سنتز و بررسي خواص ضد خوردگي پوششهاي پلي‌يورتان آب‌پايه تابش‌پز فرابنفش بر پايه فيتيك اسيد عامل دار شده با گليسيديل متاكريلات

Corrosion has always been one of the fundamental challenges in various industries, incurring significant costs. One of the effective methods to combat corrosion is the use of polymer coatings. Due to their physical barrier properties and high chemical resistance, polymer coatings are widely used in anti-corrosion applications. However, these coatings, being solvent-based, have environmental limitations and emit volatile organic compounds (VOCs). Consequently, environmentally friendly coatings like waterborne polyurethanes (WPUs) have gained attention due to their low VOC emissions, absence of additional isocyanates, and excellent weather resistance. Despite the advantages of waterborne polyurethanes, these coatings face challenges such as the presence of hydrophilic groups, which negatively impact their surface properties, water resistance, and long-term durability. To improve these properties, waterborne UV-curable coatings are used, which enhance chemical and mechanical properties and water resistance through the formation of additional covalent bonds. However, the curing process of these coatings involves shrinkage, which induces internal stresses and can affect mechanical properties like adhesion to the substrate. In this research, phytic acid (PA), a natural and environmentally friendly substance capable of forming chelates with metal surfaces, was modified with glycidyl methacrylate (GMA) and added to UV-curable waterborne polyurethane. This modification increased the coatingʹs adhesion to metal and formed covalent bonds with the phytic acid, thereby improving anti-corrosion properties. The modified phytic acid with glycidyl methacrylate (PA-GMA) was characterized using FT-IR, 1H NMR, and XPS analyses, which confirmed the successful modification of PA-GMA. The stability of pure UV-curable waterborne polyurethane (UV-WPU) and those containing 1%, 3%, and 5% by weight of PA-GMA was investigated over a month, and stability without coagulation and clumping was confirmed. The properties of pure UV-WPU films and those containing different amounts of PA-GMA were eva‎luated using FTIR-ATR, contact angle, Tensile, TGA, and FESEM analyses. FESEM results showed that up to 3% by weight of PA-GMA exhibited the best dispersion in the polyurethane film. The pull-off test for measuring adhesion of the coating to the metal surface showed that the pure coating had an adhesion of 2.39 MPa, while the coating containing 3% by weight of PA-GMA had an adhesion of 5.4 MPa, which is comparable to industrial polyurethane coatings with adhesion values ranging from 2 to 6 MPa. To examine the anti-corrosion properties of the samples, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDS) tests were used. The results indicated that the coating containing 3% by weight of PA-GMA had the highest corrosion resistance with an efficiency of 99.37%, making this sample a promising candidate for use as an anti-corrosion coating.

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