Temperature dependence of the electrical conductivity of epoxy/expanded graphite nanosheet composites

The electrical conductivity of composites obtained by mixing epoxy resin and expanded graphite (EG) nanosheets has been investigated. Conductivity changes of up to 11 orders of magnitude were observed as the filler load increased from 0 to 8 wt.%, while the percolation threshold was around 3 wt.%. It was also shown that epoxy/EG composites with intermediate filler contents exhibit a “phase transition” from predominantly “contact conductivity” to “tunneling conductivity” during heating from room temperature to 120 °C.