硅烷类外给电子体对Ziegler-Natta催化剂催化丙烯聚合的影响

Effect of Alkoxysilane External Donor on Propylene Polymerization Catalyzed by Ziegler-Natta Catalyst

研究了硅烷类外给电子体对Ziegler-Natta催化剂催化丙烯聚合的影响,并利用DSC,GPC,WAXRD等方法分析了外给电子体对聚丙烯性能的影响。实验结果表明,二烷氧基硅烷类外给电子体具有较高的聚合活性和立构定向性;多烷氧基硅烷类外给电子体比二烷氧基硅烷类外给电子体具有更好的氢调敏感性;在相同聚合条件下,采用二烷氧基硅烷类外给电子体制得的聚丙烯的相对分子质量分布较宽;加氢量对聚丙烯的晶型无影响,相对分子质量低和等规度低的聚丙烯发生多重熔融的几率较大。二烷氧基硅烷类外给电子体的最高占据轨道能级较高,因此具有较好的立构定向性。

The effect of alkoxysilane external donors on propylene polymerization catalyzed by Ziegler-Natta catalyst was studied and the as-polymerized polypropylene（PP） was characterized by means of DSC, GPC and WAXRD. The results indicate that dialkoxysilanes show the high activity and stereo-regularity while tetraalkoxysilanes exhibit the high hydrogen response. Under the same polymerization conditions, the distribution of the average molecular mass of PP prepared with dialkoxysilane is broader. The amount of H2 has no influence on the crystallization of PP. The probability of PP with high relative molecular mass and stereo-regularity occurring multiple melting is small. Considering that the energy level of the highest occupied molecular orbits of dialkoxysilanes is higher than that of the other external donors, it shows higher stereo-regularity.