PE and LLDPE/spherical-silica composite synthesized via in situ polymerization with zirconocene/MAO catalyst

Abstract

Polyethylene (PE) and linear low density polyethylene (LLDPE) were filled with spherical-silica during in situ polymerization in the presence of metallocene/MAO catalyst to obtain PE and LLDPE/spherical-silica composites. The particle sizes of the spherical silica introduced into PE and LLDPE productions varied with four sizes; 0.5, 3, 5 and 10 m. It was found that the catalytic activities of the in situ polymerization systems with the spherical silica increased with particle sizes in the first range and then slightly decreased for both productions. The properties of the obtained polymer composites including melting temperatures, crystallinity and comonomer insertion were investigated by means of X-ray diffractrometer (XRD), differential scanning calorimeter (DSC) and nuclear magnetic resonance (NMR). It was observed that most properties were influenced by the variation in particle sizes of the spherical silica. Considering on the morphologies of the obtained polymer composites, it can see that leaching of the spherical silica existed in both PE and LLDPE composites. The spherical shape and the smooth surface of the silica filler are likely to be the major reason for the leaching.