The effects of polypropylene (PP) and ultrasonic irradiation on the processing and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE) are studied. The results show that PP can effectively improve the fluidity and mechanical properties of UHMWPE. The Izod notched impact strength increases from 92 kJ/m(2) for pure UHMWPE to 109.2 kJ/m(2) for the blend of UHMWPE with 10 wt % PP. The Young's modulus increases from 528 MPa for pure UHMWPE to 1128 MPa when 25 wt % PP is contained in the blend, and the yield strength also rises when PP is added. The application of ultrasonic vibrations during extrusion can prominently decrease the die pressure and apparent viscosity of the melt, thus increasing the output of extrudate. An appropriate ultrasonic intensity and irradiation time can further promote the mechanical properties, while an overdose of irradiation destroys them. (C) 2003 Wiley Periodicals, Inc.