POLYPROPYLENE GROWTH ON SILICA-SUPPORTED METALLOCENE CATALYSTS - A MICROSCOPIC STUDY TO EXPLAIN KINETIC-BEHAVIOR ESPECIALLY IN EARLY POLYMERIZATION STAGES

The polypropylene growth on metallocene/MAO catalysts supported on a s ilica carrier has been examined by scanning electron microscopy. The k inetic induction period in early polymerization stages can be explaine d by the formation of a discrete polymer layer only on the outer surfa ce of the catalyst particle. Differences in the fragmentation process at later stages are pointed out, depending on the supporting procedure of the catalyst system.