Properties of the Uncured Epoxy System

The properties of epoxy adhesives in their uncured condition will determine primarily how easily the adhesive can be processed, applied, and cured. They will also determine, to some extent, the performance characteristics of the cured joint. The properties of the individual components as well as that for the mixed formulation are important. 

Properties often used by epoxy resin manufacturers to specify particular grades of resin include the epoxy content, viscosity or softening point, and color. In addition, properties such as density, vapor pressure, flash point, refractive index, solubility characteristics, and hydroxyl content are often reported. The important properties of uncured epoxy formulations with regard to most adhesive applications are 

These are essential considerations for a practical adhesive system. The adhesive composition must have sufficient reactivity to cure under conditions that are convenient and practical to the end user. It must have viscosity that allows easy mixing and application. Once on the substrate, the adhesive must be able to flow over the substrate and come into intimate contact with it—a process called wetting. 

---