TACTICITY DISTRIBUTIONS OF POLYPROPYLENE PREPARED WITH SUPPORTED ZIEGLER-NATTA CATALYSTS

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)(%)/Delta t values indicates the presence of plural active sites in the catalysts, Experimental results show that both external and intern al electron donors can narrow the tacticity distribution of PP, When e xternal and internal electron donors are present in the catalysts, the obtained PP has the narrowest tacticity distribution.