Effects of Acrylic Monomers on the Polymerization of Propylene with TiCl₃-AlEtCl₂ Catalyst System

Abstract

The effets of the addition of methyl methacrylate (MMA), methyl acrylate (MA) and acrylonitrile (AN) on the catalytic activity of TiC13-AIEtC12 for propylene polymerization have been studied. TiCls-AIEtC12 was inactive without additives. On the addition of MMA or MA to the system highly stereoregular polypropylene (1.1.=94N96%e) was obtained, although the activity was lower and less stable than that ef TiCls-AIEt2Cl. The system with AN was inactive for propylene polymerization.
On the basis of the kinetics of propylene polymerization with TiCls+{AIEtC12 MMA (or MA)}, it has been conc1uded that a complex formed from AIEtC12 and MMA (or MA), AIEtC12. MMA (or A12Et2Cl, MA), acts as an active cocatalyst for TiC13, while free MMA (or MA)acts as a poison for TiCls-surface. The active complexes evolved considerable amount of ethane and ethylene when they were mixed with TiCls at 830C, but inactive ones, AIEtC12 and AIEtC12, AN, did not. This result suggests that MMA and MA activate Al-Et bond. The polymerization activities of these complexes have been discussed in connection with NMR data of these additives.