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LetterstotheEditorP55S「『JFhJPlP100170016101520143013401250Wavenumber(cm-1)Fig.1Ramanspectraoflateralmeasuredcarbonfibres595REFERENCES1.F.TuistraandJ.L.Koenig,Journal01ChemPhys.1126(1970).2.c.H.Chang,R.ABeyerlein,andS.A.Chan,Carbon22,393(1984).3.R.P.Vidano,D.B.Fischbach,L.J.Willis,andT.M.L伺hr，SolidStateCom,39,341(1981).4.P.Lespade,R.Al-JishiandM.S.Dresselhaus,Carbon,20,427(1982).5.A.Richter,H.-J.Scheibe,W.Pompe,K.-W.Brzezinkaand1.Muhling,1.Non-Cryst.Sol.,88,131(1986).6.H.Sakata,G.Dress巳lhaus，andM.Endo,inProceedingsofthe18thCarb.Conf.(WorcesterPolytechnic1nstitute,Worcester,MAUSA)(1987),p.18.7.E.FitzerandF.Rozploch,HighTemperatures­HighPressures(tobepublished).8.c.A.Coulson,inProceedings01the4thCarbonConf.PergamonPress,NewYork(1960),p.215.9.K.Morita,Y.Murata,A.Ishitani,K.MarayamaandT.Ono,A.Nakajiama,PureandAppl.Chem.,58,455(1986).10.E.Fitzer,E.Gantner,F.RozplochandD.Steinert,HighTemperature-HighPressures(tobepublished).Preparationofmeso-carbonmicrobeadswithanarrowsizedistribution(Received28January1988;acceptedinrevisedform30March1988)KeyWords-Meso-carbonmicrobeads,bulkmesphasepitch,particlesizedistribution1tiswidelyknownthattheformationofmesophasetakesplaceinorganicmaterials,suchascoal-tarpitch,coal­liquefactionproducts,petroleumheavyresid-ualoil,etc.Whenthes巳pitchmaterialsareheattreatedatatemperaturebetween350and450oC,thecarbonaceousmesophasespherulesformedinthepitchesaregenerallycalledmeso-carbonmicrobeads[1,2].Althoughtherehav巳beenmanystudi巳sonthepreparationofmeso-carbonmicrobeads[3-6],meso­carbonmicrobeadswithan盯rowsizedistributionhavenotbeenobtainedsofarbecauseofdifficultiesincontrollingthereactionprocessandinseparatingthemeso-carbonmicrobeadsfromthematrix.Ifmeso­carbonmicrobeadswithanarrowsizedistributionwere596LetterstotheEditorpri叩aredeffectively,therew'Ouldbeagl∞dpossibility'Ofûsingthemassúpp'Ortsinliquidchromatograp~:y，cataÍysissubstrates~ãndasfunctionalcarbonmaterials[2,7].Thisc'Ommunicati'Ondescribesanewmethodf'Orpreparati'On'Ofmes'O-carbonmicr'Obeadswithanaπowsizedistributi'On.1ngeneral,anemulsi'Onrepresentsasyst~mwhichhasaliquiddispers'Oidinaliquiddispersiònmedium.τbeliquiddispers'Oid怯kesasph在ricalshapeinthissystembecause'Ofsurfacetension._Bulkmes'Ophas~pitch.beginst'Os'Oftenar'Ounditss'Ofteningpointandsh'Owsaliq运idstateh在.vingal'Owviscosityatahighertemperature.Thus,thespher'Oidizingofmesophasepitchparticlesispossibleinanemulsionsystemconsistîng'Ofames'OphasepitchasadisPl!rsoidandatherm'Ostablesilic'One'Oilasadispersionmedium.Bulkmes'Ophasepitchasstartingmaterialwaspreparedfromc'Oal-tarpítchandwaspassedthrough2∞'Or325τ'ylermesh.Thepr'Opertìesofthispìtchwere在Sf'Ollows:mes'Ophasec'Ontent,100%;quinolineins'Olublefracti'On,0.9%;ash,0%;s'Ofteningp'Oint,3070C.(Oneofsimi1arquinolinesolublemes'OphasehasbeendiscussedbyH.H'Ondaetal.[8,9].)Theschematicfl'Owf'Orpreparati'Onofmes'O­carb'Onmicrobeadsissh'OwninFig.1.Tw'Ogramsofthemes'Ophasepitchwereplacedint'O150mlofsilîc'One'Oilandagitatedbysupers'Onicdispersi'Onwithblowingnìtr'Ogengasf'Or30mìn.Thenthesusp在nsi'Onofpitchandsilíconeoilwaschargedintoaglassreactorandheatedwithstirringinanitrogenatmospheretotheprescribedtemperatureandheldtheref'Ortheprescribedtimes.在1etemperaturewasincreasedatarateofabout60Clmin.t'Othefinaltemperature‘Thereactorwasthenco'Oledtor'O'Omtemperature,themeso-carbonmicr'Obeadsw钉在separatedfr'Omthesilic'One'Oilbycentrifugati'Onandwerewell-rinsedwíthbenzene.BulkMeS'ODhase(S.D.3070C)Suspension(Pitch)/(Si丑c'One'Oil)=2.0g/15Omllnea问StirringEmulsiontCoolingSuspensi'On臼ntrifugati'OnRinsing(Benzene)jDryingiMeso翩car.bonMicrobeadsFig.1Flowchartforpreparationofmeso-carbonmicrobeads食'Ombulkmesophasepîtch.Fig.2Scanningelectronmicrographsofmeso-carbonmfcr'Obeadspreparedatatemperatur军3100Cfor20min.Figure2showsthescanningelectronmicrographsofmes'O咽carbonmicrobeadspreparedatatemperatureof31OoCf'Or20min.Theyieldbased'Onaweig以ofchargedmes'Ophasepitch有asmore注lan90号。­Thepitchparticles,whichhadbeenangul盯andirregularinshape,weretransformedtoauniforInsphericalshape.Theparticlesurfacewassmoothandneithercracksnorholeswereobserved.Asarule,apitchdoesnothaveaclearmeltingpoint,becauseitcomprisesamixture'Ofmanymoleculeshavingvariousmolecularweights.However,inthisnewme岱1od'softening'Ofthepitchisa咆nificantfactorformodífyingthepitchparticles.Forthisreason,theconditi'Ons,especiallyintheemulsionstateofsilicon'Oilandpitch,forthepreparationoff.1eSO崎carbonmicr'Obeadsshouldbeexaminedwithregardtotreatmenttemperatuτeandtime.Figure3showstherelati'Onshipbetweentreatmenttimeandtreatmenttemperatureforthepreparationofmes'O-carbonmicrobeads.Theshadedp削indicates在regionwhichiscapableofprovîdîngmeso-carbonmicr'Obeadshavingasatisfactorysphericalshape,whilethedashedlíneindicatesthesofteningpointofthemesophasepitchused.Itisobservedthatthesphe技calparticlesarepreparedattemperaturesbetw由n290and3500Cwi也intimes'Of60min.Ashorttimeissufficientathightemperatures,andal'Ongertreatmenttimeisrequired-tospheroidizeata10有ertemperature.Ontheotherhand,thesphericalparticleswer巳notobtainedoutsideofthesha~e~r~