新型石墨烯超高分子量聚乙烯納米復(fù)合材料講義

1、優(yōu)選文檔優(yōu)選文檔PAGEPAGE45優(yōu)選文檔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在功能化石墨烯納米片分別體上采用可支持的單中心催化劑經(jīng)過聚合填充制備新式石墨烯超高分子量聚乙烯納米復(fù)合資料大綱：制備含有平均分散功能化石墨烯（FG）納米片的新式石墨烯超高分子量聚乙烯納米復(fù)合資料，準(zhǔn)備借聚合填充技術(shù)（PFT）。與其他碳和水軟鋁石納米復(fù)合資料對照，F(xiàn)G/UHMWPE在剛性上表現(xiàn)出不平時(shí)的同步提高，斷裂伸長率，聚乙烯結(jié)晶僅為1（重量）。FG納米片是極薄的，厚度只有一個(gè)碳原子和幾個(gè)微米的橫向尺寸。由于表面羥基上的FG存在下，單FG/甲基鋁氧烷（MAO）的納米

15、片能夠有效地分別在正庚烷，從而使一個(gè)被MAO活化的鉻（CR1）上的FG單活性中心催化劑固定化。而對照之下，納米級炭黑（CB），多壁碳納米管（CNT），石墨和納米勃姆石，難以形成牢固的分別體，F(xiàn)G/MAO/Cr1供給最高的催化劑活性和優(yōu)異的形態(tài)控制。在聚合填充物，納米顆粒分別體的交融到聚合過程除掉了平時(shí)需要由納米粒子擁有超低容積密度的混雜安全和辦理措施。序言超高分子量聚乙烯（UHMWPE），摩爾質(zhì)量高出100萬，它最主要的特點(diǎn)是擁有超高韌性結(jié)合高耐磨性，特別低的摩擦系數(shù)，低吸濕性和優(yōu)異的化學(xué)牢固性。床單，部件和纖維都是有超高分子量聚乙烯生產(chǎn)的。應(yīng)用范圍從耐磨輸送皮帶和增強(qiáng)工程塑料生物質(zhì)料，植入的

16、髖，膝，脊柱和代替使用，高強(qiáng)度凝膠紡絲UHMWPE織物用來做做防水繩索，防割手套，防彈車身、防彈衣.關(guān)于好多應(yīng)用，特別希望改進(jìn)超高分子量聚乙烯的結(jié)晶速率，韌性/剛性平衡，特別是電和熱傳導(dǎo)性，由于超高分子量聚乙烯是熱和電的絕緣體。前提是實(shí)現(xiàn)有效的分散，各向異性納米顆粒可顯然改進(jìn)聚烯烴的性能。UHMWPE納米和與碳黑微觀復(fù)合，石墨，和多壁碳納米管（MWCNT），經(jīng)過壓縮成型裝置進(jìn)行了辦理，獲得了開發(fā)，以提高導(dǎo)電性。應(yīng)該指出的該干粉混雜納米粒子的安全預(yù)防措施和辦理程序，以防范排放，粉塵爆炸，吸入或吸取納米粒子而產(chǎn)生健康危害。近來的進(jìn)展，石墨烯納米薄片的推出6-8納米的平均厚度和120-150平方米/

17、克的比表面積的靜電噴涂（石墨烯納米薄片）懸浮液。這樣的石墨烯納米薄片含有高出60石墨烯納米片生產(chǎn)超高分子量聚乙烯/石墨烯納米薄片納米復(fù)合膜表現(xiàn)出顯然改進(jìn)的斷裂韌性和抗張強(qiáng)度含量僅為0.1（重量）.傳統(tǒng)生產(chǎn)超高分子量聚乙烯復(fù)合資料，是將石墨氧化物（GO）和化學(xué)還原的石墨氧化物分別在稀釋劑如乙醇，爾后在模壓前噴涂到超高分子量聚乙烯粉末。為了優(yōu)化資料的性能，希望實(shí)現(xiàn)納米填料的分別并直接進(jìn)入乙烯聚合，液體的低粘度有利于聚合介質(zhì)，從而防范納米粒子的發(fā)射在同一時(shí)間。在催化聚合填料（“原位聚合”）的存在下，以生產(chǎn)傳統(tǒng)的熱塑性聚烯烴化合物被廣泛地使用，擁有特別高的填料含量。在聚合填充工藝，該填料被用作催化劑載

18、體，以使基質(zhì)直接從納米填料表面生長。在聚合進(jìn)行中填充技術(shù)（PFT）聚烯烴向出處Dubois和Kaminsky改進(jìn).單活性中心催化劑審查技術(shù)供給剪裁烯烴激動(dòng)人心的新時(shí)機(jī)聚合11和PFT流程經(jīng)過設(shè)計(jì)兩個(gè)聚烯烴分子結(jié)構(gòu)和聚烯烴粒子形態(tài)。PFT能供給聚烯烴納米復(fù)合資料顯然改進(jìn)CNT的分別性和導(dǎo)電性，從而使老例聚烯烴產(chǎn)生有效電磁障蔽但是，相當(dāng)少的已知與關(guān)于PFT生產(chǎn)超高分子量聚乙烯復(fù)合資料。近來，Rastogi醫(yī)師等。報(bào)告了超高分子量聚乙烯的形成使用水楊醛制備的納米復(fù)合資料PFT支持TiO2，ZrO2和碳納米管的催化劑。由此納米復(fù)合資料表現(xiàn)出改進(jìn)的納米填料的分別性和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較高的摩爾圍繞包塊。在我們的研究中，我們檢查的PFT與FG納米片作為納米填料和催化劑載體。石墨烯是擁有1個(gè)碳原子厚度的碳片。SP2-這個(gè)單層雜化的碳原子排列在一個(gè)蜂窩狀格。是0.14納

38、米的原子直徑和幾個(gè)微米寬度的片材，典型的石墨烯的長寬比大于10000。他們表現(xiàn)出優(yōu)異的性能，包括超高強(qiáng)度，在室溫下傳達(dá)超高速電子，特別高的剛性，耐磨性和性以及強(qiáng)烈的紫外線和紅外線吸取.其他到高度圓滿的理想石墨烯，多種羥基官能石墨烯是可用的。16-19FG的制備是由貝姆和同事在1969年利用氧化石墨（GO）首創(chuàng)的，這是160多年前首次由布羅迪在牛津大學(xué)合成的.22熱或GO的化學(xué)還原供給FG納米薄片.23，24這種層狀化合物中的氧含量在還原過程中的溫度被控制，并減緩提高還原溫度。主要的氧在溫度高于400的功能對應(yīng)于羥基基團(tuán)，而環(huán)氧基，羰基和羧基基團(tuán)進(jìn)行在這樣的溫度下快速熱解。FG的比表面積一般在6

39、00-1200平方米/克的范圍內(nèi)。這是較理想的石墨烯（2630平方米/小得多G）.25,26剪切后的微米級，手風(fēng)琴狀FG的顆粒形態(tài)借助于超聲辦理，大功能化石墨烯顆粒完好崩潰供給單FG納米片。這是經(jīng)過大量增加的反射比表面積為600?1800左右m2/g.27由于FG擁有高表面積超低體積密度，PFT是用于生產(chǎn)聚烯烴/FG母粒能夠被增加到老例聚烯烴基質(zhì)。據(jù)Yanetal.，以前除了1（重量）的FG壓縮成形顯然提高了耐磨損性。28同時(shí)擁有改進(jìn)的耐磨損性的超高分子量聚乙烯的生物相容性不受影響.29一些研究小組已經(jīng)在聚合填充中使用石墨和FG。但是，與助催化劑甲基鋁氧烷（MAO）的填料是一最常用的方法為有效

40、的固定化金屬茂和過氧化茂催化劑.11,30-35的杜波依斯成功地采用微米級石墨填料在PFT工藝生產(chǎn)熱塑性聚乙烯/石墨復(fù)合資料的分別體。36FG納米復(fù)合資料與低分子量熱塑性高密度聚乙烯，低密度聚乙烯37,38，39線性低密度聚乙烯，聚丙烯40，41和其他聚合物如聚苯胺已被報(bào)道.42-46要盡我們的知識，還沒有對聚合填充報(bào)告，使用FG納米片生產(chǎn)超高分子量聚乙烯/FG納米復(fù)合資料作為催化劑載體。在這里，我們對單中心鉻（III）拘束幾何催化劑固定化在無乳化劑的MAO浸漬的FG納米片的分別體中的正庚烷進(jìn)行報(bào)告。這種新式催化劑的產(chǎn)生是受益于PFT產(chǎn)生新的超高分子量聚乙烯/FG納米復(fù)合資料。FG與比較其他納

41、米粒子比較，如MWCNT，納米尺度的勃姆石，炭黑，和傳統(tǒng)的石墨。對該催化劑的活性和超高分子量聚乙烯的熱，機(jī)械和電氣性能納米復(fù)合資料進(jìn)行了研究。實(shí)驗(yàn)部分資料與一般注意事項(xiàng)。所有涉及的反響空氣和濕氣敏感的化合物，分別使用標(biāo)準(zhǔn)Schlenk技術(shù)和氬氣氛手套箱進(jìn)行干燥。甲苯（無水），正庚烷（無水的），和三異丁基鋁（TIBAL，1M的己烷溶液）購自Sigma-Aldrich公司購買。甲苯和庚烷使用真空進(jìn)一步純化大氣有限公司溶劑凈化器。催化劑，二氯-3,4,5-三甲基-1-（8-喹啉基）-2-三甲基硅烷基-環(huán)戊二烯基鉻（三）（CR1），由恩澤斯博士S.馬克在海德堡大學(xué)合成，下面的程序前面報(bào)道過.MAO，購

42、自Crompton，Al含量為10重量的甲苯、在干燥的氬氣氛下，儲藏在一個(gè)手套箱（布勞恩MB150B-G-II）。乙烯（3.0）是由法國液化空氣供給并且在使用時(shí)無需進(jìn)一步純化。以下商業(yè)，碳系催化劑載體是使用：CNT（的BaytubesC150P，拜耳公司），炭黑（的PrintexXE2B，贏創(chuàng)工業(yè)公司），石墨（KFL99.5，）和薄水鋁石（40的Disperal，由Sasol德國友情供給）。介孔二氧化硅，NF20，是由改進(jìn)方法斯塔基等合成的al.48，使用改進(jìn)的過程，F(xiàn)G是由經(jīng)過改進(jìn)法從石墨氧化物獲得的炭黑合成的，這是由熱減少快速加熱（750）在N2氣氛下，以產(chǎn)生FG中使用的納米顆粒的納米薄片

43、聚合填充的屬性匯總于表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.資料用作催化劑載體資料比表面積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未檢測出多壁碳碳納米管25097.0（C）納米泡沫NF201200未檢測出

60、確定采用BETN2吸附。經(jīng)過元素確定解析。未檢測出=未測定催化劑的制備及乙烯聚合。該制備催化劑，經(jīng)過在110C的真空中在加熱2小時(shí)制備。爾后將其分別在正庚烷（10毫克/毫升）中，超聲辦理40分鐘內(nèi)。加入甲苯（10重量）助催化劑，且將混雜物超聲辦理20分鐘。催化劑的Cr1在甲苯（0.1毫克/mL）溶液用注射器加入，并且將混雜物攪拌20分鐘。由此活化的催化劑轉(zhuǎn)移到反響器中，并且開始聚合。當(dāng)使用了無機(jī)載體，溫度保持在160下在真空中16小時(shí)。其他，其他乙烯聚合物在一個(gè)200毫升的雙夾套鋼反響器中配有進(jìn)行機(jī)械攪拌器并連接到一個(gè)恒溫器。向反響器中分別加入無水正庚烷（80mL）和三異丁基鋁（TIBAL;0