Copolymerization of propylene with 1-octene catalyzed by rac-Me2Si(2,4,6-Me-3-Ind)(2)ZrCl2/methyl aluminoxane

The copolymerization of propylene with 1-octene was carried out with rac-di methylsilylbis(2,4,6-trimethylindenyl) zirconium dichloride as a catalyst a ctivated by methylaluminoxane (MAO) and an MAO/triisobutylaluminum mixture. The copolymerization conditions, including the polymerization temperature, Al/Zr molar ratio, and 1-octene concentration in the feed, significantly i nfluenced the catalyst activity, 1-octene incorporation, polymer molecular weight, and melting temperature. The addition of 1-octene to the polymeriza tion system caused a decrease in the activity, whereas the melting temperat ure and intrinsic viscosity of the polymer increased. The microstructure of the propylene-1-octene copolymer was characterized by C-13 NMR, and the re activity ratios of the copolymerization were estimated from the dyad distri bution of the monomer sequences. The amount of regioirregular structures ar ising from 2,1- and 1,3-misinserted propylene decreased as the l-octene con tent increased. The influence of the propagation chain on the polymerizatio n mechanism is proposed to be the main reason for the changes in the reacti vity ratios and regioirregularity with the polymerization conditions. (C) 2 000 John Wiley & Sons, Inc.