Polyaniline, Polypyrrole Doped Conductivity And Corrosion Resistance

UV spectrum, infrared spectrum, SEM, and polarization curve were applied in this paper. The synthesis method and capability of the exploratory study PANI, Ppy and doped-Ppy on magnesium were investigated based on polymer dopping. The followings are the main points:Firstly, the anti-corrosion capability of PANI was studied. The result indicated the film containing doped-PANI having the anti-corrosion capability to metal in certain extent. Because there was an oxidated film between the metal and the epoxy resin, which can protect the metal. However, its application was limited due to its lower conductivity.Secondly, the capability of Ppy was investigated. The result indicated Ppy has higher conductivity than PANI. The film containing Ppy and epoxy resin exhibited the anti-corrosion performance. However, the lower conductivity of Ppy and the insolubility of Ppy restrict its application.Thirdly, the conductivity and anti-corrosion performances of doped-Ppy were studied. Doped-Polypyrrole was synthesized from pyrrole using p- tolyl sulfonic acid as a doping agent and ferric chloride as an oxidant. The effect of dosage of the doping agent and the oxidant on the conductivity of doped polypyrrole was investigated, and the optimized conditions were obtained. The molecular structure of the polypyrrole was characterized by UV and IR spectra, and its morphology was studied by SEM. The results indicated that the polypyrrole was regular, and its conductivity reached 42.7 S·cm^-1 when the ratio of p- tolyl sulfonic acid : pyrrole : ferric chloride was 0.75 : 1 : 0.5. A film containing the polypyrrole was prepared on magnesium surface, and its anticorrosion property was investigated by potentiodynamic polarization curves and open circuit potential. It was found that the polypyrrole showed an excellent anticorrosion property for magnesium, the corrosion current and voltage were measured to be 0.0981 A and -0.88 V, respectively, and a passivation layer was formed between the film and magnesium surface. Lastly, in order to obtain the functional material which have conductivity and anti-corrosion capability at the same time, doped-Ppy was applied and mixed with epoxy resin. According to the Tafel curve study, the optimal anti-corrosion ratio was obtained(0.55% eigenstate polypyrrole in epoxy resin and quality scores of 0.01% of doping polypyrrole with the help of polyhydroxylated resin (FS-2060A,FS-3070 and FS-4365A). The Tafel curve preliminary explored the possible mechanism of preservation, which is the existence of the oxidated film between the metal and the epoxy resin.