Dielectric properties of epoxy resins with oxide nanofillers and their accelerated ageing

The aim of this paper is to discuss the impact of nanoparticles in epoxy matrix on dielectric parameters in the course of ageing. One of the directions pursued in the development of epoxy resins is the addition of nanofillers which act as efficient barriers for the propagation of electrical trees. In view of the prospects for the potential replacement of currently-used epoxy-based electric insulations with epoxy nanocomposites, it is necessary to know the behavior of such epoxy resins with nanofillers during aging. For this purpose, epoxy nanocomposites were exposed to accelerated aging and changes in dielectric properties were observed. Experimental samples were manufactured from bisphenol-A based epoxy resin for high voltage applications and oxide nanofillers. The volume of nanofiller added into epoxy resin was 1.5 wt %. Sample thickness was of the order of a few hundreds of μm. Complex permittivity (ε), inner resistivity (ρ_i) and loss factor (tan δ) were measured at temperatures from -153 °C to +167 °C and in the frequency range 10^-2 to 10⁶ Hz.