Enhancing thermal conductivity of segregated structural PE/PVDF/BN composites: Role of viscosities

It is challenging to fabricate polymer composites with high thermal conductivity at a low concentration of fillers. In this work, Polyethylene (PE)/Poly (vinylidene fluoride) (PVDF)/Boron nitride (BN, average size of 25 mu m and specific surface area of 2-4) segregated structural composites were prepared to investigate the effect of micro-structure evolution along with a wide range of matrix viscosity ratios (0.08-20.96) on the thermal conductivities. The PE/PVDF/BN composite with a viscosity ratio of 20.96 shows a high thermal conductivity of 2.36 W/(m.K), outperforming the composite with a viscosity ratio near 1 (1.34 W/(m.K)) by 177%. Moreover, the orientation of BN was characterized by the X-ray diffractometer, which demonstrated that I100/I002 could be altered by different viscosity ratios, indicating a higher alignment in the vertical direction. Besides, infrared thermal images and energy harvest measurements further confirmed the composite with high viscosity ratio presents a stronger capability to dissipate the heat. The obtained results enlightened to the valuable fundamental design and the fabrication of the highly thermal-conductive polymer-matrix composites by controlling viscosity ratio, expecting to be applied as advanced thermal management materials.