Abstract: Electrochemical impedance spectra (EIS) technique was adopted to evaluate the water sorption behaviour of an epoxy freestanding film in a 0.5 mol/L sodium chloride solution at 20℃. The methods for obtaining the capacitance data from EIS data were compared. The Brasher-Kingsbury (BK) and corresponding modified version (Modi-BK) models were used to calculate the water uptake in film and the gravimetric results were presented for comparisons. According to the discussion of the discrepancy of water content in film obtained from two models, a new method was proposed to indicate the organic film structure.

Key words: Epoxy, Capacitance, Water sorption, EIS