水性聚氨酯涂膜的附着力、致密性和收缩性等方面存在不足,使其在金属防腐涂料领域没有获得广泛的应用.针对水性聚氨酯反应性官能团少和交联度低的特点对其进行改性,并对涂层的性能进行了研究.采用Tafel曲线外推法,EIS交流阻抗等电化学方法研究不同—NCO/—OH 值涂层在5％NaCl溶液中的电化学行为.结果表明,红外光谱分析表明实验成功制得了预期产物,热分析表面涂层具有良好的耐热性.—NCO/—OH 值为1．90的涂膜性能最优,腐蚀电流为1．83×10－7 A/cm2,阻抗模值为666723Ω.cm2.
Waterborne polyurethane coating has some shortages in adhesion,compactness,andcontractility which limits its application in the field of metal anti-corrosion coatings.In this paper,the waterborne polyurethane was modified to overcome the shortcomings of lacking reactive functional groups and low degree of cross link-ing.The properties of waterborne polyurethane coating were investigated.Fourier transform infrared (FT-IR) shows that the composite polyurethane was successfully prepared and thermogravimetry (TG)shows that the coating has excellent thermostability.In addition,tafel curve and electrochemical impedance were applied to study the electrochemical behaviors of different coatings made at diverse —NCO/—OH value in 5% NaCl solu-tion.The results showed that the corrosion current of blank galvanize steel sheet was 6.48×10-5 A/cm2 and the impedance value was 349.6 Ω.cm2 .As the —NCO/—OH value was 1.90,the corrosion current was 1.83 × 10-7 A/cm2 and the impedance value was 666 723 Ω.cm2 ,which had the best performance.
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