Study on Failure Behavior of Fluorinated Polyurethane-acrylic Coatings

Objective To investigate failure behaviors of fluorinated acrylic polyurethane coating in air environment and xenon accelerated aging test environment. Methods Water contact angle,attenuated total reflection-fourier transform infrared spectroscopy( ATR-FTIR),atomic force microscope( AFM) and Electrochemical Impedance Spectroscopy( EIS) were conducted to monitor the property variation of the coating. Results The results showed that coating contact angle decreased definitely in xenon accelerated aging test. ATR-FTIR spectra and AFM analysis indicated that the fluorine content decreased,while the oxygen content increased,and the coating surface roughness increased during the xenon lamp accelerated aging process. Coating resistance attenuated faster in xenon lamp accelerated aging test than in neutral salt spray test. Conclusion Photoaging began with a rupture of molecular chain,which led to a decrease of fluorine content,while coating resistance diminished along with time of aging.