Volume fraction effects on interfacial adhesion strength of glass-fiber-reinforced polymer composites

The performance of fiber-reinforced composites is often controlled by the properties of the fiber–matrix interface. Good interfacial bonding (or adhesion), to ensure load transfer from matrix to reinforcement, is a primary requirement for effective use of reinforcement properties. Thus, a fundamental understanding of interfacial properties and a quantitative characterization of interfacial adhesion strength can help in evaluating the mechanical behavior and capabilities of composite materials. A large number of analytical techniques have been developed for understanding interfacial adhesion of glass-fiber-reinforced polymers. Among these techniques, the vibration damping technique has the advantage of being non-destructive as well as highly sensitive for evaluating the interfacial region, and it can allow the materials industry to rapidly determine the mechanical properties of composites. In the present study, a simple optical system was contributed for measuring the damping factor of uniaxial fiber-reinforced polymer composites in the shape of cantilever beams. The interfacial damping factors in glass-fiber-reinforced epoxy resin composites were correlated with transverse tensile strength, which is a qualitative measurement of adhesion at the fiber–matrix interface. Four different composite systems were tested in this study. In each system, three different surface treatments of glass-fiber at three different volume fractions were evaluated. The experimental results show an inverse relationship between damping contributed by the interface and composite transverse tensile strength.