紫外线辐照对高密度聚乙烯结晶行为及热分解动力学参数的影响

THE EFFECTS OF ULTRAVIOLET IRRADIATION ON CRYSTALLIZATION BEHAVIOR AND THERMAL KINETIC PARAMETERS OF DEGRADATION OF HDPE

采用ＤＳＣ、ＷＡＸＤ研究了紫外线辐照对高密度聚乙烯（ＨＤＰＥ）结晶性能的影响。结果表明，随辐照时间的增加，ＨＤＰＥ结晶度增大，熔融峰向低温方向移动，但晶胞结构基本保持不变。通过ＴＧＡ对紫外线辐照ＨＤＰＥ的热稳定性进行了研究，采用４８６微机对紫外线辐照ＨＤＰＥ分解动力学方程：ｄα／ｄｔ＝ｋ（１—α）￣ｎ＝Ａｅｘｐ（—Ｅ／ＲＴ）（１—α）￣ｎ进行了模拟，用Ｇｒａｆｔｏｏｌ图形处理软件对动力学方程进行了拟合，通过一条ＴＧＡ曲线，即可在微机上计算频率因子（Ａ）、分解活化能（Ｅ）、分解反应级数（ｎ）等动力学参数。研究结果表明，随紫外线辐照时间的延长，ＨＤＰＥ起始分解温度、分解活化能、反应级数降低，频率因子升高。

The effects of ultraviolet(UV) irradiation on the crystallization behavior and thermal stability of HDPE were studied by DBC,WAXD and TGA.The results show that the crystallinity of HDPE is increased and its heat resistance is decreased during irradiation.The crystallite structure,however,keeps unchanged. The thermal stability of HDPE under UV irradiation was determined with TGA.A simple method is developed for obtaining the kinetic parameters during thermal degradation by means of microcomputer simulation.