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 I I 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 degrees C. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.