STRUCTURE AND PROPERTIES OF HDPE/STC BLEND COMPATIBILIZED WITH ULTRAVIOLET LIGHT IRRADIATED HDPE

摘要

The structure and properties of ultraviolet light irradiated HDPE (uv-HDPE) and HDPE/STC (sericite-tridymite-cristobalite) system compatilized with uv-HDPE were studied with FTIR, ESCA, contact angle measurement, GPC, DSC, WAXD, SEM, mechanical properties test, MI and crosslinking degree measurement etc. in this paper. The results show that HDPE can be very quickly functionlized by uv irradiation in presence of ozone, -C(=O), -C(=O)O-, -C-O- and -C-OH etc. oxygen-containing groups (Table 1) are introduced onto HDPE molecular chain, its contact angle with water is decreased. Compared with unirradiated HDPE, the molecular weight of uv -HDPE is decreased, the melt index is increased, the crystalline structure (cell parameter, face space and grain size) almost remains unchanged, no crosslinking structure is detected. Irradiated HDPE exhibits almost the same thermostability as that of unirradiated sample. The yield strength and the Young's modulus of uv -HDPE are increased, the notched impact strength and the elongation at break are decreased. Compared with unirradiated HDPE/STC (60/40), the yield strength and the notched impact strength of irradiated HDPE/STC (60/40) are increased from 25.5 MPa and 61 J/m to 30.3 MPa and 462 J/m respectively (Table 2).The yield strength and notched impact strength of HDPE/ uv -HDPE/STC (42/18/40) blend are 29.4 MPa and 259 J/m (Table 3), indicating that the compatibility of the blend is really improved owing to the presence of uv -HDPE.