Studying the water permeation in coatings
The objective of a new work is to develop and evaluate experimental approaches with different analytical techniques to measure the permeability, diffusivity, and solubility of water in model coatings.
These properties are of primary relevance in studies of coatings for corrosion protection. For water permeation measurements, setups were designed and prepared to facilitate measurements by microcalorimetry, gravimetry, and thermogravimetric analysis. For sorption measurements, films were prepared in various thicknesses to allow a proper analysis with Fourier-transform infrared spectroscopy in transmission mode and gravimetry.
Both methods successful
Both methods have been successful in following water uptake kinetic curves, being complementary in film thickness ranges that can be analysed. The validity of the permeabilities calculated from permeation measurements was then compared to results from group contribution methods and reported values in the literature. Diffusivities were determined using data from the transient region in sorption and permeation measurements, as well as from the steady-state permeation rate and equilibrium solubility in permeation and sorption measurements, respectively.