Development of a new experimental method to determine critical pigment-volume-concentrations using impedance spectroscopy: Part III: Water-based coatings with components typical for commercial organic anticorrosion coatings

Electrochemical impedance spectroscopy (EIS), which has been previously demonstrated to be a suitable method to determine the CPVC of organic coatings [R.E. Lobnig, W. Villalba, K. Goll, J. Vogelsang, I. Winkels, R. Schmidt, P. Zanger, J. Soetemann, Development of a new experimental method to determine critical pigment-volume-concentrations using impedance spectroscopy, Prog. Org. Coat. 55 (2006) 363–374], was applied to three series of coatings with components typical for water-based commercial organic anticorrosion coatings and to one with components typical for a wall paint. The new method led to CPVC-values for all four coating series, but up to 5–10% higher than those determined from cross sections with scanning electron microscopy (SEM), for one coating series to the exact reference value. The CPVC could be identified best from EIS data by visual comparison of the shape of Bode plots or from pore resistance (Rp)-time plots. The constant phase element (CPE), that characterizes the coating, was less useful for the determination of the CPVC of most water-based coatings.