Effect of filler orientation induced by force on thermal conductivity of AlN/BN/CNTs/SR composites

Abstract

With the development of technology, the amount of heat generated by electronic components has increased significantly. Therefore, it is increasingly urgent to develop materials with high thermal conductivity and high insulation properties. Thermally conductive composites were prepared by mechanical blending using methyl vinyl silicone rubber (SR) as the matrix, and some particles including carbon nanotubes (CNTs), hexagonal boron nitride (BN) and aluminum nitride (AlN) as thermally conductive fillers. The effect of hybridization of three kinds of fillers on the thermal conductivity, electrical insulation and mechanical properties of the composites was studied. The influence of the filler orientation on the thermal conductivity of the composites was investigated. The effect of the heating time on the surface temperature of the composites was also investigated and the theoretical thermal conductivity of the composites was fitted according to Agari model. The composites were characterized by an infrared thermal image, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results show that with the decreased addition of AlN and the increased loadings of BN and CNTs, the thermal conductivity of the composites is gradually increased. When the content of AlN, BN and CNTs is 80, 68 phr and 2 phr respectively, the composites show better overall performance, where the out-plane and in-plane thermal conductivity of the composites is 1.857 W·m-1·K-1 and 2.853 W·m-1·K-1, and the volume resistivity and the tensile strength is 2.18×1012 Ω·cm and 4.3 MPa, respectively.

Keywords

• silicone rubber
• boron nitride
• aluminum nitride
• carbon nanotube
• thermal conduction
• orientation