The effect of aluminium compounds in the copolymerization of ethylene / α‐olefins

Abstract

Abstract Two types of copolymerizations were found with the catalyst system Cp 2 ZrCl 2 /MAO. One was a less exothermic reaction, and another was a more exothermic one. The former provided a polymer with a single composition distribution because of a single cationic active site. The latter provided a polymer with a bimodal composition distribution, indicating the existence of two active sites. The two active sites were investigated through the comparison of MAO systems and alkylaluminium / borate systems. We speculated that the two active sites were the normal cationic site and the active site where the interaction between a cationic metallocene and an aluminium compound was strong.