Investigating thermal conductivities of functionalized graphene and graphene/epoxy nanocomposites

This research investigated the thermal conductivities of functionalized graphene (FG) and FG/epoxy nanocomposites by using molecular dynamics simulation. The functional groups considered in FG are carboxyl and amine groups. The results indicated that the thermal conductivity of FG is markedly reduced compared with that of pristine graphene. However, the FG/epoxy nanocomposites demonstrated higher thermal conductivity than did the pristine graphene nanocomposites. To understand the enhancement mechanism, the interfacial thermal conductance (ITC) between the FG and the surrounding epoxy matrix was examined. The effects of the FG on ITC were explicated using vibrational density of state and normalized interaction energy. The improvement of the thermal conductivity of FG/epoxy nanocomposites was attributable to the enhancement of the ITC resulting from the functional groups grafted on the graphene surface. In addition, establishing the functional groups facilitates atomistic interaction between the graphene and epoxy, which can reduce the phonon mismatch and enhance the thermal transport efficiency in the nanocomposite. The enhanced thermal conductivity in the FG/epoxy nanocomposites was validated by experimental observation. (C) 2016 Elsevier B.V. All rights reserved.