Influence of process parameters on ethylene-norbornene copolymers made by using [2,2′-methylenebis(1,3-dimethylcyclopentadienyl)]-zirconium dichloride and MAO

Ethylene-norbornene copolymerization was investigated by using metallocene catalysts, [2,2′-methylenebis(1,3-dimethylcyclopentadienyl)]zirconium dichloride(2,2′-CH₂(1,3-Me₂Cp)₂ZrCl₂ , Catalyst A) and racemic-ethylenebis(indenly)zirconium dichloride (rac-Et(Ind)₂ZrCl₂, Catalyst B), in the presence of methylaluminoxane as a cocatalyst. The influences of different process parameters such as polymerization temperature and ethylene pressure were studied by using a 56 wt% norbornene solution in toluene. The results show that Catalyst A has a higher activity in copolymerization than Catalyst B. Catalyst A also has a superior norbornene insertion performance to Catalyst B, resulting in polymers with higher glass transition temperatures, by approximately 70 °C, at similar polymerization conditions, indicative of a great commercial potential of Catalyst A.