Utilization of hybrid fillers with high thermal conductivity enhancement (TCE) efficiency is an effective method for the large-scale fabrication of polymeric thermal interface materials (TIMs) with exceptional thermal conductivity. Herein, we report the thermally conductive properties of thermoplastic urethane (TPU) composites incorporated with expanded graphite (EG) and multi-layer graphene (MLG). The effect of percolation behavior of EG/MLG hybrid fillers on the thermal conductivity is systematically revealed. It is found that the high-loading TPU composite with 20 wt% EG and 10 wt% MLG reveals an exceptional thermal conductivity of 8.52 Wm⁻¹K⁻¹, which corresponds to a TCE of 3450% compared to that (0.24 Wm⁻¹K⁻¹) of pure TPU matrix. Notably, the TCE per 1 wt% filler reaches a substantial value of 115%. The thermally conductive mechanism is proposed based on morphology and thermal contact resistance analyses. Moreover, the application of such TPU composites in thermal management of light-emitting diode lamps is exhibited, and the effectiveness is further verified through finite element simulation. Our results shed light on the significant thermal synergy between EG and MLG and demonstrate their application potential in high-performance TIMs.

利用具有高导热性增强 (TCE) 效率的混合填料是大规模制造具有优异导热性的聚合物热界面材料 (TIM) 的有效方法。在此，我们报告了与膨胀石墨 (EG) 和多层石墨烯 (MLG) 结合的热塑性聚氨酯 (TPU) 复合材料的导热性能。EG/MLG 混合填料的渗透行为对热导率的影响被系统地揭示。发现具有 20 wt% EG 和 10 wt% MLG 的高负载 TPU 复合材料显示出优异的导热系数 8.52 Wm ^-1 K ^-1，这对应于 3450% 的 TCE 相比（0.24 Wm ^-1 K ^-1) 的纯 TPU 矩阵。值得注意的是，每 1 wt% 填料的 TCE 达到了 115% 的实际值。基于形态和热接触电阻分析提出了导热机制。此外，展示了此类TPU复合材料在发光二极管灯热管理中的应用，并通过有限元仿真进一步验证了其有效性。我们的结果阐明了 EG 和 MLG 之间显着的热协同作用，并证明了它们在高性能 TIM 中的应用潜力。