Effect of Prepolymerization on the Kinetics of Ethylene Polymerization and Ethylene/1-Hexene Copolymerization with a Ziegler-Natta Catalyst in Slurry Reactors

The effect of prepolymerization on ethylene homopolymerization and ethylene/1-hexene copolymerization with a commercial TiCl4/MgCl2 catalyst was investigated and the apparent homo- and copolymerization rate constants were estimated by varying polymerization temperature, pressure, time, and 1-hexene/ethylene molar ratio during the prepolymerization. The apparent rate constants for activation, propagation, and deactivation depend on the prepolymerization conditions, showing that the prepolymerization stage strongly regulates the behavior of the catalyst in the main polymerization. Interestingly, the surface morphology of the prepolymer particles correlates to and explains these changes in polymerization kinetics behavior.