A significant cause of joint weakening is the effect of water in the interface between adhesive and substrates. There is evidence that the transport kinetics of water in the adhesive bulk do not correspond to the kinetics in the adhesive joint, studies show that water can be absorbed much faster by the interface than by the bulk. [1, 2] The study of the kinetics of water absorption in the interface is a particular challenge, and is also gravimetrically hardly detectable. A powerful and established method which can detect directly the corrosion induced delamination of polymer coatings is the scanning Kelvin probe (SKP). 
In the present work the SKP is used to study the water uptake of adhesive bonds. To determine the water uptake processes of an adhesive joint by means of SKP, an adhesive is applied to a metal surface, and as second substrate a very thin non-conductive barrier layer is used. Several scanning Kelvin probe experiments are carried out, under different environmental conditions, to define which are the most suitable
adhesives, substrates and barrier layers to investigate the water diffusion in situ and near the interface of an adhesive joint. The potential difference distribution is measured time-dependent in order to obtain information about the water absorption kinetics. The tests are accompanied by analytical and electrochemical methods, e.g., dynamic vapour sorption and electrochemical impedance spectroscopy.
 Zanni-Deffarges, M. P.; Shanahan, M.E.R. (1995): Diffusion of water into an epoxy adhesive. Comparison between bulk behaviour and adhesive joints. In International Journal of Adhesion and Adhesives 15 (3), pp. 137–142. DOI: 10.1016/0143-7496(95)91624-F.
 Wapner, K.; Grundmeier, G. (2004): Spatially resolved measurements of the diffusion of water in a model adhesive/silicon lap joint using FTIR-transmission-microscopy. In International Journal of Adhesion and Adhesives 24 (3), pp. 193–200. DOI: 10.1016/j.ijadhadh.2003.09.008.
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