An epoxy is a polymer that is often used for its binding and mechanical properties. It is formed by combining two monomers, which when reacted for a crosslinked structure that is very hard and tough. It is a thermosetting polymer, meaning that an irreversible exothermic reaction occurs when the two polymers are combined. Once the reaction has occurred the epoxy is, for all intents and purposes, permanently cured.
Epoxy has basically limitless applications and can be seen in fields ranging from aerospace to electronics. They are used as both electrical insulators when alone, and also electrical conductors when combined with silver. They are used architecturally as a material for walls, ceilings, and especially floors. They can be used as paint. They are also used for fastening bolts, and as castings. Moreover, epoxy as been used as a medium for art.
Epoxy is often used in the developing world for its uses in building. In fact, China accounts for 30% of the worldwide usage of epoxy ($15 billion world wide). The three largest producers of Epoxy are Hexion, Dow Chemical, and Huntsman's Corporation for Advanced Materials. Each of these companies allow the epoxy to be easily tuned for adhesive and mechanical properties using a variety of chemicals in addition to the basic monomers, such as things to increase or reduce viscosity.