Preparation of mesocarbon microbeads by dispersing mesophase pitch in isotropic pitches Original Research Article

Mesocarbon microbeads of 1–10 μm were prepared through dispersing the synthetic mesophase pitches in synthetic isotropic pitches and successive solvent extraction. The suitable ratio of mesophase pitch/isotropic pitch, temperature and rapid agitation at dispersion were found to be key factors to obtain the high yields of tetrahydrofuran and pyridine insoluble microbeads which were 34 and 20 wt%, of the highest yield, respectively. In contrast, the combinations of coal tar derived mesophase pitch/synthetic pitch or synthetic mesophase pitch/petroleum A240 pitch failed to disperse spheres of mesophase pitch in the isotropic matrix, leaving bulk grains of mesophase pitch at the bottom of the matrix. The melt mesophase pitch of adequate viscosity is dispersed by the agitation into viscous droplets in the isotropic matrix, while the droplets stay afloat because of their similar specific gravities. The lighter component in the droplet of the mesophase pitch was extracted into the isotropic matrix while the mesophase pitch is melted, leaving spheres of smooth surface. Extraction by the solvent at a lower temperature than the softening point leaves mesocarbon microbeads isolated, removing the solvent soluble fraction.