高压脉冲电压下聚酰亚胺的电老化机理

在高压脉冲电压下对聚酰亚胺膜的绝缘寿命、不同条件老化后试样的表面形貌及热刺激电流(thermally stimulated current，TSC)进行了测试。TSC曲线在20~200℃温区内由I峰和II峰两个单峰叠加而成。通过图谱分析发现聚酰亚胺膜早期电老化时陷阱的发展可用陷阱理论解释，但老化后期陷阱理论中陷阱密度变化规律的描述不再适用。电老化主要破坏聚酰亚胺内II峰对应的大分子链，I峰对应的分子链中小运动单元破坏并不严重。聚酰亚胺膜的寿命与频率成反比，频率越高对大分子链的破坏速度越快，表明通过II峰对应的活化能和电荷变化量来判断聚酰亚胺的绝缘老化程度是可行的。

Electric Aging Mechanism of Polyimide Under High Pulse Voltage

The insulation lifetime, surface topography and thermally stimulated current (TSC) of polyimide were measured during electrical aging process under high pulse voltage. The trap property and variation of parameters were investigated through the TSC curve and surface topography. It is shown that two main well-resolved peaks, namely I and II, exist in the 20~200℃ range of TSC curve. The structure corresponding to II peak in polyimide is damaged more severely than the structure corresponding to I peak and its degradation is accelerated when frequency increases. Thus it could be deduced that the degradation of the structure corresponding to II peak is the main reason leading to breakdown of polyimide. The insulation lifetime of polyimide could be indicated by the activation energy and charge quantity of II peak.