Characterizing water sorption in 100% solids epoxy coatings

In the present work, water sorption kinetics and equilibrium in 100% solids epoxy coatings are investigated by immersion into distilled water baths from 20 to 85 °C (absorption tests) and drying in a furnace between 60 and 85 °C (desorption tests). The gravimetric liquid sorption measurements reveal a non-Fickian two-stage diffusion behaviour during both absorption and desorption. The effect of hydrothermal history was also investigated. Cycling the immersion bath temperature increases the saturation values. Alternating sorption-desorption cycles increases the speed of water movement. The hydrothermal-induced coating degradation and the sorption modes are discussed.