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SYNOPSISPolyethylene-kaolin composites were investigated with a special emphasis on the control of the interfacial adhesion. Both matrix and filler were modified for this purpose. A stearic acid and maleic anhydride-grafted polyethylene were used as potential interfacial agents and the efficiency of aminosilane-surface-treated kaolin was considered. Tensile strength, elongation, impact strength, and melt index were currently measured in relation to the processing conditions. Enhanced interfacial filler-polymer adhesion progressively results in an decreased melt index. This has been clearly shown by comparing the effect of two polymeric additives to the polymer matrix, i.e., a maleic anhydride-grafted HDPE (MAGPE) and an unmodified HDPE of a similar melt index. Compared to low molecular weight additives, such as stearic acid and aminosilane, MAGPE has proved to be a very efficient additive in improving the impact resistance of HDPE-kaolin composites even at low contents. 0 1995 John Wiley & Sons, Inc.

ABSTRACT:When it is attached onto the surface of an inorganic filler (kaolin, barite), the (BuO) 4 Ti/BuMgOct/EtAlCl 2 /Et 3 Al 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 60ЊC, the optimum Al/Ti/Mg catalyst composition is 120/0.75/10, the efficiency of which is as high as 300 kgPE/(gTi 1 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 a-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.

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