Mechanism and Limitation of Heat Conduction in Three-Phase Polymer Composites Having Carbon Nanotubes and Inorganic Nanoparticles

For the first time, an Off-Lattice Monte Carlo method is developed successfully to predict thermal conductivities ($K_{\mathrm{eff}})$ of three-phase composites having carbon nanotubes (CNTs) and tungsten disulfide (WS$_{2})$ nanoparticles more accurately and faster than previous methods such as effective medium theories, molecular dynamics and finite element methods. The $K_{\mathrm{eff}}$ predicted by our model using a random walk algorithm and taking into account various thermal boundary resistances at each interface and inter-CNT contact has an excellent agreement with experimental data. Our model can comprehensively explain the mechanism of heat conduction in complex composite structures. Effects of WS$_{2}$ and CNT morphologies (diameter, length, inter-contact, bundle), CNT concentrations, CNT orientations (parallel, random and perpendicular to heat flux) and thermal boundary resistances of CNT-polymer, WS$_{2}$-polymer, CNT-CNT, CNT-WS$_{2}$ on heat conduction limitation of the three-phase composites are also investigated systematically. Our model can be also applied to the biological and nanofluid systems.