Characteristics of meso-carbon microbeads separated from pitch

Mesophase spherules separated by solvent fractionation from heat-treated coal-tar pitch and from heat-treated asphalt at 430°C are named “meso-carbon microbeads”. Characteristics of these mesophase microbeads were studied. The meso-carbon microbeads are classified into three types, type C, type M and type P, corresponding to the raw pitch materials. The chemical composition of type C and type M consists of high molecular weight aromatic hydrocarbons having short side chains of aliphatic hydrocarbons, and that of type P consists of small ring number aromatic hydrocarbons having long side chains of aliphatic hydrocarbons. The shapes of the meso-carbon microbeads are classified into lemon-like and spherical by their shape. The meso-carbon microbeads do not fuse or melt by heat-treatment. The graphitizability of heat-treated meso-carbon microbeads is not high. When the meso-carbon microbeads are heat-treated at 300–500°C in a medium of polynuclear aromatic hydrocarbons (anthracene, pyrene, chrysene and pitch) their behavior is similar to that of mesophase spherules in pitch. However, when the ratio of the meso-carbon microbeads to the polynuclear aromatic hydrocarbon was changed, the behavior of the microbeads was peculiar.