Effect of Silane-induced Interphase on Mechanical Properties of GFRP

Abstract

Silane-treated glass fiber affects not only the interfacial strength due to silane bound to glass fiber surface but also the properties of resin near the interface between fiber and resin, that is, denatured resin interphase. Using epoxy resin for composites, the resin made denatured area induced by silane treatment for glass fiber. This phenomenon was similar to that produced with vinyl ester resin. The thickness of denatured area depended only on amount of silane on glass fiber, irrespective of amount of chemical-bonded silane on fiber, that is, silane fixation. To confirm the mechanical effect of resin interphase, the mechanical stability of interface and matrix resin has been evaluated after molding of composites. Microdroplet test has been used to determine the interfacial shear strength. Bending test has been employed using unidirectional epoxy resin composites with silane-treated glass fiber. Interfacial shear strength significantly depend on silane fixation, while bending strength seems to be indirectly reflected from interfacial reinforcement. This difference was interpreted in terms of brittleness of denatured resin area near interface of glass fiber using a result of whitening along glass fiber at breakage of GFRP.