INVESTIGATION OF A FINE-GRAIN MGCL2-SUPPORTED ZIEGLER CATALYST BY STOPPED-FLOW PROPENE POLYMERIZATION - MODEL FOR THE FORMATION OF ACTIVE-SITES INDUCED BY CATALYST FRAGMENTATION DURING POLYMERIZATION

A fine-grain catalyst, as a model of catalyst fragmentation in the cou rse of polymerization, was prepared by grinding an original MgCl2-supp orted Ziegler catalyst. In order to clarify the nature of the active s ites generated after catalyst fragmentation, the kinetic parameters fo r propene polymerization with both catalysts were estimated using the stopped-flow method. The active sites concentration of the fine-grain catalyst was higher than that of the original MgCl2-supported catalyst , indicating that the grinding treatment induced the formation of new active sites. However, the propagation rate constant and stereoregular ity of polypropene remained unaffected. This is an indication that the nature of the active sites formed after the grinding treatment was th e same as that of active sites on the original MgCl2-supported catalys t.