Waterborne Epoxy Coatings Research Articles

Achieving long term anti-corrosion waterborne epoxy coating by attapulgite loaded octadecylamine/graphene nanocomposite

Waterborne epoxy coating is an environmentally friendly anticorrosion coating that are gradually attracting people's attention. However, the anticorrosion performance of waterborne epoxy coatings is unsatisfactory. It is found that the incorporation of some nanomaterials can remarkably improve the anticorrosion properties of waterborne epoxy coatings. This study reports an environmental-friendly waterborne epoxy (EP) coating with enhanced corrosion protection performance by embedding prepared octadecylamine-attapulgite-graphene (ODA-ATP-G) nanocomposite. By the analysis of electrochemical impedance spectroscopy (EIS), it is found that ODA-ATP-G nanocomposites can significantly improve the corrosion resistance of waterborne epoxy coating and provide long-time corrosion protection for the steel substrate. Through the analysis of UV–Visible Near Infrared Spectrophotometer, SEM, EDS and Raman, it is demonstrated that the reinforcement effect of ODA-ATP-G nanocomposites should be attributed to the barrier effect of ODA-ATP-G nanocomposite, the formation of hydrophobic protective film on the steel surface with the adsorption and deposition of ODA.

A novel and green 3-amino-1,2,4-triazole modified graphene oxide nanomaterial for enhancing anti-corrosion performance of water-borne epoxy coatings on mild steel

To give full play to barrier effect of graphene oxide (GO) nanosheets for improving the unsatisfactory long-term anti-corrosion performance of water-borne epoxy (WEP) coating, eco-friendly 3-amino-1,2,4-triazole (ATA) molecules were used to modify GO for enhancing the dispersion of GO in polymer coating. The results gained from Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman and photoelectron spectroscopy (XPS) confirm that GO nanosheets were successfully modified with ATA molecules. SEM images show that ATA modification can significantly reinforce the compatibility between GO and polymer coating. The Electrochemical impedance spectroscopy (EIS) tests result shows that the ATA-GO/WEP coating (4.7 × 105 Ω cm2) has significantly higher |Z|0.1Hz than pure WEP (1.3 × 104 Ω cm2) and GO/WEP (9 × 103 Ω cm2) coatings after 30 days immersion. This indicate that the well-dispersed ATA-GO nanosheets in polymer coating can remarkably enhance coating's barrier effect, leading to significant improvement of anti-corrosion performance. We believe that this strategy could inspire the development of ATA modified inorganic nanomaterials for anti-corrosion coating applications.

Flower-like Ni-Al/LDH synergistic polyaniline anchored to the carbon sphere surface to improve the fire performance of waterborne epoxy coatings

In this study, phytic acid -doped polyaniline (PPA) was loaded on the surface of carbon spheres, resulting in a classical C-N-P flame retardant system, that has a beneficial function for the formation of residual carbon. Subsequently, using this phosphorus-nitride carbon sphere (CS/PPA) as a carrier, flower-like Ni-Al-layered double hydroxide (Ni-Al/LDH) were uniformly grown on its surface, thus obtaining a novel nano-fire retardant with a graded structure to heighten the fire-resistant properties of aqueous epoxy resin. Importantly, the intervention of Ni-Al/LDH nanosheets not only imparts a gas-phase fire retardant function to the coating, but also the presence of Ni and Al bimetals can effectively catalyze the formation of more residual carbon in the combustion process. The highest residual carbon (30.7 %) in thermal weight loss experiments of the CS/PPA@Ni-Al/LDH/EP composite coating confirmed this view. Tests on the thermal insulation behavior of coatings illustrated that the backside temperature (168.8 °C) for CS/PPA@Ni-Al/LDH/EP was significantly smaller than that of other coatings, and that this optimum thermal shielding is inextricably linked to the high residual carbon and the residual metal oxides. Furthermore, the CS/PPA@Ni-Al/LDH/EP specimen shown the greatest expansion height (25.1 mm), expansion ratio (19.61) as well as the smallest smoke density rating (39.1 %), proving that its expansion property and smoke suppression were effectively improved. Moreover, the microstructure for the expanded carbon layer demonstrated that the CS/PPA@Ni-Al/LDH filled EP possessed a more complete and dense residual carbon after burning. Moreover, the high degree of graphitization of the residual carbon for CS/PPA@Ni-Al/LDH/EP determined its high thermal stability. The lowest cracked gas phase products and CO release of the CS/PPA@Ni-Al/LDH/EP composite coating during TG-IR testing confirmed its lowest fire toxicity. The development of such a composite flame retardant with a graded structure could help to advance the progress of waterborne intumescent fire coatings.

The unique flake ZnAl alloy and OIT anti-corrosion and anti-mildew waterborne epoxy coatings

The unique flake ZnAl alloy and OIT anti-corrosion and anti-mildew waterborne epoxy coatings

Polydopamine wrapped polyaniline nanosheets: Synthesis and anticorrosion application for waterborne epoxy coatings

Two-dimensional materials have been proved to be effective in improving the performance of anticorrosive coatings. However, most of the reported two-dimensional materials only have the ability to passively block corrosive media and cannot effectively inhibit localized corrosion reactions at the metal/coating interface. Herein, we first synthesized a novel polyaniline (PANI) nanosheet with both barrier and passivation functions for metals. In addition, polydopamine (PDA) wrapped PANI nanosheets (PANI@PDA) were obtained by in situ self-polymerization reaction of dopamine on the PANI surface, which enhance its interfacial interaction with polymeric resin. The chemical structure, morphology and corrosion inhibition properties of the nanosheets were systematically analyzed. The incorporated PANI@PDA nanosheets in composite coating provide a longer penetration path for corrosive mediums. Secondly, the uniformly dispersed two-dimensional nanosheets induce the formation of passivation film on the metal substrate. The protective effect of PANI@PDA nanosheets on coatings was verified by electrochemical impedance spectroscopy (EIS). Results indicated that the prepared composite coating exhibited excellent corrosion resistance throughout the test cycle. This simple and effective modification strategy based on conductive polymers provides a new insight into the development of environmentally adaptive composite coatings with active and passive protection.

Mechanical-induced functionalization of graphene with sodium carboxymethyl cellulose toward enhancing anticorrosion performance of waterborne epoxy coatings

Mechanical-induced functionalization of graphene with sodium carboxymethyl cellulose toward enhancing anticorrosion performance of waterborne epoxy coatings

Ti3C2Tx MXene@STPP novel waterborne long-term anti-corrosion coating with "3 + 1" multiple high-performance active-passive protection barrier mechanisms

Although environmentally friendly waterborne epoxy (WEP) coatings have the advantage of low volatile organic compounds (VOCs), their barrier performance is rather inferior to achieve long-term corrosion protection. Herein, we grafted the coupling agents KH560 and KH550 onto the etched Ti3C2Tx and sodium tripolyphosphate (STPP), respectively. On the one hand, Ti-O-Si covalent bonds can be formed to improve the water dispersion stability, and on the other hand, as a bridging agent, the functionalized modification yielded the interface-enhanced Ti3C2Tx@STPP filler. The Ti3C2Tx@STPP/WEP composite coating exhibits a high impedance value of 7.981 × 1010 Ω·cm2 after 120 days of saltwater immersion, which is at least two orders of magnitude higher than that of the pure WEP coating. Likewise, the chelating-passivation advantage of STPP with metal cations is fully exploited. The precipitation-oxidation self-healing corrosion inhibition mechanism was proposed and demonstrated by Tafel, EIS, XPS, and Raman experiments. The remarkable long-term corrosion protection performance can be concluded as (1) interface-enhanced two-dimensional Ti3C2Tx with extraordinary physical barrier to prolong the corrosion path; (2) due to high barrier properties, the further electrochemical reactions of steel surfaces can be effectively inhibited under low utilization of water and oxygen, and the Fe(OH)3 and Fe(OH)2 are converted into non-conductive Fe3O4 and/or Fe2O3 films after water loss, (3) and active protection by the chelation of STPP with iron ions to form iron tripolyphosphate passivation films, and (4) passive defense by the coating and resin itself. Therefore, a novel "3 + 1" high-performance protective coating, which integrates interface enhancement, physical barrier, and active-passive protection, is successfully prepared to achieve long-term corrosion protection of the coating.

Bioinspired polydopamine nanosheets for the enhancement in anti-corrosion performance of water-borne epoxy coatings

The utilization of two-dimensional (2D) inorganic nanomaterials as nanofillers in the anticorrosion fields has garnered significant attention due to their exceptional barrier properties. However, uniform dispersion of nanofillers and good interfacial compatibility with organic coatings still remain a substantial challenge. Consequently, there is a need to explore novel and eco-friendly 2D nanomaterials for anticorrosive applications. In this study, two-dimensional polydopamine nanosheets (PDANS) were synthesized through a facile template method, and incorporated into water-borne epoxy (WEP) coating as green anticorrosive additives. Compared to WEP coating, the prepared PDANS/WEP coatings exhibited significantly enhanced corrosion protection performance, with a nearly 50% reduction in water uptake and a 22-fold increase in the |Z|f=0.01Hz value at a 0.5 wt% PDANS loading. These improvements can be attributed to the favorable interfacial compatibility between PDANS and WEP matrix, as well as the superior barrier properties of PDANS. Furthermore, local electrochemical impedance spectroscopy (LEIS) results demonstrated that the damaged PDANS/WEP coating provided enhanced corrosion protection by inhibiting steel corrosion through the chelating interaction between PDANS and steel, thereby reducing the coating delamination. Based on these findings, it can be inferred that PDANS hold great promise for the development of innovative anticorrosive coatings.

Enhanced Corrosion Resistance of Waterborne Epoxy Coatings by Polyaniline Nanorods and Nitrogen and Fluorine Dual-Doped Graphene Oxide Composites

Enhanced Corrosion Resistance of Waterborne Epoxy Coatings by Polyaniline Nanorods and Nitrogen and Fluorine Dual-Doped Graphene Oxide Composites

Corrosion Protection of Water-borne Epoxy Coatings Incorporated with Graphene

Corrosion Protection of Water-borne Epoxy Coatings Incorporated with Graphene

Halloysite@Polyaniline Nanoparticles Loaded with the Praseodymium (III) Cation for Improving Active Corrosion Protection of Waterborne Epoxy Coating.

The corrosion resistance of the waterborne epoxy coating is poor during long-term service, which greatly limits its widespread application. In this paper, the halloysite nanotubes (HNTs) were modified by polyaniline (PANI) and then used as nanocontainers to encapsulate the green corrosion inhibitor praseodymium (III) cations (Pr3+), obtaining HNTs@PANI@Pr3+ nanoparticles. A scanning electron microscope, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were applied to characterize the formation of PANI and the absorption of Pr3+ cations. The corrosion-inhibiting ability of the HNTs@PANI@Pr3+ nanoparticles for iron sheets and the anticorrosion properties of the nanocomposite coatings were evaluated by the electrochemical impedance spectroscopy technique. The results indicated that the coating containing HNTs@PANI@Pr3+ nanoparticles exhibited excellent anticorrosion performance. After immersion in 3.5 wt % NaCl solution for 50 days, its Zf=0.01Hz value was still as high as 9.4 × 108 Ω cm2. The icorr value was 3 orders of magnitude lower than that of the pure WEP coating. The excellent anticorrosion property of the HNTs@PANI@Pr3+ coating could be attributed to the synergy of three beneficial factors, including evenly distributed nanoparticles, PANI, and Pr3+ cations. This research will provide theoretical and technical support for the development of waterborne coatings with high corrosion resistance.

Bionic coral-like PANI-modified graphene oxide for enhancing corrosion resistance of waterborne epoxy coatings: High barrier and self-healing properties

Herein, bionic coral-like PANI-loaded graphene oxide (GO@coral-like PANI) nanomaterials were successfully prepared by gas carbon formed by submicron calcium carbonate as a sacrificial template during the polymerization of PANI with graphene oxide. The unique bionic coral-like PANI outer layer not only enhances the passive barrier ability and dispersion stability of the GO nanosheets, but also provides self-healing capability to the composite coating through the ability to promote the oxidation of iron ions to Fe2O3/Fe3O4 and the loaded corrosion inhibitors (BTA and Ce ions). While the structure, morphology and properties of the GO@PANI/BTA/Ce (GPBC) nanocomposites have been systematically characterized, the barrier and self-healing properties of the composite coatings were tested by electrochemical, salt spray tests and corrosion product elemental analysis. The samples with GPBC exhibited an extended failure time of 30 d and an increased duration of 200 h in the salt spray test compared to pure WEC, as well as self-healing properties after 4 h of coating rupture. The results demonstrated that the WEC loaded with GPBC nanomaterials provides a long-lasting passive barrier effect and self-healing ability.

Improvement of wear-resistance and anti-corrosion of waterborne epoxy coating by synergistic modification of glass flake with phytic acid and Zn2+

Waterborne epoxy (WEP) coatings have been widely applied in the industry due to their environmental friendliness. However, the original defects of WEP coatings significantly affect their mechanical properties and corrosive resistance. A type of modified filler has been designed and fabricated to improve the wear resistance and anti-corrosion properties of WEP coatings. First, glass flakes (GF) have been modified with 3-Triethoxysilylpropylamine (kh560) to improve their surface activity and endow epoxy groups. Subsequently, the PA-Zn2+-m-GF hybrids have been fabricated via the grafting of phytic acid (PA) and zinc ions (Zn2+) on the surface of modified GF fillers (m-GF). PA and Zn2+ are more firmly grafted onto the surface of GF, owing to the functionality of kh560. The obtained PA-Zn2+-m-GF hybrids serve as fillers to substantially boost the wear resistance and anti-corrosion of WEP coating. The PA-Zn2+-m-GF/WEP coating exhibits good wear-resistant and excellent anti-corrosion properties at 20 wt% filler content. The related thickness loss is about 30% after 1000 cycles of friction experiments, and the impedance modulus maintains above 107 Ω cm2 after 144 h of immersion in 3.5 wt% NaCl solution. The anti-corrosion system is constituted by the synergy of organic and inorganic inhibitors and the corresponding anti-corrosion mechanism in WEP coating has been thoroughly discussed in this work.

Amorphous cellulose edge-functionalized graphene oxide for anticorrosive reinforcement of waterborne epoxy coatings

Graphene oxide (GO) has been extensively used as a filler in anticorrosion coatings; however, it is still limited by its dispersity and interfacial compatibility in the coating matrix. In this study, amorphous cellulose (AC) edge-functionalized GO was fabricated by electrostatic self-assembly of negatively charged AC (NAC) and positively charged GO (NGO). The assembly structure was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and further directly observed by high-resolution transmission electron microscopy (HRTEM). NAC enhanced the anticorrosion performance of NGO as a nano-filler in waterborne epoxy resin (WEP) coatings, because the NAC/NGO composite was well dispersed and had strong interfacial interactions with the matrix. Furthermore, even when the immersion time was 1024 h, impedance values of 2.0 wt% NAC/NGO@EP at the low-frequency (f = 0.1 Hz) was 8.955 × 108 Ω·cm2, which is three orders of magnitude higher than that of pure epoxy resin (EP). Thus, the developed method of amorphization and electrostatic self-assembly is suitable to fabricate composites of cellulose and other two-dimensional (2D) materials.

A multifunctional and long-term waterborne anti-corrosion coating with excellent ‘hexagonal warrior’ properties

Environmentally friendly waterborne coatings tend to form polar pathways due to more hydrophilic groups, resulting in poor coating corrosion resistance and reduced coating service life. The anisotropic Janus is used as a filler for waterborne epoxy (WEP) coatings to reduce the number of hydrophilic groups and improve interface compatibility by cross-linking the hydrophilic end with the resin; at the same time, the hydrophobic groups are used to improve the water resistance of the coating. In this paper, we synthesized sheet-like silica Janus (JNS) materials by interface-induced self-assembly via sol–gel reaction in oil-in-water emulsions to prepare novel water-based JNS/WEP anticorrosion coatings. The excellent corrosion resistance of JNS/WEP coatings is explained by the fact that the hydrophilic end of JNS reduces internal defects in the coating and enhanced interfacial interaction; the hydrophobic end improves the water resistance of the coating. Similarly, the physical barrier advantage of flake JNS is brought into play to reduce the high availability of water and oxygen, inhibit electrochemical corrosion on the surface of carbon steel and form a passivation film; the active group at the hydrophilic end of JNS can be chelated with Fe3+ for active protection by synergistic. Among them, immersed in 3.5 wt% NaCl solution for 130 days, the impedance modulus of 1.0 % JNS/WEP coating is 2 orders of magnitude higher than that of WEP coating, up to 2.59 × 1010 O cm2. Therefore, it exhibits outstanding anti-corrosion performance under multiple synergistic protection.

Organic silicone-modified waterborne epoxy coatings using aqueous curing agents technology

PurposeThe silicone modifications of two-component epoxy resin coatings are commonly built on epoxy resins rather than on epoxy curing agents. The silicone-modified epoxy curing agent system is rarely reported yet. This study aims to prepare the polysiloxane (PS)-modified waterborne epoxy coatings based on aqueous curing agents technology.Design/methodology/approachWaterborne epoxy curing agents with different contents of terminal epoxy PS were synthesized by reacting with triethylenetetramine, followed by incorporating of epoxy resin (NPEL-128) and polyethylene glycol diglycidyl ether. The waterborne epoxy coatings were prepared with the above curing agents, and their performance was investigated through thermogravimetric analysis, scanning electron microscopy, mechanical characterization, gloss measurement, chemical resistance test and ultraviolet (UV) aging experiment.FindingsThe results showed that the epoxy coating prepared by silicon-modified curing agent has higher gloss, better chemical resistance and UV resistance than the coating from unmodified curing agent with terminal epoxy PS and commercially available waterborne epoxy curing agent (Aradur 3986), as well as the competitive mechanical properties and heat resistance. Reduced water absorption on fibrous paper was also obtained with the help of silicon-modified curing agent.Originality/valueThese findings will be valuable for resin researchers in addressing the modification issues about waterborne epoxy resin and curing agent.

Benzotriazole corrosion inhibitor loaded nanocontainer based on g-C3N4 and hollow polyaniline spheres towards enhancing anticorrosion performance of waterborne epoxy coatings

Multi-dimensional composite nanocontainers provided an opportunity to prolong the service life of waterborne self-healing coatings through combining intelligent protection with physical barrier. Herein, we constructed a benzotriazole (BTA) corrosion inhibitor loaded nanocontainer with barrier/controlled release/corrosion inhibition properties by assembling graphitic (g)-C3N4 lamella, hollow polyaniline capsule and outer polydopamine wall. Hollow polyaniline and g-C3N4 lamella with adsorption properties provide effective space and sites for loading BTA corrosion inhibitor. Outer polydopamine wall can not only realize the controlled release of corrosion inhibitor, but also ensure the good compatibility between the composite container and the water-based epoxy resin. In addition, polydopamine (PDA) and polyaniline (PANI) as a container frame can also serve as active inhibitors after the release of corrosion inhibitor to enhance the self-healing protection effect of waterborne coatings. In comparative evaluation, the composite coatings containing BTA-loaded nanocontainers (0.5 wt.%) exhibit obviously physical barrier effect after soaking in 3.5 wt.% NaCl solution for 40 days, and maintains good protective performance after immersion for 80 days. Meanwhile, the artificial scratch experiment verified the effective self-repair protection of the composite container to the coating under the condition of damage. To be sure, it will provide an effective improvement idea for the long-term application of waterborne epoxy coating in marine environment.

Optimal preparation and characterization of self-curing concrete containing internal superabsorbent polymer and external waterborne epoxy coating

This study aimed to develop a novel type of self-curing concrete, that is, concrete specimens concurrently cured with a superabsorbent polymer (SAP) and waterborne epoxy coating (WEC). First, the flowability, mechanical properties, and durability performance of the SAP internally cured concrete were tested to optimize its material composition. Subsequently, a modified grey target decision-making method based on a range analysis and grey target decision model was adopted to optimize the application parameters of the WEC materials. Furthermore, the performance of concretes cured with separate or composite SAP-WEC materials was evaluated by measuring the compressive strength, flexural strength, and chloride permeability. Finally, scanning electron microscopy was used to characterize the surfaces, interfaces, and internal microstructures of the samples. The optimal comprehensive performance of the concrete was obtained when WEC materials with a stoichiometry of 5:25 were applied at a rate of 240 g/m2 with double-layer sprays. The self-curing concrete possessed good properties in terms of high compressive strength and chloride resistance, followed by the concrete cured with the WEC materials, and then the SAP internally cured concrete. The microstructural analysis results showed that the simultaneous application of internal SAP and external WEC materials is conducive to ensuring moisture retention in concrete, thereby improving the hydration reaction degree and strength development. This work can serve as a solid base for the efficient utilization of self-curing concrete in engineering.

Mxene structure: A key parameter in corrosion barrier performance of organic coatings

In this research, the effects of fresh and oxidized MXene on the surface, adhesion, and corrosion-resistant properties of waterborne epoxy coatings are considered. The oxidized MXene is prepared through storage of fresh MXene nanosheets in an open vial for 1 month. The results confirm that the waterborne epoxy coating loaded with silane functionalized fresh MXene nanosheets (epoxy/F-MXene) has significantly higher barrier performance and anti-corrosion behavior than the sample modified with silane functionalized oxidized MXene nanosheets (epoxy/F-O-MXene). Indeed, the F-MXene nanosheets (with defect-free and large two dimensional morphology) are able to effectively inhibit the path of corrosive media as well as increment the epoxy matrix compactness compared to the F-O-MXene (with broken nanosheet morphology composed of TiO2 nanoparticles) due to rapid oxidation of the MXene nanosheets in the environment. Besides, the epoxy/F-MXene nanocomposite coating has slightly higher water contact angle and adhesion strength to the metallic substrate compared to the epoxy/F-O-MXene. The results of this research clearly reveal the importance of preventing MXene oxidation before application as nanofiller in the polymer coatings.

Study on anticorrosion properties of reduced graphene oxide reinforced waterborne epoxy coating

Background: The traditional epoxy zinc-rich coating releases some harmful substances such as VOC during the service process, which pollutes the environment and causes great harm to people. Waterborne epoxy coating is an environmentally friendly, non-polluting potential coating. Objective: In this paper, a new reduced graphene oxide (RGO) reinforced waterborne epoxy coating is developed. Methods: Reduced graphene oxide (RGO) is obtained by modifying graphene oxide (GO). The addition of RGO to waterborne epoxy coatings is designed to improve the corrosion resistance of the coatings. The anticorrosion properties of the coating are investigated by electrochemical methods. Results: After the coating was immersed in 3.5wt% NaCl solution for 15 days, the corrosion current of the coating without RGO is greater than that of the coating containing RGO. Coatings with RGO have higher impedance modulus than coatings without RGO. Coating with 0.3% RGO has better corrosion resistance. After the coating was immersed in the salt solution for 55 days, the impedance modulus of the coating with 0.3% RGO increased by 349.11% compared to the coating without RGO. The coating with 0.3% RGO has the minimum corrosion current density, and the maximum polarization resistance and corrosion voltage. Conclusion: The waterborne epoxy coating with 0.3% RGO has the best anticorrosion.