The Preparation And Anticorrosion Performance Study Of Polyaniline ／ Epoxy Composite Coatings

On account of its various types and wide application rage, epoxy resin is used in many areas such as terrace, sealant, and coating. Therein, epoxy coatings can also be divided into many types, for example, one, two, and multicomponent coatings based on their curing compositions or liquid and powdery coatings according to their existing forms. As a kind of widely used anticorrosion coating, epoxy coating appears almost everywhere. However, with the development of modern industry and people’s gradual attention on environmental protection, the anticorrosive fillers which were used in traditional epoxy coatings have been unable to meet the increasingly harsh usage requirements, which draws people’s attention to green and high-efficiency polyaniline. As a kind of conductive polymer, polyaniline has become one of the most promising fillers with the stable property and environmental friendly feature.This paper chose the already mass-produced polyaniline of Cornell Chemical Company as anticorrosive filler. Through the properties characterization, polyaniline was confirmed to be suitable for the subsequent corrosion experiments. E44 epoxy resin is usually selected as film-forming resin. The author prepared a series of coatings with different formulations, sprayed them to form films and compared their mechanical properties through coating hardness and impact resistance tests. The author then compared the coatings’ water resistance property through soaking experiments and also investigated their anticorrosion performances by measuring the electrochemical impedance spectroscopy(EIS) under different soak time. Meanwhile, the functional mechanism of the coatings in the whole protective process was studied. At last, the author made an impersonal evaluation on the properties of coatings with different formulations.The epoxy resin selected in this paper has a high viscosity under room temperature. The author then chose a mixed solution of xylene and n-butyl alcohol with a 4:3 mass ratio as the diluent. Through the screening of solvent dosage, 15%-30% was regarded as the optimal. Moreover, the specific additive amount could be adjusted according to the requirement of individual coating thickness. The optimum dosage of thixotropic agent was also filtered as an addition of 100 portions to 200 portions of epoxy resin solution. Through the screening of curing agent type, curing time and dosage, the author concluded that the NX-2015 curing agent could be used for prolonging coating operation time in higher temperature. On the opposite, in lower temperature, LITE-3100 curing agent was usually used to reduce the curing time of the coatings. In addition, both of their optimal usage were 70% of epoxy resin. The author chose titanium dioxide and carbon black as the fillers for the purpose of coating beauty.In this paper, the composite coatings which contained 0%~5% polyaniline were prepared. Though the electrochemical impedance spectroscopy tests of the coatings in 3.5% sodium chloride solution, the author investigated their anticorrosion properties. As shown in the results, the coating which contained 4% polyaniline behaved the best. It possessed a good anticorrosion performance even after 90 days of soaking.The author concluded eventually that the addition of polyaniline could enhance the anticorrosion properties of the coating and the optimal additive amount was 4%.