INFLUENCE OF MOISTURE ON THE THERMAL AND MECHANICAL-PROPERTIES OF AUTOCLAVED AND OVEN-CURED KEVLAR-49 EPOXY LAMINATES/

Moisture absorption behaviour and the influence of moisture on the the rmal and mechanical properties of Kelvar-49/epoxy-resin laminates have been studied. The laminates were prepared by two different routes, na mely autoclaving and oven-curing, and their properties were compared. The oven-cured laminates contained a greater percentage of voids which resulted in a greater amount of moisture absorption and higher values of moisture diffusivity. Moisture absorption caused an associated dep ression in the glass-transition temperature and deterioration in mecha nical properties. Furthermore, two distinct relaxation transitions wer e indicated beyond a certain level of moisture absorption. Strongly hy groscopic Kevlar fibre is considered to provide an easy route for mois ture ingress and led to the observed inhomogeneity in the plasticisati on of specimens. (C) 1997 Elsevier Science Limited.