Effect of graphene arrangement on the thermal conductivity of graphene/polymer nanocomposites

Due to its high thermal conductivity (up to 5300 W/mK), graphene is considered an ideal filler for composites with a polymer matrix to form a thermal interface material with excellent thermal performance. The thermal conductivity of graphene/polymer nanocomposites can be effectively improved by increasing the aspect ratio of graphene, simultaneously increasing the lateral size and thickness of graphene at a constant aspect ratio or changing the ordered orientation of graphene nanosheets (GNSs) filled in the polymer matrix. Experimental results have shown that the ultrahigh thermal conductivity of the composites can be achieved in the in-plane direction due to the minimum interface thermal resistance along this direction. To detect the arrangement structure of GNSs on the thermal conductivity of the composites, this paper obtained the expressions of the effective thermal conductivity for anisotropic GNSs/polymer composites based on the multiple-scattering theory, where the effect of the number of GNSs layers on the interface thermal resistance and thermal conductivity of GNSs is considered. The numerical results show that the composites parallel to the aligned direction of GNSs have greater thermal conductivity than those perpendicular to it. The ordered orientation of GNSs can effectively improve the thermal conductivity for GNSs/polymer nanocomposites.