Abstract: Rheological behavior of high molecular weight polyethylene/paraffin oil blends was studied by a constant speed high pressure capillary rheometer. The influence of molecular weight, paraffin oil content, and temperature on the pressure was analyzed. It was observed that the higher the molecular weight, the lower the critical shear rate, and the higher the extrusion pressure oscillation frequency and amplitude. The lower the paraffin oil content, the higher the extrusion pressure at a same shear rate. When the oil content was 30 %, the extrusion pressure became stable, i.e., the extrusion pressure oscillation disappeared when the shear rate changed. With increasing extrusion temperature, the extrusion pressure decreased, the frequency and amplitude of pressure oscillation also decreased.

Key words: high molecular weight polyethylene, high pressure rheology, pressure oscillation