Enhancing thermal conductivity via conductive network conversion from high to low thermal dissipation in the polydimethylsiloxane composites

Abstract: The thermal conductive network (TCN) in the polymer composites was divided into high thermal dissipation TCN and low thermal dissipation TCN according to the rate of heat loss during the transmissions. The limited thermal conductivity (TC) enhancement in the composites prepared by traditional compounding methods was due to high thermal dissipation of TCNs. In this study, the TC enhancement based on conductive network conversion from high to low thermal dissipation was demonstrated in the polydimethylsiloxane/short carbon fiber/glass bubble (PDMS/SCF/GB) composites. Two approaches, i.e., the densification of TCN by spatial confining forced network assembly (SCFNA) method and the volume exclusion by adding rigid particles, were used to realize the TCN conversions from high to low thermal dissipation. Compared with the TC of the PDMS/SCF(30 wt%) composites prepared by traditional compounding method (1.053 W/mK), the TC (11.423 W/mK) of the same composites was increased by more than 9 times using SCFNA method. The TC even presented an unexpected ~13% enhancement to 13.004 W/mK after adding 2 wt% GB with a relatively low TC of 0.15 W/mK. In summary, a proper combination and optimization of these two approaches would lead to a TC enhancement by one order of magnitude and more compared with traditional compounding methods.