X-RAY PHOTOELECTRON SPECTROSCOPIC STUDIES OF CARBON-FIBERS .14. ELECTROCHEMICAL TREATMENT OF PITCH-BASED FIBERS AND THE SURFACE AND BULK STRUCTURE CHANGES MONITORED BY XPS, XRD, AND SEM

Core and valence band X-ray Photoelectron Spectroscopy, as well as X-ray Diffraction and Scanning Electron Microscopy, has been used to monitor the surface chemistry and bulk structure changes when DuPont E-120 high-modulus pitch-based carbon fibers are anodically oxidized in 1 M HNO3 solution at different anodic potentials. Electrochemical treatments changed both the surface and bulk chemistry of the fiber, while plasma treatment only affected the surface structure. Electrochemically treated fibers showed significant surface functional group decomposition after exposure to the x-ray radiation during the x-ray photoelectron spectroscopy experiment, but the decomposition occurred only on the top surface layer.