Long Chain Branching in Ethylene/Propylene Solution Polymerization Using Constrained Geometry Catalyst

Ethylene (E)/propylene (P) solution copolymerizations with low propylene ratios were carried out using constrained geometry catalyst, [C5Me4(SiMe2NtBu)]TiMe2 (CGC), and ansa-zirconocene, rac-Et(Ind)2ZrCl2 (EBI), at 130−150 °C and 3.45 × 103 kPa. Ethylene/propylene copolymers with long chain branch (LCB) densities from 0.30 to 0.96 carbons per 10 000 carbons, molecular weight distributions close to 2, and narrow comonomer composition distributions were synthesized with CGC. Broad molecular weight and comonomer composition distributions were found in the EBI copolymers. Reactivity ratios showed that CGC was more active for propylene incorporation than EBI. Terminal group analysis indicated that more terminal unsaturation occurred with EBI than with CGC. Two additional types of terminal unsaturated groups, vinylidene with side group having more than three carbons (2VD) and trans-vinylene (VE), were found with EBI while the terminal vinyl (V) and vinylidene with methyl side group (1VD) were determined in both CGC and EBI copolymers. Long chain branch structures were formed by the V type macromonomer incorporation. The long chain branching rate constants were also estimated.