Liquid diffusion in polymeric adhesives by electrochemical-impedance spectroscopy (EIS)

Preliminary results on a technique of electrochemical-impedance spectroscopy (EIS) applied to the characterisation of diffusion and absorption properties of water in an epoxy adhesive are reported. Thin films of polymer adhering to aluminium constitute simulated adhesive bonds. Immersion in water and assessment via electro-chemical impedance measurements allowed an estimation of diffusion rates and water uptake. In parallel, classic gravimetric experiments were undertaken on thin, free films of the same polymer. Agreement between the results obtained with the two techniques was found to be good, and indicates that an EIS could be developed as a tool for in situ assessment of adhesives, or other confined polymer films.