Polymer Properties: EXPERIMENT 2 Hardness Test

8/19/2019 Polymer Properties: EXPERIMENT 2 Hardness Test

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Polymer Properties (EBT 326) Exp. 2: Hardness Test

EXPERIMENT 2

Hardness Test

1.0 OBJECTIVE

1.1 To measure hardness of Ultra High Molecule Weight Polyetalline (UHMWPE)

samples using Shore (durometer) hardness test.

2.0 INTRODUCTION

Hardness is the property of a material that enales it to resist plastic deformation! usually y

penetration. Ho"e#er! the term hardness may also refer to resistance of ending! scratching!arasion or cutting. The hardness testing of plastics is most commonly measured y the Shore

($urometer) test or %oc&"ell hardness test. 'oth methods measure the resistance of the plastic

to"ard indentation. 'oth scales pro#ide an empirical hardness #alue that doesnt correlate to

other properties or fundamental characteristics.

n this e*periment! "e use the Shore (durometer) test to measure the hardness of the samples.

$urometer! li&e many other hardness tests! measures the depth of an indentation in the material

created y a gi#en force on a standardi+ed presser foot. This depth is dependent on the hardness

of the material! its #iscoelastic properties! the shape of the presser foot! and the duration of the

test. ,STM $--/ durometers allo"s for a measurement of the initial hardness! or the

indentation hardness after a gi#en period of time. The asic test re0uires applying the force in a

consistent manner! "ithout shoc&! and measuring the hardness (depth of the indentation). f a

timed hardness is desired! force is applied for the re0uired time and then read. The material under

test should e a minimum of . mm. 213

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4igure 15 $iagram for durometer application

4igure -5 Type of durometer shore

The results otained from this test are a useful measure of relati#e resistance to indentation of

#arious grades of polymers. Ho"e#er! the Shore (durometer) hardness test does not ser#e "ell as

a predictor of other properties such as strength or resistance to scratches! arasion! or "ear! and

should not e used alone for product design specifications.

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3.0 COMPONENTS AND EUIPMENT

6.1 Shore (durometer) hardness test

4igure 65 $urometer

6.- Ultra High Molecule Weight Polyethylene (UHMWPE) samples

4igure 5 The Sample of UHMWPE "ith /7 8n9 (pure)

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4igure :5 The Sample of UHMWPE "ith 1-7 8n9

4igure 5 The Sample of UHMWPE "ith -:7 8n9

4igure ;5 The Sample of UHMWPE "ith 17


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4igure =5 The Sample of UHMWPE "ith -7 5 The Sample of UHMWPE "ith 67


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.6 The hardness reading "as read from the scale.

. ,STM $ --/ "as referred for more details.

".0 RESU#TS AND DISCUSSION

Tale 15 The hardness reading of different ratio of +inc o*ide and chitosan of UHWMPE samples and

their a#erage hardness.

Sa$%&es Rat'( )nO *

C+H11NO!, -

Read'n 1, N Read'n 2, N Read'n 3, N A/erae

Hardness HA, N

Sa$%&e 1 /5/ /.: :>.: -./ /.;

Sa$%&e 2 1-5/ 1./ 1.: 1.: 1.666666

Sa$%&e 3 -5/ :6./ :./ :./ :.666666

Sa$%&e ! 1-51 6./ :.: ./ .1;

Sa$%&e " 1-5- ./ -./ 6.: 6.1;

Sa$%&e + 1-51 :;./ :.: :./ ::.=66666

Tale -5 The con#ersion of a#erage hardness! H$ of different ratio of +inc o*ide and chitosan of

UHWMPE samples to the force.

Sa$%&es Rat'( )nO *

C+H11NO!, -

A/erae Hardness HA, N (re, 4 !!"HD , N

Sa$%&e 1 /5/ /.; ->>=.1:

Sa$%&e 2 1-5/ 1.666666 -;->1.=:

Sa$%&e 3 -5/ :.666666 -1;.=:Sa$%&e ! 1-51 .1; -=:::.:

Sa$%&e " 1-5- 6.1; -=11/.:

Sa$%&e + 1-51 ::.=66666 -=.6:

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:.1 Plot graph hardness #s. load for all the samples tested. $iscuss.

1 2 3 4 5 64

5!

52

54

56

5

6!

62

64

66

The Graph of Average Hardness vs Ratio of Sample !"

Ratio of sample !"

Average Hardness #"

4igure 1-5 The graph of a#erage hardness (?) #s ratio of sample (7)

'ased on the graph at 4igure 1-! it sho"s that the trend for the graph of a#erage

hardness #s. ratio of sample UHWMPE is fluctuated. The highest #alue of a#erage

hardness elongs to sample "hich is contained 17 of chitosan and 1-7 of +inc o*ide

"ith .1;? and the lo"est #alue of a#erage hardness elongs to sample 6 that ha#e

-:7 of +inc o*ide "ith :.66?.

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1 2 3 4 5 6

21!!!

22!!!

23!!!

24!!!

25!!!

26!!!

2"!!!

2!!!

2#!!!

The Graph of %or&e #" vs Ratio of Sample !"

Ratio of sample !"

%or&e #"

4igure 165 The graph of force (?) #s ratio of sample (7)

'ased on the graph at 4igure 16! it also sho"s that the trend for the graph of force #s.

ratio of sample UHWMPE is fluctuated. The #alue of force for e#ery samples is otained

y using a formula for shore $! 4@:H$. This graph also sho"s the t"o same samples

that ha#e highest and lo"est #alue of parameters state! force. The highest #alue of force

elongs to sample "hich is contained 17 of chitosan and 1-7 of +inc o*ide "ith

-=:::.:? and the lo"est #alue of a#erage hardness elongs to sample 6 that ha#e -:7

of +inc o*ide "ith -1;.=:?.

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21!!!22!!!23!!!24!!!25!!!26!!!

2"!!!2!!!2#!!!

The Graph of %or&e #" vs Average Hardness #"

Average Hardness #"

%or&e #"

4igure 15 The graph of force (?) #s a#erage hardness (?)

4igure 1 sho"s the graph of force (?) #s a#erage hardness (?). Ha#ing the same trend

"ith pre#iously t"o graphs! it sho"s fluctuated trend "ith the same samples that ha#e

highest and lo"est #alues of parameters stated. n this graph! the highest #alue force is-=:::.:? "ith respect to its a#erage hardness! .1;?. Mean"hile the #alue of the

lo"est is -1;.=:? "ith a#erage hardness of :.666?. ,s #alues of modulus of

elasticity and hardness arise! the #alues of force also arise ecause force is directly

proportional "ith a#erage hardness.

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:.- Ho" to ma*imi+e the performance of durometer.

There are fe" aspects that "e can consider for ma*imi+ing the performance of

durometer5

:.-.1 ,lignment


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:.-. Test Times

When comparing results it is important to use the same test times.

Some materials e*hiit a large degree of flo" after the full test load is

applied. , one or t"o second difference in ta&ing the reading can causesignificant #ariations.

:.-.: %ound Part TestingSmall round parts! li&e oArings! are particularly difficult to test.


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:.6 Ho" to relate the durometer results "ith stiffness of tested material

$urometer is an indirect measure of the stiffness! or more correctly the modulus

of an elastomeric material. Modulus is a property of elastomers! analogous to the

same property of metals! "hich is the ratio of stress to strain in the elastomer at some

loading condition. Unli&e metals "hich is typically ha#e a linear stressAstrain cur#e

elo" their yield point! the stressAstrain relationship of elastomers is nonAlinear o#er a

range of loading condition and can e significantly influenced y amient

temperature. ,s a result! the modulus of an elastomer is highly dependent on the

conditions under "hich it is measured. This fact ma&es the understanding of

elastomers and their properties important in the understanding of the performance of

elastomeric #iration and shoc& isolators.n a relati#e sense! lo" durometer or hardness correlates to a lo" modulus or

stiffness. Similarly! as durometer increases so does modulus and #iceA#ersa. Ho"e#er!

the correlation et"een durometer and modulus is not directly proportional! douling

in durometer #alue does not e0uate to a douling in modulus.

solator stiffness is a direct function of elastomer modulus and part geometry. So!

as "ith the relationship et"een durometer and elastomer modulus! part stiffness

cannot e estimated for a &no"n durometer. Ho"e#er! part stiffness "ill increase in

durometer! part stiffness "ill decrease "ith a decrease of durometer too.

+.0 CONC#USION4rom the e*periment! "e can conclude that the Shore ($urometer) Hardness "hich is

used durometer "ith type of shore $ is used to determine the relati#e hardness of soft

materials! usually plastic or ruer. The hardness test measures the penetration of a specified

indentor into the samples under specified conditions of force and time. 'esides! "e also can

conclude that sample of Ultra High Molecule Weight Polyethylene "ith the presence of filler

+inc o*ide content increase "hen it has 1-7 +inc o*ide ut decrease "hen it ha#e -:7 +inc

o*ide. Mean"hile "hen chitosan content is added into the samples! it indicated rising in

graph ut fell "hen the content is increased.

5.0 REERENCES

213 http5CC""".ptc1.comC"hatDisDdurometer.htm

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http://www.ptc1.com/what_is_durometer.htmhttp://www.ptc1.com/what_is_durometer.htm


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2-3 """.intes+t.huCP$4C/1CShoreDgeneralDcatalogue.pdf

263 http5CC""".usplastic.comC&no"ledgeaseCarticle.asp*content&ey@/=

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Polymer Properties: EXPERIMENT 2 Hardness Test

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