Method of characterizing the interphase’s mean water diffusion properties of a bonded assembly in immersion

The durability of bonded structures in wet environments is the subject of a large number of studies. The long-term behaviour of these structures is affected and driven by the water diffusion within the adhesive. The literature highlights that the creation of interphases, particular area where chemical and physical bonds are established between the adhesive and the substrate, play an important role in water diffusion kinetics. The aim of this study is to provide amethod to characterize the mean water diffusive properties of the interphases of a bonded assembly in immersion. This approach includes global gravimetric tests of an assembly and an analytical model to characterize its water diffusive parameters. The model divides the bonded joint into two separate layers: one layer representing the adhesive and the other the interfacial area. The water content of each layer can then be estimated using analytical equations. Diffusion parameters are then deduced from these water contents. A greater and faster water diffusion within the interfacial zone has been highlighted. The approach presented here allows to quantify it.