Carbon black modification of mesophase pitch-based carbon fibers

The effects of carbon black (CB) on the microstructural development within mesophase pitch-based carbon fibers are reported. Unlike carbon nanotubes, which were previously studied for modifying fiber microstructure, CB represents a significantly lower cost alternative making it more favorable for industrial application. Additionally, the aspect ratio of CB is much closer to unity than carbon nanotubes, which have an aspect ratio ∼100 to 1000. Fibers were produced by first dispersing CB into a synthetic mesophase pitch at a dilute concentration of 0.3 wt%. These precursor materials were spun and then processed into carbon fibers. Unmodified (0 wt%) carbon fibers exhibited a severe radial texture with increasing orientation of graphitic pleats away from the fiber core. Carbon fibers modified with CB showed a strong flat layer structure, with only a slight increase in pleat folding away from the core. This difference in structure was also accompanied by a decrease in the number of fibers that exhibited “pac-man” splitting. No discernable reduction was observed in the graphitic crystallinity (interplanar spacing and crystallite size) or axial orientation of crystallites within the fiber, as a result of nanomodification.