Study On Synthesis And Anticorrosion Properties Of Polyaniline Composite Containing Coating

In this paper, the polyaniline (PANI) were synthesized by chemical oxidation method with ammonium persulfate as the oxidant. The hydrochloric acid, dodecylbenzene sulfonate, and sulfosalicylic acid were used as doped acid, respectively. The PANI were charactered by infrared spectrum analysis, X-ray diffraction analysis, thermogravimetric analysis. The antioxidant dosage, reaction time, temperature and other factors which impacted the structure of polyaniline were investigated.Polyaniline-SiO₂ composites (PANI-SiO₂) were synthesized by in-situ ploymerization method. The results showed that in acid conditions polyaniline adsorbed on the surface of SiO₂ firstly. When m_aniline:m_SiO2=9:5, PANI-SiO₂ composite have the best proper of the crystallization. The chemical bond which exists between the polyaniline and Silica was proved by FT-IR. Thermal stabily of PANI-SiO₂ composites were fairly well and its decomposition temperature was 270℃.On this basis, the paint consisted of PANI-SiO₂ composites and epoxy resin was formed, and the PANI-SiO₂ containing coating was prepared on the tinplate and Mg-Li alloy surface. When all groups of the ratio was E-44:C-4:PANI-SiO₂=100:40:2, the adhesion, hardness, water absorption properties of coating were best.The electrochemical test results showed that PANI-SiO₂ containing coating has excellent anti-corrosion performance on the tinplate and Mg-Li alloy surface. PANI-SiO₂ containing coating provided good shield during immersion in 3.0% NaCl solution has a significant protective effect of the anodic protection accompanied with change of potential, a decrease of corrosion, and an increase of resistance of coating. EIS tests showed that the coating impedance always above 10⁶Ω·cm^-1, and the corrosion rate of tinplate and Mg-Li alloy can be decreased six magnitude comparing with expoy resin coating. The PANI-SiO₂ composite materials of addition provide a significant strengthen of the role of anti-corrosion. At last, the anti-corrosion models of PANI-SiO₂ containing coating were built. The protection of the PANI-SiO₂ containing coating is due to its shield, inhibition and anodic protection.