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制备间规聚苯乙烯的新型催化剂的研究 总被引:1,自引:0,他引:1
对位卤素取代的苯酚与五甲基三氯单茂钛在三乙胺存在下进行酯化反应,制得4种五甲基茂基三(对—卤代苯氧基)钛的新型茂钛化合物[Cp^*Ti(O—C6H4—X)3,(X为F、Cl、Br、D)]。经元素分析、质谱、核磁共振谱证实了上述结构。在甲基铝氧烷和三异丁基铝活化下,4种茂钛化合物对苯乙烯间规聚合显示出极高的催化活性,制得的间规聚合物间规度(大于96%)和熔点(大于270℃)高。4种茂钛化合物的活性从大到小依次为:五甲基茂基三(对—氟苯氧基)钛、五甲基茂基三(对—氯苯氧基)钛、五甲基茂基三(对—溴苯氧基)钛、五甲基茂基三(对—碘苯氧基)钛。 相似文献
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非茂金属催化剂用于苯乙烯间规聚合 总被引:2,自引:0,他引:2
研究开发了非茂金属催化剂用于苯乙烯的间规聚合,合成了β-二酮钛配合物/MAO,引入烷氧基的β-二铜钛配合物/MAO,8-羟基喹啉钛配合物/MAO和β-联萘酚钛配合物/MAO等催化体系,其中最好的催化体系用于苯乙烯本体聚合时,在80℃和Al/Ti比为500的聚合条件下,活性达到6×10^5g(PS)/mol(Ti).h,聚合物间规度〉95%,熔点达270℃,本文也能催化剂结构和性能关系的研究结果进行 相似文献
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茂钛催化剂合成及苯乙烯间规聚合 总被引:2,自引:0,他引:2
介绍了茂钛催化剂CpTi(OPh)3(Cp为环戊二烯基)的合成。使用CpTi(OPh)3/MAO均相催化体系,研究了工艺条件对苯乙烯间规聚合的影响。初步探讨了以带有反应性功能基团的聚苯乙烯为载体,负载CpTiCl3后进行的苯乙烯间规聚合。同时采用了不同配体的CpTi(OR)3催化剂用于苯乙与乙烯或丙烯共聚合,得到的共聚产物是一类应用前景良好的工程塑料。 相似文献
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间规聚苯乙烯的特性及应用前景 总被引:4,自引:0,他引:4
用茂金属催化剂制得间规聚苯乙烯(sPS)是一类新型结晶聚合物,具有优良的耐热性,耐化学性和电气性能。综合考虑价格/性能因素,sPS在工程塑料的应用市场上具有很强的竞争力,本文对sPS的物性及应用景景作一简要介绍。 相似文献
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间规聚苯乙烯具有低比重、优良的电气特性、耐水解性、易成型以及良好的耐热性、耐化学药品性、尺寸稳定性,在未来的许多领域具有应用价值。上海石油化工院和中山大学已经完成了新型茂钛间规聚苯乙烯催化剂的研究,创制出具有自己专利技术的产品,产品性能已达到国外同类催化剂的先进水平,同时还对聚合物的加工做了更深入的研究。 相似文献
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《精细与专用化学品》2000,8(14):19-20
中科院化学研究所合成了新型非茂钛类配合物,研究了该类催化剂在溶液和本体条件下催化苯乙烯间规聚合,完成了苯乙烯间规聚合的模试实验,并研究了所得间规聚苯乙烯的物理性能和加工性能。 相似文献
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介绍了一种新型有机金属配合物-单茂钛,它与MAO构成的催化体系实现了间规聚苯乙烯的本体聚合,同时得到了苯乙烯间规小试聚合的优化工艺条件,铝钛比500;聚合温度40℃,聚合时间30min。 相似文献
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Syndiotactic polystyrene (sPS) was synthesized with a novel monotitanocene complex of η5‐pentamethylcyclopentadienyltri‐4‐methoxyphenoxy titanium [Cp*Ti(OC6H4OCH3)3] activated by methylaluminoxane (MAO) in different polymerization media, including heptane, toluene, chlorobenzene, and neat styrene. In all cases bulk polymerization produced sPS with the highest activity and molecular weight. Solution polymerization produced much better activity in heptane than in the other solvents. Using a solvent with a higher dipole moment, such as chlorobenzene resulted in lower activity and syndiotacticity because of the stronger coordination of solvent with the Ti(III) active species, which controlled syndiospecific polymerization of styrene. With bulk polymerization at a higher polymerization temperature the Cp*Ti(OC6H4OCH3)3–MAO catalyst produced sPS with high catalytic activity and molecular weight. The external addition of triisobutylaluminum (TIBA) to the Cp*Ti(OC6H4OCH3)3–MAO system catalyzing styrene polymerization led to significant improvement of activity at a lower Al:Ti molar ratio, while the syndiotacticity and molecular weight of the yields were little affected. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1243–1248, 2001 相似文献
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Roghieh Jamjah Gholam Hossien Zohuri Mitra Masnadi Saied Ahmadjo Mehdi Nekomanesh 《应用聚合物科学杂志》2006,101(4):2216-2221
Syndiotactic polystyrene (s‐PS) was prepared using monotitanocene catalyst of cyclopentadienyl titanium trichloride (CpTiCl3) activated by methylaluminoxane (MAO). Solution polymerization was carried out in toluene using different polymerization conditions. Syndiotacticity index (SI) between 68 and 91.6% was obtained. Increasing Al/Ti molar ratio shows an increase in both conversion percentage and SI. The conversion increased linearly with increasing Al/Ti molar ratio in the range studied. The conversion reached to an optimum value of about 65% at styrene/Al molar ratio of 2.83, while no regular behavior of SI was observed with changing the ratio. Effect of temperature of the range 50–80°C on polymerization was studied. The most favorable temperature for the polymerization regarding activity is 70°C; however SI decreased with temperature up to 80°C. H2 value to 140 mL/100 mL solvent increased the productivity of the catalyst, however further increase of H2 reduced the activity of the catalyst. Polymerization time of 15 to 125 min shows a decrease in activity. The decrease was sharper for about 30 min of polymerization than longer time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2216–2221, 2006 相似文献
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A kinetic study of a syndiospecific polymerization was performed with two kinds of catalysts: Cp*Ti(O(C6H4)CMe2(C6H4)O)TiCp* [bimetallic system] and Cp*Ti(OMe)3 [monometallic system]. The purpose of this study was to determine the reasons behind the high activity of a bimetallic catalyst system. The active site structures of the two kinds of catalysts appears to be similar to the cationic Ti [III] species having η5‐pentamethylcyclopentadienyl ligand, while the rate of the activation process of the bimetallic catalyst was found to be higher than that of the monometallic catalyst. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
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The kinetics of syndiospecific slurry polymerization of styrene in heptane has been investigated with pentamethyl cyclopentadienyl titanium trimethoxide [Cp??Ti(OMe)3] catalyst with methylalmuninoxane. The experimental studies at different styrene/heptane ratios indicate that no global gelation occurs at low styrene/heptane ratios even at high styrene conversion. The effective propagation rate constant tends to decrease as polymerization rate is increased at higher initial styrene concentrations. To analyze the effect of catalyst deactivation, a novel three‐stage polymerization experiment has been designed and carried out where monomer is added during the polymerization. The experimental results show that the catalyst activity is very high at the beginning of polymerization but it decreases significantly as catalyst sites are occluded in the solid phase. We also observe that the catalyst remains active for more than 3 h and the rate decay is not solely due to intrinsic catalyst deactivation. Our experimental data suggests that physical transport effects cause the decay in the polymerization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2132–2137, 2003 相似文献
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Syndiospecific styrene (St) polymerization, catalyzed by the CpTiCl3/methylaluminoxane (MAO) system, was investigated using two different activation procedures. The polymerization parameters included polymerization time, temperature (~25–100°C), ratio of [Al]/[Ti] (~100–1000), and catalyst precursor concentration (~0.5–10.0 × 10?4 mol Ti/L). It was found that adding reactants in the order of (CpTiCl3 + MAO) + St (Injection of Styrene mode) gave much higher monomer conversion rates, higher weight‐average molecular weights, and narrower molecular weight distributions than for the (St + MAO) + CpTiCl3 (Injection of Catalyst mode). The former also yielded significantly higher syndiotacticity fractions. Differential scanning calorimetry measurements showed multiple peaks exhibiting polymorphism in crystalline syndiotactic polystyrene samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1449–1455, 2004 相似文献
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Rate and molecular weight distribution modeling of syndiospecific styrene polymerization over silica-supported metallocene catalyst 总被引:2,自引:0,他引:2
The kinetics of syndiospecific polymerization of styrene over silica-supported Cp∗Ti(OCH3)3/MAO catalyst has been investigated through experimentation and theoretical modeling. At low monomer concentrations, the polymerization rate increases almost linearly with monomer conversion, but the reaction rate becomes independent of monomer concentration at high bulk phase monomer concentrations. A kinetic model that incorporates the monomer partition effect between the solid and the liquid phases has been proposed. The model simulations show that the observed non-linear kinetics can be adequately modeled by the monomer partition model. The polymer molecular weight has also been found to increase with the monomer concentration and the polymer molecular weight distribution (MWD) is quite broad, suggesting that the catalytic behavior deviates from the single site catalytic polymerization model. The MWD broadening is modeled by a two-site kinetic model and a good agreement between the model and the experimental data has been obtained. 相似文献