Factors Affecting the Processing of Epoxy Film Adhesives: I. Room Temperature Aging

Differential scanning calorimetry, dielectric analysis, and infrared spectroscopy were used to study the changes which occur at room temperature in an epoxy film adhesive cured, in part, with dicyandiamide. The principal reaction involved interaction of the catalyst with the lower molecular weight resins in the formulation. The overall effect was demonstrated by an increase in resin viscosity, softening point and overall cure time, accompanied by a decrease in resin flow and ultimate bonded joint strength.