Vinyl ester resins
THe vinyl ester resins are similar in molecular structure to polyesters, but differ mainly in reactive parts located only at the ends of the molecular chains. Since the entire length of the molecular chain is available for shock absorption, this makes the vinyl ester resins stronger and more resistant to polyesters. The vinyl ester molecule has few ester groups. The ester groups are susceptible to water degradation by hydrolysis, which means that vinyl ester resins exhibit better water resistance and many other chemicals from their polyester colleagues and are common in applications such as pipelines and chemical storage tanks.
By reducing the number of ester groups in the vinyl ester molecule compared to the polyester, the resin is less susceptible to damage by hydrolysis. Therefore, the material is sometimes used as a barrier or "skin" layer for polyester laminate to be immersed in water, such as the boat body. The stored molecular structure of the vinyl ester resin also means that it tends to be more rigid than the polyester, although in order to achieve these resin properties, there should usually be an increase in the temperature for accelerated hardening.