硬段含量对TDI-BDO-PPG水性聚氨酯涂层穴蚀性能的影响

Effects of Hard-segment Content on Cavitation Property of TDI-BDO-PPG Waterborne Polyurethane Coating

目的研究硬段含量对TDI-BDO-PPG水性聚氨酯(主要以TDI作硬段、BDO作扩链剂,PPG作软段的水性聚氨酯系列)在海水中穴蚀性能的影响。方法制备不同硬段含量的TDI-BDO-PPG水性聚氨酯,用超声波气蚀试验机对其进行穴蚀模拟试验。利用傅里叶红外光谱仪、拉伸试验机、激光共聚焦显微镜等设备,研究聚氨酯的结构特征峰、试样的拉伸性能及100%定伸永久变形率和试样穴蚀前后的表面形貌。结果涂有TDI-BDO-PPG水性聚氨酯的普通碳钢较其本身有更好的耐穴蚀性能。随着硬段含量从27%到50%逐渐增加,与氢键相关的振动峰明显增强,试样的伸长率降低,拉伸强度增加,100%定伸永久变形率增加,耐穴蚀时间逐渐缩短。试样耐穴蚀时间与硬段含量之间并非呈线性关系,而是当硬段含量在30%左右时才会表现出更好的耐穴蚀性能。穴蚀后,硬段含量为50%的涂层表面出现大范围细小均匀裂纹,硬段含量为35%的涂层表面局部出现少量大裂纹。结论硬段含量对TDI-BDO-PPG水性聚氨酯在海水中的穴蚀性能有显著影响。当硬段含量在较低范围内时,TDI-BDO-PPG水性聚氨酯表现出优异的拉伸性能、弹性性能及耐穴蚀性能。其中,硬段含量为30%的水性聚氨酯涂层的耐穴蚀性能最佳。

The work aims to study effects of hard-segment content on cavitation performance of TDI-BDO-PPG waterborne polyurethane （waterborne polyurethane series mainly with TDI as hard segment, BDO as chain extender, PPG as soft segment） in seawater. TDI-BDO-PPG waterborne polyurethane with different hard-segment content was prepared, and cavitation simula- tion test was performed to it by using ultrasonic cavitation tester. Structural characteristic peak of the polyurethane, tensile prop- erties of the specimens, 100% fixed elongation permanent deformation rate as well as morphology of the specimens before and after cavitation were studied by using fourier infrared spectrometer, tensile testing machine, laser confocal microscope, etc. Or- dinary carbon steel coated with TDI-BDO-PPG waterborne polyurethane exhibited better cavitation resistance than itself. As the hard-segment content increased from 27% to 50% gradually, vibration peak associated with hydrogen bond obviously increased, elongation of the specimens decreased, tensile strength increased, 100% fixed elongation permanent deformation rate increased and cavitation-resistant time gradually shortened. There was no linear relationship between cavitation resistance time andhard-segment content, but better cavitation resistance was exhibited when the hard-segment content was about 30%. After the cavitation, a wide range of fine uniform cracks appeared on the coating containing 50% hard segment. The hard-segment content has a significant effect on cavitation resistance of TDI-BDO-PPG waterborne polyurethane in seawater. TDI-BDO-PPG water- borne polyurethane exhibits excellent tensile property, elastic property and cavitation resistance when the hard content is low. Among them. the waterborne nolvurethane cnatin~, cnntainina qO~/, hard ~aomt^nf aYhihit~ tha hP^t envi＊~tinn rgeict^nr.,~