X-ray photoelectron spectroscopic studies of carbon fiber surfaces. 24. Interfacial interactions between polyimide resin and electrochemically oxidized PAN-based carbon fibers

The interfacial interaction between PAN-based IM7 carbon fibers and Avimid K3B, a thermoplastic polyimide resin was investigated using core and valenc e band X-ray photoelectron spectroscopy (XPS). The extent of interaction be tween the fiber and the matrix material has a significant effect on the str ength of the ultimate composite. The fibers were treated to remove the surf ace treatment applied to the fibers by the manufacturer by resistive heatin g in a vacuum. The interaction of the detreated fiber, subjected to subsequ ent electrochemical treatment, with the resin was compared to the interacti on of the commercially surface-treated fiber with the resin. Better interac tion between the fiber and matrix was found in the case of the electrochemi cally surface-treated fiber than with a commercially surface-treated fiber, emphasizing the importance of tailoring the surface treatment to the matri x chemistry. Based on chemical shifts seen in the core region and differenc es in the valence band region, a reaction scheme is suggested for the possi ble interaction between the fiber and the resin.