Effects of carbon black addition on the carbonization of mesophase pitch

Carbonization of a mesophase pitch produced catalytically from naphthalene with HF/BF₃ was examined by blending carbon black particles to suppress its severe expansion just before the resolidification that was its major disadvantage for the application as a composite binding substance. The carbon blacks were found effective to suppress the expansion of the mesophase pitch, the particle of large surface area or high oil absorption ability in the pitch such as Ketjen Black (KB) being most effective. The KB particles were found well dispersed in the whole area of the pitch, extending the chain structure, breaking the molecular stacking into smaller optical units (fine mozaic), and hindering the graphitization at the calcined and graphitized stages of the mesophase pitch. Such dispersed particles are expected to release the evolved gases from the molten mesophase pitch along their surface. It is noted that the slurry of the mesophase pitch with carbon blacks maintained the viscosity low enough for smooth impregnation before the carbonization, although the blending certainly increased apparent viscosity.