Summary:
The polypropylene growth process on silica supported metallocene catalysts was examined by electron microscopy and kinetic investigations. It was possible to identify different polymerization stages with different characteristic kinetic data in the slurry phase which led to the development of a refined polymer growth model [1-2]. Tomographical reconstruction of shortly polymerized catalyst particles obtained by electron micrographs of serial microtome sections turned out to be a useful tool to achieve a better understanding of the heterogeneous polymerization process and the influence of the support structure on polymer growth.
1. Introduction
Single-site metallocene catalysts produce extremely uniform polymers with molecular weight distributions (MWD) of 2 or less and very narrow compositional distributions in comparison to conventional Ziegler-catalysts. For industrial gas phase or bulk polymerization in existing plants (drop-in-technology) it is necessary to fix the catalytically active components on a heterogeneous support.