Thermal and electrical anisotropy of polymer matrix composite materials reinforced with graphene nanoplatelets and aluminum-based particles

Graphene nanoplatelet-reinforced polymers are one of the most potential thermal interface materials used for thermal management of electronic devices and systems. These uncured polymer matrix composite materials are typically anisotropic, leading to both advantageous and disadvantageous effects. Graphene nanoplatelet-based thermal interface materials benefit from thermal anisotropy. What is not entirely clear, however, is how to avoid the adverse effects caused by thermal and electrical anisotropy. Accordingly, the primary focus of this study was on how to effectively reduce thermal resistance and electrical conductivity for graphene nanoplatelet-based thermal interface materials. The relative performance of thermal interface materials reinforced with various thermally conductive fillers was evaluated. Design rules were developed for the optimization of anisotropic composite materials. The results indicated that additional reinforcement material such as aluminum-based particles should be further incorporated into a graphene nanoplatelet-based thermal interface material so that the overall performance is not adversely affected by thermal and electrical anisotropy after improvements in physical properties. With such a hybrid filler, a two-fold increase in thermal conductivity can be achieved due to the synergistic effect existing within the resultant composite material, and the degree of electrical anisotropy can be reduced by at least one order of magnitude. Furthermore, there exists an optimum hybrid-filler weight fraction, at which both thermal resistance and electrical conductivity are minimum and a low degree of anisotropy can be achieved. Finally, the results will provide a theoretical basis for the development of effective graphene nanoplatelet-based thermal interface materials.