Aging characteristics of epoxy resin in hygrothermal environment

Because of excellent electrical properties, epoxy resin is widely used in packaging and casting power equipment. Moisture and temperature in the environment are inclined to seriously affect the insulation tolerance of epoxy resin. This work focuses on the aging characteristics of epoxy resin in hygrothermal environment. The effect of hygrothermal aging on the properties of epoxy resin was deeply studied. Scanning electron microscopy images show that there are micro-crack, micro-slit and deterioration of resin in the hygrothermal aging process. The moisture adsorption process undergoes three equilibrium stages and it does not follow the Fick's second law. In the hygrothermal environment, the content of small free molecules produced by the oxidation and hydrolysis of the material and the absorbed water molecules dynamically changes, which leads to an increase-decrease-increase variation in ε'. After the aged sample is dried, its ε' descends, but because the internal structure is destroyed, its original dielectric properties cannot completely restored. It is found that after chemical moisture adsorption emerging, the equipment is damaged severely.