关键词: Ziegler－Natta, 催化剂, 聚丙烯, 分级

Abstract: Polypropylene samples prepared with supported Ziegler-Natta catalysts were fractionated with temperature rising elution fractionation(TREF) technique and the tacticity distributions were obtained. It is found that the polypropylene sample has a broad tacticity distribution when there exists no electron donor in the catalyst. the mutiple maximal w_i(%)/At values indicates the presence of plural active sites in the catalysts. Experimental results show that both external and internal electron donors can narrow the tacticity distribution of PP.When external and internal electron donors are present in the catalysts, the obtained PPhas the narrowest tacticity distribution.

Key words: Ziegler-Natta catalyst, Polypropylene, Fractionation