To improve the processability of ethylene-alpha-olefin copolymers (POE), POE and POE/polystyrene (PS) blends were extruded in the presence Of ultrasound. On the one hand, the effect Of ultrasound on the die pressure drop, extrudate productivity, melt viscosity of POE, and the processing behaviors of POE and POE/PS (80/20) blend were studied. The results showed that with increasing ultrasound power, the die pressure and melt-apparent viscosity of POE decreased whereas the productivity of POE extrudates increased, then the processability of POE was greatly improved. On the other hand, the effects of Ultrasound on the morphology, rheological, and mechanical properties of POE/PS (80/26) blend were Studied. Capillary rheological results showed that the merger of ultrasound and the addition of PS showed a synergistic improvement of processability of POE. From morphological observation and rheological analysis, the compatibility of the blend was also improved in the presence of 200W ultrasound. As a result, the stress at break of compatibilized POE/PS (80/20) blend increased from 9.2 to 11.0 MPa, and the dynamic storage modulus increased at experimental temperature range, indicating that the mechanical properties of POE/PS blends can be improved by ultrasound-assisted extrusion. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112:2136-2142, 2009