A two-part adhesive used extensively in applications requiring high strength. Chemically, a compound in which an oxygen atom is joined to two carbon atoms in a chain to form a bridge. Specifically, a resin containing epoxy groups, that polymerizes spontaneously when mixed with a phenol (see phenolic), forming a strong, hard, resistant adhesive. Epoxy is probably the most commonly used adhesive in high power rocket construction. It comes in several formulations, mostly having to do with the time it takes to cure. Epoxy's only disadvantages as a rocketry adhesive are its relatively high weight and its low (approx. 200o F.) melting point.