Preparation and thermal properties of polyacrylonitrile-based carbon fiber–silicon carbide core–shell hybrid

• A polyacrylonitrile-based carbon fiber–SiC core–shell hybrid was prepared.
• Dip coating of SiO2 sol on the fiber surface was followed by carbothermal reduction.
• The SiC coating raised the decomposition temperature and thermal conductivity.
• Longer carbothermal reduction further increased the thermal conductivity.

A polyacrylonitrile (PAN)-based carbon fiber–silicon carbide core–shell hybrid (SiC/PAN-CF) was prepared by carbothermal reduction of SiO2/PAN-CF, which was obtained by dip coating a SiO2 sol on the surface of PAN-CF. The surface of the PAN-CF was uniformly covered with the SiC, and the decomposition temperature of SiC/PAN-CF was higher than that of the uncoated PAN-CF. In addition, the thermal conductivity of epoxy composites consisting of PAN-CF or SiC/PAN-CF was measured using a laser flash method. At a 80 wt% filler loading, the thermal conductivity of SiC/PAN-CF-epoxy composite was found to be 0.750 W/mK, which is 2 times higher than that of the PAN-CF-epoxy composite and approximately 3.5 times greater than that of unmodified epoxy resin. Furthermore, the thermal conductivity of SiC/PAN-CF-epoxy composite increased with increasing carbothermal reduction time. This increased thermal conductivity is due to improving the specific surface area and wettability with epoxy matrix, thus resulting in an improved the interfacial adhesion with epoxy matrix.