Journal of Coatings Technology and Research最新文献

The paper examines the significance of anti-corrosion coating systems for steel bridges within transportation networks, with a particular focus on their long-term sustainability. The study assesses the long-term sustainability of four coating systems, analyzing their performance, cost, and environmental impact over a hypothetical 75-year bridge lifespan. Key considerations include the service life of each coating system, the frequency and extent of maintenance required, the emission of volatile organic compounds (VOCs), and the broader social costs, such as public inconvenience due to maintenance activities. The research presents detailed data, equations for estimating costs, and methodologies for sustainability analysis in varying corrosive environments (C2, C3, and C5). The findings underscore the necessity of selecting low-VOC materials to minimize environmental impact, while also considering the efficacy of corrosion protection and the associated social impacts. This comprehensive approach aims to guide stakeholders in selecting the most sustainable corrosion protection strategies, ensuring relevance in diverse and evolving environmental and societal contexts.

To enhance the corrosion resistance of 304 stainless steel in a chloride ion environment, titanium dioxide (TiO₂) coatings doped with polytetrafluoroethylene (PTFE) were deposited on its surface using the sol–gel method. The surface morphology and microstructure were characterized using a scanning electron microscope (SEM), X-ray energy spectrometer (EDS), and Fourier-transform infrared spectrometer (FTIR). The hydrophobicity of the coatings was measured using a contact angle goniometer, and their corrosion resistance was tested using an electrochemical workstation. The results show that the prepared coatings are complete and dense, and their surface roughness increases after doping with an appropriate amount of PTFE. With an increase in the doping concentration of PTFE, the surface water contact angle increases from 48° for the substrate to 123°, exhibiting hydrophobicity. The titanium dioxide coating doped with 11.5 vol% PTFE exhibits the best corrosion resistance, with a corrosion current density of 0.02 μA/cm², which is two orders of magnitude lower than that of the substrate. In addition, the coating doped with 11.5 vol% PTFE has the largest capacitive arc radius and the best hydrophobicity.

Rheological modifiers are essential for controlling the flow behavior of paint and adjusting characteristics like leveling, sagging, settling, and thixotropy. Bentonites, natural phyllosilicate clays, require an activation process to function as rheological modifiers to improve the sag resistance of paint. This study aims to understand the role of bentonite as a rheological agent in organic coatings, evaluate the factors influencing its activation mechanism, and propose a method that maximizes its benefits. It was found that an optimum type and amount of polar solvent are crucial for the best activation. Solvents like methanol and ethanol, which are highly polar, small in molecular size, and capable of forming hydrogen bonds, are the most effective. However, these solvents play a minimal role in the intercalation and exfoliation of bentonite layers during production. Instead, they increase viscosity by forming intermolecular bonds between platelets. It was observed that ultrasonic processors and inline dispersers are more effective tools for activation, as they provide higher shear rates and can increase the temperature, facilitating the mobility of platelets and polar activators to form bonds. With the optimal activation procedure, the sag resistance film thickness was increased from 138 to 250 µm using the same amount of bentonite.

The antifouling performance of ship coatings is a crucial factor affecting both shipping efficiency and the marine ecosystem. Traditional antifouling coatings typically rely on the release of biocides, but prolonged use can be harmful to the environment. This paper reviews the progress of microencapsulation based on inorganic and organic biocides in ship antifouling, focusing on the properties of both types of biocides and their advantages and challenges in microencapsulation. Inorganic biocides are of interest because of their efficient bactericidal properties, while organic biocides exhibit excellent chemical stability and environmental friendliness. The high performance and greening of antifouling coatings on marine vessels can be further promoted through the rational design of microencapsulation systems of biocides combined with multifunctional antifouling strategies. In addition, this paper analyzes the potential of inorganic biocide and organic biocide-based microencapsulation technology in realizing coating self-repair, antifouling longevity and environmental compatibility, and looks forward to the future development direction.

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The widely used indicator, 2-(5-bromo-2-pyridylazo)− 5-diethylaminophenol (Br-PADAP), can enable color tracing of radioactive contaminants when incorporated into strippable decontamination materials. However, its practical application is hindered by poor dispersion in aqueous substrates. To address this issue, this study prepared an amphiphilic diblock copolymer, PEA-b-PAA, using a one-pot synthesis method. Ethyl acrylate (EA) and acrylic acid (AA) were used as monomers, with S,S,S-trisulfanyl dibenzyl carbonate (DBTTC) serving as the initiator for reversible addition-fragmentation chain transfer (RAFT) polymerization. Test results demonstrated that block copolymers with EA:AA monomer ratios of 2:1, 1.5:1, and 1:1 effectively dispersed and stabilized the Br-PADAP indicator. Among these, the copolymer with a 1.5:1 monomer ratio, added at a concentration of 4%, improved the mechanical properties of the peelable decontamination material without compromising the color tracing function of Br-PADAP. This enhancement facilitates practical applications by enabling incorporation into aqueous peelable substrates, while maintaining the indicator’s color development mechanism. The resulting materials exhibit both effective decontamination and reliable color tracing capabilities.

This work proposes a process for the fabrication of a thermal insulation and flame-retardant silica aerogel composites coating. First, the silica aerogel was prepared by a simple experimental Soxhlet extraction method to minimize handling of the sample by the operator, while also providing excellent thermal insulation owing to three-dimensional network structures. The highest specific surface area of silica aerogel fabricated by the Soxhlet extraction method was 740.4 m²/g. Meanwhile, the silica aerogels obtained from the Soxhlet extraction method enabled thermal conductivity as low as 25.13 mW/m·K. The properties of silica aerogel prepared by the Soxhlet extraction method were better than those of the silica aerogels obtained from the static method and commercial aerogel. Subsequently, the silica aerogel composites coating (20SAC) not only had good tensile strength and plasticity but also had excellent thermal insulation performance. Furthermore, silica aerogel composites coating was found to exhibit an excellent flame-retardant property. The present work provides a viable way for developing silica aerogel composites coating with thermal insulation and flame-retardant properties.

The commonly used dispersants for graphene dispersions reduce the conductivity of the composite. In this work, a dispersant with an amphiphilic structure, CA-g-PANI, has been designed and synthesized. The dispersant grafts citric acid (CA) onto polyaniline via an amide reaction, which gives CA-g-PANI the hydrophilic groups (carboxyl groups) and the benzene ring structures that can be π–π conjugated with graphene, and it can improve the dispersion properties of graphene; CA-g-PANI contains the polyaniline structure, which is electrically conductive and enhances the electrical conductivity of graphene dispersions. The molecular structure and properties of the dispersant were systematically characterized through FTIR spectra, UV absorption spectra, and other methods. The graphene-based composites were prepared by screen printing method, and the dispersibility and resistivity of CA-g-PANI were compared with gum arabic and alkali lignin (natural dispersants). Graphene concentration reached up to 30 mg/mL in the presence of CA-g-PANI at the weight ratio of 1:0.03 (CA-g-PANI: graphene). CA-g-PANI also exhibited good performance for stabilizing graphene (stable for 6 days), with an electrical conductivity of up to 917.43 S/m. In the study, it was shown that CA-g-PANI as a graphene dispersant improved the conductivity of graphene dispersions while enhancing the dispersing properties of graphene.

In this paper, four kinds of bio-based alkyd polyols were prepared from bio-based oleic acid and coconut oleic acid as raw materials. Subsequently, UV-curable waterborne polyurethane acrylate dispersions (UV-WPUAs) were synthesized using the four bio-based alkyd polyols, respectively. Furthermore, these UV-WPUAs were employed to prepare UV-curable waterborne polyurethane acrylate coatings (UV-WPUA coatings). The study focused on comparing the effects of the four bio-based alkyd polyols on the performance of the UV-WPUAs and the resulting UV-WPUA coatings. The results showed that all the UV-WPUAs prepared from the above four bio-based alkyd polyols exhibited semitransparent, low viscosity, small particle size and high zeta potential. Additionally, the UV-WPUA-2 (alkyd polyol was prepared from oleic acid, hexahydrophthalic anhydride, neopentyl glycol and trimethylolpropane) coating exhibited excellent coating properties, such as excellent physical properties, chemical resistance and acceptable yellowing resistance. This phenomenon can be attributed to the higher crosslinking density of the UV-WPUA-2 coating, along with the lack of a benzene ring structure that is typically associated with yellowing. In conclusion, the result of this study confirms that bio-based alkyd polyols are suitable for preparing UV-curable waterborne polyurethane acrylate.

Acrylic copolymers have myriad uses in both architectural and industrial coatings. Waterborne acrylic emulsions are employed for exterior and interior architectural finishes with minimal volatile organic compound (VOC) content. However, there are still solvent-based coatings for industrial and automotive applications which result in a considerable amount of VOC. Environmental regulations to control the amount of VOC from coatings are getting stringent in most countries. Researchers across the globe are working toward reducing the VOC by either using high-solid resins or moving toward waterborne resins. The monomers employed for synthesizing acrylic resins come from petroleum, a non-renewable fossil fuel. To reduce fossil fuel consumption, efforts have been made to use greener raw materials in the polymer synthesis. Replacement of petroleum-based acrylic monomers with greener raw materials is difficult because each acrylic monomer brings a specific structure–property relationship to the polymer synthesized. Furthermore, using alternative green sources and renewable monomers brings new challenges as the synthesized resin must be compatible with solvents, additives, and pigments and meets the required properties of the acrylic coatings. In the literature, the usage of different bio-sources-based green alternatives of acrylic monomers like hydroxyl ethyl methacrylate, methyl methacrylate, butyl acrylate, methacrylic acid, and acrylic acid has been reported. As styrene is part of most acrylic resin formulations, the bio-sources of styrene and its green alternatives have also been mentioned. The alternate green monomers and their potential use in coatings’ field are also explored. A short perspective on whether green monomers and renewable sources for acrylic monomers can be commercially used to produce coatings for various applications is also discussed.

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