Classes of Polymeric Materials Elastomers

8/19/2019 Classes of Polymeric Materials Elastomers

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Classes of Polymeric Materials

Elastomers

Professor Joe Greene

CSU, CHIC


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Elastomers

! Elastomers are r"##er li$e polymers that are thermoset

or thermoplastic % #"tyl r"##er& nat"ral r"##er

% thermoset& poly"rethane, silicone

% thermoplastic& thermoplastic "rethanes '(PU), thermoplasticelastomers '(PE), thermoplastic olefins '(P), thermoplastic

r"##ers '(P*)

! Elastomers e+hi#it more elastic properties ers"s plastics

-hich plastically .eform an. hae a lo-er elastic limit/! *"##ers hae the .istinction of #eing stretche. 200

an. ret"rne. to original shape/ Elastic limit is 200


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*"##ers! *"##ers hae the .istinction of #eing stretche. 200 an.

ret"rne. to original shape/ Elastic limit is 200

! at"ral r"##er 'isoprene) is pro."ce. from g"m resin ofcertain trees an. plants that gro- in so"theast 3sia, Ceylon,

4i#eria, an. the Congo/ % (he sap is an em"lsion containing 50 -ater 6 70 r"##er particles

! 8"lcani9ation occ"rs -ith the a..ition of s"lf"r '5)/ % S"lf"r pro."ces cross:lin$s to ma$e the r"##er stiffer an. har.er/

% (he cross:lin$ages re."ce the slippage #et-een chains an. res"lts in higher

elasticity/

% Some of the .o"#le coalent #on.s #et-een molec"les are #ro$en, allo-ing thes"lf"r atoms to form cross:lin$s/

% Soft r"##er has 5 s"lf"r an. is 10 cross:lin$e./

% Har. r"##er 'e#onite) has 5; s"lf"r an. is highly cross:lin$e./


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*"##er 3..ities an. Mo.ifiers

!


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8"lcani9a#le Elastomeric Compo"n.s! *"##ers are compo"n.e. into practical elastomers

% (he r"##er 'elastomer) is the ma=or component an. other components are gien as -eight perh"n.re. -eight r"##er 'phr)

! S"lf"r is a..e. in less than 10 phr ! 3ccelerators an. actiators -ith the s"lf"r

% he+amethylene tetramine 'HM(3)

% 9inc o+i.e as actiators

! Protectie agents are "se. to s"ppress the effects of o+ygen an. o9one % phenyl #eta#aphthylamine an. al$yl paraphenylene .iamine '3PP>)

! *einforcing filler % car#on #lac$

% silica -hen light colors are re?"ire.

% calci"m car#onate, clay, $aoilin

! Processing ai.s -hich re."ce stiffness an. cost % Plastici9ers, l"#ricants, mineral oils, paraffin -a+es,


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8"lcani9a#le *"##er

! (ypical tire trea.

% at"ral r"##er smo$e. sheet '100),

% s"lf"r '2/;) s"lfenami.e '0/;), M@(S '0/1), strearic aci. '), 9inc

o+i.e '), P@3 '2), H3< car#on #lac$ '5;), an. mineral oil ')

!(ypical shoe sole compo"n. % S@* 'styrene:#"ta.iene:r"##er) '100) an. clay 'A0)

! (ypical electrical ca#le coer

% polychloroprene '100), $aolin '120),


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Synthetic *"##er ! *eactie system elastomers

% 4o- molec"lar -eight monomers are reacte. in a polymeri9ation step -ith ery little cross:lin$ing/

% *eaction is triggere. #y heat, catalyst, an. mi+ing! Urethanes processe. -ith *eaction In=ection Mol.ing '*IM)

! Silicones processe. -ith in=ection mol.ing or e+tr"sion

! (hermoplastic Elastomers % Processing inoles melting of polymers, not thermoset reaction

% Processe. #y in=ection mol.ing, e+tr"sion, #lo- mol.ing, film #lo-ing, or rotational mol.ing/! In=ection mol.e. soles for foot-ear

% 3.antages of thermoplastic elastomers! 4ess e+pensie ."e to fast cycle times

! More comple+ .esigns are possi#le

! i.er range of properties ."e to copolymeri9ation

% >isa.antage of thermoplastic elastomers! Higher creep


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D

(hermoplastic Elastomers!


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(hermoplastic Elastomers! Poly"rethanes

% Hae a har. #loc$ segment an. soft #loc$ segment! Soft #loc$ correspon.s to polyol inole. in polymeri9ation in ether #ase.

! Har. #loc$s inole the isocyanates an. chain e+ten.ers

! Polyesters are etheresters or copolyester thermoplastic

elastomer % Soft #loc$s contain ether gro"ps are amorpo"s an. fle+i#le

% Har. #loc$s can consist of poly#"tylene terephthalate 'P@()

! Polyertherami.e or polyether#loc$ami.e elastomer

% Har. #loc$s consits of a crystalli9ing polyami.e

Soft Har.Har.

Har.

Soft Soft


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Commercial Elastomers! >iene CFC .o"#le #on.s an. *elate. Elastomers

% Polyisoprene: 'C;HD)20,000

! @asic str"ct"re of nat"ral r"##er

! Can #e pro."ce. as a synthetic polymer

! Capa#le of ery slo- crystalli9ation

! (m F 2DC, (g F :B0C for cis polyisoprene

! (m F 7DC, (g F :B0C for trans polyisoprene

% (rans is ma=or component of g"tta percha, the first plastic

% at"ral r"##er -as first crosslin$e. into highly elastic net-or$ #y Charles Goo.year '"lcani9ation -iths"lf"r in 1DB)

!S"lf"r crosslin$e. -ith the "nsat"rations CFC

% at"ral r"##er in "nfille. form is -i.ely "se. for pro."cts -ith! ery large elastic .eformations or ery high resilience,

! resistance to col. flo- 'lo- compression set) an.

! resistance to a#rasion, -ear, an. fatig"e/

% at"ral r"##er .oes not hae goo. intrinsic resistance to s"nlight, o+ygen, o9one, heat aging, oils, orf"els/

C

H

C

C

H

HHH

H C C

CH

CH

HH

HC C

CH

Cis

(rans


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Commercial Elastomers! Poly#"ta.iene

% @asis for synthetic r"##er as a ma=or component in copolymers Styrene:@"ta.iene*"##er 'S@*, @*) or in

% @len.s -ith other r"##ers '*, S@*)

% Can improe lo-:temperat"re properties, resilence, an. a#rasion or -ear resistance! (g F :;0C

! Polychloroprene % Polychloroprene or neoprene -as the ery first synthetic r"##er

% >"e to polar nat"re of molec"le from Cl atom it has ery goo. resistance to oils an.is flame resistant 'Cl gas coats s"rface)

% Use. for f"el lines, hoses, gas$ets, ca#le coers, protectie #oots, #ri.ge pa.s,roofing materials, fa#ric coatings, an. a.hesies

% (g F :7;C/

H HCH

CH HHC C

H HCH C Cl HH C C


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Commercial Elastomers! @"tyl r"##er: a..ition polymer of iso#"tylene/

% Copolymer -ith a fe- isoprene "nits, (g F:7;C

% Contains only a fe- percent .o"#le #on.s from isoprene % Small e+tent of sat"ration are "se. for "lcani9ation

% Goo. reg"larity of the polymer chain ma$es it possi#le for the elastomer to crystalli9e onstretching

% Soft polymer is "s"ally compo"n.e. -ith car#on #lac$ to increase mo."l"s

! itrile r"##er

% Copolymer of #"ta.iene an. acrylonitrile % Solent resistant r"##er ."e to nitrile C&&&

% Irreg"lar chain str"ct"re -ill not crystalli9e on stretching, li$e S@*

% "lcani9ation is achiee. -ith s"lf"r li$e S@* an. nat"ral r"##er

! (hio$ol: ethylene .ichlori.e polymeri9e. -ith so.i"m polys"lfi.e/ S"lf"r ma$esthio$ol r"##er self "lcani9ing/

H HC

CHHCC


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(hermoplastic Elastomers! (hermoplastic Elastomers res"lt from copolymeri9ation of

t-o or more monomers/ % ne monomer is "se. to proi.e the har., crystalline feat"res, -hereas

the other monomer pro."ces the soft, amorpho"s feat"res/

% Com#ine. these form a thermoplastic material that e+hi#its propertiessimilar to the har., "lcani9e. elastomers/

! (hermoplastic Urethanes '(PU) % (he first (hermoplastic Elastomer '(PE) "se. for seals gas$ets,

etc/

! ther (PEs % Copolyester for hy.ra"lic hoses, co"plings, an. ca#le ins"lation/

% Styrene copolymers are less e+pensie than (PU -ith lo-er strength

% Styrene:#"ta.iene 'S@*) for me.ical pro."cts, t"#ing, pac$aging, etc/

% lefins '(P) for t"#ing, seals, gas$ets, electrical, an. a"tomotie/


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(hermoplastic Elastomers! Styrene:#"ta.iene r"##er 'S@*)

% >eelope. ."ring II! Germany "n.er the name of @U3:S/

! orth 3merica as G*:S,Goernment r"##er:styrene/

% *an.om copolymer of #"ta.iene '7B:D;) an. styrene '1;:)

% (g of typical B;2; #len. is %70C

% ot capa#le of crystalli9ing "n.er strain an. th"s re?"ires reinforcingfiller, car#on #lac$, to get goo. properties/

% ne of the least e+pensie r"##ers an. generally processes easily/

% Inferior to nat"ral r"##er in mechanical properties

% S"perior to nat"ral r"##er in -ear, heat aging, o9one resistance, an.resistance to oils/

% 3pplications incl".e tires, foot-ear, -ire, ca#le ins"lation, in."strialr"##er pro."cts, a.hesies, paints 'late+ or em"lsion)

! More than half of the -orl.s synthetic r"##er is S@*

! orl. "sage of S@* e?"als nat"ral r"##er

C CH

H H

n

H HC

H

C

H HH

C C


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3crylonitrile:#"ta.iene r"##er '@*)

! 3lso calle. itrile r"##er % >eelope. as an oil resistant r"##er ."e to

! the polar C&&& polar #on./ *esistant to oils, f"els, an. solents/

% Copolymer of acrylonitrile '20:;0) an. #"ta.iene'D0:;0)

% Mo.erate cost an. a general p"rpose r"##er/

% E+cellent properties for heat aging an. a#rasion resistance % Poor properties for o9one an. -eathering resistance/

% Has high .ielectric losses an. limite. lo- temperat"re fle+i#ility

% 3pplications incl".e f"el an. oil t"#ingK hose, gas$ets, an. sealsK coneyer #elts, print rolls, an. pa.s/

% Car#o+ylate. nitrile r"##ers 'CL:@*) has car#o+yl si.e gro"ps'CH)-hich improe

! 3#rasion an. -ear resistanceK o9one resistanceK an. lo- temperat"re fle+i#ility

% @* an. P8C for misci#le, #"t .istinct polymer #len. or polyalloy

! 0 a..ition of P8C improes o9one an. fire resistance

H H

CH

CH HHC C C C

H C&&&

H H

nm


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Ethylene:propylene r"##er 'EP*)! EP* an. EP>M

% M), constr"ction parts, -eather strips, -ire an. ca#le ins"lation, hose an. #elt pro."cts, coate.fa#rics/

C CH H

H H

n

C CH CH

H H

m

C CH CH2

H H

mCH

CH

CH


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1B

Ethylene *elate. Elastomers! Chloros"lfonate. Polyethylene 'CSPE)

% Mo.erate ran.om chlorination of PE '25:5)

% Infre?"ent chloros"lfonic gro"ps 'S2Cl) % S"lf"r content is 1:1/;/

% CSPE is note. for e+cellent -eathering resistance

! Goo. resistance to o9ones, heat, chemicals, solents/

! Goo. electrical properties, lo- gas permea#ility, goo. a.hesion to s"#strates

% 3pplications incl".e hose pro."cts, roll coers, tan$ linings, -ire an. ca#lecoers, foot-ear, an. #"il.ing pro."cts

! Chlorinate. Polyethylene 'CPE) % Mo.erate ran.om chlorination

! S"ppresses crystallinity 'r"##er)

! Can #e crosslin$e. -ith pero+i.es

! Cl range is 7:52 ers"s ;7/D for P8C

% Properties incl".e goo. heat, oil, an. o9one resistance

% Use. as plastici9er for P8C

C CH H

H H

n

CCl

H

m

CS

H

$ Cl


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1D

Ethylene *elate. Elastomers! Ethylene:inylacetate Copolymer 'E83)

% *an.om copolymer of E an. 83! 3morpho"s an. th"s elastomeric

! 83range is 50:70

! Can #e crosslin$e. thro"gh organic pero+i.es

% Properties incl".e

! Goo. heat, o9one, an. -eather resistance

! Ethylene:acrylate copolymer 'E3*) % Copolymer of Ethylene an. methacrylate

! Contains car#o+ylic si.e gro"ps 'CH)

% Properties incl".e! E+cellent resistance to o9one an.

! E+cellent energy a#sor#ers

% @etter than #"tyl r"##ers

C CH H

H H

n

C C

H

H H

FCCH

m

C C

H H

H H

n

C C

H C

H H

CH

m


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1A


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Silicone Polymers! Silicone polymers or polysilo+anes 'P>MS)

% Polymeric chains feat"ring !

(g F :12;C! 8ery sta#le alternating com#ination of

! Silicone an. o+ygen, an. a ariety of organic si.e gro"ps attache. to Si

% (-o methyl, CH, are ery common si.e gro"p generates poly.imethylsilo+ane 'P>MS)

! Unmo.ifie. P>MS has ery fle+i#le chains correspon.ing to lo- (g

! Mo.ifie. P>MS has s"#stit"tion of #"l$y si.e gro"ps ';:10)

% Phenylmethlsilo+ane or .iphenylsilo+ane s"ppress crystalli9ation

! S"#stit"te. si.e gro"ps, e/g/, inyl gro"ps '/;) feat"ring .o"#le #on.s '"nsat"rations ) ena#lescrosslin$ing to form inylmethylsilo+ane '8MS)

! >egree of polymeri9ation, >P, of polysilo+ane F 200:1,000 for lo- consistency chains to ,000:10,000for high consistency resins/

! Mechanism of crosslin$ing can #e from a inyl "nsat"ration or reactie en. gro"ps 'al$o+y, aceto+y)

Si

CH

CH

m


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Silicone Polymers! Silicone polymers or polysilo+anes 'P>MS)

% Properties! Me.iocre tear properties

! High temperat"re resistance from :A0C to 2;0C/

! S"rface properties are characteri9e. #y ery lo- s"rface energy 's"rfacetension) giing goo. slip, l"#ricity, an. release properties 'antistic$) nan.-ater repellency/

! E+cellent a.hesion is o#taine. for c"ring compo"n.s for ca"l$/

Si

CH

CH

m


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Silicones! Unmo.ifie. P>MS has ery fle+i#le chains -ith a lo- (g/

% *eg"lar str"ct"re allo-s for crystalli9ation #elo- (m

% 3..ition of small amo"nt of #"l$y si.e gro"ps are "se. tos"ppress crystalli9ation

! (rifl"oropropyl si.e gro"ps enhance the resistance to solent s-elling an.are calle. fl"orosilicones

! 4inear form '"ncrosslin$e.) polysilo+ane correspon.s to >P of 200:1000

for lo- consistency to ,000:10,000 for high consistency resins! Mechanism for crosslin$ing '"lcani9ation) can #e #ase. "pon inyl

"nsat"rations or reactie en. gro"ps 'al$o+y)

% Silicone polymers are mostly elastomers -ith me.iocre tear properties, #"t -ith a..ition of silica can hae o"tstan.ing properties "naffecte. #y

a -i.e temp range from %A0C to 2;0C! S"rface properties hae lo- s"rface energy, giing goo. slip, l"#ricity,release properties, -ater repellency, e+cellent a.hesion for ca"l$s

! Goo. chemical inertness #"t sensitie to s-elling #y hy.rocar#ons

! Goo. resistance to oils an. solents, U8 ra.iation, temperat"re

! Electrical properties are e+cellent an. sta#le for ins"lation an. .ielectric


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Silicones! Properties

% 4o- in.e+ of reflection gies silicone contains "sef"l com#ination of hightransmission an. lo- reflectance

% Can #e #iologically inert an. -ith lo- to+icity are -ell tolerate. #y #o.ytiss"e

% Polymers are normally crosslin$e. in the "lcani9ation stage/


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Silicones! Properties

% 4S* elastomers inole lo- molec"lar -eight polysilo+anes #"t a .ifferent

c"ring system ! *elatiely high temperat"re '1;0C) for a faster c"re '10:0s)

! Mi+e. system is largely "nreactie at room temp 'long pot life)

! S"ita#le for high spee. li?"i. in=ection mol.ing of small parts/

% H(8 elastomers contain "nsat"rations that are s"ita#le for conentional

r"##er processing/! Heat c"ra#le elastomers 'HCE) are cross lin$e. thro"gh high temperat"re "lcani9ation

'H(8) -ith the "se of pero+i.es/

% *igi. silicones are cross lin$e. into tight net-or$s/

! on:crosslin$e. systems are sta#le only in sol"tions that are limite. to paints, arnishes,

coatings, an. matrices for laminates! Cross:lin$ing ta$es place -hen the solent eaporates/

! Post c"ring is recommen.e. to complete reaction, e/g/, silicone:epo+y systems for

electrical encaps"lation/

li i


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Silicones 3pplications! Most applications inole elastomeric form/

!


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2B

Miscellaneo"s ther Elastomers! 3crylic *"##er '3*)

% Polyethylacrylate 'PE3) copolymeri9e. -ith a small amo"nt ';) of 2:

chloro:ethyl:inyl:ether CE8E, -hich is a c"re site/ % (he (g of PE3 is a#o"t :2BC an. acrylic r"##er is not s"ita#le for lo-

temperat"re applications/

% Poly#"tylacrylate 'P@*) has a (g of :5;C/

% 3pplications

! *esistant to high temperat"res, l"#ricating oils, incl".ing s"lf"r:#earing

oils/

! Incl".e seals, gas$ets, an. hoses/

! Epichlorohy.rin *"##er 'ECH*)

% Polymeri9ation of epichlorohy.rin -ith a repeat "nit of PECH/

% E+cellent resistant to oils, f"els an. flame resistance/ 'Cl presence)

% Copolymer -ith fle+i#le ethyleneo+i.e 'E) proi.es (g F :50C

% 3pplications incl".e seals, gas$ets, .iaphragms, -ire coers

Mi ll h El


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2D

Miscellaneo"s ther Elastomers

! Polys"lfi.e *"##ers 'S*)

% ne of the first synthetic r"##ers/ (g F:2BC, PES (hio$ol 3 % Consists of a.=acent ethylene an. s"lfi.e "nits giing a stiff chain/

%


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2A

Miscellaneo"s ther Elastomers! Polynor#orene 'P@)

% or#orene polymeri9es into highly molec"lar -eight P@/

% (g F ;C #"t can #e plastici9e. -ith oils an. "lcani9e. into anelastomer -ith lo-er (g F :7;C/

% E+cellent .amping properties that can #e a.="ste./

! Polyorgano:phospha9enes 'PP)

%


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Commercial Elastomers

! Characteristics

Name Chemical Name Vucanization agentNatural rubber cis polyisoprene sulfur

Polyisoprene cis polyisoprene sulfur

Polybutadiene Polybutadiene sulfur

SBR Polybutadiene-styrene sulfur

Nitrile Polybutadiene-acrylonitrile sulfur

Butyl Poly isobutylene-isoprene sulfur EPR (EPDM) Poly ethylene propylene- diene Peroxies or sulfur

Neoprene Polychloroprene Mg

Silicone Polydi!ethylsiloxane peroxides

"hio#ol Polysl#ylenesulfide $n

%rethanes Polyester or polyether urethanes Diisocycanates

C i l El


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Commercial Elastomers

! Costs

Name Consumption 1983 (metric tons) $/lb Type

Natural rubber &'&&' *+, .eneral Purpose

Polyisoprene *+,' .eneral Purpose

Polybutadiene //001 *+,' .eneral Purpose

SBR 22'++0 *+,&& .eneral Purpose

Nitrile 0'/3 *1,1+ Sol4ent Resistant

Butyl *+,'& .eneral Purpose

EPR (EPDM) 113+ *1,+1 .eneral Purpose

Neoprene 20+3& *1,3 Sol4ent Resistant

Silicone *,+ 5eat Resistant

"hio#ol Psulfides *1,2/ Sol4ent Resistant%rethanes */,'+ Sol4ent Resistant

Polymeri9ation Mechanisms


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Polymeri9ation Mechanisms

! Step:-ise 'Con.ensation) Polymeri9ation

% Monomers com#ine to form #loc$s 2 "nits long % 2 "nit #loc$s form 5, -hich intern form D an. son on

"ntil the process is terminate./

% *es"lts in #y:pro."cts 'C2, H2, 3cetic aci., HCl

etc/)

! Chain Gro-th '3..ition) Polymeri9ation % Polymeri9ation #egins at one location on the monomer

#y an initiator

% Instantaneo"sly, the polymer chain forms -ith no #y:

pro."cts


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Con.ensation Polymeri9ation E+ample! Polyami.es

% Con.ensation Polymeri9ation! ylon 77 #eca"se #oth the aci. an. amine contain

7 car#on atoms

H2'CH2)7 H2 Q CH'CH2)5CHHe+amethylene .iamene 3.ipic aci.

nH2'CH2)7 H2 RC'CH2)5CH 'heat) ylon salt

H'CH2)5 H R C'CH2)5Cn Q nH2 ylon 7,7 polymer chain


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Con.ensation Polymeri9ation E+ample! Poly"rethane

% *eaction of isocyanate an. polyether:alcohol 'polyol)

! Polyester % Polymeri9ation of aci. an. an. alcohol

! Polycar#onate

% Polycar#onates are linear, amorpho"s polyesters #eca"se they contain esters of car#onic aci. an. an aromatic #isphenol 'C 7H;H)

Phenol Q 3cetone @isphenol:3 Q -ater

2

H

QH2QC CH2CH

C

CH2

CH2HH

th C . ti P l


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ther Con.ensation Polymers! (hermoplastic Polyesters

% Sat"rate. polyesters '>acron)/! 4inear polymers -ith high M an. no crosslin$ing/

! Polyethylene (erephthalate 'PE()/ Controlle. crystallinity/! Poly#"tylene (erephthalate 'P@()/

% 3romatic polyesters 'Mylar)

C

* C

*

C

C

* *

Step Gro-th Polymeri9ation


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Step:Gro-th Polymeri9ation

Con.ensation Polymeri9atio

! Main feat"re is that all molec"lar species in thesystem can react -ith each other to form higher

molec"lar -eight species/

% Step:gro-th polymeri9ation reactions fall into t-o

classes

! 3:*1:3 Q @:*2:@ F 3:*1:*2:@ Q 3@

! 3:*1:3 Q @:*2:@ F 3:*1:3@:*2:@

% -here 3 an. @ are repeat polymer gro"ps -hich react -ith each otherKT E+ample, for poly"rethanes 3 F Isocyanate an. @ F Polyol an. the

#y:pro."ct is -ater/

% an. *1 an. *2 are long chain polymers


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Chain Gro-th '3..ition)

Polymeri9ation

! Chain Gro-th '3..ition) Polymeri9ation #y


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Chain Gro-th '3..ition)

Polymeri9ation

! Special case of >iene polymeri9ation % 8ery important in elastomers: mostly a..ition

% Poly.ienes are the #ac$#one of the synthetic

r"##er are pro."ce. #y free ra.ical polymeri9ation

% Early attempts of polymeri9ation -as slo- an.

pro."ce. lo- molec"lar -eight polymers 'oils) % Em"lsion polymeri9ation '1A0s) -as intro."ce.

to spee. "p polymeri9ation an. higher Molec"lar-eights


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Polymeri9ation Metho.s! 5 Metho.s to pro."ce polymers

% Some polymers hae #een pro."ce. #y all fo"r metho.s! PE, PP an. P8C are can #e pro."ce. #y seeral of these

metho.s

! (he choice of metho. .epen.s "pon the final polymer form, the

intrinsic polymer arrangement 'isotactic, atactic, etc), an. the

yiel. an. thro"ghp"t of the polymer .esire./

% @"l$ Polymeri9ation

% Sol"tion Polymeri9ation % S"spension Polymeri9ation

% Em"lsion Polymeri9ation


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PE H>PE PP

% P8C PS

C C

H H

H H

n

C C

H H

H H

n

C C

H CH

H H

n

C C

H Cl

H H

n

C C

H

H H

n

ther 3..ition Polymers


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ther 3..ition Polymers! 8inyl: 4arge gro"p of a..ition

polymers -ith the form"la& % *a.icals 'L,) may #e attache. to this repeating

inyl gro"p as si.e gro"ps to form seeral relate. polymers/

! Polyinyls % Polyinyl chlori.e

% Polyinyl .ichlori.e

'polyinyli.ene chlori.e)

% Polyinyl 3cetate 'P83c)

C C

H L

H

or C C

H L

H H

CC

H Cl

H H

C C

H Cl

H Cl

C C

H CCH

H H

Man"fact"ring of Em"lsion S@*


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!


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! Polymeri9ation

% Col. S@*& at ; to 10C is calle. the col. process,! @etter a#rasion resistant, trea.-ear, an. .ynamic properties/

% Hot S@*& at a#o"t ;0C is calle. the hot process/

! Conersion is allo-e. to procee. to B0

! Higher #ranching occ"rs an. incipient gelation/

% (ypical S@* recipes, (a#le from Mortons *"##er

technology



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! Compo"n.ing an. Processing

% Similar to nat"ral r"##er % Materials for large scale "se, e/g/, tires, #ase. on

! *"##er, fillers 'car#on #lac$), e+ten.ing oils, 9inc o+i.e, s"lf"r,

accelerators, antio+i.ants, antio9onants, an. -a+es/

% Materials are mi+e. in a mill or t-in rollers or calen.ere.

% Processing into smooth compo"n.s that can #e ?"ic$ly

presse., sheete., calen.ere., or e+tr".e.

! *ecipes % 4arge parts, e/g/, tires an. hoses, are gien in (a#les B/7,

B/B, B/D, an. B/A

P l i ti f El t


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Polymeri9ation of Elastomers! @"ta.iene:3crylonitrile 'itrile) *"##er

% Pro."ce. #y em"lsion polymeri9ation % itrile r"##ers hae nitrile contents from 10 to 50/

! Chloroprene r"##er

% Pro."ce. #y em"lsion polymeri9ation % Pro."ce. as a homopolymer that has a high trans 1,5

chain str"ct"re an. is s"scepti#le to strain:in."ce.

crystalli9ation, m"ch li$e nat"ral r"##er/

! 4ea.s to high tensile strength

% >oes not lea. itself to copolymeri9ation

P l i ti f El t


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Polymeri9ation of Elastomers! @"tyl *"##er:

% nly important commercial r"##er prepare. #y cationic polymeri9ation

! Processes -ith 3lCl at %AD to %A0°C

% Copolymer of iso#"tene an. isoprene -ith isoprene "se.

in 1/; ?"antities

! (he isoprene is intro."ce. to proi.e s"fficient "nsat"rations

for s"lf"r "lcani9ation/

% M is in the range of 00,000 to ;00,000

Processing of Elastomers


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Processing of Elastomers! *"##er Pro."cts

% ;0 of all r"##er pro."ce. goes into a"tomo#ile tiresK % ;0 goes into mechanical parts s"ch as

! mo"ntings, gas$ets, #elts, an. hoses, as -ell as

! cons"mer pro."cts s"ch as shoes, clothing, f"rnit"re, an. toys

! Elastomers an. *"##ers

% (hermoset r"##ers

! Compo"n.ing the ingre.ients in recipe into the ra- r"##er -ith a

mill, calen.er, or @an#"ry 'internal) mi+er

! Compression mol.ing of tires

% (hermoplastic elastomers

! Compression mol.ing, e+tr"sion, in=ection mol.ing, casting/



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! *"##er Processors

% Mills an. @an#"ry mi+ers

Compression Mol.ing Process


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Compression Mol.ing Process! Materials

!Elastomers&!(hermoplastic

!(hermoplastic lefin '(P), (hermoplastic Elastomer '(PE),(hermoplastic *"##er '(P*)

!(hermoset r"##ers!Styrene @"ta.iene *"##er, isoprene

(hermoplastic&

Heat Plastic

prior to mol.ing

(hermosets&

Heat Mol.

."ring mol.ing

Poly"rethane Processing


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Poly"rethane Processing

! Poly"rethane can #e processe. #y

% Slo- process& Casting or foaming, or

%


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;2

In=ection Mol.ing Glass Elastomers

! Plastic pellets -ith copolymer elastomers/

% Similar processing re?"irements as -ith in=ectionmol.ing of commo.ity an. engineering plastics

! In=ection press"res, tonnage, pac$ press"re, shrin$age

(ransfer Mol.ing of *"##ers


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;

(ransfer Mol.ing of *"##ers! (ransfer mol.ing is a process #y -hich "nc"re. r"##er

compo"n. is transferre. from a hol.ing essel 'transfer pot) to

the mol. caities "sing a hy.ra"lically operate. piston/(ransfer mol.ing is especially con."cie to m"lticaity .esigns

an. can pro."ce nearly flashless parts/

Calen.ering of *"##ers


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Calen.ering of *"##ers! Calen.ering is the process for pro."cing long r"ns of "niform

thic$ness sheets of r"##er either "ns"pporte. or on a fa#ric

#ac$ing/ 3 stan.ar. or 5 roll calen.er -ith linear spee. rangeof 2 to 10 feetmin"te is typical for silicone r"##er/


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;;

C"ring of *"##ers! E+tr".e. profile may #e c"re. #y hot air "lcani9ation 'H38),

steam "lcani9ation 'C8) or li?"i.:me.i"m c"re/ H38 consists

of a heate. t"nnel thro"gh -hich the profile is fe. contin"o"slyon a moing coneyor/ 3ir temperat"re reaches 700< to1200C@P:;0 ora..ition c"re, #oth of -hich proi.e rapi. c"re -ith no

porosity/! Steam c"re commonly refers to the steam c"ring systems "se. #y the -ire an. ca#le in."stry an. consists of cham#ers 5O %7O in .iameter an. 100 % 1;0 feet in length/ Steam press"rearies from ;0 psig to 22; psig .epen.ing on -all thic$ness of

the ins"lation/!


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Polymer 4ength

! Polymer 4ength

% Polymer notation represents the repeating gro"p

! E+ample, :3:n -here 3 is the repeating monomer an. n represents the

n"m#er of repeating "nits/

! Molec"lar eight

% ay to meas"re the aerage chain length of the polymer

% >efine. as s"m of the atomic -eights of each of the atoms in the

molec"le/

! E+ample,

% ater 'H2) is 2 H '1g) an. one '17g) F 2V'1) Q 1V'17)F 1Dgmole

% Methane CH5 is 1 C '12g) an. 5 H '1g)F 1V'12) Q 5 V'1) F 17gmole

% Polyethylene :'C2H5):1000 F 2 C '12g) Q 5H '1g) F 2Dgmole V 1000 F 2D,000

gmole

Molec"lar eight


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;B

Molec"lar eight

! 3erage Molec"lar eight

% Polymers are ma.e "p of many molec"lar -eights or a

.istri#"tion of chain lengths/

! (he polymer is comprise. of a #ag of -orms of the same

repeating "nit, ethylene 'C2H5) -ith .ifferent lengthsK somelonger than others/

! E+ample,

% Polyethylene :'C2H5):1000 has some chains '-orms) -ith 1001 repeating

ethylene "nits, some -ith 1010 ethylene "nits, some -ith AAA repeating

"nits, an. some -ith AA0 repeating "nits/

% (he aerage n"m#er of repeating "nits or chain length is 1000 repeating

ethylene "nits for a molec"lar -eight of 2DV1000 or 2D,000 gmole /

Molec"lar eight


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;D

Molec"lar eight! 3erage Molec"lar eight

% >istri#"tion of al"es is "sef"l statistical -ay tocharacteri9e polymers/

!


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;A

Molec"lar eight! Molec"lar eight >istri#"tion

% Co"nt the n"m#er of molec"les of each molec"lar -eight

% (he molec"lar -eights are co"nte. in al"es or gro"ps that hae similar lengths,

e/g/, #et-een 100,000 an. 110,000

!


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Molec"lar eight! 3erage Molec"lar eight

% >etermine. #y s"mming the -eights of all of the chainsan. then .ii.ing #y the total n"m#er of chains/

% 3erage molec"lar -eight is an important metho. of

characteri9ing polymers/

% -ays to represent 3erage molec"lar -eight

! "m#er aerage molec"lar -eight

! eight aerage molec"lar -eight

! :aerage molec"lar -eight

Gel Permeation Chromatography


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Gel Permeation Chromatography! GPC Use. to meas"re Molec"lar eights

% form of si9e:e+cl"sion chromatography % smallest molec"les pass thro"gh #ea. pores, res"lting in

a relatiely long flo- path

% largest molec"les flo- aro"n. #ea.s, res"lting in a

relatiely short flo- path

% chromatogram o#taine. sho-s intensity s/ el"tion

ol"me

% correct pore si9es an. solent critical



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"m#er 3erage Molec"lar eight, Mn


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g g , n!

! -here Mi is the molec"lar -eight of that species 'on the +:a+is)! -here i is the n"m#er of molec"les of a partic"lar molec"lar species I 'on

the y:a+is)/

% "m#er 3erage Molec"lar eight gies the same -eight to all polymerlengths, long an. short/

! E+ample, hat is the molec"lar -eight of a polymer sample in -hich the polymersmolec"les are .ii.e. into ; categories/ % Gro"p


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Molec"lar eight! "m#er 3erage Molec"lar eight/ P/

% >P relates the amo"nt ofmonomer that has #een conerte. to polymer/

0 M

M n

n=

eight 3erage Molec"lar eight, M-


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g g g , -

! eight 3erage Molec"lar eight, M-

%


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3erage Molec"lar eight

% Emphasi9es large molec"les een more than M-

% Usef"l for some calc"lations inoling mechanical

properties/

% Metho. "ses a centrif"ge to separate the polymer

///

///2

2

22

2

11

22

11

2

+++

+++==

∑∑

M N M N M N

M N M N M N

M N

M N M

ii

ii

z

Molec"lar eight >istri#"tion


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Molec"lar eight >istri#"tion

! Molec"lar eight >istri#"tion represents the

fre?"ency of the polymer lengths! (he fre?"ency can #e arro- or @roa.,


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7D

y p y

Implications of M an. M>

! Higher M increases! (ensile Strength, impact to"ghness, creep resistance, an.

melting temperat"re/

% >"e to entanglement, -hich is -rapping of polymer

chains aro"n. each other/

% Higher M implies higher entanglement -hich yiel.s

higher mechanical properties/

% Entanglement res"lts in similar forces as secon.ary orhy.rogen #on.ing, -hich re?"ire lo-er energy to #rea$

than crosslin$s/

Physical and Mechanical Property Implications


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y p y p

of MW and MWD! Higher M increases tensile strength

! *esistance to an applie. loa. p"lling in opposite .irections! (ension forces ca"se the polymers to align an. re."ce the n"m#er of

entanglements/ If the polymer has many entanglements, the force -o"l. #e

greater/

! @roa.er M >istri#"tion .ecreases tensile strength

! @roa. M .istri#"tion represents polymer -ith many shorter molec"les

-hich are not as entangle. an. sli.e easily/

! Higher M increases impact strength

! Impact to"ghness or impact strength are increase. -ith longer polymer

chains #eca"se the energy is transmitte. .o-n chain/

! @roa.er M >istri#"tion .ecreases impact strength

! Shorter chains .o not transmit as m"ch energy ."ring impact

Thermal Property Implications of MW & MWD


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B0

p y p

! Higher M increases Melting Point

! Melting point is a meas"re of the amo"nt of energy necessary

to hae molec"les sli.e freely past one another/

! If the polymer has many entanglements, the energy re?"ire.

-o"l. #e greater/

! 4o- molec"lar -eights re."ce melting point an. increase ease

of processing/

! @roa.er M >istri#"tion .ecreases Melting Point

! @roa. M .istri#"tion represents polymer -ith many shorter

molec"les -hich are not as entangle. an. melt sooner/

! @roa. M .istri#"tion yiel.s an easier processe. polymer

M

e c a n i c

a l

P r o

p e r t i e

s

M

e l t i n

g

P o i n t V >ecomposition

Example of High Molecular Weight


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p g g

! Ultra High Molec"lar eight Polyethylene 'UHMPE)! Mo.ifying the M> of Polyethylene yiel.s a polymer -ith

% E+tremely long polymer chains -ith narro- .istri#"tion % E+cellent strength

% E+cellent to"ghness an. high melting point/

! Material -or$s -ell in in=ection mol.ing 'tho"gh high melt ()

! >oes not -or$ -ell in e+tr"sion or #lo- mol.ing, -hichre?"ire high melt strength/

! Melt temperat"re range is narro- an. to"gh to process/

! Properties improe. if lo-er M polyethylene % 3cts as a lo-:melting l"#ricant

% Proi.es #imo.al .istri#"tions,

Documents

Classes of Polymeric Materials Elastomers