Efficient Polymer-Immobilized Metallocene Catalysts for the Synthesis of Stereoregular Polypropylene

摘要

Based on dichloride derivatives of zirconocenes with C_2 symmetry and borates,active catalysts of propylene polymerization were formed on a polymer support,PE with a grafted poly(acrylic acid) treated with poly (methylaluminoxane).It was shown that the nature of aluminoxane affects the activity of the catalytic system:when aluminoxane is synthesized on the support surface,the activity of the catalytic increases.The influence of the nature of zirconocene and borate on the catalytic behavior of a system containing triisobutylaluminum as a cocatalyst was studied.Variation in the polymerization conditions (liquefied propylene or heptane suspension) was found not to affect the kinetics of polymerization,characterized by the steady-state rate of monomer consumption.Particle-size analysis of the polymers prepared using various systems is presented together with molecualr masses,melting temperatures,and isotacticity indices.