摘要
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。
Outdoor exposure dynamic law and corrosion mechanism of acrylic polyurethane coating exposed in representative atmosphere （Wuhsn and Lassa） was investigated by EIS and FTIR, environment aging intensity of different zone was compared： Conversion of EEC during degradation of acrylic polyurethane coating was also discussed. The experimental results were obtained as follows： （i） With the prolongation of exposure time porosity was increased and pore structure was enlarged in coating, EEC changed accordingly from one-time constant feature to two-time constant feature. accordingly entryway of corrosive ions through coating to metal was formed gradually, metal under the coating was corroded. Accompany increase of corrosion rate of the metal and corrosion products, metal capacity was not pure capacity but was substituted by differential capacity. （ii） Debasement of corrosion resisting property of acrylic polyurethann coating was doe to brokerage of chain. -NH was broken and NH： was generated with the prolongation of aging time. （iii） Compnrad with Lassa, degradation rate of acrytic polyurethane coating was smallnr in Wuhan.
出处
《环境技术》
2006年第6期19-22,25,共5页
Environmental Technology
基金
科技部重大项目子项(50499331)
