Engrtyring
Properties of New Synthetic Rubbers and Plastics
Process development
G. BRYANT BACHMAN, L. J. FILAR!, R . W. FINHOLP, L. V. HEISEY', H. M. HELLMAN,, L. L. LEWIS;, A N D D. D. MICUCCID PURDUE UNIVERSITY A N D PURDUE RESEARCH FOUNDATION, LAFAYETTE, IND.
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I his work was tindertalien i n order to stud? the effect o f a varietj- of dinerent tjpes of olefins 011 the physical properties of synthetic rubbers prepared 1,> c-opol>.rneriziiig these olefins r+.ithbutadiene. A large anioiriit of data tias been acciiinulatetl sho\\iiig the variations in phj-sical properties o f a niiiiihcr o f ne\\ synthetic rubbers. Hotli hot and cold tests h a \ e heeri
( ~ prepir:itioii, f iwiii' :iv:iil:i\iility 01' 1ic:cess:il.y iiitermrtli:itea, : i l i i l other siniihr rt*:t*iiiis jxevcnted thv p r q ~ a r : i t i o lof ~ suliie of t t i r n i e sthe* pl i i i I:rigcq :iiiiouiit>, T:ilile I11 g i I w the p ~ ' ( i p ( ~ t iof roliolyinc*t.~.Thew ni:itwi:ils \ v ( w p i w l i l l m a l l test t u w. S i 1 :ittruipt \v:i* i i i : i t l i L t o tlvterniirie the optimum conditions l i l t , Iiol?.iiii~iiz:ttii,li.tlics n i o l c ~ c * u l : r i\\-c,ight ~ of tlw product, or the elf w t ( I ( purilyiiig th(s ~ m l y i i i ~hy r wprc'ripitation. It is felt, h n ~ ~ v rt hr a, t thc. procedure employed \ ~ o u l dnot fail to detect a vinl-l i~~~iiipoiiiicl oiititantlingly \\-ell suitpil for conimercial utilientioir .
made. ilarge numhey of ne\\ copol>-niersof the thcrnioplastic t ?pe ha\-e heen prepared and physical properties studied. -\ new method of determining the refracti\e index of transparent solids has heeii developed. \ ne\+ propert j- of plas tics-the ' * R ticking poiii t "-i s defined and H method proposed for measuring it con\-enientlj. The principal significance of the work lies in show-inp how variations in properties of sj-tithetic rulhers m a > -be obtained b y altering the chemical composition of materials used in their preparation. This will provide a fundamental hasis for further de\ elopment of desirahle elastomers. The ne\+ rnettiod of determining the refracti\e index and the sticking point w-ill be \-aluahle i n further fnndamentul studies of' elastomer%.
PHOPEHTIES OF SYNTHETIC RUBBERS
I~ic~Iiliiic~~ is t i,rpoi,ted ~ r e ~ i ~ ~(5) to give copolyniers \\-it11 1)ut:idiene \\-hick :ii'e superior t o GR-S in several w:tys, /)ut esperialli. i i i inihliility :ind h o t proli(arties. It is interesting to note thr. v t fcct of other su1)stituents i n nuclexr positions of styrene. S o n l i ~ of these ronipounds give i,uli\iers clearly superior to OR-S aitil :tre conipnrablp to tiic~hloi~ostyrenerubhers i n t h r propertic,. tested. Thc 3-trifiuoro1iie~hyl-4-Huorost~re1ietind the C ( I I F I TP ix,nd i ii g 01- 111 t' t hy1s t v r n e appear to give copolymers whirti :Ire 110 IIcxttcJr t l l i i l l (+It- , Honeever, in these vases the pcil>.merizatiuir~\\-ei'c.run t(J very high conversions. I t is likely tii:it Iletter piilyiiirr.* \\-oulti i w u l t a t lo\ver conversions. The pol^.iiierizatioir recipes :inti thc compounding reripe cniployed : i n ' skown in T:ihIc i V , ('eitniii iiioiioniers requirt. special coniment. 3-Trifiuor~1iiiethylstyreiicj give uridesir:Lljly soft rubbers unless the iiniouii t of niotlifiei~ \\-;is rmluced somewhat. This low modifier ( ~ i i c i + ti,:itioii \\;is u s t ~ l:idv:iritageously with cert:iin other ~ i i o n o n i o ~ ' . ~ :tlso. T h e a-inetliylrtyrcrres usuully gave c~ipolyinersc o i n p i . : i l ) l c ~ to t h o w 1'1,oni the corresponding st.yi,eiies. f i o w t ~ e r ,:11l (1rthot.ulistitutc'ti a-methylstyrelic:: (except 0-Huoro) failed t o copolymer iztl . ( )tiit.r r oiiinien t s o i l t hi3 orth&roup hindrniic,i, :ind o n otlicr p(~1yiiierizatinncharacteristics i d 1 be found i i i the. p r ( 4 o r i s : i i , t i i . l w t1cac~riI)ing1irep;rration of the monomers ( 1 ) . PROPERTIES OF PLASTICS X h q t of the viriyl compounds copolymerized readily \\ i t l i styrelic., inetliyl meth:icrylnte, aiid maleic* anhydride. ~ I N I I J . (lid iiot p~lyiiiei~ize alone ur copolymerize with vinyl acet:rtc. untlci, tlica usual conditious of peroxidc-cut:il>-setl hulk poly-
iiicrizut,iori. a-llethylvinyl compounds ilicl not polynierizc. :ilonc, the oiily exception heing 2-isoprope11~lt1erizoi'ul.an,whiclr gave a dehiite polymer in the absence of other vinyl compounds. This compound probably behaves like n diene, n i t h the douhlt~ Ilonti of the furan ring entering into the po1ymeria:ition. I t is difficult to draw generalizations (.overing the relationshij) lietween chemical structures of monomers arid the physical I)ropertie.j of the plastics derived froin theni. The refractiw intlicrs for the iiio,-iiirr'
Only U.2 p a r t O E I ,)sed; a t converrtoii I N J I ~ ~ L I VU~ I I ~ rti1,lmry l > n t somewhat b r i t t l e .It 100yc conver3ioii iiolyioer \\-a* r u b b e r ) , tenrunulily bait I?un i n foriiiula 11; polynicr \vas r u b b e r y b u t r a t h e r brittle .It 100': conversion ~ ~ n l y ~ iviavst Iiritt1e. ~ l i n d little t P n < i r n c y t u fur:ir i i l i ~ ~ . Rubbery cupolyiiiei. Rubbery copulynier .\t 93L: conversion 1,olyrilvr i(as rra,unutil\ Fiitt atill R a t h e r b r i t t l e , rubbery polymer .It S 5 c c conversion polymer was r u b b e r y , renstinatrly soit .kt l O O q conversion polymer wa, reasonably s o f t , formed yuixl t i l i i l Only conversion o b t a i n e d ; f o r m a t i o n of a copolymer iinprobahle.kt 100yc conversion polyiiirr wa5 n r r r y , formed fair film. S o copolyriier .It 9 7 5 conversion polytiier \T-ns rubbery. r a t h e r nervy R u b b e r y c o p o l y m r r a t loor; conversion (18 days) S o copolvmrr conversion o b t a i n e d ; formation ui copolyiiier d o i > t > t i i t con\-ersion polynier w a s rubbery biit rather hrittlr conversiun iiolymcr was x i b b e r y bnt drjcon\-ernioti polymer \va$ d r y a n d brittle roitrerqion. polyiiier \vas rubbery, reasonably .oft P,iil?bery roi,nlyii~er a t 1 0 0 7 runversion (6 days): formPd rxcrlli,tir
DETER?vIISA'~IOh Ob REFRACTIVE rwmx
Determining the refractive index of oil-soluble solids accurately is laborious. I t w n h felt t h a t D methoci of e v a l u a ing this property t,o the seconil ilccimnl place \\-oultl be suffii.ieiit to i~evcnl:my uriusual 1 ' ~ ' irnctive propertics outsidc the, r m g c of most cominercial plastics. Therefore n rapid nn(l 3imple method was developeil for determining the refract,ivi, index on small c y 1 i n d r i r ; i I pieces of polymer such as art. formed by polymerization i i t 2-inch test tuhc? (it' 10-nini. dinmetcr.
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fillll, cor.rer,iuri olitaitiivl, fortnation of c t i p o l y i u e r d o i i b t f i i l S o polyiiier A t 100pc cunverSton Imlynier was rubber);, iorined uood filnr. T o n g l i , brittle copolymer a t 9 4 5 conversion .J.littlca n e r v y b u t good riihhpr
Only X?'
S e r v j co1,olynirr S e r v y copolymer 'Tough. nervy copolymer S o copolymer S o cuuolymer S o polymer S o polymer '1 8 = s t y r e n e l h I Y = o,-iiietlivIrt~-reIle,T = t h i o p h e u e . I' = f u i t i t i 1' = jiyriditie, (2 nlercaptan modifier, S a u g a t u v k C'he~;iical Dirision. b All copolymerizations n-ere c o n d u c t i d a t 40' C . : time f o r S \viis 27 liorirs. : Unless otherwise n o t e d , recipe I was used. 5Iethiodide g a v e nn p o l y m e r n f t e r 68 hours.
I. 7
7
1.6
--
=
999
cl,iirioline. 0b;I =
The pieces of a p p : r r a t ~ needed in this method are :i single-filamentmlight bulb, lens. urotractor. and a mirror SUDported on'two blocks of n-&l nnd having a vertical slit scratched through the reflecting surface The cylinder of plastic is attached t o the back surface of thc, mirror, SO t h a t the light beam passing through the slit is normal to the cylinder and the cylinder axis parallel t o the slit. Thid assembly is then placed on a sheet' of paper a t approximatel! the point, of focus of the light. The method of using the ai)paratus and the underlying .~ theory are developed in the following paragraphs. I n Figure 1the circle represents the circumference of a cylindci of plastic material. Light from line source A enters the pol\mi~i. :ind travels in all directions. A beam of light uassing froni . I through the center of the circle emerges from t h i polyhc~iuiiitsiracted along line A B . Ho\."= s t y r e n e , A ~ I S= a-inetliylstyrcne, rlliollllene, F = f , l r n n , 1' = ,)\y.i~lint,,C)
