Mechanical properties of carbon fiber/vinylester composites exposed to marine environments

The effects of seawater exposure on the mechanical properties of unidirectional T700 carbon fiber/vinylester (510A) composites have been examined. Carbon fibers with two different types of sizings (F and G) were studied. Dynamic mechanical analysis testing of the neat resin and a carbon/vinylester composite revealed similar viscoelastic responses and glass transition temperatures indicating same type of cured resin for both cases. An analysis of moisture absorption dynamics of the composites revealed Fickian behavior. The composites absorbed more moisture than the resin. The moisture up‐take in the composites is dominated by the fiber/matrix region. A comprehensive mechanical test program involving tension, compression, and shear tests was conducted on the composites at dry and saturated conditions. Composites with F‐sized carbon fibers displayed overall higher strengths than those with G‐sized fibers at both dry and moisture‐saturated conditions. Moisture absorption was found to have a moderate influence on most composite strengths, except for the in‐plane and interlaminar shear strengths, where reductions in the range of 10–16% occurred. POLYM. COMPOS., 35:1559–1569, 2014.