Synergistic effect of carbon fiber and alumina in improving the thermal conductivity of polydimethylsiloxane composite

•A high-performance thermal pad was obtained by using a hybrid filler made of carbon fiber and alumina.•This paper reports the synergistic effect of carbon fiber and alumina on improving the thermal conductivity of polydimethylsiloxane composite.•The synergy is attributed to an optimized heat transfer network and reduced interfacial thermal resistance. The combination of various fillers can improve the thermal conductivity of polymer composites, because an efficient heat conduction network synergistically formed in matrix. The synergistic effect of two fillers, carbon fiber and alumina particle, in polydimethylsiloxane (PDMS) is investigated in this work. A filler combination results in higher thermally conductive composite than any of the single filler. The volume ratio of 4:1 shows the greatest thermal conductivity. The thermal conductivity of PDMS composite filled with 24 vol% carbon fiber and 6 vol% alumina reaches 7.91 W m−1K−1, which was 34% higher than that of 30 vol% CF/PDMS. The combined filler composite also shown better process performance due to the lower viscosity. The synergy is attributed to the optimized heat transfer network and reduced interfacial thermal resistance. Therefore, a combined filler achieved better thermally conductive performance and better process performance with cost-effective source materials. [Display omitted]