Studies on the polymerization of propylene using high activity ziegler‐natta catalysts. 1: Kinetic models for rate decay in ziegler‐natta polymerization

Abstract Kinetic models for describing the time dependence of the polymerization rate and active centre concentration for high activity Ziegler‐Natta catalyst systems are discussed. It is demonstrated that the decay in the rate of polymerization and in the concentration of active centres with time for the polymerization of propylene with the heterogeneous catalyst system MgCl 2 /EB/TiCl 4 Al(i‐Bu) 3 /EB can be represented better by a modified multi‐centre first order decay model than by the other models which are considered.