A KINETIC-MODEL FOR THE POLYMERIZATION OF PROPYLENE OVER A ZIEGLER-NATTA CATALYST

A kinetic model involving two types of active sites of mixed stereospecifities is proposed for the polymerization of propylene over a supported TiCl4/MgCl2 Ziegler-Natta catalyst. From a proposed reaction sequence, a set of mass balance expressions is derived and solved to evaluate continuous changes in polymerization rate and polymer properties with time. Discrepancies were observed between predicted and measured total polymer polydispersities, while lack of mechanistic information rendered the estimation of model parameters somewhat speculative. It is expected that, as further mechanistic knowledge is gained, models such as that presented here will prove useful in the study of supported Ziegler Natta catalysts. © 1990.