Thermal conductivity enhancement via conductive network conversion from sand-like to stone-like in the polydimethylsiloxane composites

Different from traditional compounding methods, a conversion method from sand-like to stone-like conductive network aimed at improving the thermal conductivity (TC) of polymer composites was proposed in this paper. Herein, sand-like and stone-like channels represented the thermal conductive networks (TCNs) with high and low thermal dissipation performances in polymer composites. The densification of TCNs and the adding of specific rigid particles were found to be two effective ways to realize the conductive network conversion from sand-like to stone-like. In this research, the polydimethylsiloxane/short carbon fiber/glass bubble (PDMS/SCF/GB) composite was selected to verify the practicability of this conversion theory. The SCF contents changed from 10 to 30 wt% to reveal the influence of filling content on the sand-stone conversion of TCNs. A constant content of 2 wt% GBs was selected based on our previous experience to highlight the beneficial effect of adding rigid particles. Meanwhile, the influence of product thickness on the PDMS composites was also systematically investigated. The TC of PDMS/SCF/GB composite with 0.1 mm thickness reached 11.690 W/m.K, 42.30 times higher than that of pure PDMS (0.27 W/m.K). Moreover, the superior flexibility and mechanical property of final product provided convenience for their application as thermal management materials in electronics.