Space Charge Distribution and Nonlinear Conduction of Epoxy Nanocomposites

Space charge suppression is advantageous to the development of polymeric insulation and electrical equipment, and can be achieved by introducing deep traps into the polymeric insulation or by improving the conduction. In this study, we investigated the relationship between the space charge distribution and the nonlinear conduction. Five types of epoxy-resin-based nanocomposites were prepared by the introduction of SiC and A1203 nanoparticles. The pulsed electroacoustic (PEA) and DC conduction measurements were used to measure the space charge distribution and DC conductivity, respectively. The space charge distributions of pure epoxy, epoxy/A1203 nanocomposites, and 1 wt% epoxy/SiC nanocomposite reveal that homocharges are injected from the cathode, whereas that of 10 wt% epoxy/SiC nanocomposite scarcely reveals space charges. The DC current densities of these nanocomposites are different from each other and are attributed to the effect of the interaction zone around nanoparticles. Moreover, the 10 wt% epoxy/SiC nanocomposite shows the strongest nonlinear conduction property, whereas the epoxy/ A1203 nanocomposites hardly show it. The discrepancy in the space charge distribution of pure epoxy and epoxy nanocomposites is discussed on the basis of the variations in conduction and nonlinearity exponent. The analysis indicates that the nonlinearity exponent plays an important role in the space charge distribution.