Inter-carbon nanotube contact in thermal transport of controlled-morphology polymernanocomposites

Abstract

Directional thermal conductivities of aligned carbon nanotube (CNT) polymernanocomposites were calculated using a random walk simulation with and withoutinter-CNT contact effects. The CNT contact effect has not been explored for its role inthermal transport, and it is shown here to significantly affect the effective transportproperties including anisotropy ratios. The primary focus of the paper is on thenon-isotropic heat conduction in aligned-CNT polymeric composites, because this geometryis an ideal thermal layer as well as constituting a representative volume element ofCNT-reinforced polymer matrices in hybrid advanced composites under development. Theeffects of CNT orientation, type (single-versus multi-wall), inter-CNT contact,volume fraction and thermal boundary resistance on the effective conductivities ofCNT composites are quantified. It is found that when the CNT–CNT thermalcontact is taken into account, the maximum effective thermal conductivity ofthe nanocomposites having their CNTs parallel to the heat flux decreases by∼4 timesand ∼2 times for the single-walled and the multi-walled CNTs, respectively, at 20% CNT volumefraction.