Influence of the Void Structure on Thermal Performance in HGM/ER Composites

The heat transfer mechanism of hollow glass microsphere/epoxy resin composites (HGM/ER) is intricate, and the formation of void structures during material preparation complicates the prediction of thermal conductivity. To investigate the microscopic heat transfer mechanisms of HGM/ER materials with void structures and analyze the impact of void variables on the overall thermal performance, this study addresses the issue of low packing density and poor uniformity in traditional cellular unit structures. An improved random sequential adsorption (RSA) algorithm is proposed, increasing the upper limit of particle fill rate by 25% relative to traditional RSA algorithms. The Benveniste equivalent microsphere thermal conductivity model is selected for thermal performance simulation, demonstrating its high correlation with the three-component model (air, glass, resin), with a maximum relative error of only 1.32%. A classification method for void types in HGM/ER materials is proposed, categorizing them into interfacial and free voids. The microscopic heat transfer mechanisms of HGM/ER materials are investigated under different voids levels and void types, and it was found that the effect of interfacial voids on thermal conductivity is 60% higher than that of free voids. Based on the measured voids of the material, this study provides a reference for the convenient prediction of thermal conductivity in practical engineering applications of HGM/ER composites.