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本文采用交流阻抗测试技术、傅立叶红外测试技术研究了丙烯酸聚氨酯涂层在我国典型大气环境(武汉、拉萨)下户外降解规律,分析了其降解机理,比较了不同地区的环境老化强度,并探讨了丙烯酸聚氨酯涂层降解过程中电化学等效回路模型的转换问题。结果表明：(i)随曝露时间的延长,涂层的孔隙率增加、孔隙结构增大,体系由一个时间常数特征转为两个时间常数特征,涂层内逐渐形成了腐蚀性离子通往基底金属的通道,基底金属发生腐蚀,随金属腐蚀产物的增加,金属/溶液双电层电容逐渐被具有弥散效应的电容元件替换；(ii)丙烯酸聚氨酯涂层抗蚀性能的降低主要由涂层内高分子链节的断裂所致,随曝露时间的延长,在仲酰胺处发生断裂,生成了新的基团伯酰胺；(iii)丙烯酸聚氨酯涂层在拉萨地区的降解速率较武汉地区快。
In this paper, outdoor degradation of acrylic polyurethane coating under typical atmospheric environment (Wuhan, Lhasa) was studied by means of AC impedance test and Fourier transform infrared spectroscopy. The degradation mechanism was analyzed and the environmental aging intensities in different regions were compared. Conversion Problem of Electrochemical Equivalent Circuit Model During the Degradation of Acrylic Polyurethane Coatings. The results show that: (i) With the extension of exposure time, the porosity of the coating increases and the pore structure increases. The system changes from a time constant characteristic to two time constant characteristics, and the corrosive ions gradually form into the coating to the substrate Metal channel, the base metal corrosion occurs, with the metal corrosion products increase, the metal / solution electric double layer capacitor is gradually replaced by the diffusion effect of the capacitor element; (ii) acrylic polyurethane coating corrosion resistance reduction mainly by the coating Due to the breakage of macromolecular chain links, with the prolongation of exposure time, the secondary amides break and generate new primary amide groups. (Iii) Acrylic polyurethane coating degrades faster in Lhasa than in Wuhan.