Mechanism of thermal and electrical conductivity in polymer-nanocarbon composites

The electrical and thermal conductivity of nanocarbon filled polymers were studied by adding nanocarbon fillers (thermoexfoliated graphite (TEG) and dispersed TEG (nanoTEG)) to epoxy resin (ED) or polyethylene oxide (PEO). The content of filler in composite materials (CM) was (0.5-10) wt%. The temperature range of the investigations was (77-300) K for electrical conductivity and (150-423) K for thermal conductivity, respectively. It was found that electrical conductivity of CM obeys percolation dependence with low critical concentration C-cr similar to(1-2) wt% (phi(cr)similar to(0.56-1.1) vol%) and characterised by a positive temperature coefficient. The thermal conductivity is approximately linear on nanocarbon content. The model describing the mechanisms of electrical and thermal conductivity of CM had been proposed. The basic parameters of this model are following: content of nanocarbon anisotropic particles and their distribution in polymer matrix; the contact thermal (electrical) resistance both between the filler particles and on the inter-face of two phases - polymer-carbon filler.