Studies On Preparation And Anticorrosive Performance Of PPy And Its Composites

With the large-scale application of steel materials in modern construction and industrial fields,the corrosion problem has become a hot issue as the international community suffers from huge economic losses every year because of steel corrosion.At present,with the research progress of steel corrosion protection,more and more steel corrosion protection technologies have been reported in the world,such as hot galvanizing,inorganic coating such as chromate as well as addition of corrosion inhibitors,etc.However,these technologies are subjected to prominent limitations.Based on the above situation,it is necessary to develop some new technologies for iron and steel corrosion protection.In recent years,with the development of conducting polymer research,more and more researchers focus on the application of conductive polymer in metal anticorrosion.Polypyrrole is favored by researchers because of its nontoxic and easy to obtain characteristics.In this paper,the corrosion protection properties of conductive polymer polypyrrole and it’s complexes on Q235 steel were studied.The main work is as following:（1）Under the condition of ice bath and stirring,the electrolyte is 0.10 M Py monomer and 0.10 M dopant,dopant is twelve sodium dodecyl benzene sulfonate（SDBS）,p-toluenesulfonic acid（PTSA）,amino sulfonic acid（SA）,phytic acid（PA）,oxalic acid（OA）),respectively.Polypyrrole films doped with different dopants were prepared on the surface of Q235 steel by electrochemical potentiostatic deposition.The corrosion protection performance was tested in the 3.5%sodium chloride solution.The results showed that the SDBS doped polypyrrole,the SDBS-PPy/Q235 film,has the best anti-corrosion property,and the corrosion current density is 4.34μA cm^-2,the corrosion rate is only 0.050 mm/year,it’s 1/25 of bare Q235 steel.On this basis,the effects of different concentrations of SDBS on the anticorrosion properties of doped polypyrrole films were studied,and the mechanism of concentration change was discussed.The optimum doping concentration was chosen as0.10 M.（2）On the basis of determining the optimum dopant and concentration,SiO₂-PPy and ZnO-PPy composites were prepared by electrochemical method.The morphology,composition,hydrophobicity and anticorrosive properties of different series of samples were systematically studied.The results showed that the particle density of the SiO₂-PPy composite prepared by the TEOS has the smallest aggregate size and the highest film density.The water contact angle test showed that its hydrophobicity was the best,and the water contact angle was 95°.The results of anti-corrosion performance study through potentiodynamic polarization curve,electrochemical impedance spectroscopy indicates that the SiO₂-PPy composite prepared by the TEOS has the excellent anticorrosive property.On the oher hand,the particle density and compactness of ZnO-PPy composites prepared by zinc acetate were the highest.The water contact angle test showed that the hydrophobicity was the best,and the water contact angle was 126.3°.The electrochemical test results showed that the open circuit potential,dynamic potential polarization curve and AC impedance spectrum all showed its excellent anticorrosion performance.（3）The performance of polypyrrole inorganic particle composites in anti-corrosion is better than that of polypyrrole.However,due to the lack of adhesion,the long time of corrosion protection is not ideal.Therefore,PPy/inorganic particle composites materials are compounded with the epoxy resin.The results after salt spray test and soaking test showed that the anticorrosive properties of the samples after blending with epoxy resin were obviously improved than that of the Bare Q235.After 20 days of salt spray test,the Bare Q235 showed that the pitting corrosion were obvious,and the depth of the pitting corrosion was 185μm,and the corrosion resistance of the samples was higher than that of the Bare Q235.The corrosion pitting depth of the Bare Q235 was 230μm in 1 mol/L H⁺solution for30 days,and the corrosion pitting depth of the Bare Q235 was 150μm in 1 mol/L OH^-solution for 30 days.The anticorrosive properties of the prepared samples have been significant improved.