Effective Heat Transfer Properties of Graphene Sheet Nanocomposites and Comparison to Carbon Nanotube Nanocomposites

By incorporating nanoinclusions (carbon nanotubes, graphene sheets) with exceptional thermal conductivity into a polymer matrix, one would expect to improve the heat performance of resulting nanocomposites. However, the effective thermal conductivity of carbon-based nanocomposites is strongly influenced by the Kapitza interfacial resistance. In this study, a comparison between carbon nanotubes and graphene sheet nanocomposites that takes into account dispersion patterns of the nanoinclusions and the Kapitza resistance is performed by means of a Monte Carlo simulation. It is found that graphene-based nanocomposites can be more efficient thermal conductors than carbon nanotube ones not only because of smaller Kapitza resistance but also because of the geometry of the graphene sheet. When the Kapitza resistance is reduced by appropriate functionalization of the graphene sheets and when the graphene sheet inclusions yield nematic patterns, our calculations suggest the possibility of obtaining composite materials with effective thermal conductivity up to 350 times larger in the direction parallel to the graphene sheets than in the direction perpendicular to them.