Corrosion protection of steel by poly(3-hexylthiophene) polymer blends

Abstract

Purpose – The purpose of this paper is to study the effect of thermal treatment on the corrosion protection of steel by using poly(3-hexylthiophene) (P3HT) and P3HT/PS(polystyrene) or P3HT/PMMA(polymethyl methacrylate) blends coatings in sulfuric acid solution. Design/methodology/approach – The polymer coatings were thermally treated at two different temperatures (100 and 200°C, respectively) and were compared with the polymer coatings dried at room temperature in their application as protective coatings against corrosion of A36 steel. The corrosion resistance of polymer coatings-covered steel substrates was evaluated by using potentiodynamic polarization curves and linear polarization resistance. Findings – At 25 and 100°C, polymer coatings showed a better protection of the A36 steel, and the corrosion rate diminished in three orders of magnitude with regard to the bare steel. Morphological study showed that the increased temperature benefited the integration of the two polymeric phases; however; the temperature of 200°C affected the film quality, generated cracks and holes, which affected the barrier properties of the coatings. Research limitations/implications – The research involved the synthesis and physicochemical characterization of the polymeric coatings (P3HT, PS/P3HT y PMMA/P3HT), as well as their application as coatings in the steel to prevent corrosion. The effect of thermal treatment of the protective coatings on steel corrosion was studied. Practical implications – This paper aims to contribute to reducing the problem of metal corrosion through the use of polymer coatings. Social implications – Today, majority of metal surfaces are subject under the protection to prevent a very common phenomenon, that is corrosion. Corrosion is the result of chemical reactions that occur between a metal or a metal alloy and its environment. Corrosion creates a degradation of the material that has an impact on some economic, environmental and even social aspects, here the great importance of its protection. Originality/value – It is shown in this study that the P3HT coating provides better corrosion protection of the A36 steel than the PS and PMMA coatings. However, mixtures of P3HT with PMMA and PS protected the steel from corrosion by two and three orders of magnitude similar to the simple P3HT coating. Polymer blends improved adhesion to the substrate and mechanical property of the coating, and in addition, the polymer blends made cheaper coating.