rubber properties materials

7/24/2019 Rubber properties materials

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Rubber

Yun-Che Wang


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Terminologies

Amorphous polymer

Crystalline polymer

Elastomer: synthetic rubber Rubber: natural and synthetic

Thermal plastic

Thermal setting


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Microstructures ofpolymer


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History of rubber

The Atecs !"#$"% A&' Me(ico) used rubber toma*e balls for their ceremonial ball games+

,n "."' American in/entor 0amuel 1ealobtained a patent for the production of rubber-coated 2atertight te(tiles+ 3ater rain coats 2erede/eloped by Charles Macintosh+

Thomas Hancoc* !"4%-"4%5) produced rubberboots+

English minister and scientist 6oseph 1riestley!"##-"478) reported rubber to be best used forerasing pencil mar*s+


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9ulcaniation of rubber

0cottish chemist Charles Macintosh !"%%-"48#) used ,ndia rubber !from the sap ofHe/ea brasiliensis trees) to produce rain

coats' too sti in cold and stic*y in 2arm2eather+

American in/entor Charles ;oodyear !"477-"4%7' not related to ;oodyear tire and rubber

company)' used the process of /ulcaniationof rubber 2ith sulfur and heat' to ma*e therubber dry and


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What happened in/ulcaniation

0ulfur is mi(ed into rubber and the sulfur atomsmay brea* up the double bonds in t2o ad=acentchains of either polyisoprene or polybutadiene+

A lateral bond may be formed bet2een t2ocarbon atoms in dierent chains 2ith a sulfuratom in the middle+

>ree chains become shorter' and rubberbecomes less elastic as in /ulcanite+

The sulfur bonds pre/ent the chains from slidingpast each other so that /ulcanied rubber ismore resistant to heat than natural rubber+


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He/ea

He/ea and ?ic*(ia !an African similar plant)pro/ide 2hite sap 2hich loo*s li*e mil* andtherefore is called late(+

@ne tree yields 87 mlday' 2hich gi/es % literper season for "57 days of a tapping season+

#B is rubber !as microscopic rubberparticles) and 5B is 2ater+

Dy drying' smo*ing or addition of acids' late(coagulates' similar to the beha/ior of mil*+


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Rubber usage

,n "447' the production of rubber reached"7'777 tons+

,n "4.5' 7'777 tons+

,n ".7"' #7'777 tons+ ,n "."7' "77'777 tons+ 1rice 77 per "77 *g+

,n ".#8' "'777'777 tons+ 1rice "5 per "77 *g+

Fo2adays' no 2ild rubber+ Rubber from

plantations amounts to about % million tonsand from synthesis about . million tons+


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Gse of rubber throughindustry

,rish doctor 6ohn Doyd &unlop !"487-".")in/ented pneumatic rubber tire in ".44+

>rench brothers Andre and Edouard

Michelin !"45#-".#" and "45.-".87) usedrubber for automobile tires+

Har/ey 0amuel >irestone !"4%4-".#4)became >ords supplier of pneumatics+Henry >ord !"4%#-".8) in/enting cars2ith rubber tires+


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,soprene

English physicist Michael >araday!"."-"4%) in "4% or EnglishChemist ;re/ille Williams in "4%7

identiIed C5H4 !isoprene or methyl-butadiene)J the basic unit of rubber !a*ind of rubber' to be distinguished

from polybutadiene rubber)+


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1olymeriation

Williams obser/ed the isoprene


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Acceleration ofpolymeriation

,n ".7.' ;erman chemist >ritHomann !"4%4-".7) acceleratedthe polymeriation process by

heating+

England Harris synthesied rubberfrom isoprene by heating AF& adding

acetic acid+


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1olybutadiene orpolyisoprene

Dutadiene is similar to isoprene' but2ith a single H atom instead of themethyl group CH#+

Dy using butadiene' the processbecomes cheaper and ra2 materialsare abundant+

Most synthesied rubber ispolybutadiene+


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Dutadiene is synthesied from

limestone and coal

mestone !CaC@#) is heated to gi/e Kuic*lime !Ca@) and C@+uic*lime is heated 2ith coal to pro/ide carbide CaC and C@+

Carbide and 2ater react to pro/ide acetylene CH+

Acetylene combines 2ith 2ater' catalyed bymercury salts' to produce acetaldehydeCH#CH@+


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o molecules of acetaldehyde combine to aldol 2ith sodalye Fa@H as catalyer+

nder pressure aldol combines 2ith hydrogen to produce butylene glycole+

tadiene is obtained by splitting t2o 2ater molecules o from the butylene glyc


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Dutadiene is polymeried to pro/ide

polybutadiene chains 2ith metallicsodium Fa as a catalyer

This rubber on the mar*et is called Duna'and it is a little better than naturalrubber in terms of resilience' 2ear and

elasticity' but more energy consumption+


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@ther *inds of rubber

Dutyl rubber consists ofpolyisobutylene and polychloroprene'2hich is *no2n under the

commercial names of &uprene orFeoprene+

Duna is the Irst synthetic rubber

manufactured on a large scale+ Dunas original ingredients: lime and

coal+

Feoprenes original ingredients:


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rubber properties materials

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