Evidencing antagonist effects of water uptake and leaching processes in marine organic coatings by gravimetry and EIS |
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Authors: | N Fredj S CohendozS Mallarino X FeaugasS Touzain |
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Affiliation: | Laboratoire d’Etudes des Matériaux en Milieux Agressifs, Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle cedex 01, France |
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Abstract: | Two distinct marine epoxy organic coatings were aged in a sodium chloride (30 g L−1) solution at different temperatures. The water absorption was evaluated using gravimetric tests onto free films and EIS experiments were realized onto attached films. A strong leaching process was evidenced by gravimetry and the FT-IR analysis of the solution after ageing revealed the presence of extracted organic components. However, EIS results were not sensitive to this phenomenon and the water uptake values, obtained with a modified Brasher–Kingsbury equation, were found to be higher than gravimetric values. The comparison of the water volume fraction obtained by EIS with the apparent water mass fraction allowed following the species desorption with immersion time. It was proposed that this leaching process was related to a loss of the polymer density and the results showed that this phenomenon was thermally activated. |
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Keywords: | Organic coating Water uptake Gravimetry Electrochemical impedance spectroscopy Leaching |
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