Microstructural heterogeneity on the cylindrical surface of carbon fibers analyzed by Raman spectroscopy

A polyacrylonitrile-based carbon fiber monofilament was characterized by a confocal micro Raman spectrometer with the aid of a stage that allowed the axial rotation of the fiber so that the whole surface area could be examined. Results indicate that disorder is localized and aligned along the axial direction of the fiber. L_a values in defective regions are relatively lower than in others. The changes in the amount of amorphous carbon in different regions are significant.