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Influence of silane functionalized nanoclay on the barrier, mechanical and hydrophobic properties by clay nanocomposite films in an aggressive chloride medium
Colloids and Surfaces A: Physicochemical and Engineering Aspects ( IF 4.9 ) Pub Date : 2021-09-25 , DOI: 10.1016/j.colsurfa.2021.127625
J. Raja Beryl 1 , Joseph Raj Xavier 1
Affiliation  

The surface alteration of silica clay by a silane coupling agent was done to improve the compatibility with epoxy polymer matrix. It can be attained with ethoxy based silanes namely (3-mercaptopropyl) triethoxysilane (MPTES), propyltriethoxysilane (PTES) and 3-aminopropyl(diethoxy)methylsilane (APDES) in order to enhance the anticorrosion potential of epoxy coatings on mild steel. The structural and thermal properties of the functionalized clay nanoparticles are studied by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The morphological features of the functional nanoclay were also described by employing field emission scanning electron microscopy with energy dispersive x-ray analysis (FE-SEM/ EDX) and TEM (Transmission electron microscopy) analysis. These analyses showed the well functionalization of nanoclay by silanes. The well dispersion of functionalized nanoclay in the epoxy resin produces better nanocomposites which are coated on the mild steel. The coated steel samples were analyzed in terms of microstructure and corrosion resistant properties in 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SECM), salt spray analysis, and analysis of oxygen and water permeability were applied to assess the barrier properties against water permeation, oxygen penetration and protectiveness of silane-modified epoxy coatings. It was found that all the modified coatings showed higher barrier resistance and superior corrosion resistance than pure epoxy coating, which were described by higher charge transfer resistance (Rct) 6815.36 kΩcm2 and lower double-layer capacitance (Cdl) 405.51 µF at the electrolyte/metal interface. The tensile strength was found to be 113 MPa for EP-MPTES/clay nanocomposite while the value of pure epoxy coated specimen was 41 MPa. Therefore, the silane grafted clay nanoparticles results in slower diffusion processes, which specifically slow down the anodic reaction, thus blocking the overall corrosion path. Modified clay-epoxy nanocomposite displays good thermostability, better dispersion, outstanding mechanical property and superior water resistance property. Among the examined silanes, MPTES shows an effective functionalization of nanoclay, followed by the APDES and PTES. A possible mechanism has also been proposed.



中文翻译:

硅烷官能化纳米粘土对腐蚀性氯化物介质中粘土纳米复合膜的阻隔、机械和疏水性能的影响

通过硅烷偶联剂对硅土进行表面改性,以提高与环氧聚合物基体的相容性。它可以通过乙氧基硅烷实现,即(3-巯基丙基)三乙氧基硅烷(MPTES)、丙基三乙氧基硅烷(PTES)和 3-氨基丙基(二乙氧基)甲基硅烷(APDES),以提高低碳钢上环氧涂层的防腐潜力。通过 X 射线衍射 (XRD) 和热重分析 (TGA) 研究了官能化粘土纳米粒子的结构和热性能。功能纳米粘土的形态特征也通过使用场发射扫描电子显微镜和能量色散 X 射线分析 (FE-SEM/EDX) 和 TEM (透射电子显微镜) 分析来描述。这些分析表明硅烷对纳米粘土的良好功能化。官能化纳米粘土在环氧树脂中的良好分散会产生更好的纳米复合材料,这些复合材料涂覆在低碳钢上。在 3.5% NaCl 溶液中对涂层钢样品的微观结构和耐腐蚀性能进行了分析。应用电化学阻抗谱 (EIS)、扫描电化学显微镜 (SECM)、盐雾分析以及氧气和水渗透性分析来评估硅烷改性环氧涂层的防水渗透、氧气渗透和保护性的阻隔性能。结果发现,所有改性涂层都表现出比纯环氧涂层更高的阻隔性和优异的耐腐蚀性,这表现为更高的电荷转移阻力(在 3.5% NaCl 溶液中对涂层钢样品的微观结构和耐腐蚀性能进行了分析。应用电化学阻抗谱 (EIS)、扫描电化学显微镜 (SECM)、盐雾分析以及氧气和水渗透性分析来评估硅烷改性环氧涂层的防水渗透、氧气渗透和保护性的阻隔性能。结果发现,所有改性涂层都表现出比纯环氧涂层更高的阻隔性和优异的耐腐蚀性,这表现为更高的电荷转移阻力(在 3.5% NaCl 溶液中对涂层钢样品的微观结构和耐腐蚀性能进行了分析。应用电化学阻抗谱 (EIS)、扫描电化学显微镜 (SECM)、盐雾分析以及氧气和水渗透性分析来评估硅烷改性环氧涂层的防水渗透、氧气渗透和保护性的阻隔性能。结果表明,所有改性涂层均表现出比纯环氧涂层更高的阻隔性和优异的耐腐蚀性,这表现为更高的电荷转移阻力(应用氧气和水渗透率分析来评估硅烷改性环氧涂料的抗水渗透、氧气渗透和保护性的阻隔性能。结果表明,所有改性涂层均表现出比纯环氧涂层更高的阻隔性和优异的耐腐蚀性,这表现为更高的电荷转移阻力(应用氧气和水渗透率分析来评估硅烷改性环氧涂料的抗水渗透、氧气渗透和保护性的阻隔性能。结果表明,所有改性涂层均表现出比纯环氧涂层更高的阻隔性和优异的耐腐蚀性,这表现为更高的电荷转移阻力(R ct ) 6815.36 kΩcm 2和较低的双层电容 ( C dl ) 405.51 µF 在电解质/金属界面。发现 EP-MPTES/粘土纳米复合材料的拉伸强度为 113 MPa,而纯环氧树脂涂层试样的值为 41 MPa。因此,硅烷接枝的粘土纳米粒子导致扩散过程变慢,这特别减慢了阳极反应,从而阻止了整体腐蚀路径。改性粘土-环氧纳米复合材料具有良好的热稳定性、更好的分散性、优异的机械性能和优异的耐水性。在所研究的硅烷中,MPTES 显示出纳米粘土的有效功能化,其次是 APDES 和 PTES。还提出了一种可能的机制。

更新日期:2021-10-06
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