The effect of TiBr4 on ethylene polymerization catalyzed by tetrabenzyltitanium

The kinetics of the ethylene polymerization catalyzed by Ti(CH2C6H5)4/TiBr4 in toluene at 0°C was studied. The effects of the mole ratio of the catalyst components and of the quantity of catalyst on the polymerization were investigated. Using the number of active centres, the rate constant of the propagation reaction was evaluated. The number of active centres was determined by quenching the polymerization with 1-butanol tritiated at the hydroxyl group. Compared with the kinetic data of the catalyst system Ti(CH2C6H5)4/AlBr3, the present results indicate that the nature of the cocatalyst mainly affects the conditions for the formation of active centres, but has no essential influence on their reactivity. These results support the concept of monometallic structure of the active centres in Ziegler-Natta catalysts.