Avaliação do desempenho anticorrosivo de revestimentos de epóxi contendo microcápsulas poliméricas de poli(ureiaformaldeído) (PUF) preenchidas com 5-etilideno-2-norboneno (ENB)

Abstract

Corrosion of metals is one of the main challenges faced by the industry, which can cause serious structural failures and great economic losses. One of the most commonly used corrosion prevention methods is anticorrosive coatings, which can be inorganic, organic or hybrid. Organic coatings have advantages such as easy application and good cost-benefit, however, these coatings are susceptible to damage caused by mechanical or environmental factors, which can compromise barrier protection against corrosion. To overcome this problem, anticorrosive coatings containing self-healing materials, such as polymeric microcapsules, have been developed in recent years. In this work, poly(urea-formaldehyde) (PUF) microcapsules filled with 5-ethylidene-2-norbonene (ENB) previously synthesized by in situ polymerization, in 11 synthesis conditions resulting from a complete factorial design, were applied in coatings to epoxy base for evaluating anticorrosive efficiency on metallic substrates. The coatings containing the microcapsules were applied to steel substrates, previously cleaned and prepared, using the dip coating method. The anticorrosive properties of the coatings and the performance of the microcapsules were evaluated using a corrosion test by immersion in a saline solution, after simulating damage through scratches. The results of the corrosion test showed better performance for the coatings containing the microcapsules obtained under the PUF/ENB 1 and PUF/ENB 9 synthesis conditions. Analyzes by stereoscopy and optical microscopy showed good dispersion of these microcapsules in the scratch regions, which contributed to the best performance of coatings. Scanning electron microscopy analyzes showed greater details of the interface between coating and metallic substrate and reinforced what had been observed in the corrosion test results.