Preparation Of Acid Doped Polypyrrole/Epoxy Resin Composite Coating And Its Anti-corrosion Properties

Metal corrosion will not only cause economic losses,but also bring potential safety hazards and cause waste of resources.Brushing organic coatings on metal surfaces is currently the most commonly used corrosion protection measure.Polypyrrole has the advantages of easy synthesis,easy film formation,good conductivity,good stability and environmental friendliness.It has broad research prospects in the field of corrosion protection.Polypyrrole and epoxy resin can be blended into composite coatings.This article first uses chemical oxidation method to prepare polypyrrole,uses a variety of characterization methods to characterize the synthesized polypyrrole,then optimizes the epoxy resin coating formulation,selects the appropriate epoxy resin diluent and the amount of polypyrrole added.Finally,after mixing the acid-doped polypyrrole prepared previously with the epoxy resin uniformly,brushing it on the surface of Q235 steel to prepare an acid-doped polypyrrole / epoxy composite coating,the corrosion resistance of polypyrrole coating was studied by electrochemical test and accelerated immersion test in 3.5wt% Na Cl solution.The main research work and results of the paper are as follows:1)The acid-doped polypyrrole was synthesized by adding hydrochloric acid,sulfuric acid,nitric acid,phosphoric acid,phytic acid,sulfosalicylic acid,oxalic acid,and tartaric acid as the doping acids respectively during the chemical oxidation synthesis of polypyrrole.SEM,XRD,electrical conductivity and other characterization methods to characterize the morphology and structure of polypyrrole.2)The synthetic intrinsic polypyrrole was added to the epoxy resin coating,and then the coating was evenly brushed on the surface of Q235 steel with a brush to prepare the cost intrinsic polypyrrole/epoxy resin composite coating.Then the composite coating was optimized by morphological analysis,electrochemical experiments and water absorption analysis of the coating.The experimental results showed that the composite coating showed excellent anticorrosion performance when the mixed solvent(m(xylene): m(n-butanol)=7:3)was used as the epoxy resin solvent and the polypyrrole additive amount was 0.6wt%.3)The acid-doped polypyrrole and the epoxy resin coating were mixed uniformly to prepare anticorrosive coatings,and their corrosion resistance in 3.5 wt% Na Cl corrosion solution was compared.The experimental results show that the anticorrosive effect of polypyrrole doped with phosphoric acid in inorganic acids is the best,and the anticorrosive effect of polypyrrole doped with sulfosalicylic acid in organic acids is the best.Adding it to epoxy resin coating can significantly reduce the corrosion rate of the metal matrix.The anticorrosion mechanism of polypyrrole is:(1)Reduce the micropores in the coating,thereby improving the shielding performance of the coating,impeding the diffusion of corrosive media in the coating,and reducing the corrosion rate of metals;(2)Polypyrrole doped anions will be released during the redox process of polypyrrole and react with iron ions to form a protective film on the metal surface to prevent the metal matrix from being eroded by corrosive media and play a certain protective role on the metal matrix.