Unsaturated polyesters are the third-largest class of thermoset molding resins. They are produced by the condensation of a diol with a blend of saturated and unsaturated anhydrides. … The anhydrides and acids can also be condensed with epoxy resins such as epichlorhydrin or bisphenol A diglycidyl ether.
Gelcoat or ‘Gel Coat’ is a material used to provide a high-quality finish on the visible surface of a fibre-reinforced composite. The most common gelcoats are thermosetting polymers based on epoxy or unsaturated polyester resin chemistry. Gelcoats are modified resins which are applied to moulds in the liquid state.
Vinyl Ester Resin is a common resin in the marine industry due to its corrosion resistance and ability to withstand water absorption. Vinyl ester resin is extensively used to manufacture FRP tanks and vessels as per BS4994. For laminating process, vinyl ester is usually initiated with methyl ethyl ketone peroxide.