Preparation of graphene modified epoxy resin with high thermal conductivity by optimizing the morphology of filler

Reduced graphene oxide (RGO) modified epoxy resin with identical mass fraction of filler display varied thermal conductivities in previous reports, leading to the absence of an unified standard to judge the ability of RGO acting as a thermal conductive filler. We have found that the distinction in residual amount of surface functional groups of the RGO is one of the root causes for this phenomenon. In this study, we further explore the influence on thermal conductivity of the resulting composite from the average size and thickness of the adopted RGO. Appropriate morphology of the filler is beneficial for obtaining high thermal performance (2950% higher than that of the pristine organics after adding 20 wt% RGO), and the reasonable explanation is proposed after analyzing the sources of thermal resistance of the as-prepared composites. Moreover, the thermal performance stability of the samples under high temperature is further optimized, lesser functional groups, smaller average size and thinner layer of the RGO sheets bring about higher stability of the thermal performance because the decrease of Kapitza boundary scattering becomes more evidently with the increased temperature. The mechanical performances of the resulting composites maintain a high level, simultaneously. This work contributes to the further practical application of the RGO assisted thermal interface materials in the microelectronic area.