Study on Residual Stress of Epoxy Resin under different cooling methods

Epoxy resin and acid anhydride curing system plays a significant role in the manufacture of electrical insulating materials due to its excellent dielectric property. However, the theoretical strength of the epoxy resin is much greater than the actual strength, and one of the reasons for the low actual strength is residual stress in the cured epoxy resin. The thermal conductivity of the epoxy resin is poor. After vacuum, heating, cooling and a series of the process of curing process, different cooling conditions and different cooling rate will form temperature difference within the cured epoxy resin. With the uneven volume shrinkage of cured epoxy resin, residual stress will be produce and reduce the performance of the cured epoxy resin. Residual stress also has a certain influence on the properties of epoxy resin insulators. Therefore, the internal residual stress of epoxy resin insulating materials must be studied. In this paper, we used epoxy resin and anhydride to prepare samples. In the different parts of sample, the residual stresses were measured by electric resistance strain gauge. Under different cooling ways, the residual stresses of the cured epoxy resin were compared. The results suggest that residual stress in center part of epoxy resin sample is the largest. The residual stresses mainly appear in the cooling process, and the cooling ways have an influence on the residual stress.