AbstractThe effect of post-curing on the moisture absorption characteristics of Fibredux 914/T300 carbon fibre–epoxy composites, and hence on their thermomechanical behaviour, has been examined. Laminates 1 mm thick were post-cured at 190 or 210°C for 4 or 10 h. The various cross-link densities thus established had almost no effect on the moisture absorption behaviour. Interlaminar shear strength and torsion pendulum tests gave similar results, in that the cross-link density had almost no influence on the dynamic shear modulus or the mechanical dissipation factor. From these findings, environmental degradation of the composite is shown to depend on the content of absorbed water. The behaviour of the composite in hot, humid conditions therefore cannot be improved by post-curing treatment.MST/400