Effects of fullerene addition on the carbonization of synthetic naphthalene isotropic pitch

The toluene soluble fraction of fullerene soot, consisting of C₆₀ and C₇₀ and other fullerenes, was co-carbonized with synthesized isotropic pitch derived from naphthalene. Mixtures of fullerene and pitch gave carbons in higher yield than expected from their single carbonizations at fullerene contents <30 wt%. The fullerenes suppressed the expansion of the pitch during carbonizations, and changed the optical textures of resultant carbons. At levels of addition of fullerenes <30 wt%, no fullerenes could be detected in resultant carbons by spectroscopy, but were detected as spheres of ca. 10-20 nm diameter in the carbons by TEM. It is considered that fullerenes remove hydrogen from the naphthenic structures of the pitch and so alter carbonization characteristics. Hydrogenation breaks the spheroidal fullerene framework.