Interface Effects in Interlaminar Fracture of Thermoplastic Composites

Abstract

Mode I interlaminar fracture toughness was determined on a series of uni directional poly(phenylene oxide)/carbon fiber composites using the double cantilever beam test. Initial toughness for growth of a delamination from an insert depends on fiber type, and ranges from 190 to 440 J/m², with intermediate modulus fibers tending to give lower values than high-strain fibers. Low toughness values are attributed to poor fiber-matrix adhesion. As a delamination progress down the beam, fiber bridging increases the appar ent toughness by up to a factor of 7, depending on the fiber.