One-pot Synthesis of Long Chain Branch PP(LCBPP)Using Ziegler-Natta Catalyst and Branching Reagents

摘要

A new class of long chain branched isotactic polypropylene(LCBPP)polymers with high molecular weights and well-controlled structures are preparedvia a combination of rac-Me2S42-Me-4-Ph-Ind)ZrC12/MAO catalyst and a T-reagent,such as p-(3-butenyl)styrene.The T-reagent can simultaneously serve two functions(comonomer and chain transfer agent) during metallocene-mediated propylenepolymerization in the presence of a small amount of hydrogen. 'H NMR and SECequipped with triple detectors revealed most of polymer chain containing LCBstructure. LCBPPs displayed a systematic increase in zero-shear viscosity andArrhenius flow activation energy as branch density increased.LCBPPs with highbranch point density displayed thermorheologically complex behavior,and strainhardening was observed in extensional flow