If they ever create a hall of fame for materials, epoxy resin would be a shoe-in. This exceptional substance is the adhesive of choice when you really do not want two surfaces to come unstuck; holding bits of an aircraft together, for example, or the rotor blades of wind turbines. Epoxy resin is also resistant to heat and chemicals, while some epoxies are waterproof and even capable of curing underwater. They are also excellent electrical insulators.
Epoxy is a thermosetting plastic. That is to say, when it is mixed with a "hardener" or catalyst, it forms crosslinks with itself, curing into a robust material with the properties mentioned above. The raw compound comes in many forms, including a low-viscosity liquid and a powder. Because the hardener is also highly variable, a broad suite of cured polymers can be created with differing properties.
Swiss chemist Pierre Castan (1899-1985) and the American Sylvan Greenlee share the credit for this invention. In 1936, Castan, working on materials for denture repair, reacted the compounds bisphenol A and epichlorhydrin to produce an amber material with a low melting point. Meanwhile, across the Atlantic, Greenlee was investigating a similar reaction and produced his own resin, which varied from Castan's only in that it had a higher molecular weight. Both scientists filed patents at the same time, and went on to bag further intellectual property exploiting the versatility of epoxy chemistry to develop alternative resins with different physical properties.
The biggest market for epoxy resins is as a protective coating. Here again, the ability to fix tightly to a surface and resistance to just about everything make epoxy ideal for coating washing machines, pipes, and the insides of tin cans.
