Influence of graphene nano-platelets on thermal transport performance of carbon fiber-polymer hybrid composites: Overall assessment of microstructural aspects

Abstract This study comprehensively investigates the thermal transport behavior of unidirectional hybrid composites (UHCs) by means of a micromechanical methodology. The constructional feature of the UHC is that the continuous carbon fibers are embedded in the graphene nano-platelets (GNPs)-modified epoxy resin. The influences of volume fraction, length, thickness, and alignment of GNPs, the interfacial thermal resistance (ITR) between the nano-graphene and polymer matrix, as well as the volume fraction, arrangement type, and off-axis angle of carbon fibers on the thermal conductivities of UHCs are extensively analyzed. Further, the micromechanical model is extended to account the effect of GNP agglomeration on the UHC thermal conductivities. The results show that uniformly dispersed GNPs play a dominant role in improving the UHC thermal conductivity along the transverse direction, while the axial thermal conductivity is insignificantly influenced by the nano-graphene particles. Besides, using the GNPs with a higher aspect ratio (length/thickness) is an efficient manner to obtain much better thermal transport performance for the UHCs. It is observed that the formation of GNP agglomeration within the epoxy resin severely decreases the transverse thermal conductivity. The presence of GNP/epoxy ITR is a lowering factor of the thermal conductivity. As compared to the hexagonal and random arrays, the square array of carbon fibers within the GNP-modified epoxy produces the largest transverse thermal conductivity. On the basis of comparative studies, the model predictions agree very well with the experimental data available in the literature.