Hygroscopic Effects in Aramid Fiber/Epoxy Composite

Abstract

Hygroscopic effects in aramid fiber composites are assessed semi-empirically using a combination of micromechanics models and experimental data. It is pointed out that the in situ moisture concentration of the fiber should be known as it affects diffusional as well as expansional properties. The micromechanics models for moisture absorption indicate that the in situ moisture concentration is lower than the bulk value. The interfacial radial stress can be tensile in wet unidirectional composites, and ply cracks are shown to increase moisture diffusion in laminates.