Effect of graphene and carbon-nitride nanofillers on the thermal transport properties of polymer nanocomposites: A combined molecular dynamics and finite element study.

Low thermal conductivity of polymers, which is one of the considerable drawbacks of commonly used composite structures, has been the focus of many researchers aiming to achieve high-performance polymer-based nanocomposites through the inclusion of highly thermally conductive fillers inside the polymer matrices. Thus, in the present study, a multiscale scheme using nonequilibrium molecular dynamics and the finite element method is developed to explore the impact of different nanosized fillers (carbon-nitride and graphene) on the effective thermal conductivity of polyethylene-based nanocomposites. We show that the thermal conductivity of amorphous polyethylene at room temperature using the reactive bond order interatomic potential is nearly 0.36±0.05W/mK. Also, the atomistic results predict that, compared to the C_{3}N and graphene nanosheets, the C_{2}N nanofilm presents a much stronger interfacial thermal conductance with polyethylene. Furthermore, the results indicate that the effective thermal conductivity values of C_{2}N-polyethylene, C_{3}N-polyethylene, and graphene-polyethylene nanocomposite, at constant volume fractions of 1%, are about 0.47, 0.56, and 0.74W/mK, respectively. In other words, the results of our models reveal that the thermal conductivity of fillers is the dominant factor that defines the effective thermal conductivity of nanocomposites.