Epoxy – Epoxy resins were originally made by condensing epichlorohydrin and bisphenol A, but now epoxies are usually formed from low molecular weight diglycidyl ethers of bisphenol A and various modifications. Epoxy resins are available in a wide variety of thermosetting structures and curing-agent variations. Physical properties can thus be varied over a wide range of rigidity and flexibility. Epoxies generally offer high mechanical and electrical properties, good colorability, and excellent heat resistance. This group of resins forms the foundation for the structural adhesives industry, as well as being used extensively in fiber reinforced composites. A number of epoxy resins are now available which are nonflammable due to introduction of bromine in aromatic ring substitution. Also, a few hybrids have been introduced such as epoxy urethanes and epoxyimides.
Epoxy Resins first became commercially applied in the aerospace industry in the early 1950s and have rapidly infiltrated almost every industrial sector since that time.