Preparation and Corrosion Resistance of PANI/TiO2/Epoxy Coatings postprint

Abstract: Polyaniline/TiO2 nano composites with different weight ratios of polyaniline to TiO2 were synthesized using chemical oxidative polymerization through polymerizing polyaniline (PANI) onto the nano TiO2 surface. The prepared PANI/TiO2 composites were characterized by FTIR, XRD and SEM. Then PANI/TiO2/epoxy resin coating was prepared by blending epoxy resin with polyaniline/TiO2 nano powders, while coating formulation with excellent mechanical performance was acquired through orthogonal experiments and trial corrosion tests. The corrosion performance of X70 steel coated with the optimal coating was examined in S2- and Cl- containing solutions at different temperatures. The results show that there exists strong interaction between the nano TiO2 particle and PANI within the PANI/TiO2 composites. Many factors could affect the mechanical property of the coatings, according to their impact degree, which may be ranked as the following sequence: PANI＞TiO2＞curing temperature＞solvent content＞solvent ratio. The optimal PANI/TiO2/epoxy resin coating with excellent mechanical properties and corrosion performance could be acquired by an optimal process with the following parameters: the mass ratio of PANI to epoxy resin is 1 to 100; TiO2 to epoxy resin is 1 to 100; curing at 60 ℃. The content of solvent to epoxy resin is 5 to 10 and NMP/n-butanol=2/1(solvent molar ratio). Furthermore, at 72 h after immersion of the optimal coating in 3.5%NaCl solution at 65 ℃, a maximum appeared on its impedance vs time curve, whilst the coating keeps an excellent corrosion resistance even after immersion in 3%Na2S solution for 120 h at 80 ℃.