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It has been clearly demonstrated that the addition of low concentrations of nano-silica particles to a typical rubber-toughened adhesive, based upon a two-part epoxy formulation, leads to very significant increases in the toughness of the adhesive, and also to increases in the glass transition temperature and the single-lap shear strength. The nano-SiO 2 particles have an average particle diameter of 20 nm and are very well dispersed in the epoxy adhesive, and only a concentration of about 1% to 8 % by mass of such nano-particles are needed to achieve significant improvements in the mechanical and thermal performance of the rubber-toughened two-part epoxy adhesive.

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Elastomer-modified epoxy resins have grown in usage in the past 15 years in several application areas connected with structural adhesives, composites, civil engineering/construction, electrical laminates/ encapsulants and corrosion resistance. Some of this increased attention has come about through utility of telechelic butadiene/acrylonitrile liquid polymers. Both carboxyl and amine reactive liquid polymers (CTBN and ATBN) have provided chemistries amenable to this modification with the polybutadiene/acrylonitrile co polymer providing solubility parameters close to if not equaling those of base epoxy resins. It has only been within the last few years that similar elasto mer-modified epoxy resins have been examined in epoxy coatings and primers. This chapter reviews a portion of that relatively new journal and patent literature involving epoxy coal-tar, powder, photo-curable and solventless heavy duty coatings as well as metal primers. These examples are employed to illustrate such benefits of elastomer inclusion as reverse im pact, bending/crimping, corrosion resistance, ther mal shock resistance and coating adhesion. The chapter concludes with an initial reporting on in dustrial maintenance and marine coatings based on elastomer-modified epoxy resin models. Similar benefits are noted with these traditional solvent -based coatings under ambient cure.Numerous blends or alloys of thermosetting resins with elas tomers have been developed over the past four decades and found their way into continuing commercial use. A generous amount of this has been related to toughening needs : Overcoming the brittleness of highly crosslinked glassy polymers. With it came the recognition that not only was degree of elastomer/resin compati bility important but also the need for achieving a dispersed phase