Tanaka, Kenzo

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RIGHT:URL:CITATION:AUTHOR(S):ISSUE DATE:TITLE:Examination of Thin Rubber Filmsby Electron DiffractionTanaka, KenzoTanaka, Kenzo. Examination of Thin Rubber Films by Electron Diffraction. Memoirs of theCollege of Science, Kyoto Imperial University. Series A 1938, 21(5): 169-1721938-09-30http://hdl.handle.net/2433/257201Examination　of　Thin　Rubber　Films　by　　　　　　　　　　　　Electron　Diffraetien’By　Kenzo　Tanaka（Received　Aug．　8，　ig38）Absもraet　　　The　molecular　structure　of　tliin　rubber　film　depositecl　from　i‘cs　benzene　solutionop　a　polished　metal　surface　by　eV’aporating　the　s’olvent　benzene　svas　examinecl　by　themetl）od　o’f　electron　diffraction　at　various　tempercatures，　and　it　“ras　found　that　rubbermolecules　arranged　themselves　similavly　to　those　of　pavaff］n　crystal．　　　　It　was　．reported　in　a　preceding’　paperi　that　wheR　ac　thin　film　ofsonie　organic　long－chain　molecules　coating　a　polished　metal　surface　isheated，　the　regular　arrangement　of　the　molecules　of　each　substancebecomes　laaphazard　at　a　certain　temperature　which　is　characteristic　ofthe　substance　and　cliffers　from　its　melting’　poiht．　Thls　temperature　wcrts，called　t・he　transition－temperature　of　the　molecular　arrangement　of　thesubstance．　ln　the　present　experiment　the　manner　of　the　acrangementof　the　rubber　molecu！es　ln　a　thin　film　deposited　from　ii　s　benzene　solutionon　a　polished　metal　surface　was　examined　in　the　same　manner　as　before．　　　　To　obtain　rubber　films　of　different　thicl〈ness　a　small　piece　of　polished．copper　whlch　serves　as　the　bacl〈in．cr　of　the　film　was　dipped　for　a　mo－ment　in　a　benzene　solution　of　rubber．　The　range　of　the　rubber　con－centration　o£　the　solution　was　from　2　to　o．oos　per　cent．　By　subsequentevaporation　of　benzene，　uniform　coating　o£　rubber　was　obtained，　whichwas　so　thin　as　to　show　the　interference　£ringe　by　the　light　in　most　cases．　　　　The　typical　diffraction　p’alSerns　obtained　by　an　electron　beam　whichimpinged　upon　the　rubber　film　iti　a　direction　almost　parallei　to　its　surfaceare　such　as　shown　in　lli？i’（．r．　i．　But　these　are　rare　cases，　and　generallythe　rubber　films　deposited　as　above　stated　g‘ave　tise　at　first　to　diffusehalos　of，　amorphous　structure．　However　when　these’　amorphous　filmswere　heated　at　about　70℃　for　a　while　and　cooled　to　room　teinperaturethey　gave　rise　to　the　same　diffraction　patterns　Mustrated　in　Fig．　i．The　regular　pattern　showin．c．r　the　regular　arrangement　of　the　rubbermolecules圭s　well　defined　for　very　thin　film　and　becomes　more　dif壬useエ．　エミ＝．Tallaka：　These　ムエen〕oirs，21，85　（lg38）．170 Kenxo　TanakaFig．　iatoms　in　the　zigzag　structure　of　a　long－chain　molecule．the　inner　potential　estirnated　from　the　positions　of　the　layer　lines　wasless　than　one　volt．　　　　From　the　distances　of　the　spots　on　the　layer　lines　in　the　diffrac－tion　pattern　as　measured　from　the　intersection　of　the　plane　of　incidencewith　iDcreasing　thickness　of　thefilm，　as　in　the　case　of　the　Othersul〕stances．　　　　The　regular　diffraction　pat－tern　as　shown　in　Fig．　I　is　ex－Plained　as　being　due　to　a　certainregular　arrangelnent　of　10ng－chainmQlec．ules　standing　Perpendicular－1y　to　the　Hat　surface　of　the　back－ing．　The　spacing　calculated　fromthe　separat三〇ns　of　the　parallel　Iay－er　li．nes　which　are　nearly　straight　　　　　　　　　　　　　　　　　　　　　　もin　the　figure　was　2．58　A．　Thisspacing　is　the　same　as　the　dis－tance　between　alternate　CarbOn　　　　　 　　　　　　　　　　　The　value　oft’窒≠b撃?　11 2：Para缶nIndices00000000000000011012220工244・410122012444012Spacings　A弔切昭⑫調調苗可舶舛葡餌昭謁74432222fIIIII3 斗Rubberreflec亡．4・944・073・692．g82．50z372．III．791．661．471．23LITtl‘allSln．4－073・6g2．47sParathntransm．4．123・772．472．0756．iX．1－foiltransm．4」53・72：・942．472．04‘Ex”ami｝Zαあ0π（ゾTlti　Z　1～～tbber．Fil〃Z∫〃ツElectron　I）iffraction 171o£　thg　elctctron　beam　with　the　photographic　plate，　tho．　late．ral　spacing’sof　the　regular　arrangenient　of　tlae　long”一chain　inolecttles　can　be　calcalated．The　spaci．n．o，，，’s　thus　obtaiRed　are　shown　in　’the　thircl　column　of　［L’ablt）　1．In　columri　i　and　2　of　the　tabie　the　indices　and　the　spacings　of　theplanes　parallel　to　d一．ftxis　of　the　crystal　of　parailfin　found　by　lk，．’［Ullbr　areg’iven．　The　agreement　between　the　“alues　in　column　：　and　1R　’columnc）　shows　that．．　the　lateral　disposition　of　the　molecules　of　rubber　in　thepresent　case　is　the　same　as　that　o£　pavatlfiik　crystal．　This　arraAgementof　the　inolecules　of　rubber　cliffers　froni　that　found　in　stretchecl　rubb｛：．rby　means　of　X－rays．　　　　The　ag－reement　betwe，en　the　structures　of　rubber　and　ptiraflELn　xvasalso　tested　by　transmissio’n　photog’raphs．　Rubber　solutioR　ilt　benzenea1〕d　para伍n　solu．tiOll　ill　benzene　wete　sprea（i　respectively　a5　thi丘且11nson　thin　foils　of　aluminium　xvhich　had　been　carefully　cleaned．　t’X’fterthe　evapot’ation　of　the　soivents　the　difliraction　photog’raphs　were　takenby　sendi，　ng　the　electron　beam　normally　to　the　surface　of　the　films．The　results　ft．　re　shown　respectively　ii’i　columns　4　and　s　oE　rrable　1　；　andagaiR　tlie　ag’reement　is　evident．　x’Nluminlum　foils　usuaily　give　rise　tocertain　extra　rings　clue　to　sonie　fatty　substances　in　the　transmissionphotog’rapks，　such　as　shown　ln　colunin　6　of　’IL”able　1．　lrhese　extra　rin．asccxn　be　removed　by　carefully　washing’　the　£oil　；　and　in　the　examinatlonof　rubber　ancl　paraffiR　describecl　above　such　cieaned　foils　were　alwaysused．　　　　Next　to　see　whether　the　regular　diffract｛on　pattern　obtainecl　xvithrLibber　may　be　due　to　some　other　fatty　substances　present　in　the　rttbberfilm　as　a　contamlnation，　cliffraction　photographs　were　tal〈en　with　tlaeloacking　only　ancl　with　the　backing　which　was　dried　after　being　covereclthici〈ly　with　benzene　and　volatile　oil．　The　benzene　and　volatile　oil　wererespectively　the　same　as　those　used　as　the　solvent　of　rubber　E　nd　1ncieaning　the　1）acl〈ing．　IBut　in　these　cases　no　such　regular　diffractionpattern　as　shown　in　Fig．　i　appeared　even　though　the　specimens　were17eated　to　about　go℃．　Next，　the　surface　of　the　rubber　film　which　had．o．’ 奄魔?ｎ　rise　to　the　reguiar　diffraction　pattern　as　Fi，（．r．　i，　was　cleanecl　xvithvolatile　oil　to　remove　any　£atty　substance＄．　which　mlght　be　present　onthe　surface　of　the　rubber　fllm　as　a　contamination．　But　no　appreciablechange　ln　the　cliffracti．on　pattern　was　observed　with　such　specimenbefore　and　after　the　cleaning．　　　　IBy　the　results　of　tl｝ese　tests，　the　suspicion　that　the　regular　dif－fractioii　patterii　observed　with　a　thin　fiim　of　rubber　deposlteci　on　a172 f〈．　Tanaka，　Escamination　of　Thin　1？zfbber　Films　etc．smooth　surface　of　a　metal　nl｛ght　わe　cauSed　by　some　fat亡y　substancespresent　ill　the斑m　as　a　contaminat圭on，　seems　to　be　almost　removed；and　consequently　the　v至ew　that　the　rubber　molecules　arrange　themselvesin　the　same．manner　as　paraf丑n　ill　the　present　case　seems　to　be　a醒most　　　　　certaln．　　　　When　the　thin　rubber　filin　in　which　the　rubber　molecules　werearranged　regularly　as　has　been　described，　was　heated　ill　the　vac羅um　ofthe　electron　diffractionεしPParatuS，　n（）apPreciable　change　in　the　regulardi任ractfon　pattern　was　observed　at　a　temperature　below　about　60℃，　butw｛th£urther　rise　of　te1れperature　the　pattem　became　diffuse　and　finallyvanishedεしt　abo厩66。C．　Such　transition－temperature　at　whi¢h七he　regUlararrangement　of　the　molecules　becomes　haphazard，　was　measured　i　n　thesame　way　with．tell　specimens　of　different　thickness．　Th6　transition－temperatul’e　thus　rneasured　ra：、ged　from　58℃to　66。C　and　no　reguiarrelation　was　found正｝etween　the　transition－tempel－ature　and　the　thicknessQf　the　f［lm．　This　transition　of　the　molecular　arrangemgnt　of　rubberfronユ　regular　to　irregular　is　reversi｝：）1eεしnd　xvhen　the　heεしted　specimenis　cooled　the　molecules　arrange　thelnselves　reg’ularly　as　before　nearlyat　t1ユe　　tl’．ftllsitiOll一・telllr）erature．　　　　The　writer’　wishes　to　express　his　sincere　thani〈s　to　1）rof．　U’．for　his　invaltiable　sug．o’estions．Yoshidax

Examination of Thin Rubber Films by Electron Diffraction

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Examination of Thin Rubber Films by Electron Diffraction

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