EVALUATION OF INTERNAL AND EXTERNAL DONORS IN THESUPPORTED ZIEGLER-NATTA CATALYST FOR STEREOSPECIFIC PROPYLENE POLYMERIZATION

摘要

In the present work, the effects of n-butyl phthalate as internal electron donor on the preparation of MgCl_2-supported Ziegler-Natta catalyst and of dimethoxy-diphenylsilane as external electron donor were evaluated in propylene polymerization and compared with the new prepared Ziegler-Natta systems employing diverse internal and external electron donors. Polymers were characterized by infrared absorption spectroscopy, differential scanning calorimetry and by heptane extraction. The new prepared catalysts did not achieve the same polymer yields compared with the reference catalyst. On the other hand, the catalysts with the new internal donors produced polymers with isotacticity index up to 98% in the polymerization conditions employed.