Synergic enhancement of the anticorrosion properties of an epoxy coating by compositing with both graphene and halloysite nanotubes

The aim of this research was to improve the corrosion resistance of metal surfaces with polymer coatings. Both graphene and halloysite nanotubes (HNTs) were introduced together into the epoxy resin coating for the enhanced barrier protection of the metallic surface. The anticorrosion behaviors of different coatings were comparatively evaluated by the potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and neutral salt spray (NSS) tests. The potentiodynamic polarization curves showed that the coating containing 0.5 wt % HNTs and 0.8 wt % graphene (H05G08EP) together had the most positive corrosion potential and the minimum corrosion current density. The EIS results revealed that graphene endowed the composite coatings with excellent electrochemical performance for anticorrosive purposes. The NSS tests indicated that H05G08EP endured the longest NSS time. These results suggest that H05G08EP had the best corrosion resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47562.     

聚苯胺颗粒对水性环氧树脂涂层防腐性能的影响

以盐酸为掺杂剂、过硫酸铵为氧化剂、咪唑类离子液体为稳定剂,采用化学氧化聚合法合成了导电聚苯胺(PANI)颗粒,将其分散到水性环氧树脂(ER)中制成聚苯胺水性环氧防腐涂层,研究了聚苯胺颗粒对涂层防腐性能和机械性能的影响。结果表明,添加聚苯胺显著提高了水性环氧涂层的阻隔性能,信号频率f=0.01 Hz时,PANI/ER涂层的阻抗(|Z|f=0.01Hz)均高于纯ER涂层。添加5.0wt% PANI时ER涂层阻隔性能最好,浸泡0~168 h时|Z|f=0.01Hz稳定在约8.0×108 Ω?cm2,浸泡168 h后|Z|f=0.01Hz=7.5×108 Ω?cm2,远高于ER和其它PANI/ER体系。中性盐雾实验结果表明,聚苯胺赋予了涂层钝化腐蚀的能力,显著提高了涂层的防腐性能,且其添加量越高,防腐性能越好。弯曲和冲击实验结果表明,涂层的机械性能随聚苯胺含量增加先上升后降低,当聚苯胺添加量不超过5.0wt%时,涂层的机械性能优异,附着力和韧性均较好;PANI添加量增至7.0wt%时,ER涂层的脆性明显变大,机械性能下降。聚苯胺在水性环氧体系中的最宜添加量为5.0wt%,此时涂层的机械性能良好,综合防腐性能最优。     

氨基化GO/磺化聚苯胺改性水性环氧防腐涂料的制备与性能

以氯磺酸、苯胺和过硫酸铵为主要原料合成磺化聚苯胺（SPANI）,利用聚乙烯亚胺（PEI）还原GO,合成PG复合材料。利用GO上活性位点,将SPANI与PG结合,制备了SPG复合材料。利用SPG与水性环氧树脂共混制备水性环氧防腐涂料。通过FT-IR、XRD对SPG复合材料结构表征,结果表明,PEI上的氨基成功与GO结合,SPANI成功增加了PG的层间距;通过盐雾、电化学等实验对水性环氧涂层的防腐性能进行测定,并分析了涂层的物理性能。结果表明,当添加2wt%SPG时（添加量以环氧树脂和固化剂总质量为基准,下同）的水性环氧防腐涂层具有最优异的耐腐蚀性,腐蚀效率可达到99.19%,与纯EP相比,腐蚀电流密度从1080 nA?cm-2减小至307 nA?cm-2,腐蚀电压从-0.840mV升高至-0.347mV。     

Excellent corrosion protection performance of epoxy composite coatings filled with silane functionalized silicon nitride

Silicon nitride was firstly used as anticorrosive pigment in organic coatings. An effective strategy by combining inorganic fillers and organosilanes was used to enhance the dispersibility of silicon nitride in epoxy resin. The formed nanocomposites were applied to protect Q235 carbon steel from corrosion. The anticorrosive performance of modified silicon nitride with silane (KH-570) was investigated by electrochemical impedance spectroscopy (EIS), water absorption and pull-off adhesion methods. With the increase of immersion time, the corrosion resistance as well as adhesion strength of epoxy resin coating and unmodified silicon nitride coating decreased significantly. However, for the modified silicon nitride coating, the corrosion resistance and adhesion strength still maintained 5.7×10¹⁰ Ω cm² and 7.6 MPa after 2400-h and 1200-h immersion, respectively. The excellent corrosion resistance performance could be attributed to the chemical interactions between KH-570 functional groups and silicon nitride powders, which mainly came from the easy formation of Si-O-Si bonds. Furthermore, the modified silicon nitride coating formed a strong barrier to corrosive electrolyte due to the hydrophobic of modified silicon nitride powder and increased bonds.     

Partial replacement of metallic zinc dust in heavy duty protective coatings by conducting polymer

The aim of this work is to show that the high concentration of metallic zinc dust typically used in marine epoxy primers may be reduced by introducing a small concentration of conducting polymer as auxiliary anticorrosive additive. Specifically, in this work we compare the protection imparted by an epoxy coating with 79 wt.% of anticorrosive pigment with that obtained using the same formulation but reducing such concentration to 60 wt.% and adding 0.3 wt.% of polyaniline emeraldine salt. Initially, the influence of this modification in the structural, thermal and mechanical properties of the coating has been examined. After this, accelerated corrosion assays in an aggressive solution medium have been developed. The protection imparted by the unmodified and modified paint formulations has been determined using the standard method ASTM D 1654-79.     

AZ31镁合金表面防腐胶粘涂层的研制

胶粘涂层法是有效提高镁合金耐腐蚀性能的表面处理技术之一.以E-44环氧树脂、低分子量650#聚酰胺、云母氧化铁等为主要原料,制备了适用于AZ3l镁合金基体的防腐胶粘涂层.研究了填料含量对涂层外观、施工性和耐蚀性能的影响.结果发现,当填料质量分数为60%、涂层厚度为180～220μm时,防腐胶粘涂层具有良好的外观及施工性,附着力为1级,耐盐雾时间168 h.     

Corrosion protection by epoxy/poly(aniline-co-pyrrole)/ZnO nanocomposite coating

Anticorrosion behavior of epoxy/poly(aniline-co-pyrrole)/ZnO (EPAPZ) coating on stainless steel 304 alloys is investigated using the electrochemical impedance spectroscopy (EIS) method, and the coating is compared with epoxy/polyaniline/ZnO (EPAZ) and pure epoxy (EP) coatings. Scanning electron microscopy images are used for structural characterization and to compare the particle size of nanoparticles. EIS result showed that coating resistance for EPAPZ, EPAZ, and EP coatings after 90 days of immersion in 3.5% NaCl was 1.18 × 10⁷, 1.08 × 10⁶, and 4.28 × 10⁴ Ω cm⁻², respectively. In addition, the volume percentage of water absorbed by the coating, which could be obtained by coating capacitance, is 2.81, 4.21, and 9.11, respectively. Immersion tests showed 0.063, 0.194, and 0.752% of weight loss in the metals under EPAPZ, EPAZ, and EP coatings, respectively. These results show that the EPAPZ coating has superior anticorrosive performance compared with EPAZ and EP coatings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48265.     

Evaluation of an environmentally friendly anticorrosive pigment for alkyd primer

An alkyd formulation containing zinc phosphate (10 wt.%) was prepared and subsequently modified replacing the latter anticorrosive additive by a very low concentration of conducting polymer. Specifically, three modified paints, which contain polyaniline emeraldine base (undoped form), polyaniline emeraldine salt (doped form) and an eco-friendly polythiophene derivative (partially oxidized), were formulated. The properties and corrosion resistance of the four alkyd coatings have been characterized. Among the three modified paints, the one containing polythiophene shows the best adherence and the highest corrosion resistance. This has been attributed to the fact that the miscibility of the polythiophene derivative with the alkyd formulation is better than that of polyaniline. Furthermore, accelerated corrosion assays and electrochemical impedance spectroscopy measurements revealed that the corrosion resistance of the paint with polythiophene is several orders of magnitude higher than that with zinc phosphate. The polythiophene derivative has been found to induce the formation of a passivating and well-adhered layer between the coating and the surface, preventing the access of chloride anions and oxygen to the substrate.     

Study of epoxy and alkyd coatings modified with emeraldine base form of polyaniline

In this work we examine the ability of the emeraldine base form of polyaniline to impart protection against corrosion when it is used as additive of commercial paints. For this purpose, three paints, which are used as primers in marine environments, were checked: two epoxy coatings that differ in the presence or absence of inorganic anticorrosive pigment (zinc) and one alkyd coating. In a first stage, the rheological, structural, thermal and mechanical properties of the three coatings were characterized using viscosity measurements, infrared spectroscopy, thermogravimetric analyses and stress–strain assays, respectively. Furthermore, we observed that the resulting properties were not altered by the addition of a low concentration of polyaniline (0.3%, w/w). Accelerated corrosion tests were performed to compare the degree of protection of both the modified and unmodified paints. The polyaniline did not affect to the protective properties of the epoxy without inorganic anticorrosive pigment nor the alkyd formulations. In opposition, the polyaniline added to the epoxy paint with inorganic anticorrosive pigment induced the formation of a zinc oxide layer, which promoted the corrosion attack.     

Preparation of epoxy resin/CaCO3 nanocomposites and performance of resultant powder coatings

Epoxy resin/CaCO₃ nanocomposites were prepared by the methods of extruding, solution blending, and in situ and inclusion polymerization, respectively. The contents of nanoparticles in the nanocomposites were varied from 5 wt % to 15 wt %. Powder coatings with different content of nanoparticles were made from the nanocomposites. The results showed that the cupping property and impact resistance decreased with the increase of coating film thickness. The dispersion of nanoparticles in epoxy matrix affected the impact resistance and cupping property of the obtained coating films greatly. The coating films made from the nanocomposite prepared by in situ and inclusion polymerization showed that the best impact resistance and the maximum cupping property was achieved when nano‐CaCO₃ content was 5 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2656–2660, 2006     

Epoxy coating with self-healing capability based on a 2-mercaptobenzothiazole-loaded CeO2 nanocontainer

In this study, we demonstrated a facile approach for the synthesis of nanocontainers using the encapsulation of a 2-mercaptobenzothiazole (MBT) inhibitor; these nanocontainers were capable of responsively releasing a corrosion inhibitor and of self-healing performances. The anticorrosive performance of the CeO₂ nanocontainers was investigated with electrochemical impedance spectroscopy (EIS) measurement in a saline electrolyte via the incorporation of different weight percentages (0.5, 1, and 2 wt %) of synthesized nanocontainer in epoxy (EP) resin. The EIS results show that the loading of 1 wt % CeO₂ nanocontainer containing MBT inhibitor in the epoxy (EP) coating [EP/NC MBT–CeO₂ (1%)] provided the highest R_coat, the lowest constant phase element of coating, and the optimum release of MBT at different operating pHs. The highest coating resistance R_coat values of this coating (7.81 × 10⁷ Ω cm²) were about 12 and 8573 times greater than those considered for EP–CeO₂ and EP coatings, respectively. Different releases of the MBT inhibitor were detected at various pHs. We found that the coating operating in acidic media exhibited a better self-healing performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47297.     

Epoxy/polyaniline–ZnO nanorods hybrid nanocomposite coatings: Synthesis,characterization and corrosion protection performance of conducting paints

The objective of this research is the production of an epoxy coating blended with organic–inorganic hybrid nanocomposite as a corrosion inhibiting pigment applied over carbon steel grade ST37. A series of conducting polyaniline (PANI)–ZnO nanocomposites materials has been successfully prepared by an in situ chemical oxidative method of aniline monomers in the presence of ZnO nanorods with camphorsulfonic acid (CSA) and ammonium peroxydisulfate (APS) as surfactant and initiator, respectively. The synthesized polymers were characterized by X-ray diffraction pattern (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and electrical conductivity techniques. Synthesized nanocomposites were solved in tetraethylenpentamine (TEPA), and then prepared solution was mixed with epoxy and then was applied as a protective coating on carbon steel plates. The anti-corrosion behavior of the epoxy binder blended with PANI–ZnO nanocomposites were studied in 3.5% NaCl solution at a temperature of 25 °C by electrochemical techniques including electrochemical impedance spectroscopy (EIS) and chronopotentiometry at open circuit potential (OCP). It was observed that the epoxy coating containing conducting PANI–ZnO nanocomposites exhibited higher corrosion resistance and provided better barrier properties in the paint film in comparison with pure epoxy and epoxy/PANI coatings. In the case of conducting coatings, the OCP was shifted to the noble region due to presence of PANI pigments. Additionally, the possibility of formation of a passive film in the presence of PANI was reinforced at the substrate–coating interface. SEM studies taken from surface of the coatings showed that epoxy/PANI–ZnO hybrid nanocomposite coating systems (EPZ) are crack free, uniform and compact. Furthermore, it was found that the presence of ZnO nanorods beside PANI can significantly improve the barrier and corrosion protection performance of the epoxy coating due to the flaky shaped structure of the PANI–ZnO nanocomposites.     

Synthesis of bio-based epoxy resin from gallic acid with various epoxy equivalent weights and its effects on coating properties

The bio-based epoxy resins for coating application were synthesized from gallic acid (GA) in various molar ratios with epichlorohydrin (ECH). The reaction was carried out in the presence of sodium hydroxide (NaOH) and phase-transfer catalyst tetrabutylammonium bromide. The reaction progress rate at various molar ratios as 1:8, 1:12, and 1:16 with respect to time was monitored by calculating the epoxy content. The epoxy content value increases in the product as the molar ratio of GA to ECH increases. Epoxy equivalent weight of products was evaluated by physiochemical method and structure illustrated by Fourier transform infrared and ¹H-nuclear magnetic resonance spectroscopy. This bio-based epoxy resin was cured with polyamide hardener, and the coating properties such as mechanical, chemical, and solvent resistance were studied. The cured films have been evaluated for glass transition temperature (T _g) and thermal behavior by a differential scanning calorimeter and thermogravimetric analysis, respectively. The bio-based epoxy coatings show interesting mechanical, chemical, and thermal properties as compared to the conventional epoxy resin. The gel and water absorption of polyamide-cured coatings has also been evaluated.     

聚苯胺微乳液的制备及其在水性醇酸涂料中的应用

采用微乳液聚合法制备了十二烷基苯磺酸(DBSA)掺杂聚苯胺(PANI)微乳液(PANI-DBSA),制备了水性醇酸树脂与不同含量PANI-DBSA的共混防腐涂料。通过扫描电子显微镜、傅里叶变换红外光谱和热重分析对PANI-DBSA的性能进行了表征,用耐水性、耐盐水性、耐盐雾性和动电位极化曲线表征涂层防腐性能。结果表明:不同含量的PANI-DBSA没有明显改变涂层的附着力和硬度,但严重影响涂层的防腐性能。当水性醇酸涂料中含有固含量为0.4%的PANI-DBSA时,涂层耐腐蚀性最佳。     

Effect of surface modified WO3 nanoparticle on the epoxy coatings for the adhesive and anticorrosion properties of mild steel

The effect of introducing WO₃ (tungsten oxide) nanoparticle in the epoxy coating was analyzed by electrochemical impedance spectroscopy and scanning electrochemical microscopy (SECM) methods in 3.5% NaCl. The (3-glycidyloxypropyl)trimethoxysilane was treated with the nanoparticle for the proper dispersion and chemical interaction of nanoparticle with the epoxy resin. The introduction of WO₃ nanoparticle in the epoxy coating enhances the charge transfer resistance (R_ct) as well as the film resistance (R_f). The observation of iron dissolution and oxygen consumption was done by applying the appropriate SECM tip potential in the WO₃-modified nanocomposite coated steel. The epoxy and epoxy–WO₃ nanocomposite-coated samples were used to study the adhesion and anticorrosion properties. The analysis by SEM/EDX displayed that the enriched W was detected in the nanocomposite coating of steel. The presence of the nano level corrosion product containing W was confirmed by focused ion beam-transmission electron microscope analysis. The high corrosion protection properties of the epoxy-based nanocomposite coating was due to the complex nanoscale layer formed and chemical interactions of epoxy resin with surface-modified nanoparticle in nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48323.     

咪唑啉季铵盐缓蚀剂改性蒙脱土/水性环氧纳米复合涂料

以油酸、二乙烯三胺和氯化苄为原料,合成了油酸基咪唑啉季铵盐缓蚀剂。通过FTIR、¹HNMR对其结构进行了表征,并离子交换至钠基蒙脱土(DK0)层间,制备了缓蚀剂改性蒙脱土(QACDK0)。通过XRD、TGA和UV-Vis对其结构、组成及层间缓蚀剂释放性能进行了表征。结果表明,咪唑啉季铵盐缓蚀剂约占QACDK0质量的38.96%,并将蒙脱土层间距由1.28 nm(DK0)扩大至3.98 nm(QACDK0)。利用DLS及Zeta电位对添加有QACDK0的水性环氧树脂进行了稳定性测试,其Zeta电位为–27.8 m V,具有较高的稳定性。电化学阻抗谱(EIS)测试表明,在腐蚀介质中浸泡30 d后,基于QACDK0制备的清漆漆膜仍具有2.29×10⁸?·cm²的高阻抗,表明涂层具有较好的耐腐蚀性。并且在耐中性盐雾测试中,QACDK0对应的防腐色漆耐盐雾时间最长,验证了该涂层具有良好的耐盐雾性能。     

Preparation,properties, and anticorrosion application of poly(methyl methacrylate)/montmorillonite nanocomposites coating on brass via solution polymerization

The aim of this study is to improve the anticorrosive property of 7Cu3Zn brass. The methyl‐methacrylate (MMA) monomer solution, modified with fluorine radical and silicone, was used as the polymer matrix to mix with the different percentages of modified montmorillonite (MMT) loading and to exfoliate the lamellar structure of MMT on a nanometer scale during the solution polymerization process, and then form a thin nanocomposites coating on brass as a protective layer. The structural characterization was examined using Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), and transmission electron microscope (TEM). The anticorrosive property of nanocomposites was evaluated using potentiodynamics polarization and electrochemical impedance spectra. The results show that the d‐spacing of MMT was increased, and both exfoliation and intercalation microstructure were observed. Moreover, with the MMT loading increase, the appearance of the intercalation microstructure was more remarkable as a result of silicate layers aggregation. The 1.0 wt %‐coated brass coupons presented the optimistic property of anticorrosion, whose oxygen permeability, corrosion current (i_corr), polarization resistance (R_p), and corrosion rate (R_corr) were 3.5 g/(m²°h), 6.86 nA/cm², 5.81 × 10⁵ Ω°cm², and 0.103 × 10^?3 mm/year, respectively. These results indicate that nanocomposites have potential for anticorrosion application. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4135–4143, 2007     

Performance evaluation of polyaniline pigmented epoxy coating for corrosion protection of steel in concrete environment

Corrosion protection of mild steel reinforcement offered by a newly developed epoxy based coating system containing inherently conducting polyaniline as one of the pigments has been studied. The synthesis of polyaniline and preparation of epoxy based coating system containing this polyaniline are described here. The corrosion resistant property of epoxy polyaniline system, coated on mild steel was evaluated by various techniques such as electrochemical impedance spectroscopy, potential time studies, cathodic disbondment test, anodic polarization study, salt spray test and chemical resistance test. The corrosion resistance of epoxy polyaniline coating system coated on reinforcement bars embedded in concrete was also studied by an accelerated time to cracking study. The formation of polyaniline was characterized using FTIR, UV, GPC, particle size analyzer and fineness studies. Electrochemical impedance studies reveal that the resistance of the coating decreased initially and then increased due to passivating ability of the polyaniline pigment. Based on the results of different techniques, it is found that epoxy coating with polyaniline pigment is effective in corrosion protection of steel in concrete environment.     

Designing of phosphorous based highly functional dendrimeric macromolecular resin as an effective coating material for carbon steel in NaCl: Computational and experimental studies

Objective of this study is to develop a highly effective and durable phosphorus based epoxy resin as anticorrosive coating material for carbon steel in 3% NaCl medium. The hexaglycidyl N,N′,N″-tris (4,4′-ethylene dianiline) phosphoramide (HGTEDPA) was characterized using spectral methods. The anticorrosive formulation (HGTEDPA-MDA) was synthesized using HGTEDPA curing with 4,4′-methylenedianiline (MDA). The formulation (HGTEDPA-MDA) coated steel specimens were exposed to UV radiation for a specific durable (189 days) and durability of the formulation was tested along with its inhibition effectiveness. The anticorrosive property of the formulation was evaluated using electrochemical (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP)) methods. Results showed that HGTEDPA-MDA coating improved the corrosion resistance value even after exposing 180 days to the UV radiation. PDP study suggested that HGTEDPA-MDA before and after UV radiations acted as mainly anodic and cathodic type of inhibitor, respectively. The EIS and PDP results were corroborated with density functional theory (DFT) and molecular dynamic simulations (MDS) methods and a reasonable good agreement was observed. DFT study revealed that HGTEDPA-MDA interacts with the metallic surface using donor–acceptor interactions. MDS study revealed that HGTEDPA-MDA spontaneously interacts with steel surface and adsorb using horizontal orientation.     

Synergistic Effects of Montmorillonite/Cerium Nitrate Additives on the Corrosion Performance of Epoxy-Clay Nanocomposite Coatings

In this work, different amounts of montmorillonite were added to cerium nitrate epoxy mixture. Nanocomposite coatings containing cerium nitrate were applied on cold rolled steel panels. The state of dispersion and incorporation were characterized by transmission electron microscopy and atomic force microscopy. To investigate anticorrosive properties of nanocomposites, electrochemical impedance spectroscopy, polarization measurement and salt spray tests were employed. Results showed that epoxy cerium nanocomposite coatings were superior to the neat epoxy in corrosion protection properties. Also, it was observed that the best corrosion protection was achieved with nanocomposite coatings containing 4 wt.% and 2 wt.% cerium nitrate.