THE EFFECTS OF SURFACE TREATMENTS OF FIBERS ON THE INTERFACIAL PROPERTIES IN SINGLE-FIBER COMPOSITES .1. SINGLE CARBON-FIBER EPOXY-RESIN COMPOSITE SYSTEM

The interfacial properties between fibers and the matrix contribute to the overall properties in high performance composites. Plasma treatments (Ar, O2, CF4/O2, N2/H-2) have been performed on carbon fibers to improve the fiber-matrix interaction. The treatment efficiency was checked by the single-fiber technique, while the surface chemistry and morphology were characterized by X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectroscopy (SSIMS), and scanning electron microscopy (SEM). The O2- and N2/H-2-plasma treatments proved most effective both for introducing oxygen-containing functionalities at the fiber surface and for improving the interfacial shear strength of carbon fiber/epoxy composites. A relationship between the oxygen concentration at the fiber surface and the interfacial shear strength is demonstrated.