NONISOTHERMAL CRYSTALLIZATION OF UHMWPE FILLED DURING POLYMERIZATION WITH INORGANIC FILLERS

The non-isothermal crystallization of UHMWPE, filled with different in organic fillers during the polymerization on the catalyst system TiCl4 /(C2H5)2AlCl/(C6H5)2Mg has been studied by DSC and polarization micros copy, The melting conditions of UHMWPE have been established before th e crystallization experiments. It is shown that the fillers act as nuc leating agents only when the crystallization is carried out from a mel t, obtained at temperature above the flow temperature of UHMWPE, and a t slow cooling rate. It was established that the efficiency of nucleat ion passes through maximum at 50 wt.% of the filler. It is assumed tha t this is due to the reduction of, the heterogeneous sites, because of the aggregation of the filler with high concentration. The non-isothe rmal crystallization kinetics is studied by Harnisch and Muschik metho d. The Avrami exponents do not change in the presence of a filler with concentration up to 90 wt.%.