Linked from
The 6 pages that link to Unsaturated polyester resin, each with the reason it gives.
StyreneRelated: Styrene serves as a reactive diluent and cross-linking comonomer in these resins.
Fumaric acidRelated: Fumaric acid can supply unsaturation in polyester formulations.
Maleic anhydrideRelated: Maleic anhydride supplies unsaturated units in many resin formulations.
Phthalic anhydrideRelated: Phthalic anhydride can provide the aromatic component of these resins.