Role of Grinding of Titanium Trichloride in Natta's Polymerization

Abstract

THE kinetic behaviour in the initial stages of the polymerization of propylene with titanium trichloride–triethyl aluminium can be divided into two types: the build-up type (the rate increases to the stationary value) and the decay type (the rate approaches decreasingly to the value). Natta and Pasquon¹ observed that the build-up type changed into the other type as grinding the titanium trichloride, whereas the stationary rate did not change, and supposed that the produced polymer adjusted the particle size of titanium trichloride into the stationary value appropriate for the stationary polymerization. This supposition is based on the experimental result that the same stationary rate per unit weight of titanium trichloride was obtained with the use of the titanium trichloride catalysts in various particle sizes.