting machines, 254, 468 knitting yarn, 515 KOH, 404, 435, 436, 444, 445

Korea, 257 Kubelka-Munk function, 108

L lactose, 50 lamella, 408, 409, 413, 417, 419 laminar, 82, 444 lamination, 101, 242, 508 Langmuir and Freundlich adsorption isotherms, 420 laptop, 452 laser and computer technology, 532 laser beam, 166, 531, 532, 533 laser-produced surface structures, 543 lasers, 193 laser-treated polyester fiber, 533 lattice transformation, 404 law enforcement, 250 leaching, 278, 289, 294 leadership, 5 leakage, 297, 300, 361, 474 Leather, 11, 119, 121, 122, 229 LED, 64, 101, 118, 447, 448, 450, 451, 453, 454, 455, 457, 459, 460 LED light, microcontroller, 448 leisure, 226, 247 lending, 248 lens, 246, 532 leuco dyes, 210 leuco-derivative, 204, 205 leveling properties, 158 liberation, 407, 408, 411 ligand, 211 light conditions, 56, 109, 457 light- induced colour changes, 194 Light irradiation photo-activates, 300 light transmission, 115 light-emitting diodes, 189 light-emitting polymers, 189 lightfastness, 53, 54, 56, 76, 78, 184, 217, 218 lightweight optical fibers, 253 lightweight shawl fabrics, 507 lignin, 399, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 430, 432, 440, 441, 442, 443, 501, 538 lignocellulosic fibers, 404, 405 lignolytic white rot fungi, 326 limestone, 264 linear cellulose chains, 401 linen, 51, 54, 58, 315, 339, 443, 538 lipids, 24 liposomes, 351 liquid chromatography, 321, 438, 446

564

Index

liquid chromatography–tandem mass spectrometry technique, 438 liquid crystals, 193, 210, 215, 233, 247 liquid phase, 127, 244 liquid-crystal display panels, 157, 182 liquids, 414, 415, 441 Listeria monocytogenes, 384, 396 lithium, 98 lithography, 233 livestock, 250 living organism, 23, 418 longevity, 21 long-term preservation, 270, 272 long-term storage, 317 low temperatures, 202, 320 lower breaking strain, 330 lubricants, 414 luggage, 457 lumen, 476, 477 luminescence, 230, 322 Luo, 79, 80, 226, 255 luxury vintage gowns, 3 lying, 494, 537

M machinery, 84, 506 macromolecular chains, 113, 430 macromolecular systems, 212, 214 macromolecule orientation, 329 macromolecules, 214, 317, 324, 330, 333, 334 magazines, 9 magnesium, 94 magnetic field, 244, 245 magnetic resonance, 156, 467 magnetic resonance imaging, 467 magnetic shape memory alloys, 245 magnitude, 67, 277, 421, 426, 533 majority, 8, 12, 25, 102, 105, 158, 247, 252, 259, 265, 266, 273, 308 man, 158, 211, 397, 400, 471, 484, 499, 531, 536, 540 management, vii, 4, 6, 16, 18, 53, 54, 55, 58, 59, 61, 65, 66, 78, 79, 93, 191, 227, 246, 455, 471, 490 manganese, 221 manipulation, 193, 210 man-made fibres, 499 manufacturing, 22, 28, 89, 90, 93, 118, 124, 136, 158, 159, 241, 397, 457, 466, 500 manufacturing companies, 158 mapping, 210 market position, 6, 17 market segment, 227

market share, 101 marketing, 4, 5, 6, 12, 15, 17, 397 marketing literature, 4, 6 marketing strategies, 17 marketing strategy, 6 marketplace, 6 masking, 268 mass, 3, 4, 9, 32, 51, 56, 82, 158, 286, 296, 297, 300, 305, 321, 390, 422, 423, 430, 438, 446, 455, 486, 523, 525, 536 mass loss, 430 mass spectrometry, 286, 296, 297, 300, 305, 321, 438, 446 material surface, 255, 434 matrix, 107, 112, 113, 115, 116, 117, 193, 194, 242, 247, 249, 306, 350, 401, 402, 408, 443, 512, 513 matrixes, 122 matter, 190, 263, 368, 372 maxi dresses, 10, 11 maximum sorption, 418, 419 meat, 351 mechanical abrasion, 23, 25, 41 mechanical properties, 19, 29, 30, 36, 51, 248, 249, 315, 322, 329, 334, 336, 372, 386, 403, 442, 466, 472, 478, 480, 491 mechanical resistance, 240 mechanical responsive materials, 240 media, 2, 3, 4, 12, 13, 55, 63, 65, 66, 67, 92, 112, 113, 177, 190, 200, 220, 230, 292, 405, 462, 500 medical, vii, 85, 188, 210, 240, 244, 245, 247, 250, 257, 278, 344, 395, 449, 455, 460, 465, 468, 479 medical and health care applications, 278 medical textiles, vii, 85, 188, 244, 247, 449, 465, 479 medication, 474 medicinal applications, 447 medicine, 227, 240, 255, 344, 362 Mediterranean, 276 MEG, 16 MEK, 98 melamine-formaldehyde, 369 melt, 102, 157, 165, 173, 179, 183, 220 melting, 210, 216, 241, 357 melts, 241 membranes, 240, 300, 370 memory, 188, 189, 206, 210, 226, 239, 240, 244, 245, 246, 255, 432 MEMS, 77, 84, 88, 103, 118, 189, 449 mercerization, 404, 442 merchandise, 6, 10, 12, 13, 14, 15 merchandise strategy, 6 merchandising, 4, 7 mercury, 263, 280, 472 mesh-free stapled fibre, 509

Index messages, 252 metabolic processes, 483 metabolism, 484 metabolites, 317 metal corrosion products, 262, 263, 264, 275 metal fibers, 248, 542 metal ion(s), 199, 208, 218, 221, 230, 231, 262, 263, 389, 399, 412, 418, 419, 420, 422, 423, 424, 425, 426, 427, 428, 429, 436, 437, 438, 440, 441, 443, 445, 446 metal nanoparticles, 279, 285 metal oxides, 220, 221, 248, 249 metal salts, 94, 248, 249 metallic brilliance, 542 metallic glittering, 542 metals, 189, 193, 211, 219, 221, 223, 248, 249, 250, 262, 263, 264, 267, 273, 289, 400, 418, 420, 422, 430, 436, 437, 440, 443 meter, 31, 56, 489, 511, 522, 523 methacrylates, 122 methanol, 123, 127, 145, 146 methicillin-resistant, 384, 396 methodology, 76, 184 methyl methacrylate, 123, 124, 127 micro encapsulation, 189 microbial attack, 283, 317 microbial communities, 337 microbial community, 338 microbial degradation, 320, 339 microcapsules, 195, 216, 241, 242, 243, 255, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 362, 365, 455, 462 microcapsules stability, 343, 348, 349 microclimate, 243, 244 micro-disposal technique, 83, 85, 87, 90 micro-electromechanical machines, 240 micro-electronic mechanical systems, 189 microelectronics, 240 microemulsion, 77 micro-engineering industries, 54 microfibril, 401 micro-lens, 533 microorganism(s), 50, 317, 339, 377, 384 micro-organisms inhibitors, 263 microporous structure, 436 microscope, 19, 32, 33, 44, 46, 57, 58, 266, 323, 358, 531, 532, 533, 542, 543 microscopic images, 533, 534, 535, 537, 538 microscopy, viii, 44, 45, 46, 47, 284, 285, 299, 303, 304, 305, 306, 308, 310, 316, 321, 322, 326, 327, 332, 339, 341, 343, 345, 346, 531, 532, 537, 544, 545 Microsoft, 7, 462

565

Microsoft Word, 7 microspheres, 350 microstructure, 277, 286, 303, 305, 306, 307, 351, 401 microtome, 282 microwave irradiation, 167, 180 middle class, 3 middle lamella, 408, 409, 413, 417, 419 migration, 120, 158, 171, 263, 477, 501 migration resistance, 171 military, 194, 240, 244 military applications of smart textiles, 240 mineralised fibres, 263 mineralization, 177, 274 mini dresses, 11 Ministry of Education, 153, 180 mixing, 248 MMA, 123, 124, 127, 128, 131, 132, 133, 134, 139, 141, 142, 143, 149, 150, 151, 152 mobile phone, 190, 241, 450, 460 mobile phone technology, 241 mobile telecommunication, 239 modelling, 121, 274 models, 10, 78, 80, 101, 112, 113, 311, 420, 421, 450, 473, 478, 494 modifications, 216, 254, 499, 500 modified hemp fibers, 399, 405, 407, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 440 modules, 190, 251 modulus, 330, 334 mohair, 536 moisture, 123, 132, 139, 142, 147, 150, 154, 191, 242, 246, 250, 265, 283, 367, 368, 397, 410, 414, 415, 483, 484, 485, 488, 490, 493, 494, 495, 540 moisture content, 123, 132, 139, 142, 147, 150, 410, 415 moisture sorption, 154, 415 molar extinction coefficient, 157, 162 moldings, 136 mole, 172, 280 molecular chains, 262, 368 molecular motors, 201, 206, 207, 229 molecular orientation, 214, 418 molecular sensors, 230 molecular stoichiometry, 430 molecular structure, 107, 134, 143, 153, 193, 203, 211, 248, 360, 364 molecular weight, 98, 123, 124, 126, 127, 130, 131, 139, 141, 147, 149, 153, 245, 372, 379, 402, 405, 541 molecules, 34, 54, 107, 108, 109, 112, 113, 115, 116, 158, 164, 176, 193, 199, 203, 206, 210, 211, 212,

566

Index

213, 215, 220, 290, 333, 360, 367, 372, 375, 377, 402, 403, 404, 410, 413, 414, 435, 541 momentum, 82 monoazo, 158, 159, 163, 164, 165, 175, 176, 181, 184 monoazo pyridone dyes, 163, 164, 175, 176 monoclinic crystalline lattice, 404 monolayer, 286 monomer molecules, 541 monomers, 102, 154, 155, 248, 384, 541 monosaccharide, 401, 432 morphological changes, 326, 331, 336 morphology, 129, 268, 316, 326, 358, 400, 402, 406, 408, 409, 432, 436, 437, 440 motivation, 13, 25 mountain climbers, 240 mountain sheep wool, 537 mucous membrane(s), 370 multi-colour printing, 101 multidimensional, 409 multi-functional switches, 203, 207 multifunctional textiles, 240 multimillion pound industry, 1 multiples, 484 multiplication, 467 multi-wavelength laser systems, 533 murals, 101 muscles, 484 museum collections, 337 museums, vii, 259, 260, 315, 316, 317, 320, 321, 322, 324, 335, 337 music, 8, 12 mycelium, 319, 322 mycology, 316

N Na+, 221, 297, 300, 314 Na–cellulose I lattice, 404 NaCl, 127, 131, 237, 295 nano-coatings, 543 nanoimprint, 233 nanomaterials, 240 nanometer, 357, 375 nanoparticle(s), 235, 249, 278, 279, 285, 286, 289, 303, 305, 309, 310, 311, 312, 313, 344, 356, 362, 375, 376 nanotechnologies, 239 nanotechnology, 188, 240, 279, 312, 375 naphthalimide, 159, 161 naphthopyrans, 105, 122, 194, 197, 201 native cellulose, 155, 402, 430, 442 natural blood-vessel deformation, 472

natural colour, 115, 500 natural crystalline structure, 404 natural fibers, 158, 400, 404, 531, 544 natural textiles fibers, 278 needling density, 509, 510, 512, 513, 515 negative casts, 263, 264 negativity, 307 neighbourhood feel, 12 nematic liquid crystals, 210 Netherlands, 542 nettles, 538 neurobiology, 233 neutral, 23, 27, 32, 34, 35, 36, 37, 38, 39, 40, 43, 48, 99, 178, 179, 234, 313, 485 neutral cellulose, 34, 36 new spinning technologies, 520 Newtonian fluids, 94 next generation, 118 NH2, 167 nickel, 220, 248, 263, 521 NIR, 296, 341 nitrates, 156 nitration, 145, 146, 148, 149, 152 nitrides, 278, 307 nitrodiphenylamine, 159 nitrogen, 105, 147, 148, 202, 214, 217, 306, 314, 361, 365, 370, 375, 432 nitrogen content, 147, 148 N-methylol compounds, 369, 370 NMR, 123, 128, 134, 139, 143, 147, 151, 152, 155, 177, 185, 340, 341 no dimension, 509 nominal magnification, 534, 535, 538 noncellulosic components, 400, 403, 405 nonconductive threads, 253, 254 non-destructive examination, viii, 531 non-heat resistant surfaces, 279 non-invasive examination, 532 non-ionic compounds, 158 non-linear least-squares regression, 426 non-linear optics, 296 non-porous media, 92 non-radiative transition, 107 non-wearable textile, 500 North America, 259, 339 nostalgia, 9, 13 nouveau vintage, 3 novel technique, 384 nozzle density, 88 nozzle spray technique, 242 nuclear magnetic resonance, 156 nucleus, 159 numerical analysis, 467

567

Index numerical aperture, 532, 533 nutrient, 283, 295 nutrition, 317 nylon, 81, 112, 113, 115, 117, 118, 121, 157, 158, 162, 163, 164, 174, 204, 229, 246, 468

O objective rear aperture, 533 obstacles, 455 obstruction, 428 occlusion, 480 odor intensity, 349 odor measurements, 344 OFS, 256 OH, 125, 130, 141, 143, 148, 149, 157, 167, 168, 177, 285, 294, 301, 323, 329, 362, 402, 404, 406 OH-groups, 404 oil, 102, 338, 351, 352, 353, 400, 414, 415, 417, 441, 506 old clothes, 4 older customers, 9 oligomers, 102, 231, 361, 541 opacity, 476 open-end rotor, 520 openness, 490, 492 operations, 196 opportunities, 2, 10 optic sensors, 227 optical brightener, 53, 55, 63, 65 optical brightening agents, 55 optical density, 113 optical differences, viii, 531 optical examinations, 542 optical fiber, 239, 240, 247, 253, 257, 462 optical fibers, 239, 247, 253 optical light microscopy, 545 optical microscopes, 531, 532 optical microscopy, 321, 532 optical properties, 220, 247, 314 optical wide-field microscopy, 532 optimal performance, 48 optimization, 177, 297, 399, 429, 438, 440 ores, 500 organ(s), 77, 211, 241 organic chemicals, 400 organic chemicals resources, 400 organic compounds, 100, 317 organic fibres, 262, 263 organic matter, 263 organic polymers, 113, 317, 449 organic solvents, 167 organism, 23, 263

original garment, 9 originality, 2, 9 orthotropical traction stiffness, 474 Ostwald viscometer, 126 outdoor clothing, 246, 251 out-of-focus signals, 532 ownership, 3 ox, 430 oxidation, 105, 195, 196, 208, 220, 221, 248, 256, 279, 283, 285, 290, 292, 294, 297, 303, 317, 329, 333, 351, 353, 405, 406, 408, 409, 419, 434, 442 oxidative agents, 405 oxidative reaction, 341 oxidative stress, 341 oxidizing agents, 405 oxygen, 214, 261, 262, 264, 266, 273, 277, 279, 280, 290, 306, 310, 312, 314, 317, 400, 433, 434, 436, 440, 445

P padding, 343, 345 pagers, 250 pain, 449 paints, 157, 159, 211 palladium, 346 PAN, 442, 542 paper, 53, 55, 56, 58, 65, 66, 67, 69, 71, 74, 76, 80, 82, 83, 85, 101, 119, 124, 128, 154, 157, 159, 166, 256, 260, 317, 318, 337, 340, 341, 355, 448, 461, 495 paper sludge, 124, 154 parallel, 44, 301, 401, 509, 514 parentage, 5 participants, 7, 8, 9, 10, 11, 12 passive smart textiles, 240 passive thermal insulation effect, 242 pathogenic bacteria, 278, 289 pathogenic biofilms, 278 pathogens, 310, 311, 313 pathological effects, 467 pathology, 467 patients wear clothing, 449 PCA, 357, 363 PCBs, 77 PCM, 239, 241, 242, 243, 244, 255, 449 PCT, 119 peace, 450, 460 peat, 418 pectin, 399, 401, 403, 405, 418, 441, 538, 539, 543 pectin-surrounded fiber bundles, 539 pedal, 8 pendant side groups, 401

568

Index

pentose sugars, 401 peptide, 332 percolation, 249 permeability, 36, 190, 297, 361, 383, 384, 387, 395, 396, 397, 484, 490, 491, 507, 509, 512, 515, 517 permit, 123, 409, 414, 449 peroxide, 124, 125, 136, 314, 345, 406 personal communication, 260 personal contact, 5 personality, 6, 12, 13, 14 perspiration, 168, 176, 218, 251, 368, 483, 484, 485, 488, 496 perspiration resistance, 218 PES, 56, 312, 397, 541, 542, 543 pesticide(s), 352, 400, 430, 438, 439, 440, 441, 444, 445, 446 pesticide analysis, 400, 438, 440 PET, 246, 466, 474, 505 pH, 19, 27, 90, 92, 93, 94, 97, 99, 103, 158, 164, 178, 185, 192, 193, 194, 203, 210, 215, 216, 218, 219, 230, 235, 236, 237, 238, 244, 300, 301, 313, 360, 372, 380, 405, 411, 418, 455, 462 pharmaceutical(s), 54, 124, 350, 351, 362, 377, 455 phase change materials, 189, 239, 240, 241, 242, 243, 244, 344, 352, 455, 462 phase transitions, 195, 211 phase-transfer catalysis, 231 phenol, 217, 218, 402 phenolic compounds, 216, 444 phosphate, 372 phosphorescence, 193 phosphorus, 145, 361, 365, 372, 380 photocatalysis, 305, 311, 314 photocatalysts, 312, 314 photocatalytic efficiency, 288 photochromic azulene, 203, 204, 205 photochromic colorants, 109 photochromic disperse dye, 204 photochromic dyes, 81, 99, 103, 104, 105, 108, 111, 113, 115, 116, 117, 118, 121, 122, 194, 195, 228, 229 photochromic fluorescent fabrics, 203 Photochromic napthopyrans, 106 photochromic reaction, 105, 106, 107, 195, 208 photochromic smart textiles, 209 photochromic spirooxazine, 109, 111, 114, 116, 196 photochromic textiles, 112, 196, 202, 219 photodegradation, 176, 177, 184 photo-detector, 532 photoelectron spectroscopy, 291 photo-excited organic molecules, 107 photofading kinetics, 176 photographs, 32, 332, 408, 433, 534, 537

photo-induced charge transfer, 297 photoisomerization reactions, 107 photoluminescence, 189 photomultiplier, 533 photonic fibers, 240 photonics, vii, 226, 227, 240, 249 photons, 109, 194 photo-responsive, vii, 81, 82, 88, 104, 108, 109, 110, 111, 113, 116, 117, 118, 195, 197, 199, 200, 204, 205, 206, 209, 229 photo-responsive fluorescence, 204, 205 photo-responsive inkjet printed textiles, 82 photostability, 107, 176, 184, 196 photoswitching, 108, 202 photovoltaic cells, 447, 448, 449, 452, 453, 454, 460 photovoltaic fibers, 449, 452 photovoltaic-piezoelectric device, 452, 461 physical activity, 484 physical and mechanical properties, 29, 30 physical characteristics, 71, 123, 190, 492 physical environment, 215 physical exercise, 484 physical features, 384 physical properties, 132, 142, 150, 193, 194, 200, 242, 249, 364, 383, 389, 407, 440, 477, 502, 508, 517, 527, 541 physical structure, 368, 492 physical treatments, 544 physicochemical properties, 92, 116 physics, 239, 240, 497 Physiological, 386, 483, 496, 497 physiological comfort, 397, 484, 490, 491 physiological measurement sensors, 251 physiological pressure curves, 472 physiological properties, 383, 384, 401 Pie chart, 261, 262, 265, 266, 269 piezo crystals, 449 piezochromic, 246 piezoelectric drop-on demand ceramic print heads, 95 piezoelectric element, 89 piezoelectric inkjet print head, 83, 88 piezoelectric materials, 240 piezoelectric resistance, 189 pigmentation, 317 pigmented binder-less inkjet inks, 84 pigments, 82, 91, 102, 103, 163, 167, 182, 193, 195, 210, 216 pinhole size, 533 pitch, 90, 210, 534, 536 plain fabric, 343, 345, 349 plain weave, 56, 286, 385, 475 plain woven woollen fabric’s resistance, 389

Index plants, 10, 218, 264, 418, 538, 539 plaque, 476 plasma chamber, 290 plasma deposition, 286 plasma particle deposition, 286 plastic shielded wires, 253 plastics, 63, 101, 157, 159, 167, 171, 313 platelets, 467 platform, 8 playing, 84, 248 plethora of guides, 2 point defects, 289 Poiseuille flow, 467 polar, 178, 213, 277, 279, 307 polar groups, 277, 279 polar solvents, 178, 213 polarity, 105, 112, 113, 158, 177, 306, 402, 414 police, 240 pollutants, 100, 430 pollution, 123, 124, 153 pollution problems, 153 poly(ethylene terephthalate), 164 polyacetylene, 248 polyacrylonitrile, 164, 165, 542 polyacrylonitrile fast yellow shades, 165 polyacrylonitrile fiber, 164 polyamide(s), 64, 121, 157, 159, 165, 170, 172, 176, 182, 229, 278, 541 polyamide fiber, 165, 170, 182 polyaniline, 220, 223, 234, 235, 248, 250 polycarbonate, 101, 247 polycarboxylic acid, 355, 356, 357, 361, 362, 363, 364, 365, 371, 372, 373, 375, 379, 380, 381 polyconcensation fibers, 541 polycondensation, 541 polyester fibre, 502, 506, 516 polyester vascular prosthesis, 465, 479 polyesters, 157, 159, 179 polyethylene, 98, 246, 278, 286, 289, 541 polyethylene-terephthalate, 286 polyglucuronic acids, 405 polyhydric alcohol, 98, 405 polymer chain(s), 33, 245, 248, 541 polymer composites, 226, 248, 256 polymer fibers, 539, 540 polymer films, 233, 278, 289 polymer matrix, 112, 113, 194 polymer media, 112 polymer melts, 241 polymer photovoltaic solar cells, 453, 454 polymer solutions, 241 polymer structure, 389 polymer-chain scission, 317

569

polymerization, 127, 139, 147, 154, 364, 375, 379, 401, 432, 462, 541 polymethylmethacrylate, 247 polymorphic transformation, 434 polymorphism, 155 polyolefin fibers, 541 polyolefins, 157, 159 polypeptide, 333 polypeptide chains, 333 polypropylene, 98, 101, 278, 481, 501, 504, 509, 510, 511, 512, 513, 515, 516, 517, 518, 541 polypropylene fibre, 504, 509, 513 polypyrrole, 220, 223, 233, 248, 250, 256 polysaccharide(s), 23, 24, 136, 155, 377, 396, 401, 402, 418, 442 polystyrene, 220, 246, 248 polythene, 272, 515 polythiophene, 220, 223, 234, 248 polyurethane, 77, 242, 245, 250, 255, 278 polyurethane foam, 242 polyurethane foam matrix, 242 polyurethanes, 344, 541 polyvinyl chloride, 541 population, 7, 400 porosity, 81, 115, 118, 190, 263, 307, 415, 437, 473, 474, 475 porous fiber matrices, 399, 422, 429, 440 porous media, 92 porous membrane, 387 positioning statement, 6 positive correlation, 511 potassium, 98, 124, 400, 405, 406, 434, 440, 445 potassium bromide, 124, 405 potassium permanganate, 406 poverty, 3 precipitation, 92, 125, 263, 418 pregnancy, 188 preparation, 11, 53, 55, 64, 66, 88, 125, 126, 138, 146, 148, 154, 155, 163, 164, 171, 181, 182, 183, 199, 219, 248, 278, 279, 283, 305, 313, 430, 438, 444, 445, 501, 511, 531 preservation, vii, 259, 261, 262, 263, 264, 265, 266, 267, 268, 270, 271, 272, 273, 274, 275, 276, 315, 317 prestige, 6 prevention, 240, 336 preventive conservation, 273 primary fibrils, 403 primary structural network, 403 primary wall, 24, 35, 402 principles, 4, 50, 71, 76, 83, 415

570

Index

print head, 71, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 99, 100, 103, 104, 108, 118, 120, 121 print head nozzle, 94, 95, 96 print head technologies, 88, 93, 97 print media, 92 print mottle, 71, 80 print simulation, 53, 54, 55, 65, 67, 76 printed circuit boards, 54, 253, 254, 448, 450, 455 printed dress, 452 printed-textile, 82 printer color profiles, 53, 65 print-head clogging, 100 printing colors, 53, 55 printing electronic materials, 54 printing industry, 81, 84, 120 printing inks, 157, 159, 163, 167, 179, 195, 232, 250 printing technology, 54, 81, 82, 86, 88, 90, 95, 103, 104, 118, 120 procurement, 11 producers, 22 product design, 49, 210 product performance, 5 production technology, 400 professionals, 3, 260, 269, 270, 272, 273, 274 profilometer, 286 prognosis, 16 programming, 448, 450, 457, 461 project, viii, 49, 90, 153, 180, 270, 271, 274, 338, 396 propagation, 89 propane, 406 proposition, 6 proprietors, 12, 13, 14 prostheses, 466, 467, 468, 471, 474, 480 prosthesis, 465, 466, 467, 468, 469, 470, 471, 472, 474, 475, 476, 478, 479, 480 prosthesis flow properties, 467 prosthesis to kinking, 466 prosthesis wall displacements, 472 protection, vii, 81, 107, 117, 118, 194, 209, 210, 240, 320, 337, 395, 400, 403, 440, 447, 448, 449, 490 protective clothing, 243, 246, 250, 397, 447 protective coating, 133 proteinaceous fibres, 266, 267, 268, 273, 317, 318, 323, 336 proteinaceous material, 264, 316, 322, 325 proteins, 24, 145, 268, 321, 332, 341, 536 proton-accepting solvents, 178 proton-donating solvents, 179 protons, 279 prototype(s), 256, 452, 455, 469, 474, 475, 480 pseudomorph, 263

pseudo-vintage, 10 psychological variables, 484 PTFE, 471 PTT, 164, 165 public safety, 250 pulp, 125, 154, 538, 540 pulsatile flow conditions, 472, 478 pulse plasma power magnetron sputtering, 277 pulsed direct magnetron sputtering, 277 pumice stone, 19, 20, 21, 24, 25, 27, 41, 42, 43, 44, 47, 48 pumice stone-enzyme, 19, 41, 42, 47 purification, 136, 145, 400, 401, 430, 440 purity, 92, 153 PVC, 100 pyridinium group, 165 pyrolysis, 360, 430, 432, 444, 445 pyrolysis of celluloses, 430

Q quality control, 53 quantification, 545 quantum size nanoparticles, 309 quaternary ammonium, 165, 182 quaternary ammonium salt, 165, 182 Queensland, 341 questionnaire, 259, 260 quinoline derivatives, 159 quinones, 434

R radial distance, 426 radiation, 64, 65, 119, 194, 203, 205, 229, 256, 280, 375, 403, 448, 460, 483, 484, 485, 486, 487, 488, 489, 491, 492, 493, 494 radicals, 233, 279, 285, 290, 301, 357, 375 radio, 189, 280, 476 radiography, 493 radius, 415, 416, 423, 424, 427 Raman spectra, 185, 322, 323, 327, 328, 329 Raman spectroscopy, 185, 316, 321, 322, 326, 329, 332, 339, 340, 341, 357 ramie, 51, 442, 509, 538 rate of change, 425, 427 raw materials, 155, 321, 400 rayon, 51, 157, 159, 538 reactant, 356 reactants, 377, 380 reaction mechanism, 105, 106, 107, 111 reaction time, 107, 167, 294

571

Index reactions, 27, 92, 105, 107, 109, 170, 183, 200, 230, 279, 301, 357, 358, 375, 377, 405, 419, 430 reactive azo dyes, 170, 182, 183 reactive group(s), 375, 377 reactive oxygen, 278, 312 reactive polymers, 344 reactivity, 116, 132, 142, 150, 279, 289, 360, 364, 404, 405, 407, 436 reagents, 356, 362, 378 realism, 468 reality, 188, 226, 256, 311, 312 receptors, 117, 209, 490 recognition, 2, 192, 231 recombination, 301, 306, 309 recovery, 139, 244, 245, 255, 270, 283, 351, 356, 360, 367, 372, 375, 377, 381, 386, 393, 473, 477, 504 recycling, 4, 9, 10, 13, 124, 293, 297, 399, 401, 430 recycling plants, 10 red cell destruction, 467 red shift, 303 reflectance spectra, 296, 303, 304 refractive index, 105, 194, 195 refractive indices, 194 regenerated cellulose, 540 regeneration, 166 regression, 420, 426, 487 regression analysis, 420 regression equation, 487 rehabilitation, 188, 240, 252 reinforcement, 441, 500 relative humidity, 74, 315, 317, 320, 326, 410, 411 relaxation, 111, 112, 472 relaxation model, 112 relaxation process, 111 reliability, 5, 6, 54, 93, 98, 221, 250 remote sensing, 187, 225 renaissance, 400 repair, 473 reparation, 444 repeating unit, 401 repellent, 363, 365 repression, 50 reproduction, 55, 63, 71, 84 repulsion, 206 reputation, 5 requirements, 5, 54, 61, 88, 90, 91, 92, 93, 97, 100, 104, 109, 118, 191, 196, 227, 228, 239, 243, 251, 252, 253, 292, 473, 475 researchers, 23, 24, 55, 124, 191, 260, 272, 324, 363, 372, 384, 455, 467 residuals, 421, 426 residues, 34, 43, 154, 182, 307, 333, 361, 402, 444

resilience, 477, 513 resins, 321, 344, 367, 369, 378 resolution, 87, 297, 531, 532, 533, 534, 535, 536, 543, 545 resources, 6, 16, 120, 400 respiration, 240, 455, 485 response, 6, 111, 115, 184, 192, 200, 210, 219, 220, 221, 231, 244, 246, 250, 341, 350, 360, 368, 477 response time, 200, 221 restenosis, 477, 480 restoration, 337, 338 restrictions, 272 retail, 2, 3, 4, 6, 7, 13, 15, 16, 17, 18, 79, 250 retail guru, 4 retail marketing literature, 6 retail premises, 7 retailing planning context, 6 retro subculture, 3 RF-plasma pretreatment, 280 RH, 30, 31, 261, 509, 521 Rhizopus, 319 rice husk, 445 rights, 10 ring flanges, viii, 519, 520, 521 ring spinning, viii, 519, 520, 521 ring spinning machine, 519, 521 ring travellers, 519 rings, 198, 207, 208, 214, 323, 328, 329, 399, 401, 404, 436, 519 risk(s), 100, 101, 252, 316, 317, 384, 395, 474, 477 risk factors, 317 room temperature, 158, 197, 198, 208, 211, 213, 214, 222, 244, 285, 320, 386, 404 root, 306 roughness, 306, 404, 408, 413, 417, 419, 475, 500, 533 routes, 279 Royal Society, 50, 119, 228, 232, 339 rubber, 31, 157, 159, 242, 245 rubbing fastness, 165 Russia, 10 ruthenium, 221

S saccharin, 217 safety, 5, 92, 145, 187, 191, 192, 227, 250, 447, 448, 449, 453, 457, 460 salts, 94, 163, 164, 167, 170, 177, 179, 241, 248, 249, 259, 261, 263, 264, 267, 268, 273, 279, 321, 372 sample surface, 300, 306, 531, 532 SAP, 512

572

Index

satisfactory whiteness, 372 saturation, 296, 475 saturation index, 475 scaling, 478 scaling law, 478 scanning calorimetry, 361 scanning electron microscopy, 316, 321, 322, 326, 327, 341, 346, 545 scanning electronic microscope, 32 scarcity, 11 scattering, 108, 303, 341 scent, 346 school, 13, 278, 289 science, vii, 260, 269, 270, 288, 316, 336, 362, 377, 397 scope, 74, 82, 84, 190, 193, 260 screen-printing, 242 seafood, 361 second hand clothing stores, 10 second hand stock, 11 Second World, 84, 400 secondary cell, 24, 403 secondary hydroxyl groups, 130, 141, 149 secretion, 317, 319, 331 security, vii, 5, 81, 103, 107, 117, 118, 187, 194, 195, 209, 225, 250, 253, 448 sedimentation, 96 selectivity, 52, 312, 419 self-expression, 1 self-indicating alert systems, 81, 118 SEM micrographs, 346, 347, 348 semiconductor(s), 211, 222, 277, 278, 279, 289, 308, 309, 311, 314, 453 semiconductor TiO2, 279 sensation(s), 393, 490 senses, 241 sensing, 118, 187, 190, 192, 194, 209, 225, 227, 240, 244, 247, 252, 460 sensing applications, 247 sensitivity, 176, 271, 290 sensors, vii, 188, 189, 208, 226, 227, 230, 239, 240, 245, 247, 250, 251, 252, 257, 447, 448, 449, 450, 455, 460, 461, 462, 487 Serbia, ix, x, xii, xiii, 162, 163, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 319, 399 serine, 338 services, 17, 252, 253, 259, 260, 271 severe stress, 485 shade, 31, 34, 35, 36, 37, 39, 40, 41, 42, 43, 65, 164, 505, 508 shape, 107, 127, 188, 189, 190, 194, 206, 208, 226, 239, 240, 244, 245, 246, 247, 253, 255, 262, 265, 296, 346, 348, 349, 450, 471, 472, 473, 478, 490

shape memory alloys and polymers, 189, 244 shape memory materials, 226, 239 shape memory polymers, 206, 240, 245, 246 shape-memory, 245 shawl fabric, 506, 507 shear, 25, 51, 86, 93, 94, 95, 253, 467, 478 shear rates, 467, 478 shear rigidity, 25 sheep, 536, 537, 538 sheep wool, 536, 537 short-chain polysaccharides, 23 showing, 104, 182, 200, 261, 262, 265, 266, 269, 283, 291, 296, 299, 313, 314, 322, 327, 332, 533 side chain, 402 signals, 84, 134, 152, 240, 294, 448, 455, 532, 533 significance level, 527 signs, 64, 101, 227, 250, 252, 256, 329, 457, 462 silane, 404 silica, 127, 155, 362 silicon, 449 silicone treatment, 501 silicones, 375 silk, 54, 55, 78, 81, 112, 113, 115, 117, 118, 157, 158, 159, 168, 266, 268, 315, 317, 321, 325, 337, 339, 375, 400, 490, 536, 537, 538, 539 silk screen printed polyester, 168 silver, 165, 182, 246, 249, 262, 264, 267, 268, 273, 278, 280, 283, 286, 289, 294, 310, 311, 312, 313, 314, 384, 389, 397, 521, 542 silver biocidal surfaces, 278 silver treated wound dressings, 384 silvernic, 521, 524 simulation, 53, 54, 55, 56, 65, 66, 67, 71, 76, 115, 444, 467, 468, 479 simulations, 65, 467, 468, 478 Singapore, 381 SiO2, 27, 288, 362 SIP, 90 sisal, 538 skeletal muscle, 484 skeleton, 405 skin, vii, 209, 244, 250, 251, 264, 344, 370, 377, 387, 393, 460, 483, 484, 485, 487, 488, 490, 491, 495, 538 skin softeners, vii, 344 skin temperatures, 487 slip draft spinning system, 506 slow fashion, 3 sludge, 124, 154 small business sector, 4 small businesses, 55 small diameter blood vessels, 465, 466 small-scale retailers, 12

Index smart clothing, viii, 191, 192, 226, 251, 252, 253, 447, 448, 452 smart clothing design, 191 smart clothing system, 191, 192 smart materials, 189, 190, 227 smart medical textiles, 188 smart or intelligent textiles, 188 smart products, 384 smart structures, 247, 255 smart textile, vii, 187, 188, 189, 190, 191, 192, 194, 195, 196, 197, 199, 200, 201, 203, 204, 206, 207, 209, 211, 218, 219, 225, 226, 227, 239, 240, 242, 243, 244, 246, 248, 250, 251, 252, 254, 255, 344, 449, 450, 461, 462 smart wound-care materials, 188 smoothness, 475 social judgment, 3 social order, 15 societal acceptance, 1 sodium, 123, 124, 125, 126, 145, 147, 154, 155, 167, 172, 237, 241, 356, 361, 363, 364, 365, 372, 373, 375, 380, 383, 384, 385, 395, 404, 405, 406, 407, 408, 410, 417, 419, 502, 516 sodium alginate, 383, 384, 385, 395 sodium carbonate, 124, 372 sodium chlorite, 406, 407, 408, 410, 419 sodium chlorite modification, 406 sodium hydroxide, 123, 124, 125, 126, 404, 406, 410, 417, 502, 516 sodium hypochlorite, 405 Sodium periodate oxidation, 406 sodium salts, 372 softener, 374, 375 softness, 19, 36, 40, 49, 242, 501 software, 58, 59, 61, 65, 76, 79, 90, 290, 457, 533, 534, 535 softwoods, 402 solar cells, 189, 226, 449, 453, 454, 462 solar simulator, 294, 295, 297 soldier and weapons camouflage, 247 sol-gel, 277, 278, 375 sol-gel films, 277 sol-gel processes, 375 solid matrix, 107 solid phase, 244, 438 solid state, 109, 158, 232 solidification, 102 solubility, 92, 94, 98, 124, 129, 136, 140, 148, 157, 158, 159, 195, 279, 289, 418 solvatechromic, 246 solvation, 176, 427, 428 solvatochromism, 213 solvent molecules, 211

573

solvents, 87, 97, 98, 99, 100, 102, 121, 157, 167, 176, 177, 178, 179, 184, 185, 213, 216, 217, 229, 401, 402 sorption, 154, 399, 400, 403, 405, 406, 408, 413, 414, 415, 418, 419, 420, 423, 424, 428, 429, 436, 437, 440, 442, 443, 444 sorption process, 418, 419, 436, 437 sorption properties, 400, 403, 405, 406, 408, 415, 418, 440 SP, 510 Spain, x, xi, xii, xiii, 343, 345, 346, 353, 355 specialists, 271, 346 species, 112, 194, 195, 197, 208, 218, 230, 241, 278, 279, 280, 289, 290, 292, 294, 306, 312, 313, 315, 317, 318, 319, 320, 321, 325, 326, 328, 329, 331, 332, 333, 334, 336, 411, 427, 445 specific computer code, 467, 468 specific flexural rigidity, 502 specific gravity, 92 specific heat, 394, 486 specific properties, 400 specific structure, 399, 401 specific surface, 399, 402, 411, 432, 434, 435, 436, 440 specific surface area, 399, 411, 432, 434, 435, 436, 440 specific surface morphology, 402 specific thermal resistance, 509, 511, 512, 513, 514, 515 specific work of rupture, 502 specifications, 7, 20, 26, 367, 521 spectroscopy, 134, 155, 177, 185, 224, 290, 296, 312, 313, 316, 321, 322, 323, 324, 326, 329, 332, 339, 340, 341, 357, 364, 365, 379, 380 spherical shape, 346, 348, 349 spin, 289 spindle, 521 spindle speed, 521 spinnerets, 539, 542 spinning balloon angles, 526 spinning off primary fibrils, 403 spinning tension, 519, 520, 521, 522, 525, 527, 528 spirooxazines, 105, 107, 110, 115, 194, 197, 201, 213 spiropyrans, 105, 107, 194, 197, 201, 213, 216 sports clothing, 455 sports garments, 243, 247 sportsmen, 240 sportswear, 246, 457 Spring, 17 sputtering, 249, 277, 278, 283, 285, 286, 288, 289, 290, 292, 295, 296, 297, 301, 302, 303, 305, 306, 307, 312, 531

574

Index

Sri Lanka, 27 stability, 20, 27, 49, 54, 74, 92, 94, 104, 105, 107, 160, 166, 182, 198, 200, 208, 221, 243, 248, 249, 256, 288, 312, 343, 344, 345, 348, 349, 351, 355, 466, 500 stabilization, 58, 146, 198, 436 stable states, 192 stainless steel filaments, 542 stainless steel yarn, 542 standard deviation, 421, 439 standard Martindale abrasion test method, 386 standard plastic optical fiber, 247 standard relative humidity, 410 standard test method, 383, 520 standard washing procedure, 28 Staphylococcus, 279, 313, 384, 396 Staphylococcus aureus, 279, 313, 384, 396 staple yarn production process, viii, 519 starch, 23, 36, 351, 377 static electricity charges, 401, 403 statistical analysis, 55, 259, 261, 296, 394 statistical significance, 296, 384 steady and pulsatile regimes, 467 steel, 95, 248, 254, 396, 468, 476, 542, 543 stenosis, 467, 478, 479, 480 stent, 465, 475, 476, 477, 478, 480 stereoisomeric forms, 214 stereomicroscope, 57 steric obstruction for sorption, 428 sterile, 295, 319 stiffness tester, 31, 386 stigma, 3 stimuli-responsive materials, 190, 226 stimuli-responsive smart textiles, 187, 225 stimulus, 103, 116, 190, 193, 194, 200, 208, 218, 220, 226, 244, 246 STM, 30 stock, 10, 11 stoichiometry, 430 Stokes-Einsteind diffusion coefficient, 423 stone wash, 20, 21, 24, 41, 51 stone-wash effect, 25 storage, 92, 103, 104, 182, 194, 195, 210, 220, 239, 241, 242, 260, 269, 271, 272, 274, 315, 317, 320, 322, 335, 336, 337, 370, 449 storage and exhibition rooms of museums, 320 storage conditions, 320, 322, 335 store image, 12, 13 store interior, 12, 14 strategic management, 18 strategic position, 6 street style, 4

stress, 6, 241, 244, 245, 329, 330, 334, 341, 357, 409, 466, 467, 474, 475, 476, 484, 485, 496, 504 stress-strain curves, 330, 329, 330, 331, 334 stretching, 132, 134, 143, 150, 330 STRs, 511, 512 structural changes, 112, 321, 322, 323, 326, 330, 336, 339, 417 structural characteristics, 317 structural design of weaving, 499 structural formation, 213 structuring, 402 style, 2, 3, 4, 8, 9, 10, 11, 12, 13, 14, 243 stylists, 3, 9 styrene, 98 sublimation fastness, 158, 165, 176 sublimation ink, 84 sublimation transfer printing techniques, 84 substitutes, 466, 480 substitution, 106, 123, 124, 126, 129, 130, 131, 136, 138, 139, 140, 141, 147, 148, 149, 153, 341, 400 substitution reaction, 129, 131, 141, 148, 149 succession, 469 succinic acid, 319, 326, 331, 357, 360, 361, 364, 371, 375, 376, 381 sugar beet, 154 sugar industry, 154 sulfadiazine-Ag salt, 279 sulfate, 167, 169, 170 sulfuric acid, 136, 145, 543 Sun, 365, 396, 443, 446, 497 super-hydrophilic, 279 supermolecular structure, 316, 321, 322, 332, 401, 442 superpolish, 521, 523, 524, 528 supply chain, 4, 90 surface area, 279, 295, 400, 411, 412, 430, 432, 433, 434, 435, 436, 440, 484, 487, 492 surface characteristics, 20, 432 surface deformation, 390 surface energy, 92, 279, 306, 308 surface functional groups, 412, 432, 436 surface layer, 249, 326 surface modification, 382 surface plasmon resonance, 303 surface pore structure, 408 surface properties, 324, 415, 440, 490 surface reactions, 279 surface structure, 67, 384, 533, 540, 542, 543, 545 surface tension, 92, 94, 99, 416 surfactants, 99, 350 surgical technique, 474 surplus, 243 surrogates, 5

Index survival, 260, 268, 281, 282, 293, 396 sustainability, 13, 20, 22, 25, 49, 50, 118 sustainable denim, 20, 21, 22, 23, 25, 26 sustainable development, 353 suture, 468, 479 sweat, 377, 455, 488 Sweden, 83, 244 swelling, 92, 125, 404, 409, 412, 413, 415, 417, 423, 516 swelling and shrinkage of ultimate cells, 412, 417 swelling process, 423 Switzerland, x, xi, xiv, 51, 128, 136, 277 synergistic effect, 208 synthesis, v, vii, 107, 123, 124, 129, 136, 139, 140, 145, 146, 148, 157, 163, 167, 168, 170, 171, 173, 175, 179, 180, 181, 182, 183, 185, 191, 215, 216, 231, 234, 352 synthetic antibiotics, 278, 289 synthetic chemical materials, 540 synthetic fiber, 157, 163, 164, 184, 288, 400, 410, 538, 539, 545 synthetic fibers, 157, 163, 164, 184, 288, 400, 410, 538, 539, 545 synthetic organic colorants, 157, 159 synthetic textiles, 165, 317

T tailor-made eco-smart clothes, 450 tantalum, 476 tapestries, 316 target, 5, 6, 189, 283, 286, 292, 298, 438, 509 taste-makers, 3 tear resistance, 253 technical applications, 465 technical textiles, vii, 85, 189, 243, 344, 399 techniques, vii, 6, 20, 81, 82, 84, 85, 90, 92, 93, 94, 95, 103, 108, 116, 117, 118, 119, 124, 188, 189, 192, 195, 196, 199, 204, 209, 216, 220, 278, 326, 338, 340, 344, 351, 355, 356, 462, 474, 480, 490, 533 technological advancement, 274 technological advances, vii, 465 technology(ies), 5, 21, 49, 54, 55, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 90, 92, 95, 100, 101, 103, 104, 118, 120, 188, 189, 190, 191, 227, 228, 234, 240, 241, 250, 252, 253, 260, 272, 275, 344, 350, 351, 377, 400, 447, 449, 450, 452, 455, 460, 461, 466, 471, 495, 520, 532, 545 teflon, 468 telecommunications, 240 TEM, 282, 285, 303 temperature-programmed desorption, 434, 445

575

TEMPO oxidation process, 405 temporarily prevent active fungal growth, 320 tenacity, 242, 403, 409, 410, 502, 507 tensile properties, 329, 330, 334, 336, 383, 384, 387, 388, 389, 409, 442, 522 tensile strength, 19, 20, 25, 30, 33, 34, 36, 37, 39, 41, 42, 128, 132, 139, 142, 147, 150, 321, 326, 357, 360, 371, 372, 373, 381, 383, 387, 388, 389, 396, 409, 468, 475, 500 tension, 92, 93, 94, 99, 416, 466, 471, 476, 504, 519, 520, 521, 522, 525, 526, 527, 528 TEOS, 375, 381 territory, 191 test prints, 65 testing, 5, 6, 7, 51, 53, 56, 74, 76, 154, 305, 313, 326, 351, 386, 397, 480, 494, 506 tetrachloroethylene, 164 tetraethoxysilane, 375 textile artificial vessels, 467 textile conservator, 271, 272, 273 textile fabrics, 51, 78, 101, 219, 240, 281, 386, 393, 397, 496, 497, 511 textile fibers, viii, 50, 248, 345, 449, 455, 477, 490, 492, 531 textile finishing process, 384, 394 textile fragments, 264, 275 textile heart valve, 466, 476 textile heart valve prosthesis, 476 textile historians, 259, 269, 273 textile implants, 471 textile industry, vii, 20, 23, 24, 47, 49, 50, 55, 63, 124, 136, 343, 344, 353, 356, 399, 401, 440, 533 textile materials, vii, 225, 239, 257, 312, 316, 322, 339, 362, 367, 377, 378, 384, 400, 440, 443, 465, 474, 477, 480, 488, 514 textile polymer surface, 280 textile preservation, 262, 273 textile printing, 53, 54, 55, 58, 66, 77, 78, 81, 83, 84, 85, 89, 90, 100, 120 textile prostheses, 466, 467, 471 textile reinforced synthetic material, 241 textile researchers, 260, 272 textile scaffolds, 241 textile sciences, 316 textile sensors, 188, 226, 250 textile substrates, vii, 53, 56, 59, 61, 76, 99, 108, 112, 114, 115, 117, 248, 249, 253, 345, 453 textile surface structure, 384 textile synthetic substrates, 56 textile vascular prosthesis, 472, 478 textile-based drug release systems, 188 textiles excavated, 260, 261, 262, 265, 266, 269, 272, 273

576

Index

texture, 80, 115, 247, 317, 351 TGA, 360, 361 theatre, 9 therapy, 118, 189, 209, 252, 310, 460 thermal (bubble) inkjet printers, 54 thermal absorbtivity, 383, 384, 386, 391, 393, 394, 396 thermal absorbtivity values, 383, 394, 396 thermal analysis, 360, 361, 380 thermal comfort, viii, 383, 384, 395, 397, 483, 488, 489, 490, 492, 494, 496 thermal comfort properties, viii, 383, 384, 395, 483 thermal conductivity, 384, 386, 391, 392, 394, 488, 489, 490, 493, 497, 509, 517 thermal decolouration, 112, 114 thermal decomposition, 361, 365, 430, 431, 432, 445 thermal degradation, 116, 155 thermal diffusion, 386 thermal energy, 190, 241 thermal feeling, 387 thermal history, 210 thermal inkjet print heads, 86 thermal insulating applications, viii thermal insulating material, 499, 500, 515 thermal insulation, 242, 246, 397, 484, 488, 489, 490, 492, 493, 499, 500, 501, 504, 505, 506, 508, 509, 510, 514, 515, 518 thermal insulation properties, 397, 484, 488, 490, 499, 504, 518 thermal management system, 93 thermal properties, 384, 391, 485 thermal resistance, 383, 384, 386, 391, 392, 396, 484, 489, 490, 492, 493, 507, 509, 511, 512, 513, 514, 515 thermal stability, 105, 198, 208 thermal storage materials, 241 thermal transmittance, 490, 492, 494 thermal treatment, 404, 444 thermal-transfer recording, 165, 181 thermo physiological properties, 383, 384 thermochromic dye, 210 thermochromic materials, 189, 211, 214, 247 thermochromic molecular switches, 211 thermochromic pigments, 210, 216 thermodynamics, 184, 444 thermofixation, 158 thermo-regulating effect, 242, 243 thermoregulatory process of human body, viii, 483 thickness, 56, 242, 243, 286, 287, 288, 295, 306, 323, 384, 386, 391, 392, 427, 455, 478, 485, 488, 489, 490, 492, 493, 506, 507, 508, 509, 511, 512, 513, 514, 515, 533, 537 thin films, 101, 155, 224, 283, 292, 314

thinning, 94 thrombo-embolism, 474 thrombosis, 467, 471, 477 time periods, 2, 279 time use, 450 TiN-Ag nanoparticulate films, 292 tinctorial strength, 159, 171 TIR, 323 tissue, 77, 90, 128, 188, 240, 466, 472, 474, 475 tissue degeneration, 474 tissue engineering, 77, 90, 188, 240 titanate, 89 titania, 313 titanium, 220, 248, 311, 357, 364, 375, 376, 381 titanium dioxide (TiO2) nanoparticles, 375 TLC analysis, 266 tobacco, 377 tobacco smoke, 377 toluene, 128 tones, 62 torus, 377 toxic metals, 219 toxicity, 263, 289, 352, 362 toys, 195, 210, 245 trade, 7, 10, 12 traditional vintage retailers, 2 training, 101 transcripts, 7 transformation(s), 66, 73, 104, 105, 116, 194, 201, 213, 289, 313, 404, 430, 434 transition metal, 193, 211, 220, 221 transition temperature, 244, 245 translation, 87, 496 transmission, 84, 108, 115, 195, 240, 251, 297, 323, 341, 449, 479, 489, 490, 496, 497, 509 transparency, 248 transplant, 471 transport, 90, 199, 249, 260, 271, 353, 395, 399, 415, 422, 423, 427, 428, 429, 437, 438, 440, 446, 484, 486, 493 transport phenomena within the fibers, 429 transportation, 85, 447 transverse thickenings, 539 traveller coating, 519, 523, 525, 527 traveller coating’s effect, 523 traveller drive angle, 520 traveller profile cross-section, 523 traveller profiles, 524, 528 traveller weight, 519, 520, 521, 522, 523, 524, 525, 526, 527, 528 treatment methods, 384 triangular cross-section, 539 tricarboxylic acid, 379

577

Index Trichoderma ressei, 23 trickle down, 4 trisazo pyridone colorants, 173 trypsin, 442 tungsten, 64, 220, 221 Turkey, xi, xiii, 27, 383, 519, 521, 528 twill fabric, 21 twist, viii, 329, 384, 506, 517, 519, 520, 521, 522, 523, 524, 527, 528

U United Kingdom (UK), xi, xiii, xiv, 1, 3, 10, 14, 15, 18, 30, 50, 81, 84, 119, 121, 153, 187, 190, 229, 255, 259, 286, 289, 290, 292, 339, 383, 385, 386, 494, 519 ultra-high local temperature, 88 ultra-high-molecular-weight polyethylene, 541 ultra-microtome, 282 ultrasonic anemometry, 467 ultrasonic application, 385, 393, 394 ultrasonic bath, 385 ultrasonic energy, 383, 384, 387, 388, 390, 392, 394, 395, 396 ultrasonic energy application, 383, 385, 387, 390, 396 ultrasound, 396 underclothes, 251 unethical practices, 2, 3 unevenness, 524 uniform, 72, 92, 99, 112, 113, 249, 254, 279, 280, 283, 289, 305, 306, 314, 510 unique features, 124, 197 uniqueness, 1, 3, 4, 9, 13 universities, vii, 247 unpleasant mouldy odour, 317 unsaturated monomer molecules, 541 upholstery, 85, 517 urea, 54, 237, 356, 369, 370 urea-formaldehyde, 369 uronic acid monomers, 384 United States (USA), 56, 58, 59, 72, 74, 83, 99, 119, 120, 121, 190, 227, 228, 229, 235, 255, 257, 275, 345, 346, 378, 386, 495, 496 7, 364, 375, 376, 381, 400, 403, 447, 460, 490 UV absorption spectra, 184 UV irradiation, 103, 105, 106, 107, 108, 109, 110, 111, 114, 115, 117, 196, 197, 206, 317, 357, 364, 376, 381 UV light, 82, 100, 101, 102, 103, 104, 105, 107, 108, 109, 110, 111, 113, 115, 116, 117, 194, 196, 197, 200, 201, 203, 205, 206, 207, 244, 357, 460 UV protection properties, 400

UV radiation, 64, 65, 375, 403 UV-curable inkjet inks, 100, 101 UV-vis reflectance, 303

V vacancies, 296 vacuum, 88, 125, 128, 280, 281, 286, 289, 531 valence, 222, 223, 375 Valencia, 351 validation, 16, 26 valuation, 80, 480, 488, 494, 497 valve, 89, 465, 466, 474, 475, 479, 480 van der Waals forces, 306 vanadium, 220 vapor, 36, 155, 245, 290, 308, 401 variables, 154, 345, 424, 484, 510, 512, 515, 517 variance analysis, 526 variations, 66, 71, 79, 108, 157, 159, 221, 222, 242, 388, 409 varieties, 47, 199 varnishes, 157, 159, 167 vascular prostheses, 466, 471 vascular surgery, 466, 471, 473, 475, 478 vascular wall, 467, 478 VDF, 452 vegetables, 218 vehicles, 64, 352 vein, 473 velocity, 87, 88, 90, 92, 93, 96, 466, 467, 479 ventilation, 336, 484, 491 versatility, 84, 216 vessels, 266, 465, 466, 467, 468, 473, 479 vibration, 134, 330 videos, 533 vintage, vii, 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14 vintage clothing, 1, 2, 3, 4, 8, 10 vintage concept, 12, 13 vintage connoisseur, 3 vintage consumer, 3, 4, 8 vintage definitions, 2 vintage era, 10 vintage fashion, vii, 1, 2, 3, 4, 7, 8, 9, 12, 13 vintage fashion clothing, vii, 1 vintage fashion community, 12 vintage fashion consumer, 1, 2, 7 vintage fashion retailers, 1, 2, 7, 13 vintage retail store, 7 vintage retailing literature, 7 vintage trend, 2, 4, 8, 10 vinyl monomers, 154 viscoelastic character, 472

578

Index

viscose, 51, 112, 113, 115, 117, 157, 159, 340, 410, 506, 517, 540 viscose rayon, 51, 157, 159 viscosity, 54, 90, 92, 93, 95, 98, 126, 127, 130, 131, 139, 141, 149, 195, 385, 414, 416, 467 viscosity control agent, 98 visible light spectrum, 531 vision, 191, 227, 455 visual impression, 67 visual system, 71 visualization, 195, 493 vitamin A, 351 vitamins, 210, 344 volatile organic compounds, 100, 317 volatile solvent, 87, 100 volatility, 98 volume electric resistance, 410, 411

W walking, 449, 450, 484, 494 wall crimping, 467 war, 84 wardrobe designers, 9 warehouse, 8 warm body, 486, 491 warm cloth weaving, 506 warm fabrics, 500 warm garments, 499, 501, 515 warning systems, 104, 240 warp directions, 386, 387 warp-knitted fabrics, 468 wash fastness, 104, 115, 165, 176, 182, 396 washing effects, vii, 20, 21, 23, 24, 33, 41, 48, 345 washing industries, 20, 24, 47 washing process, 21, 22, 23, 24, 35, 48, 55, 348, 349 washing techniques, 20 washing/finishing treatment, 20 Washington, 50, 79, 120, 314, 336, 339, 340 waste, 22, 100, 101, 153, 338, 399, 401, 418, 430, 436, 440, 441, 443, 444, 445, 450, 455 waste disposal, 399, 401, 430 waste management, 455 wastewater, 440, 443 watches, 11 water absorption, 19, 25, 31, 33, 35, 36, 38, 39, 40, 42, 43, 48, 52, 132, 139, 142, 147, 150 water holding capacity, 413 water purification, 399, 401, 430 water repellence property, 501 water retention value, 412, 413 water sorption, 414 water vapor, 36, 245, 308

water vapour permeability, 383, 384, 395, 396 waterproof elements, 457 waterproof fabrics, 384 wavelengths, 64, 107, 116, 192, 194, 200, 210, 295, 531 WAXS, 340, 442 wealth, 190 weapons, 247, 252 wear, 10, 11, 14, 20, 21, 22, 211, 239, 242, 243, 255, 367, 386, 389, 449, 484, 490, 505 wear performance, 21, 22 wearable computers, 226, 227, 240 wearable electronics, 188, 249, 250, 447, 448, 450, 455 wearable textiles, 188, 500 wearing apparel, 136 weather conditions, viii, 74, 246, 251, 252, 253, 447, 483 weaving technique, 466, 478 web, 120, 510 websites, 7, 12 wedding dress, 8 weft directions, 30, 34, 35, 37, 38, 39, 40, 41, 42, 386, 507 weft-knitted structures, 468 weight changes, 528 weight loss, 30, 31, 34, 35, 37, 39, 40, 41, 42, 43, 48, 407, 430, 502, 503 welfare, 270, 272 wellness, 545 wet-spinning process, 241 wettability, 51, 192, 415, 416, 417 wettability relationships, 416 wetting, 92, 94, 95, 99, 249, 393, 414, 415, 417 white light source, 533 White Paper, 461 wide band-gap semiconductors, 278, 314 wide-field optical microscopy, 532 windows, 244 wires, 189, 200, 240, 248, 253, 447, 452, 462 Wisconsin, 340 withdrawal, 504 wood, 101, 124, 154, 155, 166, 264, 317, 326, 338, 339, 340, 341, 430, 441 wood residue, 124, 154 wool fabric, 325, 382, 383, 384, 385, 387, 389, 390, 391, 395 wool fibre, 266, 331, 332, 334, 336, 340, 383, 501 wool proteins, 268 wool-based material, 499 woollen blanket, 505 woollenisation, 501, 502 woollenised jute, 501, 504, 509, 510

579

Index woollenised jute yarn, 501 workers, 101, 244, 289, 316, 360, 409, 449, 493 workflow, 53 working conditions, 239 workload, 251 worldwide, 262, 400, 494 wound dressing, 289, 384, 540 wound infection, 310 woven and knitted grafts, 468 woven bifurcated prosthesis, 471 woven carpets, 504 woven fabrics, 136, 386, 390, 392, 393, 394, 480, 492, 493, 496 woven polyester fabrics, 465, 475 wrinkle resistant cotton, 367 wrinkle resistant textiles, 371 wrinkle-resistant effect, 371 wrinkling, 240, 355, 367, 368

X xerophilic species, 318 xerotolerant fungi, 320 XML, 180 X-ray photoelectron spectroscopy (XPS), 280, 282, 283, 290, 291, 292, 294, 313, 353 X-ray diffraction (XRD), 285

Y yarn breaking strength, 523 yarn characteristics, 520 yarn count, 519, 521, 522, 527 yarn elongation, 528 yarn hairiness, 519, 520, 521, 522, 525, 528 yarn irregularity, 527, 528 yarn production tension, 522 yarn properties, 329, 384, 501, 519, 520, 522, 527 yarn spinning, 242, 520, 522, 527, 528 yarn spinning systems, 520 yarn spinning tension, 527, 528 yarn structure, 474, 475, 499, 500, 501 yarn twist, 519, 520, 521, 522, 523, 527, 528 yarn twist number, 522 yarn twist value, 520 yield, 109, 127, 129, 130, 131, 132, 140, 141, 148, 149, 150, 168, 172, 208, 272, 361, 400, 430, 476 young people, 3 young professionals, 3

Z zeitgeist, 8 zero-test length, 409 zinc, 420, 421, 422, 428, 429, 436, 444, 445 ZnO, 211