Coupling Effects of Ambient Temperature and Filler Contents on Surface Charge and Discharge Behavior of Epoxy/AlN 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. The charges obtain more energy, their movement becomes more violent and makes it easier for secondary electron emission avalanche. 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 $20 ^{\circ}\mathrm {C}$. 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 $80 ^{\circ}\mathrm {C}$. 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 $20 ^{\circ}\mathrm {C}$ while the one with 5 wt% filler content shows the highest at $80 ^{\circ}\mathrm {C}$. The conclusions can help with finding different formulas to increase epoxy resin’s surface discharge strength at different operation temperatures.