Influence of graphite type on electrical and thermal properties of composite materials graphite-organic compound

The electrical resistivity and thermal conductivity of the composite materials (CM) based on graphite [natural disperse graphite (Gr), thermoexfoliated graphite (TEG)] and silicon-organic binder (SO) have been investigated. The threshold value of TEG content, when the abrupt decrease of electrical resistance is observed, was shown to be equal to similar to4 wt.% for the TEG-SO systems. The TEG-SO samples display anisotropy of the electrical properties: rho(c)/rho(a) similar to 2 for the samples with low content of TEG (similar to 8 wt.%) and rho(c)/rho(a) similar to(7-9) for the samples with maximal content of TEG (60-70 wt.%). In contrast to electrical resistivity the thermal conductivity of graphite-organic compound CM linearly depends on graphite content. This difference in behavior of electrical and thermal conductivity with increase of TEG concentration may be explained by the fact that electric current is determined by the charge carriers, while the thermal conductivity is determined predominantly by phonon transport in graphite.. (C) 2002 Elsevier Science Ltd. All rights reserved.