EIS Determination of the Water Uptake and LIFETIME of Polyurethane Coatings in NaCl Solution

摘要

The protective properties of polyurethane coatings were studied using the impedance spectroscopy technique. The effects of NaCl concentration were investigated. The results obtained can be summarized as follows: (1) The lifetime increases when the NaCl concentration is decreased.. (2)The presence of Cl~- ion can slightly increase the diffusion coefficient of water during the initial stage of immersion, however, inhibits the absorption of water at the following stage, which is mainly due to water clustering with the absorbed ions more easily than that with resin, leading to microscopic clusters and decreasing the activity of water.