POLYMERIZATION OF PROPYLENE BY MIXED ZIEGLER-NATTA AND METALLOCENE CATALYSTS

The polymerization of propylene using a mixture of racemic metallocene s and Ziegler-Natta catalysts was investigated, The polypropylene was obtained as a mixture of a fine powder and beads, with the powder bein g absorbed partially on the beads. The relative amount of the powder c an be controlled by the concentration of the metallocene, The compatib ility between the components of the mixed catalytic systems and the ef fect of the components on the rate of polymerization and on the proper ties of the new polymers were studied, The metallocene system dramatic ally affects the melt viscosity, isotacticity and molecular weight of the polymers. The two catalytic systems are able to act jointly, produ cing different polymers, for which separate melting and crystallizatio n temperatures are obtained. (C) 1998 John Wiley & Sons, Ltd.