紫外光老化PP/纳米CaCO_3复合材料结晶与熔融行为研究

用DSC和WAXD研究了紫外光老化PP/纳米CaCO3(PP/CC)和相容剂改性PP/CC复合材料的结晶与熔融行为,结果表明随着紫外光老化时间增加,PP熔融温度逐渐降低,结晶度先增加后趋于稳定;PP结晶温度先提高后降低,PP/CC结晶温度降低,相容剂改性PP/CC降低更加明显。紫外光老化PP/CC结晶温度高于纯PP,表明CC对老化PP还具有异相成核作用。未光照的PP-g-MA和POE-g-MA改性PP/CC结晶温度高于未改性的,归结于相容剂与CC相互作用形成的钙盐的异相成核作用;但紫外光老化后PP结晶温度低于未改性PP/CC的,归结于钙盐受到紫外光的作用,失去对PP结晶的异相成核作用和诱导PP生成β晶的能力。

Study on Crystallization and Melting Behavior of UV Photo-oxidative Degradated PP/nano-CaCO3 Composites

The crystallization and melting behavior of UV photo-oxidative degradated PP/nano-CaCO₃(PP/CC) and its composites modified by compatibilizers were investigated by DSC and WAXD analyses. The results indicated that with increasing the UV exposure time, the melting temperatures of PP decreased and degree of crystallization of PP increased. The crystallization temperature of PP first increased and later decreased and the crystallization temperature of PP in PP/CC composites decreased, especially its composites modified by compatibilizers. The crystallization temperatures of UV photo-oxidative degradated PP/CC were higher than that of PP. It is attributed to the heterogonous nucleation of nano CaCO3. The crystallization temperatures of PP/CC composites modified by PP-g-MA and POE-g-MA were higher than that of unmodified composites. However, the crystallization temperatures of UV photo-oxidative degradated PP/CC composites modified by compatibilizers were lower than that of unmodified composites. It is suggested that the UV photo-oxidative degradation resulted in the decreased heterogonous nucleation of carboxylate salts formed by the chemical reaction between compatibilizer and nano-CaCO₃ particles.