Achieving superior thermal conductivity in polymer bonded explosives using a preconstructed 3D graphene framework

Abstract

When subjected to complicated thermal alternation, the low thermal conductivity (k) of polymerbonded explosives (PBXs) will induce high thermal stress, which will undermine the safety and reliability of the explosives by causing cracks or damage. However, it has been proven to be a challenge to efficiently increase the k of PBXs due to the high interfacial thermal resistance (ITR) and intrinsic defects of their conductive nanofillers. By introducing AgNWs with a high aspect ratio into graphene, this study constructed a novel multi-dimensional high-k nanofiller composed of one-dimensional (1D) silver nanowires (AgNWs) and two-dimensional (2D) graphene, namely gra@AgNWs. The AgNWs decorated could remedy the intrinsic defects of graphene by passing through the interspaces within graphene nanosheets to form connections as bridges. Consequently, the k of energetic polymer composites increased significantly by 89% from 0.425 ​W ​m⁻¹ ​K⁻¹ to 0.805 ​W ​m⁻¹ ​K⁻¹ at ultralow filler loading of 0.5 ​wt%. Furthermore, the temperature gradients and thermal stress in the composite cylinder decreased significantly under complicated thermal changes owing to the enhanced k. As quantitatively demonstrated through the fitting of experimental data using a theoretical model, AgNWs significantly decreased the ITR, paving highways” for phonon transfer between adjacent graphene nanosheets. Hence an expected synergistic effect of heat transfer was produced in the composites. This study provides new insights into the design and preparation of highly thermally conductive composites.