ABSTRACT
The outstanding adhesive-bonding properties of epoxy resins were first recognized by Preiswerk and Gams in 1944 [1]. At that time epoxy-resin adhesives were recognized as the first cast-in-place adhesives featuring a versatile chemical functionality and a remarkably low shrinkage on curing. This led to adhesive joints with low internal stress. Because the transition to the cured state takes place by a polyaddition reaction, no low-molecular-weight substances are evolved. These properties were then of unusual significance in that, for the first time, it was possible to obtain reliable adhesive joints with excellent cohesion, structural integrity, and outstanding adhesion to all kinds of substrates. For example, bonds could be made to metals and glass without resorting to the application of pressure during the bonding process and without any problem in bonding irregular surfaces. It was of technological significance that the manner in which these adhesives were used was reminiscent of well-known metalsoldering techniques. Therefore, the discovery of the bonding function of epoxy resins introduced a new concept in adhesives materials and inaugurated the modern approach to the technology of adhesive bonding.
