Seawater Aging of Vinylester and Carbon Reinforced Vinylester

Abstract

The effects of marine environmental exposure on moisture absorption and the mechanical properties of vinylester resins (VE510A and VE8084) and unidirectional carbon fiber/VE510A composites have been experimentally investigated. Two carbon fiber sizings (F and G) were examined. Neat resin specimens were exposed to humid air at 50 °C and seawater at 40 °C until saturation. The composite materials were immersed in seawater at 40 °C. The resin specimens absorbed small amounts of moisture. The composite specimens absorbed more moisture than the resins. Both the neat resins and composites displayed Fickian diffusion behavior. Mass balance analysis of moisture absorption of the composites was performed which shows that moisture up-take is dominated by the fiber/matrix interface region. The moisture absorption was found to depend on the fiber sizing. Dry and moisture saturated neat resin and composite specimens were tested in tension, compression, and shear. Moisture absorption slightly improved the ductility of the neat resin specimens. Composites with F-sized carbon fibers displayed higher strengths than those with G-sized fibers at both dry and moisture saturated conditions. Moisture absorption reduced the in-plane and interlaminar shear strengths of the composites.