Studies on water absorption of epoxy resins by electrochemical impedance spectroscopy

Electrochemical impedance spectra were measured for the aluminum electrodes coated with epoxy resin films of various different crosslinking densities in 0.5 mol/L NaCl solution(room temperature) at open circuit potential, By fitting the Nyquist curves with the equivalent circuit generally used for the coated electrode, the values of the film resistance, the film capacitance, the electrochemical reaction resistance and the double layer capacitance were obtained and used to discuss the relationship between the structure and the water absorption of epoxy resins. It is found that the amount of the water absorbed in the cured epoxy resins increases with increasing extent of cure.