| Polyaniline(PANI),as a kind of important conductive polymer,Has high electrical conductivity,chemical stability,nontoxic property,chemical redox reversibility,ease of synthesis,and low cost.PANI had promising prospects in metal corrosion and antifouling.However its application was limited because of its poor aqueous dispersions.Many researchers tried to improve the water dispersible of PANI,by adding stabilize,emulsion,induced doping,etc,but this problem cannot be solved.Phosphorylated polyvinyl alcohol(PPVA)was a water-soluble polymer.PPVA has good stability and mechanical properties.PPVA has phosphoric acid ester groups with metal corrosion inhibition in the molecular chain,and can solve polyaniline water-dispersion and improve corrosion resistance.In this paper,polyaniline aqueous dispersion was prepared by grafting polyaniline(PPVA)with epoxy monomer.waterborne alkyd resin/polyaniline anticorrosive coating was prepared by using it in water-based alkyd resin.The effects of various factors on the properties of modified polyaniline aqueous dispersion and waterborne alkyd resin/polyaniline anticorrosive coating were analyzed.The optimized ratio of synthetic polyaniline dispersion and waterborne alkyd resin/polyaniline anticorrosive coating was optimized.First,we chose PVA0588 as the polymer matrix,prepared the phosphorylated poly vinyl alcohol(PPVA),which grafting rate was about 13%.Then a series of phosphorylated poly vinyl alcohol/Polyaniline dispersion(E-PPVA/PANI)were prepared by graft copolymerization of aniline in phosphorylated Poly(vinyl alcohol)solution with epoxy chloropropane.In the process of this reaction,phosphorylated poly vinyl alcohol(PPVA)was used as stabilizer and co-doped.At last,the conducting PANI dispersion(E-PPVA/PANI)was prepared by synthesized by in situ polymerization while took ammonium persulfate(APS)as oxidant and hydrochloric acid(HCl)as dopent).The properties of the composite dispersion and composite films were analyed byFTIR,XRD,UV-vis,particle size analysis,Rheology,thermogravimetric analysis(TGA)and conductivity.The effects of ECIP content and polyaniline content on the stability and conductivity of the dispersion were studied.Results indicated that the addition of ECIP could significantly improve the water dispersibility and compatibility of conducting PANI dispersion(E-PPVA/PANI),then the content of aniline was 30%,the conducting PANI dispersion(E-PPVA/PANI)has good water dispersion stability and the conductivity of the composite films was 5.6 S/cm.In order to further improve the water dispersibility and electrical conductivity of PANI,we chose glycidyl methacrylate(GMA),because it not only has reactive groups that can be graft copolymerized with aniline,but also has a double bond on GMA which provided a certain condition for access to other functional monomer.So took the phosphorylated polyvinyl alcohol(PPVA)as the substrate,and Under certain conditions,GMA reacted with PPVA to form?-methacrylic acid glycidyl ester modified phosphorylated polyvinyl alcohol(G-PPVA).And then the conducting PANI dispersion(G-PPVA/PANI)were synthesized by in situ polymerization.with aniline graft copolymerization.The influences of PANI content and GMA content on composite properties were studied.The stability of G-PPVA/PANI dispersion was also discussed.The properties and structure of the composite material were investigated by FTIR,UV-vis,XRD,Rheological,thermogravimetric analysis and conductivity etc.It turned out that the addition of GMA to the dispersion greatly improved stability and conductivity of composite,which was better than E-PPVA/PANI.When the aniline content was 50%,the conductivity of the composite film was up to 9S/cm,and the water dispersion could be stored for 90 days without precipitation.And the color still presents dark green.The successfully prepared G-PPVA/PANI dispersion was applied to metal anticorrosive coatings.The AR/G-PPVA/PANI water-based anticorrosive coating was prepared with water-based alkyd resin matrix.The effects of different G-PPVA/PANI addition on the properties of aqueous coatings were studied.The dispersion and micro morphology of water coating were researched by particle size and TEM.The results showed that the particle size of AR/G-PPVA/PANI composite coating was about 170 nm,and the dispersionindex of PDI was very small.And G-PPVA/PANI could not interfere with the core-shell structure of the alkyd resin.G-PPVA/PANI could play a synergistic role with the water-based alkyd resin to protect the metal surface.On the other hand,the mechanical properties of the coating were evaluated by testing the coating adhesion,hardness,and impact resistance.The corrosion performance of the AR/G-PPVA/PANI coating was analyzed based on the measurement of the polarisation curves and acimpedance spectra.The results showed that along with the increase of the content of G-PPVA/PANI water dispersion,the corrosion potential of the AR/G-PPVA/PANI composite anti-corrosion coating increased from-0.7 V to-0.35 V,which offset of 350 mV,the corrosion current reduced from-7.5 A.cm2 to-10 A.cm2.Through the determination of salt water,we could see that the corrosion resistance of metal was best when G-PPVA / PANI content was 3%.Compared with the waterborne alkyd resin,the addition of G-PPVA / PANI dispersion greatly improved its corrosion resistance,and the addition of G-PPVA / PANI dispersion was very little(3%),which could greatly improve its corrosion resistance.So the anti-corrosion coating has a very good industrial prospects. |
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