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This work reports novel anticorrosive epoxy coatings based on safer dimethyl sulfoxide solvent and free of zinc anticorrosive pigment. The latter was replaced by conducting polymers, as nontoxic anticorrosive pigments. The procedure used for their formulation, spectroscopic characterization, thermal and mechanical properties have been discussed and compared with those of conventional epoxy coatings. Furthermore, accelerated and longterm corrosion assays have evidenced that the new epoxy coatings protect steel from chlorine aggressive medium for 2880 h and for 2 years in atmospheric corrosive medium. Therefore, the results evidenced an excellent corrosion resistance, excellent application, and aesthetic appearance of the new coatings.

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We propose a simple rheological model to describe the thixotropic behavior of paints, since the classical hysteresis area, which is usually used, is not enough to evaluate thixotropy. The model is based on the assumption that viscosity is a direct measure of the structural level of the paint. The model depends on two equations: the Cross-Carreau equation to describe the equilibrium viscosity and a second order kinetic equation to express the time dependence of viscosity. Two characteristic thixotropic times are differentiated: one for the net structure breakdown, which is defined as a power law function of shear rate, and an other for the net structure buildup, which is not dependent on the shear rate. The knowledge of both kinetic processes can be used to improve the quality and applicability of paints. Five representative commercial protective marine paints are tested. They are based on chlorinated rubber, acrylic, alkyd, vinyl, and epoxy resins. The temperature dependence of the rheological behavior is also studied with the temperature ranging from 5 ºC to 35 ºC. It is found that the paints exhibit both shear thinning and thixotropic behavior. The model fits satisfactorily the thixotropy of the studied paints. It is also able to predict the thixotropy dependence on temperature. Both viscosity and the degree of thixotropy increase as the temperature decreases.