During the past few years there has been a rapid development in the chemical technology of epoxy resins. Currently, these resins are being widely manufactured and are available under a variety of trade names.
Industrially the epoxy resins are important for use in corrosion-resistant surface coatings, molding compounds, castings, laminating or reinforcing plastics, encapsulating electronic circuits, and adhesives, as in metal-to-metal bonding.
The generic name of these compounds is derived from the fact that they are polyethers with terminal epoxy groups. In general, they are condensation products of epichlorohydrin with p,p′-isopropylidenediphenol (bisphenol A) and have the type of chemical structure shown in the Figure (a). They have a wide range of viscosities, i. e., they range from low-viscosity liquids to high-melting-point solids. Commercial epoxy resins of the low-viscosity type usually contain, in addition to the high-molecular-weight resin, an epoxy resin modifier