The Role of Phenyltriethoxysilane as an Internal Donor for the Propylene polymerization over BuMgCl-Based Titanium Catalyst

Abstract

The effect of phenyltriethoxysilane (PTES) as an internal donor, on propylene polymerization with butylmagnesium chloride (BuMgCl)-based titanium catalyst has been investigated in terms of activity and stereospecificity. The X-ray diffraction (XRD) pattern of the catalytic system including PTES as internal donor showed that TiCl4 did not seem to diffuse into the interlayer of the MgCl2-support matrix. In comparison with the ethylbenzoate (EB)-containing or donor-free catalyst, the catalyst (MPT) with PTES as an internal donor alone showed a significant increase in isotacticity but a decrease in the catalytic activity. FTIR analysis suggested that the interaction of PTES with the catalytic titanium species seemed to be stronger than that of EB. The polypropylene prepared from the MPT catalyst showed a lower molecular weight, and the molecular weight distribution is broader (somewhat bimodal). Microstructure analysis of the boiling heptane-soluble polymer also indicated that PTES as an internal donor alone could selectively deactivate non-stereospecific active sites even without external donors. (C) 1998 Elsevier Science Ltd. All rights reserved.