滨海混凝土用的微胶囊阻锈剂制备及性能

Concrete buliding in a marine envirment is encountering serious corrosive destroy. Conventianal Corrosion inhibitors have many disadvantages in the application of concrete bulidings in a marine environment, such as toxicity, water-solubility, volatility and short corrosion inhibition time. Polymer/corrosion inhibitor microcapsules were mainly preparated by air suspension coating and spray drying. These microencapsulated corrosion inhibitors have many disadvantages, such as low toxicity, good chemical stability, adjustable release rate and long-range corrosion inhibition. It will provide a new approach for the development of the corrosion inhibitors. The effects of preparation methods, process condition of microcapsules on the morphology, dimension and wall thickness of microcapsule particles were discussed. The relationship between the basic property and morphology of corrosion inhibitor microcapsules and the release behavior and corrosion inhibitor effect was established. The release rate and corrosion inhibition property of microcapsules with the different shell materials was compared in the simulated marine concrete environment. Moreover the effects of the influence factors in the outside environment of microcapsules in the marine concrete, such as chloridion concentration, pH value and briny temperature, on the release rate and corrosion inhibiton property of the microcapsules were investigated. It will draw out the release mechanism and release dynamics of corrosion inhibitor microcapsules. In addition, the effects of the content,dimension and shell strength of microcapsules on the mechanism property of concrete/microcapsules composites were also considered and the corrosion inhibition of microcapsules in the actual concrete. The research about the preparation and release property of corrosion inhibitor microcapsules will provide the basic theory foundation for the application to the concrete in a marine environment.

滨海环境使混凝土建筑遭受严重的腐蚀破坏，现有阻锈剂存在着毒性大、水溶性和挥发性大、阻锈期短等缺陷。项目采用空气悬浮成膜法和喷雾法等微胶囊技术制备微胶囊阻锈剂，具有毒性小、化学稳定性好、释放速率可调和长期阻锈的优势，为阻锈剂的发展提供新的研究方向。通过选择不同的微胶囊结构材料，重点研究微胶囊制备方法和工艺条件对微胶囊阻锈剂的形貌、尺寸和囊壁厚度等基本形态的影响，明确微胶囊的基本性能和形态与其释放速率和阻锈效果之间的变化关系；在模拟海水混凝土环境中探讨微胶囊外界环境中的氯离子浓度、溶液pH值和环境温度对微胶囊释放和阻锈效果的影响，揭示微胶囊阻锈剂的释放机制和释放动力学。另外，微胶囊阻锈剂的用量、尺寸和壁材强度对于真实混凝土的机械强度的影响，以及微胶囊阻锈剂在真实海水混凝土中的阻锈效果也需要进行详细探讨。微胶囊阻锈剂制备及其释放行为的研究为其在滨海混凝土极端环境下的应用提供了理论依据。

阻锈剂微胶囊化可克服现有阻锈剂毒性大、水溶性和挥发性大、阻锈期短等缺陷，实现阻锈剂在混凝土中的有效保护和缓慢释放。. 项目主要采用乳液法、喷雾法、熔融挤出法和离心制粒-包衣法等微胶囊技术制备微胶囊阻锈剂，研究了制备工艺对微胶囊形貌和释放性能的影响；在模拟海水混凝土环境中用电化学分析仪对比微胶囊阻锈剂的阻锈效果，并初步研究微胶囊阻锈剂对真实混凝土力学性能和阻锈性能的影响。. 结果表明，复相乳液法制备的微胶囊形貌均匀，成球率高，乳化剂和外水相PVA浓度对乳液稳定性和微胶囊产率影响较大，但整体包埋率较低。喷雾干燥法制备的微胶囊形貌较为规整，但表面空洞导致药物含量和包埋率不高。. 熔融挤出法制备共混物在模拟海水混凝土溶液中具有缓慢释放性能，且可通过改变芯材用量、壁材种类等进行调节。钢筋的极化曲线和阻抗谱显示，共混颗粒阻锈的样品的腐蚀电流密度均比空白组和纯添加亚硝酸钙的样品低，而容抗弧较大，具有突出的阻锈效果；聚合物/单氟磷酸钠共混颗粒的阻锈效果不及亚硝酸钙明显。共混阻锈颗粒对真实混凝土同样具有较好的阻锈效果。SEM发现，共混颗粒直径的减小可改善与钢筋混凝土结合程度。熔融挤出法只能制备出圆柱形共混物，但工艺简单，包覆率高。. 离心制粒-包衣法制备的微胶囊阻锈剂，其模拟溶液的腐蚀电流密度均比空白组低，自然电位升高，EIS容抗弧直径大，具有较好的阻锈效果，钢筋腐蚀断面形貌也证实了以上结论。微胶囊对真实混凝土的抗折强度和抗压强度都有一定程度的提高；混凝土的氯离子扩散系数也有改善。离心制粒-包衣法制备微胶囊形态均一，尺寸可调。. 此外，还研究了氢氧化物共混物和微胶囊对混凝土pH值的影响。结果发现，离心制粒法制备的氢氧化物微胶囊对模拟溶液和真实混凝土的pH值均有明显提高，而熔融挤出法制备氢氧化物共混物影响较小。. 微胶囊阻锈剂的制备工艺及其阻锈作用的研究为其在滨海混凝土中的应用提供了理论依据，为提高其阻锈效率提供了新的途径。