Adheron™ EA-400 is a specialty adduct of diglycidyl ether of Bisphenol A Epoxy Resin (DGEBA) and dimerized fatty acid. When polymerized into an epoxy resin, the dimer acid improves the resin’s overall mechanical properties. The modified backbone enhances fracture toughness, peel strength and impact resistance of bonded joints. The chemical nature of the adduct provides a moisture barrier to the bond surface and reduces the tendency of the epoxy adhesive to undergo carbamate formation upon weathering. The long, flexible chain of the dimer acid molecule reduces the stiffness of the cured epoxy resin, making it more resistant to cracking and improving its ability to deform under stress; making adhesives based on Adheron EA-400 ideal for land transportation applications where vibration, torsion and three-dimensional stresses are common. The Adheron EA-400 dimer acid epoxy adduct improves adhesion of an epoxy structural adhesive to most metals with and without the presence of stamping and lubricating oils. Adheron EA-400 has both polar and non-polar regions, which can absorb the oily coating on a metal surface, allowing the adhesive to interact with the metal surface.