聚天冬氨酸酯聚脲涂层加速老化行为研究

为了系统地研究聚天冬氨酸酯(PAE)聚脲涂层的老化性能,采用扫描电镜(SEM)、原子力显微镜(AFM)、Fourier变换红外光谱(FTIR)和电化学阻抗谱(EIS),考察了涂层经盐雾老化以及紫外线/盐雾循环老化后的表面形貌、结构形态和电化学阻抗性质。研究结果表明,单纯盐雾老化对涂层表面形貌和结构形态没有产生明显影响,因此,盐雾老化25周后涂层仍具有较高的电化学阻抗。相反,在紫外线/盐雾循环老化条件下,涂层电化学阻抗随着暴露时间的延长明显降低,暴露25周后阻抗谱表现为多个时间常数。表面形貌研究发现,循环老化25周后,聚脲分子链断裂,结构有序度降低;此外,涂层表面粗糙度增加、软段相产生微裂纹、硬段形状发生改变,结构形貌破坏严重。研究结果显示出PAE涂层具有较好地抵抗盐雾老化的能力,而在紫外线/盐雾循环老化后的耐蚀性降低。

Degradation of Polyaspartic Polyurea Coating Under Different Accelerated Weathering Tests

Polyurea coating based on polyaspartic esters(PAE) were prepared from synthesized polyaspartic esters(PAE-F) and hexamethylene diisocyanate(HDI)trimer /amine terminated polyoxypropylene(Jeffamine D2000) prepolymer.The surface topography,structure and morphology and electrochemical impedance spectroscopy(EIS) features of the coating under salt fog exposure and UV/salt fog alternating exposure were investigated through SEM,AFM,FTIR and EIS.The results indicated that the performance of the coating was difference when it was tested in different ways.The surface topography and structure and morphology of the coating changed a little after 25 weeks salt fog exposure.As the result,the coating resistance hold high over the period of 25 weeks.But the performance of the coating under UV/salt fog alternating exposure after the same time was totally different.EIS features of the coating showed a rapid reduction over the period of 25 weeks alternating exposure.FTIR,SEM and AFM showed that the molecule chains of the coating were broken,and the ordered structures of hard segment decreased,which indicated that the structure of the coating was destroyed.At the same time,the surface roughness increased,cracks appeared at soft segment phase,and the shape of hard segment phase changed,showing topography changed severely.The study demonstrates that the PAE coating had good resistance of salt fog corrosion and lost resistance after UV/salt fog alternating corrosion.