PROPYLENE POLYMERIZATION THROUGH SUPPORTED METALLOCENE MAO CATALYSTS - KINETIC-ANALYSIS AND MODELING

Several propylene polymerizations are carried out with supported metallocene catalyst, prepared by reaction of silica gel with methylaluminoxane and then with rac-dimethylsilanediylbis(indenyl)zirconiumdichloride. The rate-time curves obtained are analyzed to understand the influence of support and triisobutylaluminium on the reaction. As a first attempt to model this system we developed a partially new particle growth model, based on a shell by shell fragmentation hypothesis (gradual break-up from the outside to the inside of the particle), and a final multigrain structure of the particle. A kinetic scheme including the TIBA interaction with the supported catalyst is also presented. The model prediction and the experimental data are compared for the rate-time curves and polymer properties. (C) 1995 John Wiley & Sons, Inc.