MATRIX-DOMINATED TENSILE BEHAVIOR OF UNIDIRECTIONAL T300 914 AND STRUCTURAL MODELING OF THE MATERIAL/

Unidirectional T300/914 carbon epoxy composite has been tested under t ransverse tensile loading at various temperatures and test rates. The test programme revealed a different viscoelastic response for the bulk resin modulus from that of the composite modulus and associated fract ographic examination showed the structures of the resin and composite to be complex. The resin consisted of an epoxy-based particulate phase embedded within a thermoplastic-based connecting phase. The addition of carbon fibres resulted in the formation of an irregular epoxy-based interphase region. A parameter, Lambda, has been defined th at easily characterizes the viscoelastic behaviour of the composite. Structural models have been successfully developed for both the resin and the co mposite and a cure mechanism suggested. Any plastic deformation occurr ing on failure was within the connecting phase and the weakest point o f the composite was identified as being the particle/interphase bounda ry. Property modelling has successfully accounted for the interphase i nfluence on the transverse tensile modulus and the composite transvers e tensile strength was found to be higher than the bulk resin tensile strength.