Waterborne Alkyd Research Articles

Preparation and physicochemical characterization of emulsion alkyd resins from cottonseed, Hura crepitans L. seed and palm kernel oils

The growing environmental concerns have led to the formulation of new coating strategies by employing inherently waterborne binders as a key component in order to eliminate the toxic volatile organic solvents from protective coatings. Hura crepitans L. seed oil (HCSO) was extracted from the seed pulp via solvent extraction and characterized using standard methods. Cottonseed oil (COSO), palm kernel oil (PKO), and HCSO were used in the formulation of emulsion alkyd resins (EMAR) via a two-stage alcoholysis-polyesterification process followed by the introduction of maleic anhydride in the polymer backbone and neutralization of the free acid functionality with triethylamine (TEA). Three grades EMAR (50%) were prepared using these oils, phthalic anhydride, glycerol, and maleic anhydride. The percentage yield of HCSO was 87.93%. While the iodine and acid values of HCSO were 145.90 g I2/100 g and 1.26 mg KOH/g respectively. COSO emulsion alkyd (CWAR), HCSO emulsion alkyd (HWAR), and PKO emulsion alkyd (PWAR) were highly soluble in water, while the iodine value of 81.38 gI2/100g, 85.02 gI2/100g, and 10.45 gI2/100g was recorded for CWAR, HWAR, and PWAR respectively. The solid content of the binders varied between 84.88 – 85.48%. While the viscosity varied between 1756.00 – 1768.00 mpa.s. HCSO and COSO can serve as good starting raw materials for the synthesis of environmentally friendly waterborne alkyd resin.

A synergistic system of polyaniline@ graphene-alkyd resin via a Gemini surfactant for enhanced anti-corrosion properties

The uniform dispersion and compatibility of hydrophobic polyaniline (PANI) and reduced graphene oxide (RGO) in waterborne polymer matrices always remain a key challenge. Here, cationic gemini surfactant (CGS) was used as an intercalation agent to modify RGO, and simultaneously functionalized as a dopant to assist in situ chemical oxidation polymerization of aniline on CGS modified RGO (CGG) nanosheets to prepare CGG/PANI nanocomposite. The conventional hexadecyl trimethyl ammonium bromide (CTAB) surfactant with the same structural unit as CGS was also utilized to prepare CTAB modified RGO (CTG) and CTG/PANI nanocomposite. The resulting CGG/PANI and CTG/PANI nanocomposites were added into waterborne alkyd resin (WAR) as nanofiller to prepare anti-corrosion coatings. Compared with CTAB, higher content of CGS was intercalated into the RGO nanosheets, resulting in the higher interlayer spacing of CGG. It is beneficial for the uniform chemical deposition of PANI on CGG via in situ polymerization of aniline. The CGG/PANI/WAR and CTG/PANI/WAR nanocomposite coatings displayed significantly improved adhesion, water resistance and hardness in comparison with the pristine WAR and PANI/WAR coatings. Compared with WAR coating, the corrosion current density of CGG/PANI/WAR nanocomposite coating decreased by three orders of magnitude, and the corrosion potential shifted from −0.782 V to −0.225 V. The impedance modulus of WAR, CTG/PANI/WAR and CGG/PANI/WAR nanocomposite coatings were found to be 1.56 × 105, 5.12 × 107 and 4.15 × 108 Ω·cm2, further demonstrating the significantly improved anti-corrosion properties. The anti-corrosion efficiency CGG/PANI/WAR reached 98.63 %, which was higher than that of CTG/PANI/WAR (95.35 %). Moreover, the electrochemical impedance spectroscopy and salt spray test displayed the enhanced long-term anti-corrosion properties for CGG/PANI/WAR nanocomposite coating, certifying the Gemini surfactant is more effective in fabricating a synergistic waterborne PANI@RGO-alkyd system of enhanced anti-corrosion properties.

Concurrent alkylation and crosslinking of polyaniline for enhanced anticorrosive performance of waterborne alkyd coating

The uniform dispersion and long-term stability of hydrophobic polyaniline (PANI) in waterborne polymer matrix always remains a challenge. Here, PANI was chemically modified by 1,12-dibromododecane to prepare functionalized PANI (PANI-12Br(II)), and simultaneously achieve N-alkylation and chemical crosslinking of PANI chains. In addition, 1-bromododecane was utilized to modify PANI to prepare PANI-12Br(I) as a control. The degree of alkylation of PANI-12Br(II) was higher than that of PANI-12Br(I), as well as the content of N+ species in PANI-12Br(II). Also, the interaction between the PANI-12Br(II) chains decreased. The colloidal particle size decreased from 703.9 nm to 297.3 nm, and the dispersibility and long-term colloidal stability of PANI-12Br(II) in aqueous system were significantly improved. The water adsorption of as-prepared PANI-12Br(II)/WAR nanocomposite decreased from 18.37% to 4.27%, and the contact angle increased from 63.4° to 112.5°. Compared with WAR and PANI/WAR-0.5%, the coating resistance of PANI-12Br(II)/WAR-0.5% increased by 5 and 4 orders of magnitude, and the corrosion current density decreased by 3 and 2 orders of magnitude. The PANI-12Br(II)/WAR-0.5% displayed better long-term anticorrosive performance than PANI-12Br(I)/WAR-0.5%. The anticorrosive mechanisms were also put forward. The PANI-12Br(II) can be applied as a promising class of corrosion inhibitors in waterborne polymer matrices.

Review on Solvents Based Alkyd Resins and Water Borne Alkyd Resins: Impacts of Modification on Their Coating Properties

Review on Solvents Based Alkyd Resins and Water Borne Alkyd Resins: Impacts of Modification on Their Coating Properties

Preparation of excellent-water-resistance water-borne alkyd/acrylic hybrid coatings with varied maleic anhydride content

Water-borne alkyd/acrylic hybrid resins with varied maleic anhydride (MA) content were synthesized from the reaction between alkyd intermediate (AK) and maleic anhydride modified acrylic prepolymer (AC) followed by neutralization of carboxyl groups with triethylamine. Water-borne alkyd/acrylic hybrid resins were characterized by nuclear magnetic resonance (NMR), infrared spectrum (IR), transmission electron microscope (TEM), gel permeation chromatography (GPC), laser diffraction particle size analyzer, rheometer and thermogravimetric analysis (TGA). In addition, air-drying water-borne coatings were prepared using the above-mentioned dispersions and their coatings properties were evaluated. The results showed that the microstructure of the water-borne alkyd/acrylic hybrid dispersion was loose cotton type, which induced the accessibility of fatty acid chains to oxygen is unimpeded, therefore, higher cross-linking density would be obtained and resulted in the coating with optimum MA content exhibited excellent physical properties and water resistance, up to 32 days, which is better than the water resistance of all water-borne alkyd coatings or modified water-borne alkyd coatings reported up to now, and also better than the water resistance of the commercial water-borne alkyd/acrylic hybrid coating.

Gemini surfactant-assisted fabrication of graphene oxide/polyaniline towards high-performance waterborne anti-corrosive coating

Graphene oxide/polyaniline (GO/PANI) has been demonstrated to be an effective anti-corrosive nanofiller in polymer matrix, however, its hydrophobility restricts its application in waterborne polymer coatings. Here, cetyltrimethylammonium bromide (CTAB) and cationic gemini surfactant (GS) with the same constitutional unit as CTAB were adopted to fabricate CTAB modified GO/PANI (CGO/PANI) and GS modified GO/PANI (GGO/PANI). The incorporation of GS not only increased the intercalation degree of GO nanosheets but also functionalized as dopant to improve the electrochemical properties of PANI. The dispersibility and compatibility of GGO/PANI in waterborne alkyd resin (WAR) were also higher than that of CGO/PANI, resulting in the formation of more uniform nanocomposite coating. Compared with pure WAR, the coating resistance of GGO/PANI/WAR increased by 4 orders of magnitude, the corrosion density decreased by 3 orders of magnitude and the corrosion potential shifted from −0.72 V to −0.28 V. GGO/PANI/WAR also displayed enhanced long-term anti-corrosive properties in comparison with CGO/PANI/WAR.

Comparison study on chelated and non-chelated titanate functionalized graphene nanosheets for enhancement of waterborne alkyd anticorrosion coating

Hydrophilic functionalization of reduced graphene (RGOs) is able to improve its dispersibility in aqueous polymer. However, the influence of hydrophilic segments on the chemical resistance of RGOs/polymer nanocomposites keeps indistinct. Here, we prepared RGOs functionalized with hydrophilic chelated titanate (TA) and non-chelated titanate (T), named as TARGOs and TRGOs, respectively. The intercalation reaction mechanism between titanate and GO was elucidated. The presence of hydrophilic triethanolamine in titanate had little impact on the structural disorder of RGOs, but can effectively improve the exfoliation degree and the dispersibility of functionalized RGOs in waterborne alkyd resin (WAAR). The water resistance and thermal stability of TARGOs/WAAR were inferior to that of TRGOs/WAAR. The initial impedance modulus and coating resistance of TARGOs/WAAR were higher than TRGOs/WAAR at the same RGOs content when the RGOs content is 0.5% owing to the more homogeneous distribution of TARGOs in WAAR. However, the corrosion resistance of TARGOs/WAAR significantly decreased when the TARGOs content increased to 0.7%, which can be attributed to the presence of hydrophilic regions. In contrast, TRGOs/WAAR displayed the optimum long-term corrosion resistance when the TRGOs content was 0.7%, even though the dispersion of TRGOs in WAAR cannot be comparable to TARGOs in WAAR.

Eco-friendly Waterborne Alkyd Resin from Polyethylene Terephthalate Waste

This work reports a simple and ecofriendly way of recycling polyethylene terephthalate (PET) waste. PET waste was glycolyzed using trimethylolpropane (TMP) giving tetra-functional glycolyzate, to prepare alkyd resin. 0.25% ZnOAc and the TMP to PET molar ratio of 12:1 at 220 °C produced the best yield of glycolyzate. The obtained glycolyzate was characterized by Fourier transform infrared spectroscopy (FTIR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) and further used in the synthesis of alkyd resins. The properties of the prepared alkyd resins including acid value, the pencil hardness, chemical resistance and thermal stability, were investigated. The pencil hardness of the cured resins film is 3H, which is better than the commercial alkyd resin YF-155. Thermogravimetric analysis (TGA) exhibited polymer decomposition occurred above 160 °C. When compared to commercial coatings, Zanthoxylum bungeanum seed oil (ZSO)-based alkyd resin from postconsumer PET bottles has potential for commercial applications, and may even be superior in thermal and chemical resistance.

Preparation and characterization of waterborne alkyd-amino baking coatings based on waste polyethylene terephthalate.

The recycling of polyethylene terephthalate (PET) is the most attractive method for PET waste management because it not only decreases the load on landfill space, but also provides opportunities for reducing the use of raw petrochemical products. Therefore, in this investigation, neopentyl glycol is used for alcoholysis of waste PET, and glycolyzed PET product was applied for preparation of the waterborne alkyd resin. Furthermore, the waterborne alkyd-amino baking coatings were prepared from the waterborne alkyd based on glycolyzed waste PET and melamine formaldehyde resin and applied on tinplate. The waterborne alkyd-amino resin films showed excellent adhesion, balanced hardness and flexibility, high gloss and outstanding chemical resistance except for alkali resistance owing to hydrolysis of ester bonds.

Rational design of phosphorylated poly(vinyl alcohol) grafted polyaniline for waterborne bio-based alkyd nanocomposites with high performance

Phosphorylated poly(vinyl alcohol) (PPVA) was demonstrated to be more effective to improve the dispersion stability of polyaniline (PANI). Phosphate groups also can improve corrosion resistance, but they may spatially interfere with graft reaction of PANI onto PPVA. Therefore, it is of great significance to explore the balance between phosphorylation degree, graft reaction and composite performance. Here, EPPVA-grafted-PANI (EPPVA-g-PANI) dispersions were prepared by chemical grafting polymerization of aniline on the epichlorohydrin modified PPVA (EPPVA) with different degree of phosphorylation (DP). It was found that DP has a considerable effect on microstructure, rheological behaviors, as well as the compatibility between EPPVA and PANI. Enhanced interactions and compatibility were demonstrated for EPPVA-g-PANI-8.00 %, resulting in the increase of tensile strength from 26.84 to 38.62 MPa. As-prepared EPPVA-g-PANI dispersions can be directly blended with waterborne alkyd resins (WAR) without complex post-process to fabricate high-performance WAR/EPPVA-g-PANI nanocomposites. Compared with WAR, the impedance modulus of WAR/EPPVA-g-PANI increased from 8.81×104 to 3.03×1010 Ω·cm2, corrosion current density decreased to 3.02×10−8 from 1.78×10−6 A·cm−2. Additionally, only one time constant was detected after 480 h immersion, further demonstrating excellent long-term corrosion resistance for WAR/EPPVA-g-PANI.

Synthesis and characteristics of Zanthoxylum bungeanum seed oil-based alkyd resin modified by epoxy resin and their blends with HMMM

Waterborne alkyd resins based on Zanthoxylum bungeanum seed oil modified with epoxy resin were prepared by polyesterification reaction. The different base catalysts were examined on the alcoholysis reaction. Further, epoxy-modified waterborne alkyd resins were blended with hexamethoxy methyl melamine to improve the properties like curing time, chemical resistance and thermal stability. The properties of the prepared resins (acid value, drying time, pencil hardness, adhesion, flexibility, chemical resistance and thermal stability) were studied. The prepared polymers were characterized by FT-IR spectroscopy, particle size analysis and thermogravimetric analysis. ZSO-based alkyd resins modified epoxy resin and their blends with HMMM (EWA:HMMM = 3:1) showed enhanced chemical resistance, physical properties and thermal stability.

Synthesis of rubber seed oil waterborne alkyd resin from glucitol

Solubility properties of alkyd resins from phthalic and maleic anhydrides, glucitol and rubber seed oil (RSO) as raw materials were examined. Four types of glucitol-based medium oil length alkyd resins (ALKYD A–D, two for each acid anhydride) samples were formulated with phthalic anhydride, maleic anhydride, glucitol aqueous solution, and RSO. The physical, chemical, and film characteristics of the glucitol-modified alkyd resins were examined, and the result was compared with the standard alkyd resins and soybean-based alkyd resin. It was observed that all samples were soluble in xylene and butoxyethanol but not water. All of the samples have varying solubilities in water/xylene ratio (%) and complete solubility in water/butoxyethanol (%) ratio of 40:60, 50:50, and 60:40, respectively. ALKYD A is soluble in all solvents except water where it was sparingly soluble at room temperature. The spectral analysis revealed the polyesterification reaction and hydrogen-bonding integrity of the alkyd resins and the polybasic acid. The physical and chemical properties and the performance indices of the glucitol-based alkyd resin results show that they possess acceptable drying properties, chemical resistance, and mechanical properties. Performance of ALKYD A and C gave nearly the same result as the standard alkyd resins and soybean-based alkyd resin. It has potential as a choice waterborne binder for alkyd resin paint and can help in reducing VOC.

Polydopamine modified polyaniline-graphene oxide composite for enhancement of corrosion resistance.

In this study, the composite of two-dimensional graphene oxide (GO) nanosheets and button-shaped polyaniline (PANI) was synthesized and further modified by polydopamine (PDA). The obtained PDA-PANI-GO composite was used to enhance the corrosion protection ability of nontoxic water-based alkyd varnish (WAV). The chemical composition, functional groups and surface morphologies of GO, PANI-GO and PDA-PANI-GO composites were characterized by XRD, FT-IR XPS and SEM. The anticorrosion performance was demonstrated by electrochemical impedance spectroscopy measurements and polarization tests. Due to the physical barrier effects and surface hydrophobicity of PANI-GO composite, the approaches of the caustic substances to the surface of the metal was inhibited, while the highly adhesive PDA molecules reinforced compatibility between fillers and WAV. As results, PDA-PANI-GO composite introduced WAV enhanced corrosion prevention performance. Under the optimal conditions, where the ratio of PDA to PANI-GO was kept at 2:1, the impedance values increased by over two orders of magnitude compared with bare steel.

Engineering the poly(vinyl alcohol)-polyaniline colloids for high-performance waterborne alkyd anticorrosion coating

The ecofriendly waterborne alkyd coatings generally compromise the coating performance. Incorporation of polyaniline into alkyd to form nanocomposites can improve the corrosion resistance; however, the uniform distribution of polyaniline (PANI) within the alkyd resin remains a challenge. In this work, PANI is grafted onto epoxy functionalized phosphorylated poly (vinyl alcohol) (PPVA) with different side-chain configurations in order to improve compatibility and dispersion stability. These functionalized PPVA are synthesized using epichlorohydrin (ECIP) or γ-glycidyl methacrylate (GMA) as modifying agents, and respectively labeled as E-PPVA and G-PPVA. G-PPVA/PANI dispersion is stable even at a high PANI loading of 50%, while the maximum PANI loading for E-PPVA/PANI is only 30%. With the incorporation of G-PPVA/PANI into waterborne alkyd resins (AR), the coating resistance is increased by 7 orders of magnitude, and the corrosion inhibition efficiency is up to 99.9%. The coating with the incorporation of G-PPVA/PANI also demonstrates superior long-term corrosion resistance in comparison with that AR/E-PPVA/PANI nanocomposite coating.

Mussel-Inspired Self-Healing Coatings Based on Polydopamine-Coated Nanocontainers for Corrosion Protection.

The mussel-inspired properties of dopamine have attracted immense scientific interest for surface modification of nanoparticles due to the high potential of dopamine functional groups to increase the adhesion of nanoparticles to flat surfaces. Here, we report for the first time a novel type of inhibitor-loaded nanocontainer using polydopamine (PDA) as a pH-sensitive gatekeeper for mesoporous silica nanoparticles (MSNs). The encapsulated inhibitor (benzotriazole) was loaded into MSNs at neutral pH, demonstrating fast release in an acidic environment. The self-healing effect of water-borne alkyd coatings doped with nanocontainers was achieved by both on-demand release of benzotriazole during the corrosion process and formation of the complexes between the dopamine functional groups and iron oxides, thus providing dual self-healing protection for the mild steel substrate. The coatings were characterized by electrochemical impedance spectroscopy, visual observations, and confocal Raman microscopy. In all cases, the coatings with embedded benzotriazole-loaded MSNs with PDA-decorated outer surfaces demonstrated superior self-healing effects on the damaged areas. We anticipate that dopamine-based multifunctional gatekeepers can find application potential not only in intelligent self-healing anticorrosive coatings but also in drug delivery, antimicrobial protection, and other fields.

The multiscale effects of graphene oxide on the corrosion resistance properties of waterborne alkyd resin coatings

Abstract

Moisture content of the coating determines the water permeability as measured by 1D magnetic resonance imaging

In addition to the desired aesthetical properties, a coating is applied to protect against weathering. A coating prevents moisture accumulation in wood by reducing the water uptake into the wood by its barrier function. The studies in the coating permeability has gained interest with the shift towards waterborne coatings, which make coatings intrinsically more sensitive to water. This paper presents the results of a Nuclear Magnetic Resonance (NMR) Imaging study on the influence of a coating`s moisture content on the permeability of a coating on wood. In this work, pine sapwood, oak, and teak were selected as wood types covering a whole range of low to high density wood types. Three transparent coatings were formulated: a solventborne alkyd, a waterborne alkyd and a waterborne acrylic. The aim of this study is to investigate how sensitive the permeability of coatings on wood against moisture during liquid water uptake and subsequent drying below Fiber Saturation Point. During both water uptake and subsequent drying, the coating limited transport was observed for the studied wood-coating combinations. The NMR profiles are used to calculate the water permeability of coatings on wood. We have demonstrated the direct relation of the permeability with the average water activity inside the coating, which is connected to the activities of both sides of the coating. We observed reasonably well correlation between the sorption isotherm of the coatings and the permeability, which indicates that the permeability variations are due to the amount of water present in the coating. Finally, we have shown that the permeability is not about the type of water vapour or liquid present at one side of the coating, it is all about the local moisture content in the coating.

Tannic complexes coated nanocontainers for controlled release of corrosion inhibitors in self-healing coatings

Nanocontainers with controlled release properties have been used in self-healing coatings for many years. However, the spontaneous leakage of the small molecular weight inhibitors from the nanocontainers promoted the development of nanovalves or gatekeepers to control inhibitor release. Herein, we demonstrate a facile method to encapsulate corrosion inhibitor in mesoporous silica nanoparticles (MSNs) with the help of tannic acid complexes, which endow the inhibitor loaded MSNs with pH-controlled release function. Commercial water-borne alkyd coating impregnated with 2 wt% of benzotriazole-loaded nanocontainers presented significant self-healing effect after 20 days of immersion in 0.1 M NaCl solution from both released benzotriazole and tannic acid as confirmed by electrochemical impedance spectroscopy and microscopy. The impedance modulus of coating with nanocontainers increased from 4.7 × 104 Ω cm2 to 1.8 × 105 Ω cm2 after 15 days of immersion.

Cross‐linked waterborne alkyd hybrid resin coatings modified by fluorinated acrylate‐siloxane with high waterproof and anticorrosive performance

Waterborne alkyd resin coatings are ideal for use as corrosion protection coatings because of its high cost‐effective and environmental advantages. However, their uses are restricted to general applications due to their poor acid, water, and alkali resistance. In this work, waterborne alkyd hybrid resins modified with fluorinated acrylate‐siloxane were synthesized via a surfactant‐free miniemulsion polymerization process using maleic anhydride and silicon modified alkyd resin, dodecafluoroheptyl methacrylate, methyl methacrylate, and butyl acrylate as monomers. And then, crosslinking alkyd resin films were prepared at room temperature using trimethylolpropane‐tris‐(β‐N‐azir‐idinyl) propionate (XR‐100) as the crosslinking agent. The acquired films had lower water absorption and higher water contact angles and had better mechanical/thermal properties, as well as good waterproof property. Most importantly, the electrochemical corrosion studies revealed that the cross‐linked coating exhibited superior corrosion resistance performance with an inhibition efficiency of 99.95% and a corrosion rate of 6.95 × 10−3 mm per year.

Reduced Graphene Oxide Reinforced Waterborne Soy Alkyd Nanocomposites: Formulation, Characterization, and Corrosion Inhibition Analysis

The waterborne soya alkyd (WSA) and its RGO dispersed nanocomposites (WSA-RGO) were synthesized via ex situ polymerization using a solvent-less green approach. The soya oil monoglyceride was used as precursor for waterborne alkyd. The synergistic effect of nanofillers and poly melamine coformaldehyde isobutylated solution modified organic matrix (WSA) on physicomechanical and corrosion inhibition of these coatings on finally polished carbon steel (CS) was investigated. Their physicochemical, physicomechanical, and thermal properties were analyzed using standard protocols. The electrochemical corrosion measurements of these coatings were performed using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy. The aforementioned studies revealed that the nanocomposite coatings exhibit promising corrosion protection performance which is evident from the icorr, Ecorr, impedance and phase angle values of coatings (i.e., icorr 7.736 × 10–9 Acm–2, Ecorr −0.191 V, impedance ∼107 Ω cm2, and phase a...