The evolution of microstructure and thermal conductivity of mesophase pitch-based carbon fibers with heat treatment temperature

The evolution of microstructure and morphology of mesophase pitch-based carbon fibers (MPCFs) with heat treatment temperature (HTT) was investigated by SEM, TEM, Raman spectroscopy and XRD. The thermal conductivity of the MPCFs was examined by a modified 3ω method. Results indicate that the degree of graphitization and the thermal conductivity of the MPCFs increase with HTT. The thermal conductivity of the MPCFs reaches 518 W/m·K at a HTT of 3000℃. The thermal conductivity of MPCFs varies linearly with HTT in two distinct ranges, 1000-2000 and 2300-3000℃, that respectively correspond to the growth and orientation of graphite crystallites.