Toward high efficiency thermally conductive and electrically insulating pathways through uniformly dispersed and highly oriented graphites close-packed with SiC

Abstract

The heat dissipation property of the thermally conductive and electrically insulating composites can be enhanced by constructing high efficiency thermally conductive pathways, while the mechanical properties of the final composites are always neglected. In this work, graphite (Gt), a typical carbon based filler with excellent thermal conductivity, was highly oriented and uniformly dispersed in polymer matrix to keep the electrical resistivity of the composite at a high level, even when the content of Gt was 33 wt%. Then, in order to further improve thermal conductivity, the consecutive and high efficiency thermally conductive yet electrically insulating pathways were constructed by adding silicon carbide (SiC) particles into the composites as junctions to release the thermally conductive potential of Gt via forming phonon transport channels. As a result, thermal conductivity reached 1.68 W/(m × K) when the content of SiC was 20 wt%. Meanwhile, the in-plane thermal conductivity (along the melt flow direction) was as high as 3.8 W/(m × K), which was over 5-fold larger than the through-plane thermal conductivity (along the thickness direction). Subsequently, Agari model and thermally conductive simulation based on the finite element analysis were also applied to give a deep insight into the effect of this special filler architecture on the heat dissipation performance of the composites. Furthermore, mechanical properties of such composites were also largely enhanced. Therefore, building up high efficiency thermally conductive and electrically insulating pathways through highly oriented and uniformly dispersed 1-D or 2-D anisotropic carbon based fillers close-packed with another kind of uniformly dispersed thermally conductive and electrically insulating fillers is a simple and effective method to endow the composites with excellent thermal conductivity, high electrical resistivity and great mechanical properties simultaneously.