Transient thermal behaviour of high thermal conductivity graphene based composite materials: Experiments and theoretical models

High thermal conductivity composites could be a valid alternative to traditional materials in many engineering applications. This work presents the realization of high thermal conductivity composites based on multilayer graphene sheets (GS) impregnated with polydimethylsiloxane (PDMS). Three composite configurations were prepared: discs, slab, and roll. The in-plane and out-of-plane effective thermophysical properties of GS/PDMS composites have been measured. Thermal diffusivity has been measured by a homemade Flash Method (FM) and the density by a gravimetric method. Specific heat and thermal conductivity have been calculated. The experiment results showed that the GS/PDMS composite has an in-plane thermal conductivity up to 430 W m- 1K-1 with a GS loading of 70 wt%, higher than standard metals used in heat exchangers (e.g. copper, aluminum). The out-of-plane effective thermal conductivity reached up to 1 W m- 1K-1 with a GS loading of 95 wt%, comparable with other high thermal conductivity composites that work as thermal interface materials in electronic applications. Two analytical models to predict the effective thermophysical properties of the multiphase composites were developed and presented.