Effects of interface on electrical conduction in epoxy resin composites

The effects of the epoxy-resin interface on electronic conduction were studied by using photocurrent and thermally stimulated current techniques. The electrical properties of epoxy-filler composites are greatly affected by the interfaces in various ways depending on applied field, temperature, carrier species, and mechanical stress. At low temperature, electronic carriers transported from the epoxy layer in epoxy-alumina composites can pass through the epoxy-alumina interface and move in the alumina bulk, increasing the conduction current in the alumina, but they are accumulated at the interface and lead to interfacial polarization at room temperature. At low fields and low temperature, electronic carriers from the alumina layer can pass through the epoxy-alumina interface and increase the conduction current in the epoxy resin, but they are accumulated at the interface at high field and the conduction is explained by the Maxwell-Wagner model. At room temperature, electronic carriers from the alumina layer are blocked by the potential barrier at the interface. However, electronic carriers from the epoxy layer can pass through the epoxy-silica interface and increase the conduction current in the silica at low and room temperature