Epoxy resin is prone to absorb water in humid and hot environment

thus leading to the deterioration of material properties. In order to study the water absorption characteristics and performance deterioration mechanism of epoxy resin in humid and hot environment

the humid and hot aging test on the epoxy resin is performed in this paper. The experimental results show that the water absorption of epoxy resin satisfies the LangmuirEXT1 isotherm adsorption model

and the saturated water absorption is a quadratic function of temperature. After the water absorption and aging of the epoxy resin

many tiny voids appear on the surface and section at the microscopic level

and the number of voids is proportional to the volume and aging temperature. Meanwhile

at the macroscopic level

the volume resistivity decreases rapidly after aging

the relative dielectric constant and dielectric loss angle increase

with the phenomenon of low frequency dispersion. After appearance of tiny voids

the moisture will enter into the material in large quantities through respiration

and the existence of internal void will also provide storage space for the moisture

the water absorption will further increase

and the dielectric properties and breakdown strength will also deteriorate

which eventually leads to material failure.