THIS IS THE THIRD IN A SERIES OF HISTORICAL PAPERS WHICH HAVE BEEN PREPARED IN COMMEMORATION OF THE 75TH ANNIVERSARY OF THE AMERICAN CHEMICAL SOCIETY
LIKE STEEL AND CONCRETE, RUBBER IN A HUNDRED DIVERSE FORMS I S AN
ALL-IMPORTANT PART OF CONTEMPORARYLIVING
T
111.: purpose ( i t ' thi? I)riri historj. is t o supplj- the continuity aiicl some of t,he ~ a l i e n tbackground for those development i n r u h l w chemistry which arc' conceived I)? the author to kiavti \)ern of greatest i m p o r t a n c ~in promoting the progrrsi; of the ruliber industry Actually, the art preceded the science liy many ywrs. It has seemed logical, therefore. t o include wnie references to the early p h a i r ~of the industry prior to the orpanizatiori ( i f the Ilivisioii of Riih1~t.r(:lieniistr!-. and even before t h r t(~uiidatiori of the XNERICASC m m c . I L SOCIETY itself. .it no time his it l)ren intended to supply a completr bibliography even of those se.ctions of the subject which are specifioally di.wussed, iior has it been considered possible to list the names of t h e important contributors t o the progresi of rubber chemistry. The illtent has bcen to write for the geripral interest i J f the chemist. \vhcather in the industr>-01' not, and t o touch onlju p o n thosib Iiiilwtoiies of progrrsa which appeal to the author as \ 4 n g the moat sigiiificant. This has heen done by R series of .snapshots ratlirr than a continuous panoraniic picture. The iiaiiies that ovcur are not ~ i e c ~ w a r i those ly of the riiost important contributors, but are t h s e d i i c h liappen t o appear on the scene which is depicted Tlit, author regrets that it is beyond the scope of this articlfl to iianir the scows of pioneers and brilliant contributors t o the devc~lopiiientof our rubber. chemistry. He offers them a aincrre i f aiioiiymous salute. Rubber was conceived liy nature. hut it has hecan tlie iiigeriuitlof man which has transformed this material into thc hasis for onr of the largest industries in the world. Although rulJlier ,had attracted the attention of the early cliemi.sts prior t o 1839, it was the discovery of vulcanization by C.h,rles (;oodyear in that )-ear w1iic.h laid the cornerstone of our modern industry. t5t:itistics espansion of r~ibhcrfroni R PIOW ran best show the pheiio~iic~nal ;inti frc~hleliegiming.
World
Consumption of Natural Rubber
1860 1873 1890 1900 1910 191s 1910 1925 1930 lY33 1940 1945 194i 1919
lons 1,500 9,000 30,750 49,181 66,000 165,000 "0,000 ~,26,000 684,993 873,000 1,110,000 262,500 1,100,000 1 ,X?7.500
/iZ.
27. Dbzsizzore
Since the q x i ~ i gof 1950. tlie rul,bi~r situation has become rxtreniely tense as a result of internat,ional conditions. Polit,ii.al :iffairs in Indonesia and the threat of Comniuniem in 1laIay:i :m' jeopardizing the s u x c e s of 90% of our natural rubber suppi),. IIon-ever, the events of Korld \I-ar I1 proved that such crises c a t i full>- met through the cooperation of government, it n i l iiitlustry- -if prompt a d adequatcl steps arr taken to increase the, output of synthetic rubber and t o build u p a large natural ruhtic~r stockpile. JIeasures in this direction were adopted last ye:ii . In June 1950, t h r President approwd the Senate-House c o n p~'oniieebill continuing government ownership and operation o t tlie \\-:trtime-built synt,hetic rubber plants. Under the terms ( i t tlir rompromiee bill, the Governnieiit will operate these plants until Jul?- 1932. .ibout Septembrr 1, the Rubber Division of t i l e 1)ep:irtment of Commerce took another step toward inrrra411p the federal stockpile. This mc'asure consisteii of a general 1iiiiit:ttioii C)II the usc of nen' rubber, whether it w i s crude r u h h r p t i ~ ' c1i:ised from abro:id or I>-nthetic rubber made a t home. This yt.ncral limitutioii, volunt,arily agrccd upoii, ivaq t o continue U I I I iI Jiinuary 1. 1931, or until control specifications couid lie norhi.ll out in cooperation xvitli the industry for the more precise regu1:ition of rubber consumption. -4fter January 1, because of t l i r delay in realizing full production from t h e synthetic plants i i i i ( l also because of :t growing demand for military rubber producvt arid the continuing needs of the rubber stockpile, allocatioii oi ne\y rubber WLS further curtailed for civilian uses, particul:ti,l?. \\.it11respect, t o natural rubber. The industry has given consiticirat)le thought t o t h r eliriiinatiun of niany premium articles \vIiirli consunie aii excessive aniouiit, of iiatural rubber-as, for esanil)lt:, white eidervall tires. It is expwt,ed that product specificatioiih \vi11 limit the amount of natural rubber used and t h a t such N atrictionc: will go into effcct ahout ,ipril 1 , 1951.
-
RUBBER PROGRESS PRIOR TO 1876
To understand the part that rubber chemistry has playc~li i t the development of the industry, it is necessary to note what tool, place in its earlier years. It will be possible to see that cei'titiii Ixisir discoveries and developments greatly accelerated the iridust r~.'.sespaneion and improvement. Prior to the discovery of vulcanizat,ion, useful knowledge CIJIicerning rubber was meager and the incentive for investigation \vas rat,her Ion-. I n 1791, Samuel Peal, an Englishman, took out tlic. first patent in connwtioti \vith rubber. I t involved the u*t' iii
796
I N D U S T R I A L A N D E N G I N E E R I N G C H EM I S T R Y
Vol. 43, No. 4
1890 1YOU 19111 19211 193U
1449
Illustration uppeused in book, " P t r w n a l .\-arrnt,iiy o f tlw Origin. and Progress o f the Caoutchouc or I H ~ ~ I i ' c i L h ~ r Jlnnujaacture in E'rcglun~J'' (1837)
I i i 194!', 071,000 ton,- w r e produced i n l[:iI:~y:t : i l l 1 1 i:!1,00ii tuns in Intionesi~, T h e ljic.yc.le n.a$ bcgiiining to b c c o n ~ ar populi~rI I I C ~ I I Sof I IXII.port:itiorr : i l m i t 1886, ani1 the cuneequent rrlanufiictur.lJuthiul intlustry. The! iiltrcrrluctiorr 1 1 : ieuni:rtic tire I J 1)unlop ~ in 1888 .erved 3 3 irn iIliplJrtallt sir11 in t l i p clevelopmcnt of rubber in transportation. Tlrr reclairiiinp of scrap rubber began almost :IS soon as ~ 1 cuilizc.tl artirles nl:tde. Yarious niethods for ~leutrc~ying tIii. :itt:iclicvl f':tLiric anil for plasticizing t,he rubber \ix!rc n t l o ~ ) t r ~ l . u The - Irest liii[>\vii:iricl prot.lahIy the most important !vu.* t11c. nlli;tli )[arkl und I'rice I1895 -96). T h e proccIli1rt. of the fatrric., astraction of t,he free sulfiir. rizntion of the vulcanized rubber. l'his :ti111 iilly ilescribed in thc. i l O O l i , ~~Itc~cl:~iril(!~l l{l1l,-
~ l i w ~ Int1i:i l ~ ~ riihtrer d as a t e ~ t i l e\\-:Lterprcinling :tpeilt. Ilks o l r ~ di n spirit < of turpentine, t>he ruhljer {r-ai spread c,vi'r fshric with a bruslr. T h e first C . S.patent \vas otitained Iiy ,I. 1'. \ \ - i t h i l l this period, tlw scientific studirs were prinr:ti,iIj- IIIIlaniniel in 1813 for a rubber varnish which made leatlic~rS ~ I ( J C , , virtrd to iilvt,stigatioiis of the analysis and structure c ~ fr ~ l l ~ l ~ < ~ r . w t e r p r o o f . It is believed t h a t the first. rubber factory was .hiinrig tlic, e:irly investigators were Faraday, Hirnley, lVilli;inw. established in \'ienna in 1811 b y ,J. S. Reit,hofrr, n.ho had devised Tilrleii. :tri(l tbrich:irdat. Kecognit,ion should also I r e givtlrl tll R process whereby rubber threads were woven together with linen the ir-ork of Glnd~toiie:md IIibbert, who, as a r e s u l ~of thtair wsilk, or woolen t'hreads. Considerable pioneering lvork i n the irin thi. o p t i i d arid cheniical proprrties of rubber, e s t a l ) w:iting and proofing of fabrics was done not only lby T h t ~ n ~ : ~ .warc-li ~ l i s h d t h e fact thxt rLil)lwr wis an unsaturat,ed hydrocarboil. Hullcock, who established a factory i n England i n 1x20. hilt tl,v T h ivcrrk trf C'. ( ) . Keber i n 19 and his dpvelopnirrit c r l t 1 1 1 , ~.'Ii:irlesMcIntosh at Glasgon in 1823 '.coefficieiir of vri1c:iiiiz:ction" ented the first dircsct : i r i 1 1 It was not until 1839, however, t h a t Cliarles (hodyear, hy hi. t l i ~ ~ r c r i i ~ I ~ - p:tpplic;i.tion ~~iiig of cal research to t t i p rt1I)Irc.i. virlcanization process, was able to solve the chief difficulties r r i iriiluntry (6j,6 6 ) [ l e iiivestigated t,he influence IJf tinie ariti t,clnithese early investigators. Although Goodyear \vas not a chrinkt . pc2r:iture 1111 t lie .~ilt'ur vulcanization of rubber arid dcfinctl t11r. h i 5 discovery certainly merits t h e recognit.ion of a11 r u h l w cheiriteriri " c i t y p r nf vulcnnization" as the percentage of fixed .inlfur considering t h a t he investigated the precise amount. of h w t t1i:tt c:in tie t.atiiiiated liy analj of the washed ~)rotliict, Ile xiid tlie exact quantity of sulfur t h a t were required to cure ruhlwr, came to the c.onclusion t h a t ',the lirocess consists in the format ion Furt.liermore, because he employed white lead in conjunction with w h i r , he may be said t o have been the first t o employ an "nc.1~1- of :I corrtiriuous series of addition products of sulfur and [JOIFprtane; t.he upper h i t is probnblj, represented by the forriiula r w t u r . " In fact. he originated the dry heat process of vrr1cnniz:iCInoI-IlgoSzo, the l o w r b y Cloo€I~&. Thk series is cliaractrrizrti tion. physically by the loss of espansibility and increase of solidity T h e nest outstanding discovery was t h a t of the cold vulcanix:il'roiii the lower t o thr higher nwmbrrs. T h e tem1ierat,ure n i ~ t l tion process b y Almander Parkes in 1846. I n this proces8, rubtinie of vuiixitiz:ition, as ~ r - e l las the : m o u n t of sulfur :t(lde(l, ber ie immersed in a solution of sulfur chloride in carbon disulfide, tlrterriiinr \r.hic~h nienibers of this aeries are produced." Thc. no heat being required. Although only thin-walled articlea invwtig:itioii~i ) f \\'i~Iwrstiniulated further resezirch i n t,tlis f i ~ l t l . could be prepared b y this method, it was capable of furnishing :is t:vidc:iiced lry :I wries of papers Ijy Gpcnce and his ~ ~ i i l l : t l r ~ ~ r : t t c r r ~ vulcanized articles in a soft or hard state and in a variety of colors. on the theor). of vulcnnizat~ion(51-57). For the nest fifty years, work centered around t h e development Xevt.r.thr.less, until tlie early part of the tnerrtieth c'eiiturj', IIII. o f new articles of manufacture. Rubber began t o replace leather c l t ~ v ~ ~ l o ~ ~oin ithe r n t r,~I)l)er industry steinnied almost cxclusivc~l;. f o r inany purposes. Articles such a s flexible t,nbes, bottlw, and I'roni t l i p CffIJrtS IJE ~ m r t i c a rubber l nieii. The industry 11ad Iittlp hose were introduced. Rubber or rubberized casings were being o r no ;ip[)reci:it i i i i i oi t h r part t h a t rubkrer chciniats iiiight : c i i i i applied t o inflated objects such as pillows, cushions, beds, and life 1:ctc.r \\oulcl pl:i?- i n it:: udvanccment. T h e contributions of t l i f , preservers. Rubber was also being used for door springs. railrlit~iiiist~ u p to that timc resulted c-hiefly f r o m thr>ir vir.ntitic way buffers, and carriage tires. Likewise, purely scientific invesw i r i l )sit >. I: I U I I I t :1n i r l iscwria niateri:LI. tigations were not being neglected. In 1860, Granville Williarns isolated from dist,illed crude rubber a liquid which he called isoRUBBER PROGRESS F R O M 1906-1 9 1 9 prene and which slowly turned stickj-. Later, G. Bouchardat converted the liquid isoprene, by treatment with hydrochlorii. ' l ' l i t ~ u i i i o i i i o t r i l r indiiitrj.. which rtiatlt~its first ~ o i i r r i i w i d , into a solid which did not contain chlorine and whicli it:1-1- nineties, ivits b y now gro\ving with ..uffi.-c.inbled rubber. unie :~ndthereafter inaintain a (Ioriiiii;itiiii! RUBBER PROGRESS F R O M 1876-1906
TKOevents uf importance occurred in 1876. T h a t J'PLLT i v i t iii,ssed the begimiings of the rubber plantation industry and thr. tastablishment of t h e . ~ E R I C A S c H E m c . i L S o r I E T Y . In t h a t >.enr, Sir Henry IVielrham transported 70,000 weds of the T I c ~ w : l t r c finni ~ Brazil t o Kew Gardens i n T.ondnii. Of the 2800 l r l : i i i t
yCadwell ( l e ) ,\\-ere among the first antioxidants t o he used on a eonimercial scale. ;\s a result of extensive investigations in this field, lloureu and Dufraisse proposed a hasic theory for mtioxygenic and pro-oxygenic activity ( 2 5 ) . The subsequent discovery t h a t many antioxidants specifically retard Hex-fatigue cracking creat,ed a heavy demand for niaterixls ivhich increase the resistance of tires t o tread cracking. Once more the quality of rubber goods had been improved through the rfforts of t h e rubber chemist. F a t t y acids \$-ere related to the vulcanization of ru1)I)er by Ilannerth ( 1 8 , who discovered t h a t .?everal mineral soaps (the o1e;itea and 8tear:iteF oi lead, magnesium, and calcium) were cure ;icwlrr:itora for rubber-sulfur compounds. Russell introduced stearic acid as a commercial ingredient for rubber ( 4 7 ) . Later, K h i t b l - (69) showed that the acetone extract of rubber contained fattj- acids t,hat are of prime importance when vulcanization is carried out with the aid of either inorganic or organic accelerators. According to Bedford and Winkelniann (5),both metallic osides and organic acids arc inactive one without the other. T h e y found that the natural or added acids in ruhber dissolve the inorganic accelerators to form metallic soap^ and t h a t the solution of the metallic radical in the rubber is a prerequisite t o it. action a:: an accelcJrator. T h e dirrct use of latex by the rubber indu5try began ;il)out 30 years ago. I n 1928-29, natural latex accounted for untl(ar 1 % of United States nerv rubher consumption. I n 1934-35, it accounted for 2.870; in 1940-41 natural and synthetic latices represented 1.3’7,,, I n 1949, they had grown t o 6.1% of the tonnage of rubher used in the Cnited State?: compared with 5.27, in 1948, establishing new records in each year. I n 1948--49, t h e total consumption of latices increased, alt,hough total new rubber consumption declined; c o n x m p t i o n of natural latex incrcnsed, while thc use of s y n t h ~ t i c sdcdined slightly 161). Consumption of Rubber Latices Year 1924 1930 1935 1911 19-12 1945
1919
Firestone researcher determines viscosity of synthetic latex sample held in constant-temperature bath
Long Tons
2,157 1,458 13,500 33,150 9,592 25,186 61,367
*ilthough normal latex contains a n average of from 30 t o 38% lubber, both economy and specific industrial needs have required t h a t the latex be concentrated prior t o shipment. The treatments include creaming, centrifuging, a n d evaporation. I n t h e usual creaming procedure, a n alkaline agent is added and allowed t o stand a t an elevated temperature. Numerous patents have
been issued with respect to this trentnient. The basic work of Wescott (67, 68) and Utcrmark and his collaborators (63, 64)led t o the preparat,ion of concentrated, purified, and reversible lates creams b y centrifugation. The concentration of latex by evaporation is the basis of the Revertes process (SO, 48). The l a t e s is treated, on collection, n-ith a nonvolatile alkaline preservative which stabilizes the lates until it is subjected t o the evaporation process. The evaporation is effected b y a rotary dryer of spc design. The procesgs in n-hich latex is used for the production of rubber goods include sprrading, dipping, cltctrodeposition, cheniiwl deposition, and froth or foam formation. These processes : t r ~ applied t o the manufacture of such products as cements, paints, footwear, rubber-textile combinations, flooring, pavements, and porous a n d foamed products. Today the foamed-rubber indust,ry, which xvas basically founded in l 9 2 i ( 6 Z ) , s h o w promiec of extensive development. 1-ulcanized rubber is a perishable material, and its life is detvrmined, to a considerable extent,, b y t,he degree of vulcanization it has rweived. Early recognit,ion of this fact led t o effort,s t o find a means of drternlining the optimum degree of vulcanization o r “best, cure.” Weber in 1902 (65) reported t h a t combined-sulfurcure figures did not correlate Ivith physical properties. For many years thereafter numerous investigators attempted t o correlate “best cure” with either chemical or physical properties, with varying degrees of success. Progress was hampered becausc ,relatively long periods of natural aging \\-ere required before rcsults could be compared. iiccelerated aging tests hastened progress and, today, the personal bias of the rubber compounder is b u t a minor factor in dctermining “best cure.” It was recognized t h a t in the vulcanization of heavy rubber goods-such as t i r e e t h e poor conductivity of rubber resulted in heat gradients throughout the mass, and hence, in varying states of cure. Cranor referred t o one phase of this problem in an article in 1919 ( 1 6 ) . In 1923, I r a Williams ( 7 1 ) discussed the influencc, of the geometrical shape of the vulcanized article. I n the samcx year, Cranor ( 1 7 )reported the valuable method of using thermocouplee during vulcanization for determining temperatures in various parts of a tire. I n 1921, F. J. Dugan made a series of tire heat-flow curves from vulcanizing tires, and duplicated these effects in laboratory sheets cured in a n electric press. T h a t same year, W. W. L-ogt presented before the A.C.S. Division of Rubber Chemistry a method (never published) for plotting rate of vulcanization, obtained by thermocouple measurements, against time and using t,he slope a s the “temperature cocfficient, of vulcanization.” T h e method vias fully described b y Shern-ood (50) in 1928. I n 1932, Park and Maxwell (18)reported 3 coefficient. of vulcanization for conipounds accelerat,ed with mercaptobenzothiazole. These pioneering efforts niadc it possible t o interpret t h t acltual time-temperature effect,s obtained in various parts of hulkg o r irregular-shaped object* in ternis of standard laboratory s h w t cures made a t fised tmipi,ratures. The importance of this dcvelopment in equivalent cure dttermination cannot lie over,emphasized. The fact that vulcanization coefficients are cons t a n t over a fairly \vi& range of curing temperatures points to control b y chemical reaction. T h e variation in coefficient causcd b y the use of different acce1er:Ltors is not full>-understood. The commercial usage of various chemical derivatives of natural and synthetic rubbers is another example of the ingenuity of the rubbrr chemist and has resultcd in extensive practical applicat’ions. The Thermoprenes (rubber cyclized with sulfuric, sulfonic, or chlorosulfonic acids) yere the first rubber derivatives t o bc used commercially (81 j. These products are used for adhesive purposes and for chemical-resistant paints. Plioform and Pliolite are other cyclized derivatives prepared by the use of agents euch as tin tetrachloride or chlorostannic acid (11) and are used in adhesives, paints, coatings, a n d resin mixtures. The
Butadiene plant at Borger, T e x . , provides vital raw material f o r synthetic rubber program
Operator checks one of 25,000 valves instal!ed in 125-acre synthetic rubber plant at S a r n i a , Ontario
S o a p make-up and monomer weigh t a n k s are part of Phillips’ synthetic rubber plant at Barflesville, Okla.
chlorinated rubber derivatives arc exemplified by the Parloii products, which may be used in printing ink, coatings, and adhesives. The reaction of rubber with hydrochloric acid furnishes a product known as Pliofilm, which is used in sheet form for packaging purposes ( I S ) . Rubbone, a n oxidation product of rubber, is used for coatings and cements (59). A tough thernioplastic product known as Isolac is produced by the catalytic colidensation of rubber with 2-naphthol ( 2 6 ) ; i t is primarily used as a compounding ingredient for rubber. SYNTHETIC RUBBER
At Ford rubber plantation in Brazil, natural latex slowly drips into plastic c u p
The practical developnient of the eynthetic rubbers is a striking and comparatively recent triumph of rubber technology. It is a. page of history of great importance, on n-hich there is much rcinaining to be written. Synthetic rubber is essentially a development of World War 11, although it was made on a production scale by the Germans during World War I. They manufactured “methyl rubber” from 2,3-dimethylbutadiene, and i t has been stated t h a t about 2380 tons were manufachred a t Leverkusen during the war period. Ilowever, the product was of poor quality, such as would be used oiily under the stress of necessity. The first rubberlike niatcrials to bc used on a cornniercial scale in the United States were the reaction products of ethylene dichloride and sodium polysulfide. The= wrre introduced by Patrick in the early 1920’s and arc knoir-n as the Thiokola (@, 29). Seoprene ir-as the first actual synthetic rubber which was developed successfully in this country. It was introduced b y Carothers in 1931 ( 1 4 , 15j and is the polymer of the addition product of hydrogen chloride to vinylacctylene. The attempt to prepare a synthetic rubber hydrocarbon by the emulsion procedure was first describcd by Dinsmore in 1929 (19). In this process, a diene hydrocarbon was treated with a n oleic acid soap ant1 a protective colloid containing a protein. The international hostilities of 1939 brought to a focus the f a c t that, rubber would be the most critical material shortage of the United States in the event that this country becamc a belligcreiit. (‘onsequently, in June 1940 the President declared rubber a strategic and critical material. The Rubber Reserve Co. was set up to acquire a n adequate stockpile of rubber as quickly as poc;sible. Also, prior to the entry of the United States into World JVar 11, some practical progress had been made in the synthetic rubhcr field. I n 1940, constructioii was fitarted on a neoprenc p1:int ivhich would have an annual capacity of 10,000 tone, compared n-ith production in 1939 of about 2000 tons. Certairi patc’iit rights for the butadiene-styrene type rubbers had been obtained from the Germans. Butyl rubber, a n interpolymer of isobutylene with isoprene, was discovered in 1937, and construction of u plant to produce it had been started. I n addition, there werc a few small plants producing butadiene-acrylonitrile type rubbers. However, more rubber was needed. Consequently, in ;\lay 1941 t,he Rubber Reserve Co. was assigned the resporid)ility of developing a n American synthet,ic rubber industry. The growing emergency in 1942 resulted in the appointment of the Baruch Committee, which recommended the appointment of a Rubber Director with broad powers. Under this centralized direction, i.hc wartime synthetic rubber industry was built and operated. The following statistics illustrate the growth of this emergency industry: United States Production of Synthetic Rubbers (60), Long Tons GR-S Butyl Xeoprene N-Type Total 2,464 8,363 5,692 1841 227 22,434 8,956 23 9,734 1942 3,721 231,722 33,603 14,487 182,259 1,373 1943 762 630 16,812 56,660 1944 670,266 16,800 820:373 7,871 45,672 47,426 1945 719,404 740 026 5,738 73,114 47,766 1946 613,408 515:795 6,618 68,824 1947 408,858 31,495 489,529 7,908 52,603 34,848 1948 394,170 392,690 11,072 35,215 1849 295,166 52,237
Period
....
Operator wgiilatcs rapid .flow of synthetic latex at Poly?ner Rubber Corp., Snrnia, Ontario
April 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
801
Since World War 11, the attention of the rubber industry hiiP nized by thcx national societv a n d the i ~ i ~ g a i i i / ; i t : o i of i the Divisioii been largely directed toivard the developnient of "cold" rubher, of Rubber Chemistry n new types of black, aiid new clnstomers and high polymers. Most frequently, thc meetingi; of thc' riiI)l)c~i~ division have beon *'Cold" rubber has been thct result of efl'ort,s to improve tlie held along lvith the national meetings of the. L-;ocaicsty,but becauec: tleficiencicxs of standard GR-8. Observations had bern niade of the constantly increaeing nit~nil~craliip of tho division anti the that when GR-S was polymerized a t tcniperatures lower than the increasing attendance at nictctiiigq, it has ~ C Y , I Ipri,fcarable in rccc,iit standard 122' F. there was an improvement in some of the propcryears to hold some of the meetings independeiitly of the nation:il ties of the rubber-notably its toughness a t elevated teniperasociety. .St t,he present time, the Division of Rubber Chemistry t u p s . Subsequent temperature researches finally led t o the pilot is the largest division of the AMERICASCIIE\fICAL SOCIETY. Explant production in 1946 of a cold rubber \\.hose recipe was similar cept during World War 11, when transportation facilities werr t 1 ) that of GI- the tours through Officers of the Division of Rubber Chemistry, 1919-1951 but still inferior to natural iiid~striitl plants, which ai'(' rubber. Cold rubber has uw:rlly pro\,ided. Year Chairman Secretary greater resistance to growth of I11 1927, authorization f o r t l i i , 1919 ,J. B.Tuttlc -1.11. Smith t i w d cracks than GR-S when t'urniation of local rul)Otbr 1920 W.Ii.Len-is A. H. Smith used in tires. It s h o w better grovps W I S granted by the Di1921 W.FT. Evans i\. H. Smith ivear resistnnctx. Like GR-S, vipioii of ltubber Chemistr?-. C. W.Betlford 1922 -4.H. Smith colt1 rubber is riot as yet suitaTi-hich agreed to sponsor then1 1923 W. B. Wiegand -4.IT. Smith Me for truck tire carca.qs stocks after they w r e organized. -.it 1924 E. B. Spear .i. I[. Smith liecause of the tendency fur the present time, there :iris 13 1025 c'. rt. uoggs .\. H. Smith h a t build-up, and the requirt.such l o c d groups: in A4kror~. 19% J. 31. Bierer .I. If. Smith iiieiit of black reinforcement. Boston, Buffalo, Chicago, Coii1927 R. P. Dinsmore .\. 11. Smith T h e recent int,roduction of irecticut, Lktroit, Los Angrlc~. H. L . Fisher 1928 I i . E. Sinimons liigli-abrasion furnace blacks is Sen. Toik, iiorthern Califoriii:i, .iH. . Smith 1929 11. F:. Simmons :t developnient ~-hichhasclosely Philadelphia. Rhode Islaiitl. 1930 S. Krall 11. 1.;. Simmons followed that of cold rubber. southern Oliio, and Wasliiiig1931 H. 4. Winkelniaiiii 11. 1.;. Simmons In fact, the dt~sirablepropertics ton, D. C. The various coni1932 E. R. Bridgwater I I. 1,;. Simmons of cold rubbcr are, t o a largci niittee projects sponsored I)v 1933 L. B. Sebrell I I . E. Simmons cMcnt, dependent upon the use the division are concrete vxI r a Williams 1934 11. El. Simnioiis of a high-abrasion black as a amples of hotv the division 1i:i.1935 S. D. Cadwell I r. E. Simmons winforcing ingredient. The assisted in the advancemi~ntof 1936 S. X. Shepartl C'. IT. Christensen ('ape of dispersion is one outthe indu?;tq-. 1937 IT. I,. Truniliull C. IT. Christensen standing advantage of thew I n 1912, the Rubber Section 1988 -1.R . I
