新型石墨烯超高分子量聚乙烯纳米复合材料讲义

1、优选文档优选文档PAGEPAGE45优选文档PAGENovelGrapheneUHMWPENanocompositesPreparedbyPolymerizationFillingUsingSingle-SiteCatalystsSupportedonFunctionalizedGrapheneNanosheetDispersions?rzel,*FabianKempe,YiThomann,StefanMark,MarkusEnders,*,?,?FreiburgMaterialsResearchCenter(FMF)andInstituteforMacromolecularChemistry

2、,UniversityofFreiburg,Stefan-Meier-Str.?31,D-79098Freiburg,GermanyAnorganisch-ChemischesInstitut,UniversityofHeidelberg,ImNeuenheimerFeld270,D-69120Heidelberg,GermanyABSTRACT:Novelfamiliesofultrahigh-molecular-weightpolyethy-lene(UHMWPE)nanocomposites,containinguniformlydispersed,functionalizedgraph

3、ene(FG)nanosheets,werepreparedbymeansofthepolymerization?llingtechnique(PFT).Unparalleledbyanyothercarbonandboehmitenanocomposites,FG/UHMWPEexhibitedanunusualsimultaneousimprovementinstffness,elongationatbreak,andeffectivenucleationofpolyethylenecrystallizationatonly1wt%FGcontent.FGnanosheetsareultr

4、athinwithathicknessofonlyonecarbonatomandlateraldimensionsofseveralmicrometers.OwingtothepresenceofsurfacehydroxylgroupsontheFG,singleFG/methylaluminoxane(MAO)nanosheetscanbeeffectivelydispersedinn-heptane,thusenablingimmobilizationofanMAO-activatedchromium(Cr1)single-sitecatalystonFG.Incontrasttona

5、nometer-scalecarbonblack(CB),multiwallcarbonnanotubes(CNT),graphite,andnanoboehmite,whichfailedtoformstabledispersions,FG/MAO/Cr1affordedthehighestcatalystactivitiesandexcellentmorphologicalcontrol.Inymeizi?ig,eiegiiceieiieymeiziceeimieeeepecialsafetyandhandlingprecautionstypicallyrequiredbyconventi

6、onalcompoundingofnanoparticleswithultralowbulkdensities.INTRODUCTIONUltrahigh-molecular-weightpolyethylene(UHMWPE),withmolarweightsexceeding1million,iswell-knownforitsultrahightoughnesscombinedwithhighabrasionresistance,verylowfrictioncoeffcient,lowmoistureuptake,andexcellentchemicalstability1.ee,?b

7、eecemUHMWPE.Applicationsrangefromwear-resistanttransportbeltsandsupertoughengineeringplasticstobiomaterials,implantsforuseinhip,knee,andspinereplacements,ultrastrengthgel-spunUHMWPEfabricsforwater-repellantropes,cut-resistantgloves,andbullet-proofbodyarm2For.manyapplicationsitishighlydesirabletoimpr

8、ovetheUHMWPEcrystallizationrate,toughness/stiffnessbalance,andespeciallytheelectricalaswellasthermalconductivitybecauseUHMWPEisathermalandelectricalinsulator.Providedthateffectivedispersionisachieved,anisotropicicecigi?cyimveye?em-ance3.UHMWPEnano-andmicrocompositeswithcarbonblack,graphite,4andmulti

9、wallcarbonnanotubes(MWCNT),5processedbymeansofcompressionmolding,havebeendevelopedtoimproveelectricalconductivity.Itshouldbenotedthatdrypowderblendingwithnanoparticlesrequiresspecialsafetyprecautionsandhandlingprocedurestopreventemissions,dustexplosions,andhealthhazardsresultingfromnanoparticleinhal

10、ationoradsorption.Arecentadvanceintroducedelectrostaticsprayingofgraphenenanoplatelet(GNP)suspensiwivegeice6-8meci?ccee120-150m2/g.SuchGNPstackscontainingmorethan60graphenenanosheetsproduce6878UHWPE/GNPcmie?mexibib-tiallyimprovedfracturetoughnessandtensilestrengthataverylowGNPcontentofonly0.1wt%.6In

11、conventionalapproachestowardUHMWPEnanocomposites,graphiteoxide(GO)andchemicallyreducedGOweredispersedindiluentssuchasethanolandthenspray-coatedontoUHMWPEpowderpriortocompressionmolding.7Foroptimizingthematerialpropertiesitisofgreatinteresttoimplementnano?llerdispersiondirectlyintoethylenepolymer-izi

12、bee?mewviciyeiqipolymerizationmedia,thuspreventingemissionofnano-particlesatthesametime.Catalyticpolymerizationintheeece?e(-situpolymeriz“ii”)ieexeiveycecveiemicye?cmwiveyig?ece.Iymeizi-?llingprocesses,e?eeecyebemixgwiecyme?ece.Progressinthepolymer-ization-?igeciqe(PFT)ye?beereviewedbyDuboisandKamin

13、sky.8-10Single-sitecatalysttechnologyoffeexciigewiieiige?polymerization11andPFTprocessesbydesigningbothmecye?cieceye?icemorphologies.PFTaffye?cmiewiigi?cyimveCNTieieecicc-ductivity,thusenablingeffectiveelectromagneticshieldingofReceived:July4,2012Revised:August13,2012Published:August30,2012?2012Amer

14、icanChemicalSocietyx.i.g/10.1021/m301376q|cmece2012,45,6878-6887在功能化石墨烯纳米片分别体上采用可支持的单中心催化剂经过聚合填充制备新式石墨烯超高分子量聚乙烯纳米复合资料大纲：制备含有平均分散功能化石墨烯（FG）纳米片的新式石墨烯超高分子量聚乙烯纳米复合资料，准备借聚合填充技术（PFT）。与其他碳和水软铝石纳米复合资料对照，FG/UHMWPE在刚性上表现出不平时的同步提高，断裂伸长率，聚乙烯结晶仅为1（重量）。FG纳米片是极薄的，厚度只有一个碳原子和几个微米的横向尺寸。由于表面羟基上的FG存在下，单FG/甲基铝氧烷（MAO）的纳米

15、片能够有效地分别在正庚烷，从而使一个被MAO活化的铬（CR1）上的FG单活性中心催化剂固定化。而对照之下，纳米级炭黑（CB），多壁碳纳米管（CNT），石墨和纳米勃姆石，难以形成牢固的分别体，FG/MAO/Cr1供给最高的催化剂活性和优异的形态控制。在聚合填充物，纳米颗粒分别体的交融到聚合过程除掉了平时需要由纳米粒子拥有超低容积密度的混杂安全和办理措施。序言超高分子量聚乙烯（UHMWPE），摩尔质量高出100万，它最主要的特点是拥有超高韧性结合高耐磨性，特别低的摩擦系数，低吸湿性和优异的化学牢固性。床单，部件和纤维都是有超高分子量聚乙烯生产的。应用范围从耐磨输送皮带和增强工程塑料生物质料，植入的

16、髋，膝，脊柱和代替使用，高强度凝胶纺丝UHMWPE织物用来做做防水绳索，防割手套，防弹车身、防弹衣.关于好多应用，特别希望改进超高分子量聚乙烯的结晶速率，韧性/刚性平衡，特别是电和热传导性，由于超高分子量聚乙烯是热和电的绝缘体。前提是实现有效的分散，各向异性纳米颗粒可显然改进聚烯烃的性能。UHMWPE纳米和与碳黑微观复合，石墨，和多壁碳纳米管（MWCNT），经过压缩成型装置进行了办理，获得了开发，以提高导电性。应该指出的该干粉混杂纳米粒子的安全预防措施和办理程序，以防范排放，粉尘爆炸，吸入或吸取纳米粒子而产生健康危害。近来的进展，石墨烯纳米薄片的推出6-8纳米的平均厚度和120-150平方米/

17、克的比表面积的静电喷涂（石墨烯纳米薄片）悬浮液。这样的石墨烯纳米薄片含有高出60石墨烯纳米片生产超高分子量聚乙烯/石墨烯纳米薄片纳米复合膜表现出显然改进的断裂韧性和抗张强度含量仅为0.1（重量）.传统生产超高分子量聚乙烯复合资料，是将石墨氧化物（GO）和化学还原的石墨氧化物分别在稀释剂如乙醇，尔后在模压前喷涂到超高分子量聚乙烯粉末。为了优化资料的性能，希望实现纳米填料的分别并直接进入乙烯聚合，液体的低粘度有利于聚合介质，从而防范纳米粒子的发射在同一时间。在催化聚合填料（“原位聚合”）的存在下，以生产传统的热塑性聚烯烃化合物被广泛地使用，拥有特别高的填料含量。在聚合填充工艺，该填料被用作催化剂载

18、体，以使基质直接从纳米填料表面生长。在聚合进行中填充技术（PFT）聚烯烃向出处Dubois和Kaminsky改进.单活性中心催化剂审查技术供给剪裁烯烃激动人心的新时机聚合11和PFT流程经过设计两个聚烯烃分子结构和聚烯烃粒子形态。PFT能供给聚烯烃纳米复合资料显然改进CNT的分别性和导电性，从而使老例聚烯烃产生有效电磁障蔽但是，相当少的已知与关于PFT生产超高分子量聚乙烯复合资料。近来，Rastogi医师等。报告了超高分子量聚乙烯的形成使用水杨醛制备的纳米复合资料PFT支持TiO2，ZrO2和碳纳米管的催化剂。由此纳米复合资料表现出改进的纳米填料的分别性和Macromoleculescveiy

19、e?.12Yet,considerablylessisknownwithrespecttoPFT-producingUHMWPEnanocomposites.Re-cently,Rastogietal.reportedontheformationofUHMWPEnanocompositespreparedbyPFTusingsalicylaldiminecatalystssupportedonTiO,ZrO,andCNT.Theresulting22cmieexibieimve?eieiandhigherentanglementmolarmasses.13,14Inourresearch,we

20、investigatedPFTwithFGnanosheetsas?ecy.Geeecbeewithathicknessofonecarbonatom.Thissinglelayer2-ofsphybridizedcarbonatomsisarrangedinahoneycomb-likelattice.Withanatomicdiameterof0.14nmandasheetwidthofseveralmicrometers,theaspectratiooftypicalgraphenesislargerthan10000.Theyexhibitexceptionalproperties,i

21、ncludingultrahighstrength,ultrafastelectrontransportatroomtemperature,extraordinarilyhighstiffness,andabrasionresistanceaswellasstrongUVandIRabsorption15Inaddition.tothehighlyperfectidealgraphenes,avarietyofhydroxyl-functionalizedgraphenesareavailable16-19The.preparationofFGwaspioneeredbyBoehmandco-

22、workersin196921byiggiexie(GO),wicw?yeizebyBrodieatOxfordUniversityover160yearsago22Thermal.orchemicalreductionofGOprovidesFGnanosheets23,24.Theoxygencontentofthislayeredcompoundiscontrolledbythetemperatureofthereductionprocessanddecreaseswithincreasingreductiontemperature.Thepredominantoxygenfunctio

23、nalityattemperaturesabove400Ccorrespondstohydroxylgroups,whereasepoxy,carbonyl,andcarboxylgroupsundergorapidthermolysisatsuchtemperatures.ThesurfaceareaofFGisgenerallyintherangeof-600120m2/g.Thisisconsiderablysmallerthanthatofidealgraphenes(2630/mg).25,26Uponshearingthemicrometer-sized,accordion-lik

24、eparticlemorphologyofFGbymeansofsonication,thelargeFGparticlescompletelydisintegratetoaffordsingleFGee.Tiie?ecebymiveiceeieeci?cceem6001800m2/g.27SinceFGwithahighsurfaceareahasanultralowbulkdensity,PFTisthececicecigye?/FGmebcethatcanbeaddedtocoveiye?mice.AccordingtoYanetal.,theadditionof1wt%FGpriort

25、ocmeimigigi?cyimveeweei-ance28.SimultaneouslywiththeimprovedwearresistancethebiocompatibilityofUHMWPEisnotaffected.29SeveralgroupshaveusedgraphiteandFGinPFT.However,mostcatalystsfailedtoproduceUHMWPE.Pretreatmentofe?ewiccymeymixe(AO)iethemostcommonlyusedapproachesforeffectiveimmobiliza-tionofmetallo

26、ceneandpostmetallocenecatalysts11,30.-35Duboissuccessfullyemployedmicrometerizeg-ie?einaPFTprocesstoproducethermoplasticPE/graphitecompositeswithaneffecive?eiei.36FGnano-compositeswithlow-molecular-weightthermoplasticHDPE,37,38LDPE,39LLDPE,40iPP,41andotherpolymerssuchaspolyanilinehavebeenreported42-

27、46To.thebestofourknowledge,therearenoreportsonPFTprocessesforproducingUHMWPE/FGnanocompositesusingFGnano-sheetsasthecatalystsupport.Herewereportonsingle-sitechromium(III)constrained-gemeycyimmbiizeemi?e-freeMAO-impregnatedFGnanosheetdispersionsinn-heptane.ThisnovelcatalystgenerationisemployedinPFTto

28、producenewUHMWPE/FGnanocompositefamilies.FGiscomparedwithothernanoparticlessuchasMWCNT,nanometer-scale6879Articleboehmites,carbonblack,andconventionalgraphite.Thei?ececyeicyactivityandthethermal,mechanical,andelectricalpropertiesofUHMWPEnanocompositesareinvestigated.EXPERIMENTALSECTIONMaterialsandGe

29、neralConsiderations.Allreactionsinvolvingair-andmoisture-sensitivecompoundswerecarriedoutunderadryargonatmosphereusingstandardSchlenktechniquesandaglovebox.Toluene(anhydrous),n-heptane(anhydrous),andtriisobutylalumi-num(TiBAl,1Minhexane)werepurchasedfromSigma-Aldrich.Teeeeweeei?eigVcm-3,4,5-AmeeC.ve

30、i?e.Tecy,ic5trimethyl-1-(8-quinolyl)-2-trimethylsilyl-cyclopentadienylchromium-(Cr1),wassynthesizedinthegroupofM.EndersbyDr.S.Mark,UniversityofHeidelberg,followingprocedurespreviouslyreported.47MAO,purchasedfromCrompton,hadanAlcontentof10wt%intolueneandwasstoredunderadryargonatmosphereinaglovebox(MB

31、raunMB150B-G-II).Ethylene(3.0)wassuppliedbyAirLiquideandwasusedwithoutei?ci.Thefollowingcommercial,carbon-basedcatalystsupportswereused:CNT(BaytubesC150P,BayerAG),carbonblack(PrintexXE2B,EvonikIndustries),graphite(KF99.5,mhlAG),andboehmite(Disperal40,kindlysuppliedbySasolGermany).Mesoporousiic,NF20,

32、wyeizebymi?emeofStuckyetal.48,49FGwyeizemgieigmi?eHummersmethodtoobtainGO,whichwasthermallyreducedbyrapidheating(750C)underanN2atmospheretoproduceFGnanosheets51.Thepropertiesofthenanoparticlesemployedinymeizi?igemmizeiTbe1.Table1.MaterialsUsedasCatalystSupportseci?cceeamaterial(m2/g)elementalanalysi

33、sb(%)FG60080.0(C),1.2(H),18.8(O)carbonblack104097.0(C)graphite3099.99(C)boehmite200n.d.cmultiwallcarbon25097.0(C)nanotubesnanofoamNF201200n.d.cabDeterminedusingBETN2absorption.D.d.=notdetermined.CatalystPreparationandEthylenePolymerization.Thecatalystwaspreparedbyheatingthesupportfor2hinvacuoat110C.

34、Itwasthendispersedinn-heptane(10mg/mL)andsonicatedfor40min.Thecocatalystintoluene(10wt%)wasadded,andthemixturewassonicatedfor20min.CatalystCr1intoluene(0.1mg/mL)wasaddedwithasyringe,andthemixturewasstirredfor20min.Thethus-activatedcatalystwastransferredintothereactor,andthepolymerizationwasstarted.W

35、heninorganicsupportswereused,thetemperaturewasmaintainedat160Cfor16hinvacuo.Furthermore,afteradditionofMAO,theactivatedsupportwaswashedwithfreshheptanetoremoveexcessMAO.Ethylenepolymerizationswerecarriedoutina200mLdouble-jacketsteelreactorequippedwithamechanicalstirrerandconnectedtoathermostat.Tothe

36、reactorwereaddeddryn-heptane(80mL)andtriisobutylaluminum(TiBAl;0.5mL1Minhexane)asascavenger.Duringthepolymerizationperiod,theethylenepressurewaskeptconstantat5bar,thetemperatureat40C,andthestirringspeedat1000rpm.Polymerizationwasstoppedbyijecigcii?eme.Teymew?eeffanddriedfor16hat65Cunderreducedpressu

37、retoconstantweight.Polymerizationsforonlinekineticsmeasurementswerecarriedouti600mcieecveeqiewimecicstirrerandasoftwareinterface.Thereactor,previouslychargedwithn-x.i.g/10.1021/m301376q|cmece2012,45,6878-6887较高的摩尔围绕包块。在我们的研究中，我们检查的PFT与FG纳米片作为纳米填料和催化剂载体。石墨烯是拥有1个碳原子厚度的碳片。SP2-这个单层杂化的碳原子排列在一个蜂窝状格。是0.14纳

38、米的原子直径和几个微米宽度的片材，典型的石墨烯的长宽比大于10000。他们表现出优异的性能，包括超高强度，在室温下传达超高速电子，特别高的刚性，耐磨性和性以及强烈的紫外线和红外线吸取.其他到高度圆满的理想石墨烯，多种羟基官能石墨烯是可用的。16-19FG的制备是由贝姆和同事在1969年利用氧化石墨（GO）首创的，这是160多年前首次由布罗迪在牛津大学合成的.22热或GO的化学还原供给FG纳米薄片.23，24这种层状化合物中的氧含量在还原过程中的温度被控制，并减缓提高还原温度。主要的氧在温度高于400的功能对应于羟基基团，而环氧基，羰基和羧基基团进行在这样的温度下快速热解。FG的比表面积一般在6

39、00-1200平方米/克的范围内。这是较理想的石墨烯（2630平方米/小得多G）.25,26剪切后的微米级，手风琴状FG的颗粒形态借助于超声办理，大功能化石墨烯颗粒完好崩溃供给单FG纳米片。这是经过大量增加的反射比表面积为600?1800左右m2/g.27由于FG拥有高表面积超低体积密度，PFT是用于生产聚烯烃/FG母粒能够被增加到老例聚烯烃基质。据Yanetal.，以前除了1（重量）的FG压缩成形显然提高了耐磨损性。28同时拥有改进的耐磨损性的超高分子量聚乙烯的生物相容性不受影响.29一些研究小组已经在聚合填充中使用石墨和FG。但是，与助催化剂甲基铝氧烷（MAO）的填料是一最常用的方法为有效

40、的固定化金属茂和过氧化茂催化剂.11,30-35的杜波依斯成功地采用微米级石墨填料在PFT工艺生产热塑性聚乙烯/石墨复合资料的分别体。36FG纳米复合资料与低分子量热塑性高密度聚乙烯，低密度聚乙烯37,38，39线性低密度聚乙烯，聚丙烯40，41和其他聚合物如聚苯胺已被报道.42-46要尽我们的知识，还没有对聚合填充报告，使用FG纳米片生产超高分子量聚乙烯/FG纳米复合资料作为催化剂载体。在这里，我们对单中心铬（III）拘束几何催化剂固定化在无乳化剂的MAO浸渍的FG纳米片的分别体中的正庚烷进行报告。这种新式催化剂的产生是受益于PFT产生新的超高分子量聚乙烯/FG纳米复合资料。FG与比较其他纳

41、米粒子比较，如MWCNT，纳米尺度的勃姆石，炭黑，和传统的石墨。对该催化剂的活性和超高分子量聚乙烯的热，机械和电气性能纳米复合资料进行了研究。实验部分资料与一般注意事项。所有涉及的反响空气和湿气敏感的化合物，分别使用标准Schlenk技术和氩气氛手套箱进行干燥。甲苯（无水），正庚烷（无水的），和三异丁基铝（TIBAL，1M的己烷溶液）购自Sigma-Aldrich公司购买。甲苯和庚烷使用真空进一步纯化大气有限公司溶剂净化器。催化剂，二氯-3,4,5-三甲基-1-（8-喹啉基）-2-三甲基硅烷基-环戊二烯基铬（三）（CR1），由恩泽斯博士S.马克在海德堡大学合成，下面的程序前面报道过.MAO，购

42、自Crompton，Al含量为10重量的甲苯、在干燥的氩气氛下，储藏在一个手套箱（布劳恩MB150B-G-II）。乙烯（3.0）是由法国液化空气供给并且在使用时无需进一步纯化。以下商业，碳系催化剂载体是使用：CNT（的BaytubesC150P，拜耳公司），炭黑（的PrintexXE2B，赢创工业公司），石墨（KFL99.5，）和薄水铝石（40的Disperal，由Sasol德国友情供给）。介孔二氧化硅，NF20，是由改进方法斯塔基等合成的al.48，使用改进的过程，FG是由经过改进法从石墨氧化物获得的炭黑合成的，这是由热减少快速加热（750）在N2气氛下，以产生FG中使用的纳米颗粒的纳米薄片

43、聚合填充的属性汇总于表1中。MacromoleculesheptaneandTiBAl,wassaturatedthreetimeswithethyleneCat40beforepolymerizationwasstartedbyadditionofthecatalyst.PolymerCharacterization.ThewMandMWDofthepolymersweredeterminedusingaPL-220chromatograph(PolymerLabo-ratories)equippedwithadifferentialrefractiveindex(DRI)detector,

44、adifferentialviscometer210R(Viscotek),andalow-anglelight-scattering(LASS)detector.Polyeyeewe?eUHWPEwhenitsMwexceeded106g/mol.Themeasurementswereperformedat150CwiththreePLGelOlexiscolumns,and1,2,4-trichlorobenzene(Merck)stabilizedwith0.2wt%2,6-di-tert-butyl-(4-methylphenol)(Aldrich)wasusedasve?we1.0m

45、L/min.Columnswerecalibratedusing12polystyrenesampleswithanarrowMWD.MeltingpointsandtheoverallthermalbehavioroftheneatpolymerweredeterminedbydifferentialscanningcalorimetryusingaDSC6200fromSeikoInstruments.Thepolymerwasheatedfromroomtemperatureto200C,keptatthistemperaturefor5min,ce-70C,eeegi200C.Tewa

46、skeptconstantat10K/min.TEMmicroscopywasperformedwithaLEOEM912OmegadeviceandSEMmicroscopywithaQuanta250FEG.ParticlesizesweremeasuredusingaCamsizerfromRetschTechnologies.Theresistanceofallnanocompositeswasmeasuredwithafour-pointprobe.Acorrectionfactorthatdependsonthesamplegeometrywastakenintoaccountin

47、thecalculations50The.tensilemodulusofthenanocompositeswasmeasuredwithaZwickmodelZ005(DINENISO527).PolymerProcessing.TheobtainedUHMWPE/FGnanocompo-sitesampleswerecompression-moldedinaCollin200Pmeltpress(Dr.CollinGmbH,Germany).Thetensilespecimenswerestampedoutof100702mmpolymerplates.Thecompression-mol

48、dingparametersarelistedinTable2.Table2.ConditionsforProcessingUHMWPENanocompositesstages12345temp(C)21021021021025press.(bar)1530405060ArticlereactwithMAO,thusbondingandcoatingMAOontotheFGsurface.ThisoxygenfunctionalityisessentialforproducingstableFGdispersionswithoutrequiringadditionofemulsi-?ers.5

49、4-58TheresultingFG/MAOwasusedtosupportCr1.Thesamecatalystpreparationprocedurewasappliedtoother(nano)particles(cf.Table1),suchasmultiwallCNT,conductiveCBwithanaveragesizeof20nm,andaluminumoxidehydroxide(boehmite)withaverageprimaryparticlesizeof40nmaswellasaconventionalmicrometer-sizedgraphite?e(80m)(

50、c.Tbe1).IcFG,ecbmaterialsfailedtoproducestabledispersionsinn-heptane.BothCNTandgraphitecontainfewfunctionalgroupsandareunabletoeffectivelybondMAOandCr1,whichonlylooselyadheretothecarbonsupport.Incontrast,CBhasabee-hive-likemorphology59resemblingthestructureofporouseigegraphiteandisabletoadsorbMAOand

51、Cr1initspores.Nanometer-scaleboehmitewasemployedforcomparison.Inpreviousexperiments,boehmitenanoparticleswereusedsuccessfullyinbothPFT60andmeltextrusion61toproducethermoplasticHDPEnanocompositesandiPPnanocompositeswitheffectiveboehmitedispersionandimprovedstiffness.ThemesoporoussilicateNF20(averagep

52、orediameter20nm)wassynthesizedaccordingtomethodsproposedbyStuckyetal.46,61andbyproceduresreportedearlierforHDPEformation.59Ethylenewaspolymerizedinn-heptaneat40Cand5barethylenepressureforbetween22and72mininastirredcvececmiewie?e?econtents.AtaconstantAl/Crmolarratioof1400,theFGcontentinUHMWPEwasvarie

53、d(0.5,1,2.5,5,and10wt%).TheresultsoftheethylenepolymerizationsaresummarizedinTable3.Theonlinekineticsofthepolymerizations(cf.Table3.PolymerizationFillingandVariationoftheFillerContenttime(min)103010530RESULTSANDDISCUSSIONCatalystPreparationandPolymerizationFilling.Thesyntheticstrategyforimmobilizati

54、onofsingle-sitechromium-(III)cyFGiwiceme1.Ie?e,FGScheme1.SyntheticRoutetoaSingle-SiteChromiumCatalyst(Cr1)SupportedonFGentry?llerFGFGFGFGFGCBCNT8dboehmite9graphite10e,fNF20tpolactivitybMwcwt%a(min)(g/(mmolh)(g/mol)PDc0.543200002.01063.3147181001.81063.62.534254002.11063.6522402002.21063.61028276002.

55、41063.7547185012.81064.0550176001064.8572117001063.9560143001065.351170001064.6aWt%of?llerintheproduct.bTime-averagedactivity.cDeterminedbyHT-GPC.dWashingprocessbetweencatalystadditionandadditiontothepolymerizationvesselwasincluded.eWashingprocessbetweencatalystadditionandadditiontothepolymerization

56、vesselwasincluded.fForthepolymerizationwithNF20anamountof50mgofsupportwasusedtoimmobilizethecatalyst.Polymerizationcondition:C1=2.3m/;A:C=1400:1;=5bar;mpol=10g;V=300mL;TiBAl=1mL,40ethylene2mGOccigHmmeheptaneC,n-heptane.(600m/g)weemethodandwassubsequentlythermallyreducedbyvery51rapidheatingto750C,fol

57、lowingproceduresreportedbyFigure1)implythatFGreachesthehighestactivitiesasAksayandco-workers.TheresultingFGhadanoxygencomparedtomesoporoussilica,whereasothercarbon-based52,53contentof18.8wt%andacarboncontentof80.0wt%.Inthe?llers,exceptCB,wigi?cwecyciviie.secondstep,theFGwasdispersedinn-heptanebymean

58、sofI?eceNiceA/C1eAciviysonicationpriortoaddingMAOanddichloro-3,4,5-andMolecularWeight.UHMWPEnanocompositeswere5trimethyl-1-(8-quinolyl)-2-trimethylsilylcyclopentadienyl-obtainedbypolymerizingethyleneat5barand40Cinn-chromium(III)(Cr1).ThefunctionalgroupsofFG(1.5mmolheptaneatdifferentAl/Cr1ratiosinthe

59、presenceofvariousOH/g)predominantlyconsistedofhydroxylgroups,which6880?llers.WhereashomogeneousCr1/MAOintoluenefailedtox.i.g/10.1021/m301376q|cmece2012,45,6878-688表1.资料用作催化剂载体资料比表面积AREAA（平方米/克）元素analysisb（）FG60080.0（C）1.2（H），18.8（O）炭黑104097.0（C）石墨3099.99（C）勃姆石200未检测出多壁碳碳纳米管25097.0（C）纳米泡沫NF201200未检测出

60、确定采用BETN2吸附。经过元素确定解析。未检测出=未测定催化剂的制备及乙烯聚合。该制备催化剂，经过在110C的真空中在加热2小时制备。尔后将其分别在正庚烷（10毫克/毫升）中，超声办理40分钟内。加入甲苯（10重量）助催化剂，且将混杂物超声办理20分钟。催化剂的Cr1在甲苯（0.1毫克/mL）溶液用注射器加入，并且将混杂物搅拌20分钟。由此活化的催化剂转移到反响器中，并且开始聚合。当使用了无机载体，温度保持在160下在真空中16小时。其他，其他乙烯聚合物在一个200毫升的双夹套钢反响器中配有进行机械搅拌器并连接到一个恒温器。向反响器中分别加入无水正庚烷（80mL）和三异丁基铝（TIBAL;0