EIS evaluation of attached and free polymer films

Permeability of a PVC coating attached to a metal substrate and as a free film was assessed by electrochemical impedance spectroscopy. The results were compared with those from gravimetric tests. The impedance:spectra of applied and free films have distinct behaviour. The concentration of the outer solution is determinant for the coating capacitance and for the water uptake of the film. The results revealed important differences between the two techniques. (C) 2000 Elsevier Science S.A. All rights reserved.