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制备和分析了不同粒径催化剂及其催化聚合物,研究了球形MgCl_2载体催化剂在乙烯聚合过程中的催化性能和动力学行为。结果表明:大颗粒催化剂的聚合过程中明显存在传热和传质阻力;一定的预聚合可以改善聚合物的形态和堆密度。 相似文献
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用优化乳化法制备了MgCl_2负载钛催化剂,考察了催化剂的形态结构并将其应用于丙烯催化聚合。聚合温度70℃、氢气加入量为1 L,采用二异丁基二甲氧基硅烷作为外给电子体时,催化剂具有较高的催化活性,同时聚丙烯具有较高的等规指数。 相似文献
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Ethylene-propylene copolymers have been prepared by using Ziegler-Natta catalysts based on TiCl4, MgCl2, PCl3 and (n-Bu)3PO4. The catalysts TiCl4/MgCl2/PCl3 and TiCl4/MgCl2/(n-Bu)3PO4 were prepared by reacting TiCl4 with pretreated MgCl2. The support was prepared by ball milling of MgCl2 with varied amounts of PCl3 or (n-Bu)3PO4. The addition of PCl3 has remarkably increased the MgCl2 surface area in comparison with (n-Bu)3PO4. The effects of PCl3 and (n-Bu)3PO4 on ethylene homopolymerization, ethylene-propylene copolymerization and on copolymer properties were evaluated. The catalyst
system containing PCl3 permitted to synthesize propylene-ethylene copolymers with up to 75% (w/w) of propylene and provided control of copolymer
crystallinity. The reduction of the copolymer molecular weight distribution suggested that PCl3 acted as an internal donor, poisoning some active catalytic sites.
Received: 2 April 1997/Revised: 6 June 1997/Accepted: 18 June 1997 相似文献
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Summary Copolymerization of ethylene with -olefins, i.e. propylene, butene-1, 4-methyl-pentene-1(4-MP-1), was carried out by a MgCl2 supported TiCl4 catalyst in combination with Et3Al at a temperature as high as 170 °C at which the polymerization system was homogeneous. This catalytic system showed very a high activity and produced copolymers having a density of 0.91–0.94 g/ml. Of these three kinds of comonomers, propylene showed the highest reactivity and caused most frequently the termination of a polymer growing by chain transfer reaction and produced copolymers having the broadest MWD. 相似文献
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A MgCl2‐supported catalyst containing diisobutyl phthalate (DIBP) and 2,4‐pentadiol dibenzoate (PDDB) as internal donors was prepared. Propylene polymerizations were carried out using the catalyst in the absence or presence of an external donor. The resulting polymers were characterized by 13C‐NMR, crystallization analysis fraction (CRYSTAF) and gel permeation chromatography (GPC). The performance of the catalyst was compared with that of other catalysts containing donor‐free, DIBP and PDDB as internal donors respectively. The results demonstrated that the catalyst containing mixed internal donors not only had high activity and stereospecificity but also produced the polymer with relatively broad molecular weight distribution and the highest [mmmm] value. 13C‐NMR analysis results indicated that strongly coordinating donors gave more stereoregular polymers, which was further confirmed by CRYSTAF data. The effects of mixed internal donors on the catalyst properties were discussed systematically. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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Hitoshi Matsuoka Boping Liu Hisayuki Nakatani Isa Nishiyama Minoru Terano 《Polymer International》2002,51(9):781-784
To investigate the role of the internal donor in a Ziegler–Natta catalyst, the nature and existing states of the internal donor were intentionally varied by alkylaluminium treatment before polymerization, and the catalytic properties during propene polymerization were accurately evaluated using the stopped‐flow method. A significant decrease in the amount of the remaining internal donor was observed during the initial stage of the extraction. The polymerization results show a gradual decrease in the polymer isotacticity with an increase in the extraction time. These different patterns, as a function of the extraction time, indicate that the amount of the remaining internal donor is not directly related to the isotacticity of the produced polymer. © 2002 Society of Chemical Industry 相似文献
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正辛醇改性负载钛催化体系催化异戊二烯聚合的研究 总被引:2,自引:0,他引:2
以不同用量正辛醇改性负载钛催化体系(TiCl4/MgCl2)催化异戊二烯配位聚合,考察了催化剂用量、Al剂用量及反应温度对聚合的影响,通过1H-NMR法表征了聚合产物的微观结构,通过DSC表征了聚合产物的熔点及结晶度。结果表明:改性负载钛催化体系的催化效率随正辛醇用量的增大而降低,当聚合条件为n(Al)/n(Ti)=50,n(Ti)/n(Ip)=5×10-4,聚合温度60℃时,催化效率最高。聚合产物的相对分子质量随正辛醇用量的提高而增大、随主催化剂用量的提高而降低,Al剂用量及反应条件对聚合物相对分子质量的影响同对催化活性的影响基本一致。所得聚异戊二烯的3,4-结构质量分数为8.2%,反-1,4-结构质量分数为91.8%;聚合产物的熔点及结晶度均低于TPI。 相似文献
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正辛醇改性负载钛催化体系聚合丁二烯 总被引:1,自引:0,他引:1
以不同用量正辛醇改性负载钛催化体系(简称Ti系催化剂)催化丁二烯配位聚合,考察了催化剂用量、三异丁基铝(简称A l)用量及反应条件对聚合的影响,通过红外光谱、差示扫描量热法表征了聚合产物的结构及结晶状态。结果表明,当正辛醇/Ti(摩尔比)为1~4时,改性后催化剂最佳配比为Ti/Bd(摩尔比)5×10-4,A l/Ti(摩尔比)20,反应温度60℃时催化活性最高;所得聚丁二烯的1,2-结构摩尔分数为38.4%,已达到中乙烯基聚丁二烯的范畴;结晶含量(19%~34%)明显低于反式-1,4-聚丁二烯。 相似文献
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Summary Propylene polymerization was performed with a highly active MgCl supported TiCl4 in conjunction with Et3Al and ethyl benzoate (EB). The obtained polypropylene sample was separated into four fractions by successive extraction with pentane, heptane and trichloroethylene (trichlene). Yield, Mn, Tm and microtacticity of each fraction were determined, and the effects of the concentration of EB on these items of results were investigated. It has been found that EB enhances yield, Mn and stereospecificity of trichlene insoluble (the most stereospecific) fraction, and in contrast, it decreases rapidly yields of other three fractions without changing the character of the polymers. From these findings, the functions of EB to the active centers were discussed. 相似文献
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Lowering the particle size of support is one of methods to reduce breakage of supported catalyst during polymerization, which may cause serious problems for fine polymer particles from those broken catalysts. Microspheric MgCl2 support could be obtained by emulsion way, but we found that they easily aggregated after emulsification and they are difficult to keep good spherical morphology. Up until now, hardly paper on the morphology improvement of micro size supports has been published. With the addition of an amount of Poly(propylene glycol)(PPG), microspheric MgCl2 supports with good morphology were obtained. 1, 3, 15, 35, 80% PPG were added, respectively, and the results of SEM study on obtained particles showed that appropriate addition of PPG obviously improved the morphology of supports. The optimist dosage was 3% in our experiment and the activity of catalyst supported on obtained support was 32.3 kg PP/g cat h. The function of PPG was explored preliminarily. In spite of the improvement of morphology the activity of supported catalyst was decreased gradually compared to those without PPG. So the further XRD and IR analysis were carried out to find reasons. The results indicated that PPG might plug pores of support and interfere with the reaction between supports and TiCl4. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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正辛醇改性负载钛催化剂合成聚丁二烯橡胶 总被引:3,自引:1,他引:2
In our previous work, medium vinyl polybutadiene rubbersynthesized by TiCl4/MgCl2modified with different kinds andlevels of alcohols had been reported[1]. In this communica-tion,mechanical properties of raw rubber and vulcanizate ofpolybutadiene rubber sy… 相似文献
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TiCl4/MgCl2-AIEt3体系合成聚1-丁烯 总被引:1,自引:0,他引:1
以负载钛体系(简称Ti)为主催化剂,三乙基铝(简称Al为助催化剂,加氢汽油为溶剂,用溶液聚合法合成了聚1-丁烯。研究了n(Ti)/n(Bt)、n(Al)/n(Ti)、反应温度、反应时间对转化率、催化效率、聚合物的特性粘数[η]及其全同立构含量的影响。结果表明,随n(Ti)/n(Bt)增加,转化率和催化效率都不断提高;随n(Al)/n(Ti)增加、反应温度升高,转化率和催化效率呈先上升后下降趋势;随n(Al)/n(Ti)、n(Ti)/n(Bt)增大和反应温度的升高,特性粘数逐渐下降,但其对全同立构含量影响较小。 相似文献