热老化对交联聚乙烯电缆绝缘理化结构的影响

Effect of Thermal Aging on the Physicochemical Structure of XLPE Cable Insulation

按照XLPE电缆热老化过程中绝缘材料理化结构的变化规律,对不同老化程度的电缆绝缘材料的热裂解活化能、结晶形态、分子结构进行分析。结果表明:不同温度热老化过程中羰基指数均随着老化时间的增加而增大;低温热老化有利于XLPE结晶形态的完善,XLPE活化能有所升高,高温热老化对XLPE结晶形态有显著的破坏作用,XLPE活化能成指数规律下降。电缆绝缘材料在热老化热裂解的同时也发生后交联,低温热老化电缆绝缘材料后交联作用占主导地位,而高温热老化电缆绝缘材料热裂解为主要因素。

The changes of physicochemical structure of XLPE cable insulation during thermal aging were studied, and the pyrolysis activation energy, crystalline morphology and molecular structure were ana- lyzed. The results show that the carbonyl index of XLPE increases with the increase of aging time un- der different temperature. The crystalline morphology is improved and the activation energy increases slightly during low temperature aging process. The crystalline morphology is destroyed and the activation energy decreases exponentially during high temperature aging process. It is found that the cable insula- tion contains pyrolysis and post-crosslink reaction during thermal aging process, while the post-crosslink reaction dominates at low temperature aging and the pyrolysis reaction dominates at high temperature aging.