Synergetic enhancement of thermal conductivity by constructing hybrid conductive network in the segregated polymer composites

Effectively thermal conduction pathways are essential for the thermal conductivity of polymer-based composites. In this contribution, we proposed a facile and feasible strategy to improve the thermal conductivity of polymer composites through constructing a segregated structure and hybrid conductive network. Boron nitride (BN) and aluminium nitride (AlN) were mechanically wrapped upon ultrahigh-molecular-weight polyethylene (UHMWPE) granules and then high-pressure consolidated. Morphology observation revealed that in the typical segregated pathways, polyhedral AlNs were in tandem with adjacent BN plates. A significantly synergistic enhancement in the thermal conductivity was achieved by the hybrid conductive network. At the total filler content of 50 wt%, the BN/AlN/UHMWPE composite with a filler ratio of 6:1 showed the thermal conductivity of 7.1 Wm-1 K−1, outperforming BN/UHMWPE and AlN/UHMWPE composites by 35.1% and 613%, respectively. Infrared thermal images further demonstrated that the composites with hybrid segregated structure had strongest capability to dissipate the heat against the counterparts with single segregated structure. Based on the percolation effect with an effective medium approach, the theoretical calculation suggested that AlN played a bridge role to interconnect the BN platelets in the segregated conductive pathways, leading to the formation of the more effective thermally conductive pathways. The obtained results offer valuable fundamentals to design and fabricate the highly thermal-conductive polymer composites as advanced thermal management materials.