Preparation And Anticorrosive Properties Of Polyaniline/Waterborne Alkyd-Acrylate Composite Materials

According to the authoritative data analysis made by American National Association and Corrosion Engineering(NACE),the economic loss in U.S.caused by corrosion loss was about $30 billion each year,accounting for 3%-5% of the gross national product(GDP),while the economic loss in China caused by metal corrosion accounted for 5% of GDP.Therefore,it is of great significance to find a suitable way to inhibit the corrosion of materials for the energy conservation and environmental protection and sustainable development of the society.Anti-corrosion coatings has been demonstrated to be one of the most economical and effective way to prevent the corrosion.Polyaniline(PANI)composite anticorrosive coating has unique scratch resistance and pitting corrosion resistance.It is a kind of heavy-duty anticorrosive coating which is suitable for the condition of acid,marine and aerospace.However,due to the structural characteristics,PANI can not be formed to film by itself,and the processability is poor,so it is necessary to modify it to prepare the composite anticorrosive coating with excellent performance.In this paper,p-phenylenediamine(PDA),3-aminobenzenesulfonic acid(ABSA)were used to modify PANI by copolymerization,a series of two-and three-component copolymers were prepared.The environmental protection composite anticorrosive coatings was prepared by the combination of waterborne alkyd resin as matrix resin and modified PANI.(1)A series of PANI was synthesized by using aniline(An)and PDA as monomers.The modified PANI was analyzed using FT-IR spectrum,X-ray diffraction(XRD)and Scanning electron microscopy(SEM).The experimental results confirmed that the amino group was successfully incorporated into PANI chains,resulting in the variation in interaction between PANI molecules,and reduction in the conjugation effect.It can be seen from the thermogravimetric(TG)diagram that the thermal stability of the film was improved by adding PANI as filler into the waterborne alkyd resin matrix.The salt spray and corrosion resistant of surface film(using SEM)were obtained: PANI(were prepared when the An was 2.80 g and PDA 3.20 g)as filler was added into the waterborne alkyd resin matrix,the film is soaked in salt spray for 20 d,and no rust point was observed on the surface.The electrochemical performance test and X photoelectron spectroscopy(XPS)test showed that the reaction of active monomer in coatings took place on the iron substrate,forming a layer of dense Fe2O3 oxide film,which is beneficial to improve the anticorrosion performance of waterborne alkyd resin.(2)A series of two-component copolymer(called SPANI)were prepared with An and ABSA as raw materials.FT-IR spectra confirmed that the ABSA is well copolymerized into the SPANI chain;UV-Vis,XRD,SEM and transmission electron microscopy(TEM)showed that the addition of ABSA affected the molecular structure of the SPANI,resulting in the reduciton in the degree of conjugation.The stability analysis showed that the SPANI dispersion was endowed with good stability when the An dosage is 5.03 g and the ABSA dosage is 1.04 g.The electrochemical test shows that the composite of the above-mentioned SPANI and water-based alkyd resin matrix displays good anticorrosion with corrosion voltage of-0.479 V,the resistance value of up to 9.86×106 ?cm2.In addition,effects of reaction time on the dispersion stability and anti-corrosion properties were investigated,It is found that the SPANI displays better stability and anti-corrosion proeprties when reaction 4 h.The effect of PDA endcapper on the properties of SPANI was also studied by SEM and stability test.It is found that the SPANI displays better stability when 0.32 g PDA was utilized to endcap SPANI.The electrochemical analysis showed that the corrosion voltage was-0.459 V,and the electrochemical impedance value was 3.82×108 ?cm2,the modified SPANI was endowed with good anti-corrosion proeprties.(3)Fixed the PDA content,effect of the ratio of An to ABSA on the morphology and corrosion resistance of there-component copolymer(called SPANIP)were investigated.The structure and morphology of the polymers were characterized via FT-IR,UV-Vis and XRD.The results showed that the polymer morphology became loose and porous with the increase of ABSA content,which was favorable for the polymer dispersion in water.However,the polymerization between ABSA and An was impacted when excessive ABSA was adopted,resulting the self polymerization of An and forming some rice-like self-polymers.The dispersion stability analysis showed that,the dispersion can be stabilized for 720 h when An was 5.03 g and ABSA was 1.04 g.The study on the water resistance,salt spray resistance and anticorrosion of polymer showed that the above-mentioned the SPANIP,added to the waterborne alkyd resin as filler,can improve the anticorrosion of the coating.Electrochemical studies showed that the corrosion voltage of the composte coating was-0.459 V,and the electrochemical impedance value was 3.82×108 ?cm2.XPS study showed that the SPANIP reacts with matrix to form dense Fe2O3 oxide film,which is a key factor to improve the anticorrosion coating.