Effect of microstructure on thermal conductivity of polymer composites

Thermal conductivity (TC) of polymer composites is strongly depended on thermal conductive fillers as well as heat conduction pathways formed by these fillers. In this work, we examined effects of morphology, size and arrangement of fillers on TC of polymer composites by using energy-conserving dissipative particle dynamic (e-DPD) simulation. Theoretically, we explored effects of ideal and pseudo thermal conductive pathways on composites' TC and investigated heat conduction of filler particles with cubic-center and lamellar morphology. To confirm orientation and size effects of lamellar filler particles on composites' TC, we prepared a series of Boron Nitride/Silicon rubber composites (BN/SiR). Being same with those observed in e-DPD simulation, orientation could efficiently improve TC of BN/SiR composites. The TC of composites with filled diameters about 10 micrometer of BN flats is 11 times higher than that of SiR matrix. Our researching results show that heat conduction pathways are essential to transportation of heat flux in polymer composites and even pseudo pathways by disconnected filler particles along temperature gradient can accelerate heat conduction.