Study of epoxy resin composites doped with nonlinear fillers and its electrical properties

For the purpose of obtaining desirable dielectric properties, a variety of inorganic particles fillers were doped into epoxy resin composites to change electrical behavior of epoxy resin composites. We researched electric properties of epoxy resin composites doped by nonlinear fillers, including zinc oxide(ZnO) with the size of 40nm and barium strontium titanate (BST) with the size about 100–200nm, and measured the dielectric constant (∊r) and conductivity (σ). Different mass fractions (0%, 5%, 10% and 20%) of nano-sized nonlinear powder (BST and ZnO) were doped separately into epoxy composites to obtain multi-phase dielectric composites. As the electric field changed from 10³ V/m to 10⁷ V/m, electrical properties changed accordingly. The results showed that BST and ZnO fillers tended to exhibit enhanced dielectric constant and lower dielectric loss with the increase of effective mass fraction. The influence mechanism was discussed in accordance with mass fractions, electric intensity and polarization mode of each kind of nonlinear fillers.