Polymers Lab Report No 1

 

 

Shore Hardness Testing Polymers Lab Lab Report No. 1

Submitted to: Sir Zeeshan Submitted by: Group A-3 Date of Experiment: 19-02-20 Experiment: 19-02-20 Due Date: 26-02-20 26-02-20  

Group Member Syeda Unaiza Hassan Raja Muhammad bilal Zaheer Muhammad Ali Raza Ebtassam Qamar

Registration No. 180301027 180301006 180301036 18030103 180301034 4

 

P a g e  | 2

Contents Abstract ........................................................................................................................................... 3  1 

Introduction ............................................... ..................................................................................................... .............................................................................. ........................ 4  

2 

Literature Review.................................................................................................................... 5 

3 

Importance of durometer......................................................................................................... 5   

Applications ..................................................................................................................... 5 

 

Limitations of durometer ............................................... .................................................................................................. ................................................... 5 

4 

Objectives ............................................................................................................................... 6 

5 

Apparatus and Equipment Used .............................................................................................. .................................................... .......................................... 6    

Durometer......................................................................................................................... 6 

 

Bottle cap (Polyethylene Terephthalate) .................................................. .......................................................................... ........................ 7 

 

Mobile phone cover (Silicone) ......................................................................................... ............................................... .......................................... 7  



 

6 

Keyboards (ABS) ...................................................................................................... .................................................. ........................................................... ....... 8  Procedure ................................................................................................................................ 8 

7 

Observations & Results........................................................................................................... 9 

8 

Conclusion ............................................................................................................................ 10 

9 

Precautions ...................................................................................................... ................................................ ............................................................................ ...................... 10 

10  References ................................................. ....................................................................................................... ............................................................................ ...................... 11 

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 3

 ___________________  __________ ___________________ ____________________ _______________ _____ Abstract The Shore hardness test is a quick and convenient way to measure the hardness of polymers. The test states that the specimen should be at least 6 mm thick; however, published literature suggests that researchers often use much thinner samples. The test is done using a device called Durometer. The purpose of this study is to determine the hardness of different polymers and compare them with each other .

 ___________________  __________ ___________________ ____________________ _______________ _____

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 4

1  Introduction  

HARDNESS: Hardness is a material's resistance to localized deformation.The deformation found in met als, ceramics, and most polymers is a plastic deformation of the surface.Plastic surface.Plastic hardness defines the resistance of a hard body to the penetration of a plastic. The tougher material wears or scratches the softer material.

Plastic hardness defines the resistance of a hard body to the penetration of a plastic. The tougher material wears or scratches the softer material. It is a key engineering parameter for the construction of devices, consumer products or industrial parts. This can become apparent when considering cosmetic effects such as scratching or loss of surface gloss due to to the rubbing of two materials. materials. Alternatively, wear from moving parts can be considered[1]. There is a wide array of techniques used to determine a substance's hardness. Below are a  few of the more common methods adopted: 1.  2.  3.  4. 

 

Mohs Hardness Test Brinell Hardness Test Rockwell Hardness Test Durometer Hardness Test

SHORE HARDNESS: Shore hardness is a measure of a material's resistance to the penetration of a needle-like indenter charged by a spring. Polymer hardness (rubbers, plastics) is usually measured with Shore scales.

Shore A scale is used to measure soft Elastomers and other flexible polymers. Strong elastomer hardness and most other polymer materials (Thermoplastics, Thermosets) are measured by the scale of Shore D. Shore hardness is tested using a device called Durometer. Durometer uses an indenter charged from a calibrated spring. The calculated hardness is defined by the indenter's penetration depth beneath the load. For two Shore Scales (A and D), two different indenter shapes and two different spring loads are applied. [2]

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 5

2  Literature Review  

QUALITATIVE HARDNESS TEST TEST::  A qualitative or arbitrary hardness indexing scheme was devised, which ranges from from 1 on the soft end and 100 for diamond in the Mohs scale.   QUANTITATIVE HARDNESS TEST : TEST :  It is a technique which uses a small indenter with given force into a surface of a material

to be tested. The depth or size of resulting indentation is measured and turn to its related hardness number. In the polymeric materials hardness test, the most common method is using a Shore (durometer) hardness test. Shore provides the various shore hardness scales, i.e., A, B, C, D, DO, etc. These scales are properly referred to as shore hardness types. For example, elastomeric materials and soft polymer are usually measured with Shore A, while Shore D is capable of measuring harder polymer than Shore A. Currently in ASTM D2240 — 04, 04, Types A, B, C, D, DO, E, O, OO, OOO and OOO — S, S, M, and R are recognized.

3  Importance of durometer Durometer plays a crucial role in the manufacturing process of many silicone, rubber, and  plastic materials material s and can help determine the item’s resistance to penetration. Being able to establish the hardness of the materials used in products is important regarding quality control and even design approval.

Applications The Shore A durometer is suited for softer surfaces. Its applications can include: rubber,  polyester, leather, wax, etc. The maximum hardness it can measure accurately is 100; anything higher is to be measured by the Shore D. The Shore D durometer is suited for harder surfaces. Its applications can include: wood, hard rubber, plastics, flooring, bowling balls, etc.

Limitations of durometer   Many rubber components are not flat, and do not have the required minimum thickness for Shore A testing accuracy   Hardness measurement accuracy is +/- 5 points due to mechanical limitations of instrumentation.   Rubber batches contain inherent minor variations from batch to batch based on slight differences in raw materials and processing techniques causing variations in durometer readings.   If specimen thickness is not sufficient the gauge reading is impacted by the base material (In the case of ASTM requirements, this is a flat steel surface)

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 6

4  Objectives  

To measure the hardness of polymer based materials. mat erials.   To estimate the application of materials based on hardness.   To choose the suitable material required, by comparing the hardness of different materials.

5  Apparatus and Equipment Used   Durometer In this experiment we use Durometer to measure hardness of different materials .It is a digital measuring machine which lessens the chances of reading errors. It is used by  pressing its indenter on the surface of the material whose hardness is to be measured. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and softer materials. The scale was defined by Albert Ferdinand Shore, who developed a suitable device to measure hardness in the 1920s. It was neither the first hardness tester nor the first to be called a durometer,  but today that tha t n name ame usually refers to Shore hardness. Other devices dev ices use other measures, which return corresponding results, such as for Rockwell hardness.[3]

Figure 1: Durometer [7]  

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 7  

Bottle cap (Polyethylene Terephthalate) In bottle caps basically Polyethylene terephthalate (PET or PETE) is used, a strong, stiff synthetic fiber and resin, and a member of the polyester family of polymers. PET is spun into fibers for permanent-press fabrics, blow-molded into disposable beverage bottles, and extruded into photographic film and magnetic recording tape. [4]

Figure 2: Plastic bottles (cap) [8]

 

Mobile phone cover (Silicone) Silicones, also known as polysiloxanes, are polymers that include any synthetic compound made up of repeating units of siloxane, which is a chain of alternating silicon atoms and oxygen atoms, combined with carbon, hydrogen, and sometimes other elements. They are typically heat-resistant and either liquid or rubber-like, and are used in sealants, adhesives, lubricants, medicine, cooking utensils, and thermal and electrical insulation.[5] 

Figure 3: Mobile phone cover [9]

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 8  

Keyboards (ABS) The Acryl Nitride Buta Diene Styrene was used in the keyboard to be tested.  tested.   ABS or Acrylonitrile butadiene styrene is a common thermoplastic polymer typically used for injection molding applications. This engineering plastic is popular due to its low  production cost and the ease with which the material is machined by plastic manufacturers.[6]

Figure 4: keyboard [10] 

6  Procedure The procedure followed to do the experiment is given below:  

Enter the lab and wear the lab coat.   First we have observed different materials of different polymers have thickness not less 0.6mm.   The specimen is than placed on a hard flat surface of that material. 

The indenter for the instrument is then pressed into the specimen making sure that it is    parallel to the surface.

 

The hardness is read within one or two seconds (as specified by the instructor).

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 9

7  Observations & Results We have observed different materials of different polymers and performed shore hardening experiment using shore hardness tester. Following data of different materials is recorded.

Material

P olym lyme er

H ardne ardness( ss(D D)

A ve verr age H ar dne ness ss

2.7 1.

Mobile Cover

Polyurethane

2.8

2.6

2.4 4.0 2.

Keyboard

ABS

4.1

4.2

4.5 4.4 3.

Bottle Cap

PET or PETE

4.6

4.4

4.3

Table 2: Readings taken for shore hardness

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 10

8  Conclusion After performing the shore hardness experiment for different polymer based materials mentioned in the above Table 1.We concluded that the hardness of Bottle cap is greater than the rest of them. Bottle Cap > Keyboard > Mobile Cover (Transparent) 5 4 3 2 1

4.2

4.4

Keyboard

Bottel Cap

2.6

0 Mobile Cover

Column1

9  Precautions  

The sample material must be a minimum of 6 mm.    The surface beneath the sample materials should be hard.   While taking reading the tester should be perpendicular perpendicu lar to the sample material and reading should be read with in one or two seconds

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 11

10  References [1] Hardness. (n.d.). Retrieved February 22, 2020, from https://www.oringsusa.com/html/durometer_of_o-rings.html [2] Hardness of Plastics - When to Use RockWell& Shore Scales. Sc ales. (n.d.). Retrieved February 22, 2020, from https://omnexus.specialchem.com/polymer properties/properties/hardness-introduction  properties/properties/hardness-i ntroduction [3] Hardness Testing with a Durometer | Anderson Materials Evaluation, Inc. (n.d.). Retrieved February 22, 2020, from http://www.andersonmaterials.com/hardness-testingwith-a-durometer.html [4] Polymer Solutions News Team. (2015, October 5). Metal Properties: P roperties: Hardness, Toughness, & Strength {Infographic}. Retrieved from https://www.polymersolutions.com/blog/defining-metal-properties/ [5] Schoemehl, B. (2018, January 14). The Importance of Durometer. Retrieved from https://rothkopf.com/the-importance-of-durometer/ [6] Shore (Durometer) hardness test [SubsTech]. (2013, July 27). Retrieved from https://www.substech.com/dokuwiki/doku.php?id=shore_durometer_hardness_test [7] https://top-messtechnik.com/Hardness-Tester-HT1 [8] http://jbiom.com/challenges-in-the-use-of-polyethylene-terephthalate-bottles-for packaging-drinking-water [9] https://utranex.com/product/transparent-silicon-back-cover-for-samsung-a10 [10] http://www.sealshield.com/Products/Standard-True-Type/Silver-Seal-GlowWaterproof-Keyboard_5.html

Institute of Space Technology

Dept. of Materials Science & Engineering

 

P a g e  | 12

Institute of Space Technology

Dept. of Materials Science & Engineering