Ziegler—Natta catalysis: 7. The settling period

Factors affecting the duration of the settling period in the polymerization of 4-methylpentene-1 by the catalyst system VCl 2 AIR 3 in benzene have been systematically investigated. Plots of log10 (100 — %Rp) versus time show that the so-called settling period can be divided into two distinct regions; an initial region which is not time dependent and a steady state region in which the formation of Co follows a strictly first order time dependence. The initial region is believed to arise from the removal of adsorbed AlR2Cl species, while the steady state region can be interpreted as describing a rearrangement reaction involving the production of initiated chains.