Tuning thermal conductance of graphene-polyethylene composites via graphene inclination and curvature

Abstract

Graphene-based composites are expected to be promising thermal management materials owing to the excellent thermal performance of graphene fillers. This research focuses on tuning the overall thermal conductance of graphene-polyethylene composites by filling various morphology of graphene layer. The effects of graphene inclination and curvature are systematically investigated by using molecular dynamics simulations. We found that the thermal conductance increases from 40.8 MW/m2K to 65.9 MW/m2K as the inclination angle (θ) increases from 0° to 90°. When the inclination angle increases above 60°, the embedded graphene layer would enhance the overall thermal conductance of nanocomposites attributed to the effect of planar heat transfer. It is indicated that the graphene layer will not always behave as good thermal fillers in nanocomposites. For the case of introducing the graphene curvature, the simulations show that the calculated thermal conductance evolves from 40.8 MW/m2K to 54.8 MW/m2K with curvature ratio (L/L0) varying from 1.0 to 1.75. As the graphene curvature varies from 1.4 to 1.75, the thermal conductance of composites behaves an independent trend due to the multiple contributions from the intrinsic heat transfer of graphene and the interfacial thermal coupling in nanocomposites. The curvature ratio of 1.4 could be assumed as an efficiency point for optimizing thermal property in graphene-polyethylene composites. Meanwhile, no thermal rectification effect is observed in our simulation under the opposite heat-flow impact. These results offer valuable guidance for tuning thermal conductive composites and developing graphene-based devices.