Abstract: The time dependence of ethylene-propylene copolymerization rate over TiCl₄/MgCl₂/ EB-AlEt₃ catalyst was studied.An enhanced rate of ethylene polymerization after brief copolymerization with propylene,which is much faster in comparison with that of conventional ethylene polymerization,and decaying-type kinetics were shown.It was found that the copolymerization brings about a change of morphology of the catalyst-polymer particles to loose structure.This allows the monomers diffusing more easily and developing potential activity of the catalyst,resulting in higher polymerization rate and different kinetic behavior from the homopolymerization.

Key words: Titanium catalyst, Ethylene-propylene copolymerization, Polymerization kinetics, Polymer morphology