|关键词||水性涂层 改性 壳聚糖微球 海藻酸钠微球 防腐蚀|
结果表明，壳聚糖载体微球的最佳制备参数为：水油比为1:20、交联剂香草醛和壳聚糖的质量比为3：1、pH值为9，制备的微球粒径为20-30 μm；海藻酸钠载体微球的最佳制备参数为：水油比为1:20、乳化剂和油相的体积比为2:100、醋酸和所加纳米碳酸钙的摩尔比为4:1，微球粒径约为20 μm。利用负压浸渍法成功将缓蚀剂植酸钠和酒石酸钠包覆到载体微球中，壳聚糖微球中两种缓蚀剂的包封率分别为25.79%和35.00%；海藻酸钠载体微球中两种缓蚀剂包封率分别为29.85%和30.65%。
缓蚀剂植酸钠和酒石酸钠在不同pH值环境下从载体壳聚糖微球中的释放速率均满足pH= 9> pH= 7> pH= 3，从载体海藻酸钠微球中的释放速率均满足pH= 9> pH= 3> pH= 7；K-P模型是评估缓蚀剂从微球中释放过程的最佳模型。将包覆植酸钠、酒石酸钠的壳聚糖微球按照5%的质量比分别添加到水性聚丙烯酸涂层A中，随着涂层浸泡时间的增加，电荷转移电阻以及涂层孔溶液电阻都逐渐增大；将包覆植酸钠、酒石酸钠的海藻酸钠微球按照5%的质量比分别添加到水性聚丙烯酸涂层B中，随着涂层浸泡时间的增加，电荷转移电阻以及涂层孔溶液电阻都逐渐增大；这表明四种改性的涂层均具有了自修复防腐蚀性能，海水浸泡实验从宏观上进一步证实了四种包覆缓蚀剂的微球改性后的涂层防腐蚀性能得到了提高。
In recent years, researchers have proposed to add the host carriers encapsulated or loaded with corrosion inhibitors into the coatings to obtain self-healing ability and achieve an excellent anti-corrosion performance. We reported the fabrication of eco-friendly natural polysaccharide (chitosan, Sodium alginate) microspheres loaded with corrosion inhibitor (Sodium phytate, Sodium tartrate) for the first time, and applied them in self-healing water-based polyacrylate coatings.
The optional experimental conditions were obtained by means of orthogonal experiments. The release kinetics of corrosion inhibitor from the microspheres under pH =3,7,9 was indirectly studied through examining the efficiency of the corrosion inhibitor by electrochemical measurements. The self-healing properties of the coated copper samples with water-based coating doped with corrosion inhibitor loaded microspheres were also evaluated by electrochemical measurements, and the anti-corrosin performance of the modified coatings was examined by seawater immersion tests.
The optional experimental conditions for preparing chitosan microspheres was: 1:20 of water/oil ratio, 3:1 of the mass ratio of vanilline/chitosan, pH =9 of the mixed solution, under which condition the microspheres were in perfect spheres with uniform size ranging from 20 to 30 μm. For preparing Sodium alginate microspheres, the optional experimental conditions was: 1:20 of water/oil ratio, 2:100 of emulsifier/oil ratio, 4:1 of mole ratio of acetic acid/Calcium carbonate. The size of the Sodium alginate microspheres prepared under this condition was about 20 μm. The corrosion inhibitor Sodium phytate and Sodium tartrate were successfully encapsulated in the microspheres. The load rate were respectively 25.79 wt.% and 35.00 wt.% in chitosan microspheres, as well as in Sodium alginate microspheres the load rate were 29.85 wt.% and 30.65 wt.% respectively.
The results of EIS measurements showed that the release rate of the both corrosion inhibitors in chitosan microspheres were fastest at the condition of pH= 9 followed by the release rate at pH= 7 and pH= 3, while in Sodium alginate microspheres the release rate of the both corrosion inhibitor accorded with pH= 9> pH= 3> pH= 7. K-P model was the best fit model to estimate the release kinetics of the both corrosion inhibitors.
When the chitosan and Sodium alginate microspheres loaded with corrosion inhibitors were respectively added into the water-based coating, a significant increase of charge transfer resistance could be obtained, indicating the self-healing capabilities of the modified coating. The seawater immersion test further revealed that the water-based coating modified with these four kinds corrosion inhibitor loaded microspheres could restrain corrosion process around defected areas, as a result of the release of corrosion inhibitors.
Therefore, the eco-friendly chitosan and Sodium alginate microspheres could control the release of corrosion inhibitors Sodium phytate and Sodium tartrate under different pH conditions. According to the experiment results, the modified coating not only exhibited excellent self-healing properties but also showed high anti-corrosion performance. It is anticipated that this study can open a new way to design a new strategy of preparing efficient and eco-friendly anticorrosion smart coatings.
|学科门类||理学 ; 理学::海洋科学|
|刘晓杰. 基于天然多糖缓蚀剂微球的自修复涂层及防腐蚀机理研究[D]. 中国科学院海洋研究所. 中国科学院大学,2018.|