Finite Element Modeling of the Thermal Conductivity of Polymer Composites Reinforced with Graphite Sheets

Efficient heat dissipation represents a critical challenge for maintaining device performance and reliability in modern electronic devices. Polymer composites reinforced with graphite sheets have attracted attention as thermal interface materials because of their lightweight nature and excellent thermal transport properties. Herein, the effects of graphite sheet volume fraction, sheet thickness, folding angle, and sheet orientation on the through-thickness thermal conductivity of epoxy/graphite sheet composites were investigated using finite element (FE) modeling. A reduced folding angle and increased graphite sheet thickness enhanced the through-thickness thermal conductivity. However, for the same graphite volume fraction, reducing the folding angle enhanced thermal conductivity more effectively than increasing the graphite sheet thickness, indicating the dominant role of sheet orientation in the heat transport behavior. The influence of the folding angle became significant at higher graphite volume fractions due to the formation of more continuous conductive pathways. At a graphite sheet volume fraction of 0.5, the thermal conductivity decreased from 22.27 to 11.52 W m^-1 K^-1 upon increasing the folding from 15° to 90°. Finally, a semi-empirical model exhibiting good agreement with the FE results was developed, demonstrating that optimization of graphite sheet geometry is essential for improving the thermal performance of polymer-based thermal interface materials.