Long Chain Branched Polypropene Prepared by Means of Propene Copolymerization with 1,7-Octadiene Using MAO-Activatedrac-Me2Si(2-Me-4-Phenyl-Ind)2ZrCl2

Abstract

Small amounts of 1,7-octadiene (OD) comonomer, ranging from 0.5–5.0 mol-%, were added during propene polymerization, catalyzed with methylalumoxane (MAO) activated rac-Me2Si(2-Me-4-phenyl-Ind)2ZrCl2 (MPI), in order to incorporate long chain branches and small amounts of high molecular mass polypropene (PP), thus improving melt processability of isotactic metallocene-polypropene. As a function of the OD content the PP melting temperatures varied from 120 to 160°C. The presence of long chain branches was reflected by increased zero shear viscosities combined with pronounced shear thinning behavior in the case of propene/OD copolymers with molecular mass distribution of M̄w/M̄n < 4. Rheological measurements clearly revealed crosslinking occurring at high OD content. OD addition impaired catalyst activities. However, in the presence of trace amounts of ethene, catalyst activities increased significantly even in the presence of high OD content.