Interfacial Bonding in Graphite Fiber-Resin Composites

Abstract

Interlaminar shear strength values of 4000 psi, typical of graphite fiber-epoxy composites, are so low as to hinder more widespread use of such materials. Possible reasons for the apparently weak interfacial bonding between the fiber and the resin have been advanced, but none of these has been fully satisfactory. Attacks on the problem have been mostly empirical, but some have achieved considerable success. A study of composites made from graphite fibers in which silicon carbide whiskers were grown has demonstrated dramatic improvements in interlaminar shear strength and in transverse properties. Another approach has involved chemical activation of the fiber surface by oxidizing systems; this also has provided substantial improvement in composite shear strengths. A number of other surface treatment methods which are being investigated in various laboratories are reviewed here.