新型外给电子体对Ziegler-Natta催化剂催化丙烯聚合的影响

研究了不同外给电子体对Ziegler-Natta催化剂催化丙烯聚合的影响，并用DSC和GPC等表征手段对聚丙烯结构进行分析。结果表明，外给电子体种类对催化剂性质有较大程度的影响，其中以有机胺类化合物为外给电子体的Ziegler-Natta催化剂体系表现出最高的聚合活性，而胺基硅烷类化合物表现出最低的聚合活性和最好的氢调敏感性，醚类化合物表现的聚合活性、氢调敏感性以及立构定向性介于有机胺类和胺基硅烷类之间。此外，外给电子体种类对聚合物的分子量有较大的影响，相同聚合条件下，有机胺类外给电子体合成的聚丙烯的平均分子量最高，醚类次之，羧酸酯类和胺基硅烷类最低。利用Fukui函数和反应热对二环戊基二甲氧基硅烷(DONOR-D)和四乙氧基硅烷(DONOR T)的络合能力进行了比较，结果表明，DONOR-D比DONOR T与催化剂活性中心有更强的络合能力，因此，DONOR-D与DONOR-T复配外给电子体主要呈现DONOR-D的聚合性质。

Effect of new external donors on propylene polymerization with Ziegler-Natta catalysts

A study of the influence of different external electron donors on propylene polymerization catalyzed by a Ziegler-Natta catalyst, and the microstructure of the resulting polypropylene has been investigated in detail using differential scanning calorimetry (DSC) and gel permeation chromatographic analyses (GPC). It was found that the type of external electron donor had a significant influence on the catalytic properties. The Ziegler-Natta catalyst with organic amine compounds used as external donor showed the highest activity, while the Ziegler-Natta catalyst exhibited the highest hydrogen response and the lowest activity when aminosilane compounds were used as external donor, and the polymerization ability with ether compounds fell in between organic amine compounds and aminosilane compounds. In addition, the chemical structure of the external electron donor had great influence on the average molecular weight of the polypropylene. Under the same conditions, the average molecular weight of polypropylene obtained using an organic amine catalyst system was highest, followed by that with the ether compound, and the average molecular weight of polypropylene formed by catalysis with carboxylic ester and aminosilane systems was the lowest. The Fukui function and reaction heat were used to calculate the HOMO energy level of different external donors and heat quantity, respectively. It was found that dicyclopentyl dimethoxy silane (DONOR-D) had a higher HOMO energy level and larger amount of heat than tetraethoxysilane (DONOR-T), so DONOR-D exhibited stronger complexing ability than DONOR-T, and DONOR-D/DONOR-T mixtures mainly showed the performance of DONOR-D.