Evaluation of Insulation Performance and Life of Epoxy Resin Based on Accelerated Thermal Aging

Epoxy resin (EP) is widely used as insulation materials for high frequency and ultra-high frequency sensors because of its excellent mechanical and electrical properties. Long-term thermal stress can lead to breakage of epoxy resin molecular chains and reduce the insulation performance of materials. In order to study the effect of thermal aging on the insulation performance of epoxy resin and achieve its aging evaluation, samples with different aging states are prepared according to the accelerated thermal aging criterion and the frequency domain dielectric spectrum (FDS) characteristics of different samples are investigated. The results indicate that aging has a significant effect on the middle frequency band (0.01–100 Hz) of epoxy resin tanδ-f curve, while it has little effect on other low and high frequency bands. With the increase of aging time, the middle frequency band of tanδ-f curve rises gradually and the dielectric loss increases. Then, the changes of molecular chemical bond and functional groups during aging are studied by Fourier transform infrared spectroscopy (FTIR). Finally, based on the changes in the dielectric response characteristic parameters of materials during aging, a method for evaluating insulation aging of epoxy resin is proposed, and the life distribution and reliability curve of epoxy resin under thermal aging are obtained.