Thermal and Electrical Properties of Room Temperature Cured Epoxy Resin Modified by Hydroxyl-terminated Liquid Nitrile Butadiene Rubber

Toughening epoxy resin with liquid rubber has been applied in the field of power equipment and electronic packaging. Previous studies paid little attention to the thermal and electrical properties. In this paper, hydroxyl-terminated liquid nitrile rubber (HTBN) was used to toughen a kind of room temperature cured epoxy resin, and the thermal and electrical properties were measured and analyzed. The interface formed between HTBN and epoxy matrix hinders the phonon movement and decreases the thermal conductivity and thermal diffusivity. The influence mechanism of HTBN on the relaxation process of epoxy resin was analyzed in the form of electrical modulus. HTBN introduces two relaxation processes into the matrix, which makes the dielectric loss increase sharply near the low temperature and glass transition temperature. The relaxation peak introduced in the low temperature region is caused by the α transition of HTBN molecules, while the relaxation peak near the glass transition temperature is mainly caused by the interfacial polarization. The relaxation peak intensity of high temperature conductivity in the form of electric modulus increases first and then decreases with the content of HTBN. The relaxation time accords with Arrhenius equation, and the apparent activation energy first increases and then decreases with HTBN content. The analysis of thermal and dielectric properties of epoxy toughening system in this study is helpful to the application and design of this kind of formulation system. © 2020 Chin. Soc. for Elec. Eng.