THE EFFECTS OF A WATER ENVIRONMENT ON ANOMALOUS ABSORPTION BEHAVIOR IN GRAPHITE-EPOXY COMPOSITES

The effects of a water environment on moisture (H2O) absorption charac teristics of a unidirectional T300/934 graphite/epoxy composite materi al have been investigated by the measurement and analysis of weight ch ange, hygrothermal induced expansion, surface crack formation, and sur face mass loss. Specimens were immersed in distilled water at 45, 60, 75, and 90 degrees C for more than 8000h. Weight-change profiles for t he composite exhibited divergence from the theoretical Fickian diffusi on law. Scanning electron microscopy (SEM) and dimension measurements revealed clear evidence of surface peeling and dissolution of the spec imen. A crack/mass-loss model has been used in order to explain the be havior of the composite material during the water absorption process. The general characteristics of water-induced weight gain in graphite/e poxy composites are discussed with respect to the moisture diffusion p henomenon and deviations in the weight-change profiles.