C-O, C=O, and C(=O)O oxygen-containing groups were introduced onto the molecular chain of high-density polyethylene (HDPE) through ultraviolet irradiation in air. The introduction rate of the oxygen-containing groups onto HDPE increased with increasing environmental temperature. After ultraviolet irradiation, the molecular weight of HDPE decreased, and its distribution became wider; the melting temperature, contact angle with water, and impact strength decreased; the degree of crystallinity and yield strength increased; and their variation amplitude increased with environmental temperature. The environmental temperature had an effect on the gel content of irradiated HDPE. HDPE-irradiated for 48 h at 35degrees and 50degreesC were not crosslinked. However, gelation took place in HDPE irradiated for 24 h at 70degreesC. HDPE irradiated at a high environmental temperature was more effective than that irradiated at a low environmental temperature in compatibilizing HDPE with PVA. Compared with the 83/17 HDPE/PVA blend, the yield and notched impact strength of the 73/17 HDPE/PVA blend compatibilized with 10% HDPE irradiated for 24 h at an environmental temperature of 70degreesC increased from 30.8 MPa and 110 J/m to 34.9 MPa and 142 J/m, respectively. (C) 2003 Wiley Periodicals, Inc.