Axial nano-scale microstructures in graphitized fibers inherited from liquid crystal mesophase pitch

Nano-scale structures of a mesophase puch based carbon fiber were characterized using a high-resolution scanning electron microscope (HR-SEM) and a scanning tunneling microscope (STM). Fibril was found to be sectioned by a number of pleat units, being aligned parallel along the fiber axis. The periodical size. thickness and height of pleat unit was estimated as 30-60 nm, 20-30 nm and around 7 nm, respectively. In a pleat, graphitic units of 30 60 nm long and 2-4 nm wide run principally perpendicular to the axis. The basal plane of graphite was observed at the largest magnification. Such a series of nano-structures should be related intimately to the performance of the fibers. The formation mechanism of such series of nano-structural units is discussed in relation to the nano-structure of the liquid crystal mesophase pitch and ils deformation during the spinning.