Study On Synthesis Of Ployaniline And Its Anti-corrosion Properties In Waterborne Alkyd Resin Anti-corrosion Coatings

Polyaniline is regraded as a conductive polymer material with excellent anti-corrsion properties and scratch resisitance,which has a good application in the field of metal anti-corrsion.However,polyaniline has a hard dissolve defect due to the rigid structure of polyaniline molecular chains and intermolecular interactions,which limits the application of its anti-corrsion properties.In this paper,polyaniline is uniformly dispersed in waterborne alkyd resin anti-corrsion coatings by improving the process of synthesizing polyaniline.The anti-corrsive properties of polyaniline is studied.The acid-doped polyaniline microemulsion is prepared by using a monomer droplet microemulsion method.The eigenstate polyaniline microemulsion is obtained by dedoping in ammonia.Properties of PANI are characterized with by scanning electronic microscopy,Fourier transform infrared spectrometer and thermal gravimetric analyzer.The particle size of phosphoric acid doped polyaniline and its dedoped products are nanoscale,non-agglomeration,uniform distribution.The thermal stability of eigenstate polyaniline is best.The water-based alkyd resin is used as a film-forming substance,and a certain amount of pigments and additives are added to prepare a wate-based alkyd resin anti-corrsion coating.The properties of the coating have a hardness of H,an adhesion level of 1,an impact resisitance of 50 cm and a flexibility of no more than 2 mm.The surface of the coating after immersed in water for 500 hours has not bubbling and rust.The surface of the coating after immersed in 3.5% NaCl solution for 240 h has smooth.After the salt spray test for 168 h,the unilateral erosion of the coating with scratches are less than 2 mm.Different kinds of polyaniline dispersions with different quantities are added to the waterborne alkyd resin anti-corrsion coatings.The corrsion resistance of the coating is tested by using water resisitance,salt water resisitance(3.5% NaCl solution)and salt spray resistance.The results show that cotianing a solid content 0.4% dodecylbenzene sulfonic acid doped polyaniline of coating and cotianing a solid content 0.4% phosphoric acid doped polyaniline of coating have a good corrsion resistance,which achieve water resisitance 720 h,salt water resistance 500 h and salt spray resisitance 360 h.The potentiodynamic polarizationcurves of the coating after immersed in 3.5% NaCl soultion for 240 h show that the coating containing solid content 0.4% phosphoric acid doped polyaniline has best anti-corrsion performance.The potentiodynamic polarization curves of commercially availible waterborne alkyd resin anti-corrsion coating and coating with solid content 0.4% phosphoric acid doped polyaniline after immersed in 3.5% NaCl solution for 240 h and 600 h are known.Containing a solid content 0.4% phosphoric acid doped polyaniline of coating has a best anti-corrosion performance.