Structural composites formed by reaction injection moulding Interlaminar fracture properties of glass fibre mat-copoly(urea/isocyanurate) resin composites

Abstract

Structural (SRIM) composites, comprising up to 40% by volume of random continuous glass fibres in a specially developed copoly(urea/isocyanurate) (PUrI) matrix, have been formed via reaction injection moulding (RIM). The two stage polymerisation process of the PUrI matrix provided low initial viscosity during mould filling followed by a ‘snap cure' to give tough composite materials in <30 s. Characterisation by DMTA confirmed the two phase morphology of the rubber toughened glassy matrix. Mode I and mode II interlaminar fracture tests, carried out in accordance with the ESIS protocol, gave values of G _Ic and G _IIc in the ranges 1·4-2·8 kJ m^-2 and 3·3-5·0 kJ m^{- 2}, respectively, and were an order of magnitude greater than those determined for unidirectional carbon fibre-epoxy composites. The G _Ic values for the SRIM composites are a factor of 2-3 greater than that (0·8 kJ m^-2) for the unreinforced PUrI matrix and show significant variation due to extensive fibre bridging during crack propagation.