Moisture Absorption of Graphite/Polymer Composites Under 2000 Feet of Seawater

Abstract
Studies were conducted to determine moisture absorption properties of a vinyl ester graphite fiber composite under 2000 feet of seawater pressure. The results were compared with moisture absorption curves generated on identical specimens soaking in seawater at the surface. After soaking, samples were tested for flexure strength. Results in dicate diffusion coefficients are the same in both cases, but higher equilibrium moisture contents were obtained on deep submergence samples. Also, samples subjected to pressure experienced a 15 % reduction in flexure strength and stiffness. It is proposed that higher moisture content and loss of strength and stiffness were due to the activation of damage dependent mechanisms in the composite under pressure.