Effects of nanoparticles on trap depth in epoxy resin under different temperature

Under high DC voltage, the space charge accumulation can largely alters the local field distribution in epoxy resin. And it has been revealed that nanoparticles have great influences on space charge distribution in epoxy resin. To reveal the mechanism of nanoparticles, the effects of nanoparticles on trap depth are investigated under different temperature. In this work, epoxy resin and its nano composite are cured with a thickness of 0.3mm. The space charge distribution and the decay after the removal of voltage were tested based on Pulsed Electro-Acoustic (PEA) method under different temperature (20 °C, 40 °C and 60°C). The average charge density and trap depth are achieved by PEA. To eliminate the effects of temperature on decay rate, the trap depths under different temperature are calibrated to that of 20°C. The results indicated that the incorporation of nano silica particles could suppress the space charge accumulation in epoxy resin, and the nano composites show shallower trap depth than pure epoxy. Moreover, the trap depths of nano composites changes less obviously with the variation of temperature, while the trap depths of pure epoxy become deeper with the increase of temperature. This different trap behavior is explained in terms of the thermal movement of polymer molecules in epoxy resin.