Protective Effect on Metal Substrate of Epoxy Resins Containing Corrosion Inhibitor Embedded into Suitable Nanocarriers

The corrosion of metals is a serious technological problem and a variety of methods such as cathodic protection and insulating coatings has been developed to overcome it. However, the use of an active coating on metal substrates is proposed to be an innovative and effective approach. Although 2-mercaptobenzothiazole (MBT) is an efficient corrosion inhibitor for metals, its direct addition into the polymer coating or paint is not so much effective, because it is water-soluble, photodegradable and creates discontinuities in the coating layer, thus decreasing its barrier properties. A valuable approach to improve its anticorrosion performance is the entrapment of MBT into nanocarriers. In the present work two different types of nanocarriers have been investigated. In particular, halloysite nanotubes which MBT is loaded in the inner empty lumen through a vacuum procedure, and Zn–Allayered double hydroxides (LDHs), in which MBT is intercalated through ionic-exchange, have been evaluated. Release tests of MBT from the obtained active particles in aqueous corrosive solution have been performed. Results have been correlated with the data obtained by visual inspection of anticorrosion effect of epoxy coatings used to protect commercial steel substrate during accelerated corrosion tests.