Preparation of liquid metal/thermoplastic polyurethane composites with enhanced thermal conductivity via rolling regulation

This work reports a method for preparing liquid metal/thermoplastic polyurethane (LM/TPU) elastic composite materials through melt blending, and enhancing the thermal conductivity of the composites using a rolling regulation process. Through observation of the microstructure of the composite material, it is found that the vane mixer can effectively disperse LM uniformly, which leads to a significant enhancement in thermal conductivity from 0.21 W m⁻¹ K⁻¹ of pure TPU to 2.12 W m⁻¹ K⁻¹ for composite with 50 vol % LM. After rolling regulation, SEM images reveal the formation of interconnected thermal conduction pathways within the composites. The thermal conductivity of the composite material with 30 vol % LM increases from 1.74 W m⁻¹ K⁻¹ to 2.50 W m⁻¹ K⁻¹, which is higher than the pre-regulation thermal conductivity of the composite with 50 vol % LM. Moreover, the thermal conductivity of the composite material with 50 vol % LM increases even further to 3.16 W m⁻¹ K⁻¹. The rheological behavior of the composite further substantiates the establishment of a network configuration after the rolling regulation that facilitates heat transfer. This implies that the melt blending-rolling regulation process can achieve the fabrication of composite materials with high thermal conductivity, offering a reliable strategy for industrial development of flexible thermal conductive materials.