Optimization of the Temperature-Dependent Electrical Resistivity in Epoxy/Positive Temperature Coefficient Ceramic Nanocomposites

Nano-size positive temperature coefficient (PTC) ceramic particles and epoxy composites doped with 0, 0.5, 1, 5, 10 and 20 phr of PTC nanoparticles are prepared to suppress the decrease of electrical resistivity with temperature. Electrical resistivity under 30, 50, 70, 90, and 110 degrees C, DC breakdown strength, and trap characteristic are measured. DC electric field distribution under radical temperature gradient is simulated using a simplified bushing model insulated with prepared materials. The mechanism for the regulating of electrical resistivity-temperature characteristic of epoxy composites is discussed. The electrical resistivity at 110 degrees C, DC breakdown strength at 110 degrees C, and electric field distortion of the epoxy composite with 1 phr PTC nanoparticles is 454, 131 and 74%, respectively of the neat epoxy resin, which exhibits potential to be used as insulating materials in high voltage DC electrical systems.