Temperature dependent surface charge and discharge behavior of epoxy/AIN nanocomposites

In this paper, effects of ambient temperature and nanoparticles on surface charge and discharge behavior of epoxy/aluminum nitride (AlN) nanocomposites were investigated. With the rise of ambient temperature, the surface discharge strength of epoxy resin decreases and the conductivity shows significant increase. The charges obtain higher energy, their movement becomes more violent and makes it easier for secondary electron emission avalanche. Meanwhile, the specimen's trap level increases and trap density decreases. 1, 3 and 5 wt% proportions of AlN nanoparticles were added to the epoxy resin to increase the surface discharge strength at different operation temperatures. With the rise of filler content, the trap level, trap density and surface discharge strength increase first and then decrease at 20 °C. The specimen with 5 wt% filler content shows the highest shallow trap density and the one with 1 wt% filler content shows the highest deep trap density at 80 °C. As shallow traps can handle the migration of charges while deep traps may mainly cause electric field distortion, the specimen with 1 wt% filler content shows the highest surface discharge strength at 20 °C while the one with 5 wt% filler content shows the highest at 80 °C. The conclusions can help with finding different formulas to increase epoxy resin's surface discharge strength at different operation temperatures.