TiCl4/MgH2‐supported Ziegler‐type catalyst system, 3. New findings on the concentration of active sites in ethylene/1‐hexene copolymerization

Abstract The effect of 1‐hexene on the rate constant of ethylene polymerization and on the number of active centres in the copolymerization of ethylene with 1‐hexene is reported. Using three TiCl4/MgH2Al(C2H5)3 catalysts, of different Ti contents and surface area in the polymerization reveals that the addition of small amounts of the comonomer 1‐hexene results in a two‐ to three‐fold increase in the rate of ethylene consumption when a low‐Ti‐content catalyst is used. In contrast, no fundamental change in the catalytic activity was observed when a high‐Ti‐content catalyst is employed. The determination of the concentration of active centres C* by means of the 14CO radio‐labelling technique, shows that C* in ethylene/1‐hexene copolymerization is more or less the same as in ethylene homopolymerization.