水分散性聚苯胺/环氧树脂乳液防腐蚀涂层研究

利用原位插层聚合方法制备了水分散性的聚苯胺/蒙脱土复合材料(PANI/MMT),对其结构进行了XRD表征,测试了变温电导率;并以水性环氧树脂乳液为成膜物,制备了水分散性聚苯胺/环氧树脂乳液复合防腐蚀涂层材料(PANI/MMT/EP),通过开路电位(OCP)、电化学交流阻抗谱(EIS)和塔菲尔曲线(Tafel)对其性能进行了研究,结果表明,PANI/MMT/EP复合涂层对A3钢具有较好的防腐蚀效果,腐蚀电流降低到10-9.7A/cm2。     

Preparation of PANI/epoxy/Zn nanocomposite using Zn nanoparticles and epoxy resin as additives and investigation of its corrosion protection behavior on iron

Conducting polyaniline, zinc and epoxy resin solely have anticorrosive properties by different mechanisms on metallic substrates. In this work the triple hybrid of PANI/epoxy/Zn nanocomposite was prepared as a thin layer coating (70 ± 5 μm) on iron coupons and its anticorrosion performance was investigated in HCl (0.1 M) as corrosive solution. Epoxy resin and zinc nanoparticles were applied as additives in the PANI matrix to improve the mechanical properties of PANI coating and investigate their synergetic effects on the anticorrosion performance of PANI coating. At first PANI/Zn nanocomposite coatings with different Zn contents were prepared and the zinc content optimized so that the coating achieve the best anticorrosion performance. Accordingly the iron coupons coated by PANI/Zn coating having 4 wt% Zn content showed more noble open circuit potential and lower corrosion current values. Then epoxy resin was applied as additive to the optimized formulation of PANI/Zn coating in different weight percents (0–20 wt%) and the anticorrosion performance of the related PANI/epoxy/Zn triple hybrid nanocomposite coatings was evaluated. Results showed that the addition of epoxy resin causes to the decreasing of corrosion current of iron samples coated by PANI/epoxy/Zn nanocomposite. An optimum range of 3–7 wt% was obtained for the epoxy content in the composition of PANI/epoxy/Zn nanocomposite in which the coating exhibits the best anticorrosion performance. Iron metal coupon was elementally analyzed and the PANI/Zn and PANI/epoxy/Zn nanocomposites were characterized using Fourier Transform Infrared spectroscopy, X-ray diffraction patterns and Scanning Electron Microscopy techniques.     

Effect of polyaniline-modified glass fibers on the anticorrosion performance of epoxy coatings

Polyaniline (PANI) and different mass ratios of polyaniline/glass fiber (GB) composites (PANI/GB, PGB) were prepared through in situ oxidative polymerization. The chemical structure of composites was investigated via Fourier transform infrared spectroscopy and X-ray diffraction. Epoxy coatings loaded with different mixtures of PANI and GB were applied on steel substrate and exposed to NaCl solution. The morphological properties and corrosion resistance of the coatings were investigated through environmental scanning electron microscopy, electrochemical impedance spectroscopy, and salt spray tests. Results showed that the addition of PANI, GB, and PGB composites caused an improvement in corrosion resistance. The greatest improvement in corrosion resistance was exhibited by the coatings loaded with mass ratio of 1:1 of PANI/GB. This enhancement was attributed to the corrosion resistance of PANI and penetration resistance of GB. Moreover, the uniform distribution of PGB composites in the epoxy resin is an important parameter affecting corrosion resistance of the coatings.     

Synthesis and characterization of composites of polyaniline and polyurethane‐modified epoxy

A toughened, semiconductive polyaniline/polyurethane (PANI/PU)‐epoxy nanocomposite was prepared using a conductive polymer, PANI, and a PU prepolymer‐modified diglycidyl ether of bisphenol A (DGEBA) epoxy. The formation of a nanostructure was confirmed by Fourier transform infrared spectroscopy and SEM. The mechanical properties of the composites were evaluated and compared with those of the corresponding matrix. The improvement in impact strength of the composites (especially in the PANI/PU(PPG2000)‐epoxy system) was explained after fracture surface analysis using SEM. DSC and TGA studies indicated that the thermal properties of these composites were comparable to those of DGEBA epoxy. A conductivity in the range 10^?9–10^?3 S cm^?1 was obtained, depending on the testing frequency (10³–10⁷ Hz) and the PANI content incorporated. Copyright © 2006 Society of Chemical Industry     

Epoxy resin from cardanol as partial replacement of bisphenol-A-based epoxy for coating application

With continuous depletion of petrochemical feedstock and their rising prices, the chemical industry is now looking for alternative renewable and sustainable materials. Such materials could be processed with various chemistries to produce high performance functional materials for a range of applications, such as plastics, coatings, constructions, pharmaceuticals, and food applications. Cardanol derived from cashew nut shell liquid has a reactive phenolic group and aliphatic double bond that could be exploited to produce novel functional materials for polymer and coating applications. It has previously been used for preparation of phenolics, epoxy, and phenalkamine hardeners. In this study, we report on the preparation of novel epoxy resin from cardanol via simple a two-step reaction. The prepared resin with epoxy equivalent weight of 210–220 gm/eq was analyzed using FTIR and NMR spectroscopy. The epoxy resin was then used as binder along with bisphenol-A-based epoxy resin (DGEBPA) at various weight proportions and cured with different amine hardeners. The cured coatings were analyzed for physical, mechanical, and chemical properties for optimization of the coating formulation. The study conducted showed that 40–60% of DGEBPA resulted in comparable properties to that of completely DGEBPA-based system. Further, thermal and anticorrosive properties of the optimized coatings were also evaluated.     

Linseed amide diol/DGEBA epoxy blends for coating applications: Preparation,characterization, ageing studies and coating properties

Linseed amide diol [HELA] was used as modifier for conventionally available epoxy resin [DGEBA] by blending in different ratio. Blends [DGEBA/HELA] were subjected to spectral, physico-chemical, ageing and antibacterial studies. Interesting features of the blends were complete miscibility of HELA with DGEBA, principally due to hydrogen bonding and chemical reaction between the two constituents, and their moderate antibacterial activity against S. aureus. DGEBA/HELA blends were further treated with triethylenetetramine [TETA-A] [DGEBA/HELA/A] as curing agent to evaluate their performance as corrosion protective coating materials. DGEBA/HELA/A coatings showed good physico-mechanical and chemical resistance behavior, in particular against alkaline media. Thermal analysis of DGEBA/HELA/A revealed their single to multi-step degradation behavior with safe usage upto 220 °C. Our investigations confirm the dual role of HELA as environment-friendly, reactive-modifier and mild curing agent for epoxy resins. Besides, DGEBA/HELA/A may find potential applications as “solvent free”, ambient temperature cured antibacterial coating materials.     

Investigation of corrosion protection performance of epoxy coatings modified by polyaniline/clay nanocomposites on steel surfaces

In this study, polyaniline (PANI) and polyaniline/clay nanocomposites were prepared via in situ oxidative polymerization. The morphology of nanocomposites structures was investigated by X-ray diffraction (XRD). The chemical structures of PANI and PANI/clay nanocomposites were examined via Fourier transform infrared (FT-IR) spectroscopy. Polyaniline-based pigments were introduced into epoxy paint and applied on steel substrates. The effect of clay addition and the type of clay cation, including Na⁺ in natural clay (MMT) and alkyl ammonium ions in organo-modified montmorillonite (OMMT), on the anticorrosion performance of epoxy-based coatings was investigated through electrochemical Tafel test, electrochemical impedance spectroscopy and immersion measurements in NaCl solution. The stability of the adhesion of the neat and modified epoxy coatings to the steel surface was also examined. The results indicated that introduction of PANI/OMMT nanocomposite into epoxy paint results in improved anticorrosion properties in comparison with PANI/MMT and neat PANI.     

聚苯胺-氟碳乳液复合防腐蚀涂料研究

以聚苯乙烯磺酸(PSSA)为掺杂剂,利用原位插层聚合方法制备了聚苯胺(PANI)-蒙脱土(MMT)复合材料,对其结构进行了XRD表征,测试了变温电导率;并以水性氟碳乳液为成膜物,制备了水分散体PANI-氟碳乳液复合防腐涂料,利用电化学交流阻抗谱和Tafel曲线考察了对Q235的防腐蚀性能.试验结果表明:PANI-MMT复合材料中的蒙脱土以片层剥离状态存在的;PSSA-PANI-MMT复合材料具有稳定的变温电导率;PANI-MMT-FC复合涂料具有最高的阻抗和腐蚀电位(-0.42 V)以及最低的腐蚀电流密度(10-8.6 A/cm2).对Q235有很好的防腐蚀效果.     

聚苯胺／环氧树脂共混防腐涂料的研究进展

聚苯胺具有优异的防腐蚀性,但是由于其在一般有机溶剂中的溶解性差,且其制成的涂膜附着力差等因素,通常将其与其它涂料复配,以改善涂膜性能;环氧树脂涂料具有附着力强、强度高、耐化学品、耐磨等特点,环氧树脂优异的成膜性和聚苯胺的防腐性能相结合,使聚苯胺／环氧共混涂料具有广阔的应用前景,就聚苯胺与环氧共混涂料的研究进展作了简述。     

Conductivity and anticorrosion performance of polyaniline/zinc composites: Investigation of zinc particle size and distribution effect

Polyaniline/zinc composites and nanocomposites were prepared using solution mixing method. Zinc (Zn) particles with an average particle size of 60 μm and zinc nanoparticles with an average particle size of 35 nm were used as fillers in polyaniline (PANI) matrix. Films and coatings of PANI/Zn composites and nanocomposites were prepared by the solution casting method. Electrical conductivity and anticorrosion properties of PANI/Zn composite and nanocomposite films and coatings with different zinc loadings were evaluated. According to the results, electrical conductivity and anticorrosion performances of both PANI/Zn composites and nanocomposites were increased by increasing the zinc loading. Also results showed that the PANI/Zn nanocomposite films and coatings have better electrical conductivity and corrosion protection effect on iron coupons compared to that of PANI/Zn composite.     

Positive effect of the addition of polyaniline on the anticorrosive property of polyethersulfone two-layer composite coating

In order to prepare a coating with better corrosion resistance, the double-layer coatings are designed to work together in this article. The double-layer coatings are made of polyethersulfone and epoxy resin as the matrix resin. Polyaniline (PANI) of different contents was added to the matrix resin by weight to form the primer coats, which was named as d-0, d-20, d-40, d-60. And polytetrafluoroethylene was introduced into the matrix resin to prepare the surface coats. A two-layer coating was prepared by coating the surface layer on the primer layer, named as S-0, S-20, S-40, S-60. The surface morphology of the primer coatings and the cross section morphology of the two-layer coatings were determined by field emission scanning electron microscopy. The anticorrosion property of the coatings was studied by water absorption, adhesion, salt spray corrosion acceleration test and electrochemical impedance test. The results indicate that the 40 wt% PANI composite coating shows the best corrosion resistance.     

低温快干环氧煤沥青玻璃鳞片涂料的研制

通过对比实验,确定了能在-5～5℃的温度条件固化成膜的环氧煤沥青玻璃鳞片涂料的配比,讨论了玻璃鳞片对涂膜防腐性能的影响及助剂对涂膜的影响。克服了环氧类涂料在低温条件下固化时间长甚至不能固化的缺点,使环氧煤沥青玻璃鳞片涂料在低温条件下能正常施工。     

Thermo-oxidative aging of epoxy coating systems

The thermo-oxidative behavior of unformulated (unfilled) samples of epoxy coatings has been studied at five temperatures ranging from 70 °C to 150 °C. Two epoxy networks based on diglycidyl ether of bisphenol A (DGEBA), respectively, cured by jeffamine (POPA) or polyamidoamine (PAA) were compared. Infrared spectrophotometry (IR), differential scanning (DSC) and sol–gel analysis (SGA) were used to monitor structural changes.     

Grafting of epoxy chains onto graphene oxide for epoxy composites with improved mechanical and thermal properties

Epoxy composites filled with both graphene oxide (GO) and diglycidyl ether of bisphenol-A functionalized GO (DGEBA–f–GO) sheets were prepared at different filler loading levels. The correlations between surface modification, morphology, dispersion/exfoliation and interfacial interaction of sheets and the corresponding mechanical and thermal properties of the composites were systematically investigated. The surface functionalization of DGEBA layer was found to effectively improve the compatibility and dispersion of GO sheets in epoxy matrix. The tensile test indicated that the DGEBA–f–GO/epoxy composites showed higher tensile modulus and strength than either the neat epoxy or the GO/epoxy composites. For epoxy composite with 0.25 wt% DGEBA–f–GO, the tensile modulus and strength increased from 3.15 ± 0.11 to 3.56 ± 0.08 GPa (∼13%) and 52.98 ± 5.82 to 92.94 ± 5.03 MPa (∼75%), respectively, compared to the neat epoxy resin. Furthermore, enhanced quasi-static fracture toughness (K_IC) was measured in case of the surface functionalization. The GO and DGEBA–f–GO at 0.25 wt% loading produced ∼26% and ∼41% improvements in K_IC values of epoxy composites, respectively. Fracture surface analysis revealed improved interfacial interaction between DGEBA–f–GO and matrix. Moreover, increased glass transition temperature and thermal stability of the DGEBA–f–GO/epoxy composites were also observed in the dynamic mechanical properties and thermo-gravimetric analysis compared to those of the GO/epoxy composites.     

Conducting polymers for corrosion protection: a review

Conducting polymers (CPs) such as polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) are used for the corrosion protection of metals and metal alloys. Several groups have reported diverse views about the corrosion protection by CPs and hence various mechanisms have been suggested to explain anticorrosion properties of CPs. These include anodic protection, controlled inhibitor release as well as barrier protection mechanisms. Different approaches have been developed for the use of CPs in protective coatings (dopants, composites, blends). A judicious choice of synthesis parameters leads to an improvement in the anticorrosion properties of the coatings prepared by CPs for metals and their alloys. This article is prepared as a review of the application of CPs for corrosion protection of metal alloys.     

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。     

Novel phosphorus‐containing hardeners with tailored chemical structures for epoxy resins: Synthesis and cured resin properties

A comparative evaluation of systematically tailored chemical structures of various phosphorus‐containing aminic hardeners for epoxy resins was carried out. In particular, the effect of the oxidation state of the phosphorus in the hardener molecule on the curing behavior, the mechanical, thermomechanical, and hot‐wet properties of a cured bifunctional bisphenol‐A based thermoset is discussed. Particular attention is paid to the comparative pyrolysis of neat cured epoxy resins containing phosphine oxide, phosphinate, phosphonate, and phosphate (with a phosphorus content of about 2.6 wt %) and of the fire behavior of their corresponding carbon fiber‐reinforced composites. Comparatively faster curing thermosetting system with an enhanced flame retardancy and adequate processing behavior can be formulated by taking advantage of the higher reactivity of the phosphorus‐modified hardeners. For example, a combination of the high reactivity and of induced secondary crosslinking reactions leads to a comparatively high T_g when curing the epoxy using a substoichiometric amount of the phosphinate‐based hardener. The overall mechanical performance of the materials cured with the phosphorus‐containing hardeners is comparable to that of a 4,4′‐DDS‐cured reference system. While the various phosphorus‐containing hardeners in general provide the epoxy‐based matrix with enhanced flame retardancy properties, it is the flame inhibition in the gas phase especially that determines the improvement in fire retardancy of carbon fiber‐reinforced composites. In summary, the present study provides an important contribution towards developing a better understanding of the potential use of such phosphorus‐containing compounds to provide the composite matrix with sufficient flame retardancy while simultaneously maintaining its overall mechanical performance on a suitable level. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis, characterization, and properties of novel novolac epoxy resin containing naphthalene moiety

A series of novel novolac epoxy resins containing naphthalene moiety with different molecular weights were synthesized via condensation of bisphenol A and 1-naphthaldehyde, followed by epoxidation with epichlorohydrin. The chemical structure of the naphthalene epoxy thus obtained was characterized using FTIR, ¹H NMR spectra and GPC analyses. The naphthalene epoxy was cured with 4,4′-diaminodiphenyl sulfone (DDS) and the cured products were characterized with thermogravimetric analysis, dynamic mechanical analysis, and X-ray diffraction. Compared with the diglycidyl ether of bisphenol A (DGEBA), the cured naphthalene epoxy resin showed remarkably higher glass transition temperatures (T_gs), enhanced thermal stability and better moisture resistance. When the molar ratio of 1-naphthaldehyde to bisphenol A was 0.67, the optimal thermal resistance was observed.     

Performance of corrosion protective epoxy blend-based nanocomposite coatings: a review

ABSTRACT

Epoxy is a thermosetting polymer with exceptional mechanical robustness, thermal stability, and chemical resistance. This article is devoted to updating development, processing, and physicochemical characterizations of epoxy-based anti-corrosion coatings. Incorporation of different polymers in epoxy matrix has motivated extensive research progress in the field of corrosion protection. Epoxy has been blended with polyaniline, polypyrrole, polythiophene, polyamide, polyester, polyurethane, poly(vinyl alcohol), and polydimethylsiloxane to form corrosion protective coatings. The addition of conducting polymer and nanofiller to epoxy matrix modified the nanocomposite morphology and facilitated the development of passive layer at metal/polymer interface. Consequently, nanocomposite coatings act as physical barrier to hinder the penetration of corrosive ions. Likewise, fine dispersion of nanocarbon and inorganic nanoparticles in compatible blends of epoxy/polyamide, epoxy/polyester, epoxy/polyurethane, and epoxy/poly(vinyl alcohol) has resulted in improved adhesion, wear, barrier and anticorrosion properties of the nanocomposite coatings. Design of epoxy blend-based nano-architectures may facilitate appropriate tailoring of overall performance of the resulting anti-corrosion coatings for advance technical applications including aerospace, automotive, construction, electronic devices, and biomedical relevances. New processing techniques may overcome challenges toward high performance future epoxy-based coatings.     

Studies on Mechanical Properties of Imide-Amine Cured Expoxy-Glass Fiber Laminates

Epoxy (DGEBA)-glass fiber laminates were cured with different hardeners. Imide-amine hardeners were synthesized with different chemical groups in their backbone structure. Higher curing and postcuring temperatures were required for epoxy-glass fiber laminates cured with imide-amine hardeners. Compared to epoxy cured with aromatic amine (DADPM), tensile and flexural strength increased by 38.5% and 23.1%, respectively, in the laminates cured with imide-amine with sulfone groups in the backbone structure. Fracture surface of the laminates showed good bonding between the fiber and matrix.