Chopped carbon fibers are made by cutting carbon fiber filaments through fiber chopping. Compared with carbon fiber filaments, they can be more uniformly dispersed in the matrix material. Chopped carbon fiber not only has super high mechanical strength, low density, and good thermal stability, but also is a thermally conductive material with excellent performance. It is an ideal thermally conductive filler to improve the thermal conductivity of polymer materials. However, one-dimensional materials have serious thermal anisotropy. How to fully control the vertical orientation of chopped carbon fibers in the polymer matrix material, so as to make full use of the high axial thermal conductivity of carbon fibers to obtain composites with excellent longitudinal thermal conductivity are The key to research. A commonly used method is to orient the carbon fibers in a vertical direction by applying an external electric field to the chopped carbon fibers. However, this method requires strong electric field strength and complicated process. In addition, the thickness of the composite material is limited by the length of the fiber, and it is difficult to obtain a thermally conductive composite material with a suitable thickness.
Based on the above problems, the functional carbon material team of the Surface Division of the Institute of Materials Technology and Engineering of the Chinese Academy of Sciences used the orientation guidance of ice crystals in a uniaxial temperature field to make the chopped carbon fibers oriented in the vertical direction. The structure and microstructure of the carbon fiber porous foam with a "structure" are shown in Figure 1. The "micro reed bush" structure makes full use of the axial high thermal conductivity of carbon fibers to enhance the thermal conductivity of polymer materials. The thermal conductivity of the composite material prepared by this method is as high as 6.04 Wm-1K-1, and the obtained composite material has good flexibility, and is expected to replace the traditional polymer material to solve the heat dissipation problem of electronic and electrical equipment.