Modelling the process of absorption and desorption of water by coatings made of epoxy resin

Abstract

The behaviour of coatings made of epoxy resin when in contact with water at 80° is studied. The process of water absorption is controlled by transient diffusion with a constant diffusivity, and 4% of water is absorbed at equilibrium. The drying process of the pre-saturated resin is controlled by transient diffusion through the resin and evaporation from the surface. At the end of the drying at 80°, c 16% of the initial water remains in the resin. If after drying the resin is immersed a second time in water, at 80° a higher rate of absorption with a higher diffusivity is observed. Mathematical models, with analytical expressions as well as mathematical models, are successfully tested for the processes of absorption and desorption.