Study on Corona Aging Characteristics of Epoxy Resin Under Different Hygrothermal Environments

In this article, bisphenol A epoxy resin was used as a sample for the hygrothermal corona aging test. It summarizes the characteristics of corona aging in hygrothermal environments based on the analysis of the infrared spectral characteristics, surface topography, dielectric loss, and electrical resistivity test of epoxy resin. The test results show that epoxy resin has two different stages of moisture absorption. The first stage is physical moisture absorption, which is reversible, and the second stage is chemical moisture absorption, which is irreversible. When aging, the epoxy resin will have an increasing number of cracks, accompanied by gradual oxidation. As the temperature and humidity climb up, the cross-linked structure inside the epoxy resin is decomposed, and thus, produces more free radicals. The expansion of the -OH group also promotes chemical hygroscopicity. At the same time, the bombardment by a high-energy electron beam destructs the surface structure of the epoxy resin. The sample surface becomes fluffy and even falls off due to hygroscopicity. In this sense, higher ambient temperature or relative humidity will intensify the internal deterioration of the aged epoxy resin sample, make the polar groups easier to turn, and bring up polarization relaxation losses and dielectric losses as a result. The research results aim to provide a reference for the operation and maintenance of epoxy resin materials in different electrical equipment in harsh environments.