Comparison of seawater absorption properties of thermoset resins based composites

This research studied seawater absorption ability and mechanical performance (before and after immersion in seawater) of two glass-fibre reinforced composites differing as regards the thermoset resin (isophthalic polyester or vinyl ester) but both used in boat manufacture. Experimental tests showed that vinyl ester has higher resistance to seawater absorption than isophthalic polyester due to the different cure rate and steric hindrance of the two resins. The vinyl resin cure reaction proceeded more slowly than for isophthalic polyester thereby enabling it to organize its linear macromolecular chains in a more compact structure with higher conversion rates. As a result, the vinyl ester resin composite had a lower water diffusion coefficient but higher chemical stability, stiffness and strength during its immersion in seawater than the isophthalic one.