Polymerization-filled composites prepared with highly active filler-supported Al/Ti/Mg catalysts. I. Synthesis of homogeneous polyethylene-based composites

When it is attached onto the surface of an inorganic filler (kaolin, barite), the (BuO)4Ti/BuMgOct/EtAlCl2/Et3Al system is a highly efficient and very promising catalyst for the production of high-performance polyethylene-based composites. The surface concentration of the hydroxyl groups, the Al/Ti/Mg ratio, and the purity of the reagents have a major effect on the catalyst efficiency and molecular weight, crystallinity, and physico-mechanical properties of the final composite. Under ca. 4 bar partial pressure of ethylene in heptane at 60°C, the optimum Al/Ti/Mg catalyst composition is 120/0.75/10, the efficiency of which is as high as 300 kgPE/(gTi × h) in the presence of kaolin particles (Satintone W/W). The effect of transfer agents, such as hydrogen and 1-octene, and purity of the -olefin has been investigated. Actually, the catalyst efficiency is increased in the presence of both hydrogen and octene. Scanning Electron Microscopy (SEM) has shown that the ethylene was polymerized from the filler surface. Special attention has also been paid to the effect of size, density, and surface acidity of the filler particles. The surface of basic filler has to be treated in order to become an efficient catalyst carrier.