高电压技术2023，Vol.49Issue(12)：4890-4899,10.DOI:10.13336/j.1003-6520.hve.20221613
电热作用下聚酰亚胺绝缘的电荷陷阱及微观特性
Charge Traps and Microscopic Properties of Polyimide Under Effects of Electric Field and Temperature
摘要
Abstract
Polyimide is often used as an insulating material for inverter motors due to its good thermal stability and elec-trical insulation properties,however,during its application,the charge traps generated by its conformational defects can trigger space charge effects when space charges are trapped under the influence of external factors,thus accelerating the aging of polyimide.Therefore,the microscopic behavior of polyimide molecules under the effects of electric field and temperature is simulated based on the density functional theory and molecular dynamics to help deeply analyze the trap depth of poly imide molecules,and the connection between molecular microscopic properties and electrical aging reaction is discussed using the transition state theory and free energy increment theory.The results show that,at electric fields of 0.1×1010 V/m to 0.4×1010 V/m,the polyimide molecules move directionally along the electric field,and their structures are orderly arranged;when the electric field is 0.5×1010 V/m,the molecular morphology is no longer maintained,resulting in free volume rearrangement,due to the electric field forces exceeding the intermolecular interaction forces of the polyi-mide.The energy bands of the poly imide molecules are tilted by the applied electric field and the trap depth deepens with increasing field strength.The thermal motion of the polyimide system intensifies under the effect of temperature,and the molecular chain segment movement space is stretched.Compared to the electric field,the increase in temperature leads to an overall decrease in the trap energy level,and the charge is more likely to be trapped at high temperatures.The electric aging reaction follows the transition state theory,and the electric field will change the microstructure of polyimide mole-cules and will increase the molecular vibration frequency,thus the free energy increment will change,which enables the aging reaction rate within the molecular system to accelerate.It is found that the free energy increment of polyimide sys-tem is approximately linear with the electric field,and grows with the temperature.关键词
聚酰亚胺/微观结构/陷阱/自由体积/自由能增量Key words
polyimide/microstructure/traps/free volume/free energy increment引用本文复制引用
李亚莎,瞿聪,夏宇,陈董董,王玮,王佳敏..电热作用下聚酰亚胺绝缘的电荷陷阱及微观特性[J].高电压技术,2023,49(12):4890-4899,10.基金项目
国家自然科学基金(51577105).Project supported by National Natural Science Foundation of Cbina(51577105). （51577105）
