Interfacial Bonding and Environmental Stability of Polymer Matrix Composites

Abstract

Abstract Recently developed adsorption-interdiffusion (A-I) theory of adhesion is employed to isolate the (London) dispersion γi,j d and (Keesom) polar γi,j p components of the excess interfacial free energy γi,j=γi,j d+γi,j p at the fiber-matrix interface in polymer matrix composites. For adsorption bonded interfaces the theory defines a new method of mapping the surface energy effects of an immersion phase upon the Griffith fracture energy γG. The stability of interfacial bonding between graphite fiber-epoxy matrix is defined in terms of the theoretical model and experimentally evaluated by accelerated aging studies which monitor changes in fracture energy for crack propagation perpendicular to the fiber axis. Applications of the model to control fiber surface treatments and select matrix components for optimized bond strength and environmental resistance is discussed.