The Effect of Pendent Groups at the Fiber Surface on Interfacial Adhesion

Abstract

Amine-terminated hexyl pendent groups were attached by direct chemical reaction to the surface of aramid engineering fiber. The number of groups attached was evaluated by two different methods of quantitative analysis, with parts per million sensitivity, and good agreement was found. Separate tests found no evidence for reaction of pendent groups with simple epoxy. A single filament pull-out test was used to assess directly the effect of the pendent groups on the fiber-matrix bond strength. The increased adhesive performance brought about by the presence of the pendent groups was ascribed either to a decrease in the initial crack size at the interface or to an increase in matrix modulus near the interface.