Affect of acid and alkaline on tensile stength of fibers.

STUDY THE EFFECT OF ACIDS AND BASES ON THE TENSILE STRENGTH OF A FIBRE. A Project Report Submitted by

SIDDHARTH GANGWANI In partial fulfillment of the

CBSE GRADE XI IN Chemistry AT

AECS MAGNOLIA MAARUTI PUBLIC SCHOOL Arakere, Off Bannerghatta Road, Bangalore-560076

2012-13 [1]

CERTIFICATE This is to certify that SIDDHARTH GANGWANI of Grade XI, AECS MAGNOLIA MAARUTI PUBLIC SCHOOL, BANGALORE with Roll Number C38 has satisfactorily completed the project in Chemistry on STUDY THE EFFECT OF ACIDS AND BASES ON THE TENSILE STRENGTH OF A FIBRE in partial fulfillment of the requirements as prescribed by CBSE in the year 2012-13.

Signature of the

Signature of the

Candidate

Teacher In-Charge

Signature of the

Signature of the

Principal

External Examiner

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ACKNOWLEDGEMENT I warmly acknowledge the continuous encouragement and timely suggestions offered by our dear Principal Dr. Seema Goel. I extend my hearty thanks for giving me the opportunity to make use of the facilities available in the campus to carry out the project successfully. I am highly indebted to Mrs. Kunhilakshmi K. & Mrs. Jyoti Sahu for the constant supervision, providing necessary information and supporting in completing the project. I would like to express my gratitude towards them for their kind cooperation and encouragement. Finally I extend my gratefulness to one and all who are directly or indirectly involved in the successful completion of this project work.

Signature of the Candidate

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INDEX

Sl. No. 1. 2. 3. 4. 5.

6.

7. 8.

Topic INTRODUCTION OBJECTIVE SCOPE & LIMITATION PRINCIPLE/THEORY EXPERIMENT NO.1  AIM  REQUIREMENT  PROCEDURE  OBSERVATION EXPERIMENT NO.2  AIM  REQUIREMENT  PROCEDURE  OBSERVATION RESULT AND CONCLUSION BIBLIOGRAPHY

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Page No. 6-11 12 13 14-17 18

19 20

21 22-29 30

Abbreviations:    

:-0.1 Molarity g :-Gram NaOH:-Sodium hydroxide HCl:-Hydrochloric acid N:-Newton

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INTRODUCTION Fibre is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. A fiber is an elongated tapering thick-walled plant cell that imparts elasticity, flexibility, and tensile strength. Tensile strength of fibres can be determined by hanging weights tied to it and comparing the weight a string can hold. Traditionally, natural fibers have been used in all cultures for making utilitarian products. Different parts of the plant are used. Fibers can be extracted from the bark (banana, jute, hemp, and ramie), stem (banana, palm, and bamboo), leaf (palm, screw pine, sisal, agave), husk (coir), seeds (cotton), and grass (sikki, madhurkati, benakati, munj). Animal fibers are obtained from a variety of animal coats, and insect fibers from cocoons. Even before the arrival of man-made fibers, manufacturers could create hundreds of different kinds of fabrics, differing mainly by fiber content, weight, style of weave, or sheen. Here are just a few of these historic fabrics, along with the natural fiber from which they were originally made (nearly all can be made now with other fibers, either natural or synthetic).They are very important in the biology of both plants and animals, for holding tissues together. Human uses for fibers are diverse. They can be spun into filaments, string, or rope, used as a component of composite materials, or matted into sheets to make products such as paper or felt. Fibers are often used in the manufacture of other materials. The strongest engineering materials are generally made as fibers, for example carbon fiber and Ultra-high-molecular-weight polyethylene. The history of man-made fibers is less than a century old; until 1910, there were no synthetic or chemical fibers. Today, by mixing different components, manufacturers can take the basic fibers listed below and make them more waterproof or more absorbent, warmer or cooler, thicker or thinner, stiffer or more supple. Some, like polyester and spandex, combine well with natural fibers, making fabrics that wrinkle less or are more form-fitting. Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but for clothing natural fibers can give some benefits, such as comfort, over their synthetic counterparts.

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Types of fibre Textile materials are made in three stages: 1. spinning: fibres are spun into yarns 2. weaving or knitting: yarns become fabrics 3. finishing: fabrics are finished to make them more useful There are two types of textile fibres:  

Natural Synthetic

Natural fibres Natural fibres come from plants, animals and minerals. They usually have short fibres, called staple fibres. The exception to this rule is silk, a natural fibre whose continuous filaments are up to one kilometre in length!

Sources of natural fibres    

Cotton from the cotton plant. Linen from the flax plant. Wool from sheep. Silk from silkworms.

Synthetic fibres Synthetic fibres are man-made, usually from chemical sources. They are continuous filament fibres, which means the fibres are long and do not always have to be spun into yarn.  

Sources of synthetic fibres Viscose comes from pine trees or petrochemicals. Acrylic, nylon and polyester come from oil and coal.

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Natural fibres from plants 1)Cotton Used for making jeans, T-shirts and towels and has the following qualities:       

cool to wear very absorbent, dries slowly soft handle good drape durable creases easily can be washed and ironed 2)Linen Used for summer clothing, tea towels and tablecloths and has the following qualities:

      

fresh and cool to wear very absorbent, dries quickly stiffer handle good drape durable creases badly can be washed and ironed

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Natural fibres from animals 1)Wool Used for jumpers, suits and blankets and has the following qualities:        

warm to wear absorbent, dries slowly breathable, repels rain soft or coarse handle can shrink, should be dry cleaned good drape not durable creases drop out 2)Silk Used for evening wear and ties and has the following qualities:

      

warm to wear absorbent soft handle good lustre and drape durable creases drop out dry clean

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Synthetic fibre. 1)Acrylic Used for jumpers, fleece jackets and blankets and has the following qualities:       

warm to wear non-absorbent, dries quickly stiffer handle, like wool good drape durable crease resistant easy care 2)Nylon (Tactel) Used for active sportswear, fleece jackets, socks and seat belts and has the following qualities:

       

warm to wear absorbent, dries slowly breathable, repels rain soft or coarse handle can shrink, should be dry cleaned good drape durable creases drop out 3)Polyester Used for raincoats, fleece jackets, children's nightwear, medical textiles and working clothes and has the following qualities:

       

low warmth non-absorbent, dries quickly soft handle good drape very durable crease resistant easy care can be recycled [10]

Figure-1 [11]

OBJECTIVE The objective of the project is to determine the strength of different types of fibres and the effect of alkali and acid on the tensile strength of the fibre. This project enables us to know which is the appropriate one for the appropriate use. One cannot judge the fibre thread by just looking but can conclude after performing the following experiments.

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SCOPE AND LIMITATION As this experiment is carried out to investigate whether plant fibre under tension are stronger or weaker than concrete, tensile strength has to be calculated. Theoretically, tensile strength of plant fibre should be more than 2.0 x N/m2 which is the tensile strength of concrete. However, there are a few limitations in this experiment. First, the fibre strands taken from the stem have different maturity. If extracted from different part or different plant but of the same species,the strengths may have big variations. Other than that, in a fibre, the diameter may be different at different part along the strand. For example, the end of fibre may have thicker diameter but thinner in the middle. Besides, when drying the fibre, the fibre may become over-dried. This will result in more brittleness in the fibre. Thus the fibre may snap easily even with the smallest mass of loads and give a wrong implication on their real tensile strength. The scope of this project is to study the dependence of the tensile strength of stone wool fibres on various factors and to understand the fracture characteristics. These factors are: a) Production-related factors: i. hyper quenching, ii. Melting atmosphere iii. Fibre diameter variations and iv. Applied axial tension during forming b) Fibre surfaces characteristics: i. surface homogeneity, ii. Surface roughness and iii. Surface reactivity These factors are of course highly correlated. This correlation will be discussed both in the short overview part of the thesis and in the four articles belonging to this thesis. The mechanical performances of both continuous and discontinuous fibres will be studied by measuring their tensile strength as functions of the production parameters. [13]

THEORY Depending upon the source, various fibres can be categorized as: 1. Animal fibre(e.g., silk and wool) 2. Vegetable fibre(e.g., cotton and linen) 3. Synthetic fibre(e.g., nylon and rayon) Natural fibres can be classified according to their origin. The vegetable, or cellulose-base, class includes such important fibres as cotton, flax, and jute; the animal, or protein-base, fibres include wool,mohair, and silk; an important fibre in the mineral class is asbestos. The vegetable fibres can be divided into smaller groups, based on their origin within the plant. Cotton, kapok, and coir are examples of fibres originating as hairs borne on the seeds or inner walls of the fruit, where each fibre consists of a single, long, narrow cell. Flax, hemp, jute, and ramie are bast fibres, occurring in the inner bast tissue of certain plant stems and made up of overlapping cells. Abaca, henequen, and sisal are fibres occurring as part of the fibro vascular system of the leaves. Chemically, all vegetable fibres consist mainly of cellulose, although they also contain varying amounts of such substances as hemicellulose, lignin, pectins, and waxes that must be removed or reduced by processing. The animal fibres consist exclusively of proteins and, with the exception of silk, constitute the furor hair that serves as the protective epidermal covering of animals. Silk filaments are extruded by the larvae of moths and are used to spin their cocoons. With the exception of mineral fibres, all natural fibres have an affinity for water in both liquid and vapour form. This strong affinity produces swelling of the fibres connected with the uptake of water, which facilitates dyeing in watery solutions. Unlike most synthetic fibres, all natural fibres are nonthermoplastic—that is, they do not soften when heat is applied. At temperatures below the point at which they will decompose, they show little sensitivity to dry heat, and there is no shrinkage or high extensibility upon heating, nor do they [14]

become brittle if cooled to below freezing. Natural fibres tend to yellow upon exposure to sunlight and moisture, and extended exposure results in loss of strength. All natural fibres are particularly susceptible to microbial decomposition, including mildew and rot. Cellulosic fibres are decomposed by aerobic bacteria (those that live only in oxygen) and fungi. Cellulose mildews and decomposes rapidly at high humidity and high temperatures, especially in the absence of light. Wool and silk are also subject to microbial decomposition by bacteria and molds. Animal fibres are also subject to damage by moths and carpet beetles; termites and silverfish attack cellulose fibres. Protection against both microbial damage and insect attacks can be obtained by chemical modification of the fibre substrate; modern developments allow treatment of natural fibres to make them essentially immune to such damage.

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Structure of a polysaccride.

Figure-2 Structure of a polyamide.

Figure-3

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Structure of a nylon6,6.

Figure-4

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EXPERIMENT NO:-1 AIM:-To compare tensile strength of cotton, silk and nylon fibres. Apparatus Requirements:- Cotton, wool, silk, polyester, hook, weight hanger, weights.

Procedure:1. Take equally cut pieces of cotton, silk and nylon fibres from given sample of same diameter. 2. Tie one end of the cotton fibres to hook and the other end to weight hanger. 3. Now start adding weights gradually until breaking point is reached. Note the minimum weight required to break the fibre. 4. Repeat this procedure taking silk anf then nylon thread. Make observations and record them.

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Observations:Sl. No. Type of fibre

Minimum weight required at breaking of thread.(N)

1. 2. 3. 4.

8.50 3.50 9.20 7.00

Cotton Silk Wool Polyester

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EXPERIMENT NO:-2 AIM:-To find the effect of acids and alkalies on the tensile strength of cotton, wool and silk fibres. Apparatus Requirements:- Cotton, wool, silk, polyester, hook, weight hanger, weights.

Chemical Requirement:- Hydrochloric acid( ) and sodium hydroxide( ).

Procedure:1. Cut out equal length of cotton, wool and silk threads from given samples. The threads should be nearly the same thickness. 2. Determine the tensile strength of each fibre as explained in experiment 1. 3. Soak a given thread into a dilute solution of sodium hydroxide for about 5 minutes. 4. Take it out of NaOH solution and wash it thoroughly with water and dry it in sun or oven at 40°C. 5. Determine again the tensile strength of woolen thread as explained in experiment 1 6. Now take another piece of wool thread and soak it in hydrochloric acid for about 5 minutes. Take it out and wash thoroughly with water. Dry it and again determine its tensile strength. 7. Repeat the above procedure for the sample of cotton and nylon fibres.

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Observations:Sl.no.

Type of fibre

1. 2. 3. 4.

Cotton Wool Silk Polyester

Tensile strength of fibre(N) Before soaking After soaking in After soaking in NaOH HCl 8.50 8.50 8.20 9.20 8.90 9.20 3.50 3.00 3.50 7.00 7.00 7.00

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RESULT AND CONCLUSION Conclusions drew from the experiment are:1. Alkalies decrease the tensile strength of woolen fibers. 2. Acids practically do not affect this fiber. 3. Tensile strength of cotton thread is decreased by acids and it remains unaffected by alkalis. 4. Nylon fiber is practically unaffected by both acids and alkalies.

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DEFORMATION OF FIBRES 1)

Polyster:-

A typical engineering stress-strain curve from tensile test of individual polyester (PET) fiber is shown in figure-5. According to previous literature [12], one PET fi ber consists of microfi brils aligned along the fi ber axis. These microfi brils, in turn, consistof crystalline and amorphous regions, and connected to other microfi brils by another kind of amorphous phase, known as mesamorphous phase. The different regions observed in the tensile stress-strain curve can be explained by the deformation of the different microstructural regions mentioned above. During the initial deformation, the amorphous regions within the microfi brils align themselves in the similar orientation as the mesamorphous phase. The stress-strain curve goes through another point of infl exion when the applied load starts to strain the bonds in both amorphous and crystalline phases. The fi nal part of the curve represents slippage between microfi brils. 7.00N

Figure-5 showing the stress vs strain graph of a polyester.

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2) Wool:The tensile deformation behavior in an individual wool fiber is shown in Figure 6. These fibers can be stretched about 30% of their original length before failure, much higher strains compared to other fibers. Although the fiber diameter is uniform along the length of the fibers, the expected defect distribution in the natural fiber is higher. When the variation in dynamic storage modulus with strain is plotted (Figure 6), there is a slight drop corresponding to the yield in engineering stress-strain curve. This correlates to the molecular movement in the microfi brils to align themselves along the fiber axis. As this alignment process dissipates energy, it increases the loss factor After the molecules in the microfi brils are aligned, the deformation is mostly due to stretching of various hierarchical layers along the fi ber axis. More systematic microstructural characterization is needed to completely understand the deformation process. 9.20N

Figure-6 showing the stress vs strain graph of a wool

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3)Cotton:The engineering stress-strain curve for a typical test on a single strand of cotton is shown in Figure 7. Although the cellulose crystals in the mercerized cotton fibers exhibit high modulus and strength, they are also the least ductile compared to the other fibers studied herein. The electron micrograph in Figure8 clearly shows the anisotropic crosssection of the cotton fiber. Moreover, the mechanical properties of cotton also vary with the length of the fiber and the chemical treatment it undergoes before application.

8.50N

Figure-7 showing the stress vs strain graph of a nylon.

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BIBLIOGRAPHY:     

Comprehensive practical chemistry-XI Wikipedia Encyclopedia - Britannica Online Encyclopedia www.textileschool.com www.meritnation.com. http://cp.literature.agilent.com/litweb/pdf/

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