Degradation effects in polyester and vinyl ester resins induced by accelerate ageing in seawater

This research is a study on the degradation effects caused by seawater absorption of isophthalic polyester and vinyl ester resin employed in boat manufacture. Physical and mechanical tests of the resins were performed before and after the degradation. The results highlighted that the polyester resin is more degraded than the vinyl one, due to a different network organization of the two materials. The polyester has a biphasic structure with a low compactness, so water diffusion into the bulk is highly favored. The degradation occurs mainly by the leaching of small molecules extracted from the resin bulk by the water. Damages (cracks, holes, blisters) are evident and the resin loses its mechanical performance. The vinyl network is monophasic and compact, so avoids the entry of water; its degradation occurs differently, by a hydrolytic surface erosion of resin layers. In this way, it retains its bulk better compared to the polyester one.