Study On The Preparation And Anticorrosion Of Waterborne Polyurethane-Acrylate Coatings Modified By P-Phenylenediamine-Aniline Copolymer

Polyaniline is a kind of conductive polymer with excellent peformance,low price, and can be used in metal anticorrosion, but its application is limited because of which can’t be easily dissolved and dispesed, polyanilne is modified by chemical modification to improve dispersion and availability, polyaniline and its derivatives usually be compounded with other resin matrix to prepare anticorrosive coatings due to their bad bond strength and mechaical properties. In recent years, waterborne coatings have become a trend with increasing people’s awareness of environmental protection. waterborne polyurethane-acrylate is a kind of excellent film-forming resin because of which have advantages both of polyurethane and polyacrylate. In this article, the phenylenediamine-aniline copolymers were synthesised by modifing polyaniline, and the aniline-phenylenediamine/waterborne polyurethane-acrylate composite anti-corrosion coatings were prepared according to the physical blending method. In this paper, pecific research consists of four parts:(l)High solids and solvent free waterborne polyurethane-acrylate emulison was prepared based on a surfactant monomer by using methyl methacrylate (MMA), butyl acrylate (BA), polycaprolactone diols (PCL), isophorone diisocyanate (IPDI), trimethylolpropane (TMP),2,2-dimethylolbutyric acid (DMBA) as raw materials, glycidyl methacrylate (GMA) and y-methacryloxypropyl trimethoxy silane (KH570) as an external crosslinker. the effect of the amout of AOS on emulsion and coating were studied, transmission electron microscopy (TEM) results showed that the shape of latex particles changed from irregular shape to regular spherical morphology with the increasing amount of AOS, and when the amount of AOS reaches 1%to 1.7%, the core-shell structure of latex particles were formed,and the particles distributied evenly; atomic force microscope (AFM) results indicated that the compatibility of polyurethane and polyacrylate was increased based on AOS, and the surface roughness declined, flatness improved; when the amount of AOS is 1%, water absorption of film was decreased from 6.24% to 4.1% and water resistance was improved; dynamic light scattering indicated that the the particle size of latexs were decreased and emulsion stability and dispersion were improved when AOS was added,TG results showed that the thermal stability of film was decline slightly in the presence of AOS; dynamic mechanical analysis (DMA) indicated that the glass transition temperature of films iwere increased and rigidity of segments enhanced with increasing the amount of AOS; and the emulsion stability and film hardness were improved when added AOS.(2)Polyaniline(PANI),Poly(p-phenylenediamine)(PPDA),P-phenylenediami ne-aniline copolymer P(ANI-PDA) were synthesised in hydrochloric acid by chemical oxidation method using aniline, p-phenylenediamine as monomers, ammonium persulfate as oxidant and ammonia as de-dopant. The structure, crystallinity, thermal ability and morphology were characterized by FT-IR, XRD, UV, TGA and SEM. The dispensability was tested in aqueous water. The results showed that the quinoid structure in PPDA and P(ANI-PDA) was reduced compared with PANI. P-phenylenediamine-aniline copolymer exhibited the highest crystallinity and dispensability in aqueous water. polyaniline exhibited the best thermal stability. PANI displayed irregular porous particle agglomeration structure, whereas nanosheet structure was detected in the morphology of PPDA and P(ANI-PDA)and which can increase the crystallinity and dispensability of polymers.(3)P-phenylenediamine-aniline copolymers were synthesized based on the non-ionic surfactant octyl phenol polyoxyethylene ether (OP-10) with different proportions of Aniline (An) and p-phenylenediamine (PDA) as raw materials in hydrochloric acid, ammonium persulfate as oxidant and ammonia as de-dopant. The structure, crystallinity and thermal ability were characterized by FT-IR, XRD, UV and TGA, the results indicated that the quinoid structure in polymers were reduced, the stability of copolymers were improved with increasing proportion of the amount of p-phenylenediamine,and the copolymer exhibited the highest crystallinity when the prpportion of aniline and p-phenylenediamine is 1:3.(4)Aniline-phenylenediamine/waterborne polyurethane-acrylate anti-corros -ion coatings were prepared according to the physical blending method by using self-made waterborne polyurethane-acrylate as film-forming resin matrix, aniline-phenylenediamine as anticorrosive packing. the effect of the amout of P(ANI-PDA) on emulsion and coating were studied, and the effect of the amout of P(ANI-PDA), AOS, different proportions of aniline and p-phenylenediamine on anticorrosive properties of coatings were discussed.The results are as follows: SEM showed that the bright aniline-phenylenediamine copolymer particles can be observed in cross-section film with increasing the amount of P (ANI-PDA) from 0% to 2%, this indicated that copolymer particles can be dispersed in the polyurethane-acrylic coatings; TEM and AFM indicated that the particle size of latex particles increased when added P(ANI-PDA), meanwhile, AFM showed that the birght area increased and TEM showed that the nanosheet structure P (ANI-PDA) can be observed between WPUA latex particles when the amount of P (ANI-PDA) is 2%.TGA and DTG results indicated that P(ANI-PDA) can improve the stability of the film; the anticorrosive of coatings were studied bty salt spray test, Tafel electrochemical polarization curve and EIS impedance spectroscopy, and the results showed that when the P (ANI-PDA) amount of P (ANI-PDA) is 1.5%, AOS is 0.6%, the proportion of aniline and p-phenylenediamine is 1:4, the coating displays the best salt spray resistance and anticorrosion property, the corrosion current density is minimum, which value is 2, the resistance is maximum, which value is 2.59×105 Ωcm2.