This research examines the effect of hydrolytic decomposition on the work function of polyurethane-ester rain erosion coatings (REC). Aluminum panels (AA2024-T3) coated with a primer and REC were exposed to elevated temperature (121°C) and relative humidity (100%) for various time periods. The work function of each unique exposure was measured with a scanning Kelvin probe and compared to unexposed coated panels to determine the average magnitude of change of the measured work functions caused by exposure. This analysis showed that coated panels exposed for longer periods of time exhibit a higher work function compared to unexposed panels. The polymer degradation was also characterized by thermomechanical analysis and infrared spectroscopy. Results indicate that prolonged exposure of the REC polymer coated panels to elevated temperature and relative humidity exhibit a decrease in both thermal stability (strength) and peaks in the ester vibration bands, indicating that hydrolysis of the ester segments is occurring in the coating.

Subject
Water, Coatings, Stretching, Metal surfaces, Probes, Fourier transform infrared spectrography, Polymers, Oxide surfaces, Interfaces, Polyurethane coatings, Vibration, Electric potential, Samples
Keywords:
aerospace coatings, hydrolysis, material science, polyester, polyurethane, work function
© 2019, NACE International
2019
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