Metallocene catalyzed polymerization of ethylene in the presence of graphite, 1 - Synthesis and characterization of the composites

Polyethylene/graphite composites have been prepared by two different method s. In a first approach, the ethylene polymerization has been catalyzed by m etallocene in the presence of neat graphite particles (NGC composites). A s econd series of composites (TGC) has been prepared by the polymerization-fi lling technique, which requires that the metallocene/methylalumoxane cataly st is fixed onto the graphite surface prior to the ethylene,polymerization. The two series of composites exhibit significantly different morphology an d thermal properties. The filler distribution is very heterogeneous in the NGC series. The morphology changes from an intimate mixture of PE and fille r 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 lay er of PE in the whole composition range. Differences in the thermal propert ies are discussed in relation to the morphology.