The lifetime of HV capacitors is drastically enhanced when epoxides are added to the liquid impregnant of the polypropylene films. The aim of this work was to understand the mechanism of action of such an additive. Aging of the dielectric was performed at a high AC field [135 MV/m]. The liquid impregnant, pure benzyltoluene or benzyltoluene with specially selected additives, was saturated with O-2 in order to accelerate PP aging. The degradation of the polypropylene films has been evaluated by the variation of their mean breakdown voltage and by FTIR microspectroscopy. The liquid impregnant has been characterized by gas chromatography. Our results show that the electrical stress enhances an oxidative degradation mechanism of the polymer and the liquid. Epoxides with two or more epoxy groups per molecule and other monomers of two or three functionalities inhibit this degradation. In the presence of such additives, electrical aging leads to the formation of a crosslinked polymeric deposit on the electrodes and the films. We attribute the good behavior of these components, and especially of epoxides in HV capacitors, to their ability to polymerize under an electrical stress and to form a protective layer that further prevents degradation. (C) 1996 John Wiley & Sons, Inc. [References: 24]
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机译：当将环氧化合物添加到聚丙烯薄膜的液体浸渍剂中时，HV电容器的寿命将大大延长。这项工作的目的是了解这种添加剂的作用机理。电介质的老化是在高交流电场[135 MV / m]下进行的。液态浸渍剂，纯苄基甲苯或具有特殊选择的添加剂的苄基甲苯用O-2饱和，以加速PP的老化。聚丙烯膜的降解已通过平均击穿电压的变化和FTIR显微光谱进行了评估。液体浸渍剂已通过气相色谱法表征。我们的结果表明，电应力增强了聚合物和液体的氧化降解机理。每个分子具有两个或多个环氧基的环氧化物以及具有两个或三个官能度的其他单体可抑制这种降解。在存在此类添加剂的情况下，电老化导致在电极和薄膜上形成交联的聚合物沉积物。我们将这些组件（尤其是HV电容器中的环氧化物）的良好性能归因于它们在电应力下的聚合能力以及形成进一步防止降解的保护层的能力。 （C）1996 John Wiley＆Sons，Inc. [参考：24]
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