Development of Theoretical Model for Effective ...

Thermal conductivity is an important thermal property of materials and plays an important role in determining their heat conduction/insulation capability. The present work aims to study the effect of embedded solid glass microspheres (SGM) on the effective thermal conductivity of epoxy resin. Composite samples were prepared by embedding SGMs of different sizes in the epoxy resin. Three-dimensional spheres-in-cube lattice array models were constructed using finite element method (FEM) to simulate the microstructure of composite materials for various SGM content ranging from 0 to about 17.9 vol %. Finally, guarded heat flow meter test method was used to measure the conductivity of these composites. A relevant theoretical model was deduced based on the law of minimal thermal resistance and the equal law of the specific thermal conductivity. The simulations were compared with keff values obtained from experiments and it is found that the FEM simulations and keff values of the theoretical model are fairly close to the measured keff. This study has shown that the embedment of glass microsphres results in substantial reduction of heat conductivity of epoxy resin and thereby improving its thermal insulation capability. Further, the size and content of SGMs would influence the extent of reduction of keff.