Carbon fiber/boron nitride fillers for enhancing through-plane thermal conductivity of poly(vinylidene fluoride): Synergistic effect and mechanism

Two series of thermally conductive poly(vinylidene fluoride) (PVDF) composites were prepared by adding boron nitride (BN) and carbon fiber (CF) of different mass ratios via hot-pressing. The synergistic effects of the dual fillers on the thermal conductivity enhancement were investigated. The morphology, thermal conductivity, crystallinity, thermal stability, mechanical properties, and long-term chemical stability of the PVDF composites were characterized. The results demonstrated a significant synergistic effect between the BN and the CF on enhancing the thermal conductivity of the PVDF-based composites. The maximum thermal conductivity of 1.89 W/(m·K) with an improvement of 1014 % was achieved when 15 wt% BN and 15 wt% CF were added in the PVDF matrix. The synergistic effect resulted in the formation of efficient three-dimensional thermally conductive networks with a synergistic efficiency up to 113 %. The Agari model was employed to illustrate the thermal conduction mechanism, revealing the improved ability of the dual fillers to form conductive pathways. The PVDF composites showed good crystallinity, thermal stability, mechanical strength, and long-term chemical stability. This study highlights the potential of the PVDF/BN/CF composites for applications in membrane heat exchangers and provides significant insights into the design of high-performance thermally conductive polymer composites.