Unsaturated polyester (UP) is the generic name for a variety of thermoset products, mainly prepared by polycondensation of an anhydride or a diacid (the monomer) with a glycol (the reactant). In our own formula the diacid and the glycol are bio-based. These condensation products are dissolved in a reactive monomer which is usually styrene. When this mixture is cured by the customer, a three-dimensional network is formed.