混合外给电子体环己基甲基二甲氧基硅烷/二苯基二氯硅烷对丙烯聚合的影响

THE EFFECT OF MIXED ELECTRON DONOR CMMS/DPCS ON POLYMERIZATION OF PROPENE

近年来,聚丙烯工业生产的第三代催化剂都使用烷氧基硅烷作外给电子体,不同结构的硅烷作为外给电子体,对丙烯聚合行为的影响研究表明,外给电子体能使聚合物的等规度提高,同时伴随着聚合活性下降,烷氧基硅烷等外给电子体提高等规度的作用,是由于它们选择性地使无规活性中心失活的能力远高于等规活性中心。

The effect CMMS (cyclohexylmethyl dimethoxysilane/DPCS (diphenyl dichloridesilane) as electron donor on the polymerization of propene was discussed. The solvent polymerization of propene was carried out in 60 ℃ at 1. 04×105 Pa. It was found that the catalyst activity has gone up by 20 per cent when CMMS/DPCS=1/3 under the given condition . The concentration of active titanium center (C) was determined with kinetic-molecular weight method. It turns out that the active titanium centers do not increase by using mixed electron donor CMMS/DPCS as compare with CMMS as electron donor but can increase K p by 20%. In addition, average-chain length can be achieved in five minutes with CMMS/DPCS. So polymer iso-tacticity index does not change with the time of polymerization.