Time dependent fracture behaviour of a carbon fibre composite based on a (rubber toughened) acrylic polymer

The fracture behaviour of continuous carbon fibre laminates based on plain and rubber-toughened acrylic resins was investigated focusing on the influence of rate and temperature. The tensile behaviour of the two matrices was also characterized for subsequent analysis. In all cases the experimental window was extended by applying the time-temperature equivalence postulate. Fracture toughness at varying crack propagation rate turned out to have opposite trends for the two matrices. For the plain acrylic resin, a monotonically increasing trend with crack rate was found in agreement with viscoelastic fracture theories. For the rubber-toughened resin the change of the failure mechanisms occurring at the crack tip, resulted in a monotonically decreasing trend for increasing crack rate. Rate and temperature effects were analysed in terms of volumetric strain during tensile tests. Composites turned out to be more resistant to crack propagation than the relevant matrices in both cases. Delamination fracture toughness turned out to have the same dependence on crack rate for rubber toughened matrix only. For composites based on the plain resin, no effect of crack rate on delamination fracture toughness was observed.