Design of a ternary synergistic network of HDPE/BN/CNT composites with an aligned shish-kebab structure for enhanced thermal conductivity and tensile strength

Fabricating polymer composites with excellent thermomechanical properties remains a challenge due to the tradeoff between high filler loading and loss of strength. Conventional composites made of randomly oriented lamellae and aggregated fillers fail to construct thermally conductive pathways for filler-filler or filler-crystal contacts. To address this issue, a synergistically ternary network composed of aligned BN and elongated CNT in a shish-kebab structure has been prepared by an in-house Rotation Shear System (RSS). The composite with 20 wt% BN and 5 wt% CNT achieved a high thermal conductivity of 2.37 W/(mK) under shear modification. The tensile strength and Vicat softening temperature of the composite are 2.29 times higher and 21.9 °C greater than those of unsheared samples. Such superior thermal and mechanical properties are mainly attributed to the interlocking shish-kebab structure, which serves as a support skeleton in composites, where aligned BN and CNT construct a heat-resistant barrier. This work provides an effective strategy to fabricate high thermally conductive composites with excellent mechanical properties, providing new insights into reducing material replacement frequency under extreme operating conditions.