Patent ID: 8026311

Claim:
A process for promoting ethylene incorporation into an ethylene/propylene copolymer and increasing the molecular weight of said copolymer, the process comprising: in a first stage comprising at least one polymerization reactor, polymerizing propylene in the presence of a Ziegler-Natta catalyst, wherein a first amount of an external donor is added to the first stage, passing a polymerization product from the first stage to a second stage comprising at least one polymerization reactor, and polymerizing propylene and ethylene in said second stage, in the presence of said propylene homopolymer, wherein a second amount of an external donor is added to the second stage, wherein the external donor is selected from the group consisting of cyclohexylmethyldimethoxysilane and diethylaminotriethoxysilane, and further comprising adding an antistatic inhibitor to the second stage, wherein the external donor added to the first stage is the same as the external donor added to the second stage.