Dielectric properties of hydroxyl-terminated butadiene nitrile liquid rubber toughened Epoxy Resin polymer

Epoxy Resin is one of the most popular insulation materials used in the electrical equipment. In order to enhance the toughness of epoxy resin, the elastic rubber is usually added into the formulation system, but the dielectric properties of the epoxy resin will be changed while the toughness is enhanced. In this paper,hydroxyl-terminated butadiene nitrile liquid rubber (HTBN) is used to enhance the toughness of epoxy resin. By comparing the parameters of glass-transition temperature, AC conductivity and relative permittivity with different weight proportions of HTBN, the changes of dielectric properties of epoxy resin polymer is studied, and the action mechanism of the rubber particles as the “Island” structure is analyzed. The study shows that, after the HTBN is added, the glass transition temperature decreases significantly, the relative permittivity and the AC conductivity rises with the increasing of the proportion of HTBN mixed in the epoxy resin. The relative permittivity and the AC conductivity shows a peak in each of the curves. The main reason for the change of dielectric properties is that the relaxation polarization of the natural dipole moment in the rubber particles occurs at the certain temperature and frequency. The research result shows that, when add the toughened rubber particles to the epoxy resin formulation, the impact to the dielectric properties should be considered and used.