STUDY OF THE EFFECT OF HYDROGEN IN PROPYLENE POLYMERIZATION WITH THE MGCL2-SUPPORTED ZIEGLER-NATTA CATALYST .1. KINETICS OF POLYMERIZATION

Propylene polymerization was investigated with the TiCl4/MgCl4 support ed catalyst with the stereoregulating donor pair dibutylphtalate (DBPH )/triethoxyphenylsilane (TEPS) in heptane with AlEt(3) as cocatalyst i n the presence of hydrogen. It was shown that there is an activation e ffect by the influence of hydrogen. The removal of hydrogen from the p olymerization medium results in an immediate disappearance of activati on. However, the deactivation of the system is reversible, and it is p ossible to repeat the activation effect by hydrogen more than once. It was found that the value of the activation energy is the same in the presence of hydrogen and without it and is equal to 11 kcal/mol. From the experimental results it is concluded that the maximum number of ac tive centres is realized in the catalytic system in the presence of hy drogen, but a value of the propagation rate constant is not changed. I t was also found that in the presence of hydrogen the system's decay f ollows the bimolecular law of active centres deactivation.