Metallocene Catalyzed Polymerization of Ethylene in the Presence of Graphite, 1. Synthesis and Characterization of the Composites

Abstract

Polyethylene/graphite composites have been prepared by two different methods. In a first approach, the ethylene polymerization has been catalyzed by metallocene in the presence of neat graphite particles (NGC composites). A second series of composites (TGC) has been prepared by the polymerization-filling technique, which requires that the metallocene/methylalumoxane catalyst is fixed onto the graphite surface prior to the ethylene polymerization. The two series of composites exhibit significantly different morphology and thermal properties. The filler distribution is very heterogeneous in the NGC series. The morphology changes from an intimate mixture of PE and filler particles at low graphite content to graphite covered by patches of PE at high filler loading. The graphite distribution is much more homogeneous in the TGC samples, and the morphology consists of particles covered by a layer of PE in the whole composition range. Differences in the thermal properties are discussed in relation to the morphology.