Analytical study on thermal conductivity enhancement of hybrid-filler polymer composites under high thermal contact resistance

This paper presents an investigation on the thermal conductivity (TC) enhancement for polymer composites reinforced with randomly distributed hybrid filler using both numerical and theoretical approaches. Effects of thermal contact resistances (TCR) at the interfaces between fillers and the matrix material are considered comprehensively. Consequently, the deviation of ETC under the particle distribution effect generally increases as the filler volume fraction (VF) increases. Modified Hashin-Shtrikman model proposed in previous study can be used to predict accurately the TC of composites only if two fillers have the same TCR and TCR is less than prescribed value. The ETC depends significantly on the TCR ratio between two fillers, obviously at high sum of TCRs. Particularly, the TC can be enhanced significantly and effectively even at very high TCR by increasing VF ratio while keeping other appropriate conditions. Furthermore, the optimal TC ratio between two fillers at which the ETC is maximized, was shown to be independent on the TCR only if two fillers have the same TCR. These results provide a very good guideline for synthesizing hybrid-filler polymer composites and enhancing its TC under the effects of TCR.