Studies on homo and copolymerizations of long-chained α-olefins over metallocene catalysts

Abstract

Metallocene catalysts, viz., rac-Et(Ind)2ZrCl2, rac-Me2-Si(Ind)2ZrCl2 and Ph2C(Flu)(Cp)ZrCl2, were studied in homopolymerization of 1-octadecene and the first two were used in copolymerization of ethylene with 1-octadecene. They exhibited different activities and rac-Et(Ind)2ZrCl2 was the most active in the homopolymerization carried out at 70°C. At 30°C, the activities were practically identical. In the copolymerization runs, the catalysts were similarly active, and the Et-bridged catalyst was the more active. The copolymers prepared over rac-Me2-Si(Ind)2ZrCl2 were found to have more comonomer incorporated. The composition of copolymerization products was found (13C-NMR) to vary with the catalyst system. DSC thermograms showed poly-1-octadecene prepared over rac-Et(Ind)2ZrCl2 to vary in properties with polymerization temperature (Figs. 3-5). The homopolymer prepared at 70°C showed endotherms at 41°C and 53°C and that prepared at 30°C produced one broader peak at 67°C. With rac-C-Me2Si