Metallocene catalysts - applications in the manufacture of polyethylenes and high-impact polypropylenes in gasphase polymerization processes

The advent of single-site type metallocene catalysts has had a revolutionar y impact on the manufacture of polyolefins(1)). The impact is broad and inc ludes polymer properties (rheological, mechanical) and productivity of poly olefin manufacturing processes. Constrained geometry catalysts with open an d accessible active sites give random copolymerization of alpha-olefins and macromonomers giving narrow chemical composition and molecular weight dist ributions and long chain branching. Super condensation mode of heat removal is enhanced with metallocene catalysts. The use of metallocene catalysts a nd active site poisons can improve impact polypropylene properties (bulk de nsity, powder flowability and impact strength). These topics will be discus sed in some detail.