Transverse Fracture in Unidirectional Graphite/Polysulfone Composites

Abstract

The transverse fracture properties of unidirectional graphite/polysulfone composites were used as a measure of the "in situ" fracture toughness of polysulfone, an amorphous thermoplastic matrix. At room temperature, the "in situ" plane-strain energy release rate, G_Ic , of polysulfone was a factor of four lower than the neat resin G_Ic . By comparing the temperature dependencies of the composite G_Ic to the neat resin G_Ic , we concluded that the release of residual thermal strain energy did not contribute to the observed loss of tough ness. The observed toughness loss is probably related to restriction of matrix yield zone size by the graphite fibers.