Study On The Synthesis And Anti-Corrosion Properties Of Aniline/Pyrrole Copolymer-nano Silicon Dioxide Composite Membrane

In this thesis,polyaniline?PAni?,polyaniline-pyrrole?PAni/PPy?,and polyaniline-pyrrole-nanosilicon dioxide?PAni-PPy-SiO₂?composite membrane were prepared on the surface of the 316 stainless steel?316SS?through the cyclic voltammetry?CV?method.By using CV,XPS,XRD,FT-IR and SEM,the electrochemical polymerization process,structural and morphological characteristics of the three composite membranes was characterized.By using OCP,Tafel and EIS method,the 316SS protective abilities of the three composite membranes and the preservative effects of the epoxy resin film layers on the composite membranes were investigated,where the preservative mechanism was deduced by the anodic protection mechanism and mechanical shielding effect.Results show that PAni/PPy-SiO₂composite membrane can form on the surface of 316SS by electrochemical process.Results show that Compared with PAni and PAni/PPy membrane,PAni/PPy-SiO₂composite membrane has tighter surface structure.The metal protection ability of PAni/PPy-SiO₂ of is better than that of PAni/PPy and PAni membrane.The anti-corrosion ability of membrane is improved because of the strengthening mechanical shielding effect of membrane with nano SiO₂ and the inhibition of charge transfer during the corrosion reaction process.Under forward scan condition,PAni membrane has best performance when the mixed acid is sulfuric acid,the monomer with acid concentration ratio is 0.3,the scanning rate is 50 mV/s and the scanning laps is 20 laps.In the PAni/PPy membrane,the molecular structure of PAni changes apparently and when the ratio of Ani:Py is 5:1,the PAni/PPy membrane has the best performance.When the addition amount of Py is too large,the too much Py may polymerize ahead of the metal surface,leading to the formation of a large number of irregular spherical protrusions and reducing the density of the film.Compared with PAni and PAni/PPy composite membrane,PAni/PPy-SiO₂ has a more compact surface structure.SiO₂ inhibits the charge transfer in the corrosion reaction process and improves the anticorrosive ability of the film by strengthening the mechanical shielding effect of the film layer.When the molar ratio of Ani:SiO₂ is over 10:1,PAni/PPy-SiO₂ composite membrane has the best performance in the metal protection.The mechanical shielding effect of the anticorrosion coating get greatly improved after the coating of the epoxy resin on the polymer membrane.