Polyesters, Unsaturated

Abstract Unsaturated polyester resins have been used commercially since the 1940s, establishing markets for reinforced composite plastics derived from combinations with glass‐fiber reinforcements. The availability of a wide variety of raw materials has encouraged the emergence of a diverse range of resins specifically tailored for many unique products. Fiberglass‐reinforced plastics (FRP) technology facilitates the production of large fabricated products, such as chemical and petroleum storage tanks, and a wide range of marine craft, where low cost ambient processing provides competitive advantages. The technology has also evolved for high temperature automatic molding of high volume body components used for automobiles, trucks, and recreation vehicles. Polyester resins are also used extensively in highly filled cast products for kitchen and bathroom countertop applications; polyester polymer concrete provides corrosion‐resistant surfacing for highways and bridges. High performance resins are formulated to provide optimal corrosion and thermal performance in composite products designed for the chemical process industries. Under the mandates of the U.S. Clean Air and Clean Water Regulations, FRP pipe has emerged as a cost‐effective solution to upgrade inner‐city sewer systems, and FRP duct and scrubber systems are used widely in the pulp, paper, and electrical power industries to contain noxious emissions.