Ethylene–propylene copolymerization and their terpolymerization with dienes using ansa-Zirconocene catalysts activated by borate/alkylaluminum

Copolymerization of ethylene (E) and propylene (P) and their terpolymerizations with three kinds of diene (5-ethylidene-2-norbornene (ENB), 4-vinylcyclohexene (VCH) and 1,4-hexadiene (HD)) under 4?bar monomer pressure in n-heptane solution were studied. Two ansa-zirconocenes (rac-Me2Si(2-Me-4-Ph-Ind)(2)ZrCl2 (Mt-I) and rac-Et(Ind)(2)ZrCl2 (Mt-II)) activated by (Ph3C)B(C6F5)(4)/triisobutylaluminum were used as the catalyst, respectively. In general, addition of diene depressed the polymerization activity. ENB exerted the strongest deactivation effect on Mt-I, and HD caused the strongest deactivation on Mt-II. Among the two metallocenes, activity of Mt-I was more sensitive to the diene. Increasing diene concentration in the monomer feed caused lower propylene incorporation rate and shorter average length of polypropylene sequences, and the average length of polyethylene sequences was increased by adding more HD in E/P/HD terpolymerization with Mt-II. The Mt-II/borate catalyst showed high activity and diene incorporation rate for E/P/ENB terpolymerization. In contrast, Mt-I/borate catalyst showed high activity and propylene incorporation rate for E/P copolymerization, but was nearly inactive for E/P/ENB terpolymerization.