Numerical analysis on the direction to improve thermal conductivity of polymer composites filled with spherical particles

The research on thermal conductivity of insulating polymer-matrix composites filled with spherical particles (PMCs-SP) is far below the requirements for industrial utility. To find the improving direction for the thermal conductivity of PMCs-SP (KPMCs-SP), a series of PMCs-SP models filled with randomly distributed spherical particles were established. The PMCs-SP models were validated by comparing the calculated KPMCs-SP with the experimental data. It is found that KPMCs-SP increases with the increasing volume fraction of spherical particles, and the influence of filler size and interfacial thermal resistance on KPMCs-SP shows a significant synergistic effect. The formation of heat conduction chains could effectively improve KPMCs-SP. Increasing the number of heat conduction chains and decreasing the spacing of spherical particles can both increase the KPMCs-SP. To quantify the effect of heat conduction chains on KPMCs-SP, the concept of compactness of heat flow chains (C) was creatively proposed. The KPMCs-SP-C curve presences a threshold value, C-0 = 0.6372, beyond which KPMCs-SP could be significantly enhanced. In addition, the theoretical specific thermal resistance of PMCs-SP (R-lambda(,)PMCs-SP) was first calculated. For PMCs-SP with the default parameters, the theoretical minimum R-lambda(,)PMCs-SP converged to similar to 0.72 m center dot K center dot W-1.