【正文】 MacromoleculesArticleAl/Cr ratio did not affect catalyst adsorption because theparticle suspensions were washed with heptane to removeexcess MAO prior to Cr1 addition. Such procedures were notpossible for FG/Cr1/MAO because stable dispersions wereobtained (no sedimentation over a period of 4 h). As illustratedin Figure 2, all carbonsupported Cr1/MAO catalysts affordedUHMWPE with molar masses close to or above 10 6 g/mol.The in?uence of ?ller type and Al/Cr play an important role(cf. Table 3). The highest activities of the FG/MAO/Cr1catalyst were found at an Al/Cr molar ratio of 1500. Decreasingthis ratio decreased the catalyst activity, whereas the UHMWPEmolar mass substantially increased from 600 to 3000 kg/mol.Since it is wellknown that MAO solutions contain smallamounts of trimethylaluminum (TMA), it is very likely thatsimultaneously increasing the MAO and trimethylaluminumcontents will decrease the polyethylene molar At lowAl/Cr ratios, the catalyst activity is lower because the content ofMAO is not su?cient to scavenge catalyst poisons (.,hydroxyl groups) on the surface of FG.Very similar behavior and in?uence of the Al/Cr molar ratioon the catalyst activity were found for other carbon ?llers, suchas CNT and carbon black (cf. Figure 2 and Table 4), whereinoptimum Al/Cr molar ratios are slightly different and mostlikely depend on the type of adhesion of MAO to the support.Typical polyethylene powders and PE particle size distributionsare shown in Figure 3. The Cr1/MAO and the graphite/Cr1/MAO catalysts generate ?ne powders. Such particle distributions with high proportions of small, dustlike particles areproblematic with respect to health and safety and also makeUHMWPE unsuitable for largescale processing. Excellentmorphological control was achieved in the presence of FGnanosheet dispersions. Much larger granulelike UHMWPEparticles with a monomodal size distribution and averagediameters of 4000 μm were obtained. No fouling and handlingproblems wer。 Vheptane = 300毫升。乙烯= 5巴。聚合條件： CR 1 = μmol/ L的。之間的洗滌過程催化劑添加和添加到聚合容器是包括在內。決心通過HT GPC 。聚合填充和填充物的變化內容進入 填料 重量％ POL（分鐘） 活動（克/ （毫摩爾小時） ） MW（克/摩爾） PD1 FG 43 20 000 106 2 FG 1 47 18 100 106 3 FG 34 25 400 106 4 FG 10 22 40 200 106 5 FG 10 28 27 600 106 6 CB 10 47 18 501 106 7 CNT 5 50 17 600 106 8 勃姆 5 72 11 700 106 9 石墨 5 60 14 300 106 10 NF 20 51 17 000 106 填料中的產品％（重量） 。聚合反應（參見圖1）的動力學暗示FG相比于介孔二氧化硅及其他碳基填料到達最高活動，除CB，顯示出催化劑活性顯著降低。乙烯，在40℃和5巴條件下，控制時間在22到72分鐘之間，在正庚烷中聚合，并攪拌乙烯在高溫高壓下滅菌，生產納米復合材料與填料。在以前的實驗中，勃姆石納米顆粒被成功地在這兩用在PFT，以及熔融擠出生產熱塑性復合材料高密度聚乙烯和聚丙烯納米復合材料。與此相反， CB有一個蜂箱，樣形態(tài)類似多孔結構石墨，能夠吸附MAO和CR1在其孔隙中。相同的催化劑制備過程中應用到其它（納米）顆粒（參見表1 ），如多壁CNT，具有20納米的平均尺寸，和鋁的導電CB氫氧化物（勃姆石）（平均粒徑為其他碳材料不能中在正庚烷中產生穩(wěn)定的分散體。這氧的功能是用于產生FG必需的穩(wěn)定乳液，而無需添加乳化劑。在第二步驟中， FG是借助于超聲處理之前分散在正庚烷中，并加入MAO和二氯〔 3,4,5 三甲基1 （8 喹啉基）2 三甲基甲硅烷] 鉻（III） （CR1） 。該對于單中心鉻固定化合成策略（Ⅲ）上的FG催化劑示于方案1中，在第一步驟中，根據(jù)悍馬制備方法FG（600米2 /克）購自GO ，隨后通過方案1 。壓縮成型參數(shù)列于表2中。所獲得的UHMWPE /納米復合FG樣品被壓縮成形200P熔體按（科林博士GmbH，德國） 。該納米復合材料的拉伸彈性模量的測定使用的Zwick型號Z005 （ DIN EN ISO 527 ） 。測量所有的納米復合材料的電阻用四點探針。與進行透射電鏡顯微鏡一個LEO的EM 912歐米茄設備和SEM顯微與廣達250 FEG 。所述聚合物的混合物加熱從室溫至200℃，在該溫度保持5分鐘，冷卻至70℃ ，然后再加熱到200 ℃。柱采用12聚苯乙烯樣品與校準窄MWD 。聚被定義為超高分子量聚乙烯當它的分子量超過106克/摩爾。聚合物表征。聚合網上動力學進行測量在一個600毫升BUCHI制高壓釜裝有機械攪拌器和軟件界面。聚合停止注入酸化甲醇。在聚合期間，乙烯壓力保持在5巴，在40176。向反應器中分別加入無水正庚烷（ 80mL）和三異丁基鋁（TIBAL 。當使用了無機載體，溫度保持在160℃下在真空中16小時。催化劑的Cr1在甲苯（ ）溶液用注射器加入，并且將混合物攪拌20分鐘。然后將其分散在正庚烷（ 10毫克/毫升）中，超聲處理40分鐘內。該制備催化劑，通過在110176。通過元素確定分析。C, nheptane.Figure 1) imply that FG reaches the highest activities aspared to mesoporous silica, whereas other carbonbased?llers, except CB, show signi?cant lower catalyst activities.In?uence of Nanoparticles and Al/Cr1 on the Activityand Molecular Weight. UHMWPE nanoposites wereobtained by polymerizing ethylene at 5 bar and 40 176。 Vheptane = 300 mL。 pethylene = 5 bar。C, following procedures reported byAksay and ,53 The resulting FG had an oxygencontent of wt % and a carbon content of wt %. In thesecond step, the FG was dispersed in nheptane by means ofsonication prior to adding MAO and dichloroη5[3,4,5trimethyl1(8quinolyl)2trimethylsilylcyclopentadienyl]chromium(III) (Cr1). The functional groups of FG ( mmolOH/g) predominantly consisted of hydroxyl groups, whichsupport was used to immobilize the catalyst. Polymerizationconditions: Cr1 = μmol/L。C and 5 barethylene pressure for between 22 and 72 min in a stirredautoclave to produce nanoposites with de?ned ?llercontents. At a constant Al/Cr molar ratio of 1400, the FGcontent in UHMWPE was varied (, 1, , 5, and 10 wt %).The results of the ethylene polymerizations are summarizedin Table 3. The online kinetics of the polymerizations (cf.12345Table 3. Polymerization Filling and Variation of the Fillertemp (176。C, and then heated again to 200 176。C with three PLGel Olexis columns, and 1,2,4trichlorobenzene (Merck) stabilized with wt % 2,6ditertbutyl(4methylphenol) (Aldrich) was used as a solvent at a ?ow rate of mL/min. Columns were calibrated using 12 polystyrene samples witha narrow MWD. Melting points and the overall thermal behavior ofthe neat polymer were determined by differential scanning calorimetryusing a DSC 6200 from Seiko Instruments. The polymer was heatedfrom room temperature to 200 176。Macromoleculesheptane and TiBAl, was saturated three times with ethylene at 40 176。下列商業(yè)，碳系催化