Durability of non-crimp fabric composites in aqueous environments

Glass fibre composites subjected to hot water exhibit a reduction in stiffn ess and strength owing to a combination of matrix plasticisation and fibre/ matrix interfacial degradation. If the composite system is subjected to som e form of mechanical damage such as cracking from an external impact, the n et consequence of water exposure is more difficult to predict. This paper reports on the effects of water exposure at two temperatures (65 and 93 degreesC) on non-crimp, quadriaxial, glass fabric systems with a po lyester matrix. The residual properties are measured using the compression after impact test. It is shown that the residual properties of laminates te nd to reach a minimum plateau after extended exposure to water, the value o f which is dependent on the temperature of the water. It is also seen that the effects of impact damage vary depending on whether or not the impact is experienced before or after the water exposure. Impacting after conditioni ng produces a greater density of through thickness damage, which results in a lower compression after impact strength than impacting before conditioni ng.