Curing and seawater aging effects on mechanical and physical properties of glass/epoxy filament wound cylinders

Polymer composites in marine structures that operate under seawater environment may be seriously affected, reducing durability estimates. This work aims at evaluating the effect of seawater exposure at 80 degrees C for 7-28 days on filament-wound glass fiber/epoxy composite cylinders partially cured by passing saturated steam through them just after winding seeking a faster curing route. The winding angle is varied (+/- 55, +/- 65 and +/- 75) and some of the cylinders are later post-cured for comparison. The unaged partially cured specimens do not reach complete curing, with a glass transition temperature (T-g) of 132 degrees C, below the T-g for the other samples (154-159 degrees C). Fully cured cylinders present mechanical properties slightly higher than partially cured ones. Moreover, aging in seawater for 7 days enhances the cross-linking degree of epoxy, with a positive effect on both hoop tensile strength and stiffness. Aging is, however, not critical for the radial compressive properties.