Kinetics of ethylene–propylene copolymerization

The values of the reactivity ratios for ethylene–propylene and ethylene–1‐butene copolymerization, described in previous papers, and the distribution of monomer units in different length sequences are discussed. In this paper the kinetics of ethylene–propylene copolymerization in the presence of catalysts prepared from trialkylaluminum and vanadium tetrachloride is studied. Having adopted the conditions leading to the formation of catalysts having an activity independent of time, we were able to determine that the copolymerization rate is first order with respect to the catalyst concentration and to the sum of the concentrations of the two monomers. With the total concentration of the monomers constant, the copolymerization rate increases very rapidly as the ethylene concentration increases. The activation energies of the four chain growth reactions of the copolymerization proved to be practically equal.