Water up-take evaluation of new waterborne and high solid epoxy coatings. Part II: electrochemical impedance spectroscopy

Abstract

Electrochemical impedance spectroscopy (EIS) was used to elaborate the characteristic of waterborne and high solid epoxy coatings. The clear coats were investigated under long-term immersion condition. The coating capacities and the coating resistances of the two classes of materials revealed important influences of the coating formulations, like internal or external emulsification, degree of crosslinking and type of resin and hardener. The high solid systems showed a higher water up-take for 100% crosslinking compared to 80%, which was effected by an increased number of free amine groups. For waterborne coatings the chemical nature of the hardener and the choice of emulsifier dominated the effects of different degrees of crosslinking. Waterborne coatings had always higher dielectric constants, whereas after a few hours of immersion the resistance of high solids were 1–2 order of magnitude higher.