Journal of Coatings Technology and Research最新文献

Nowadays, geopolymer coatings have been studied a lot due to their green and sustainable properties, and they have a great potential to partially replace traditional coatings in terms of corrosion resistance and economy. In this study, metakaolin-based geopolymer coating was used as the control group, and anticorrosive coatings were prepared by adding different dosages (2–8 wt%) of ZnO fillers to study the effect of ZnO on physical properties and anticorrosion properties of metakaolin-based geopolymer anticorrosive coatings. The results showed that when the mass fraction of the zinc oxide was 8%, it had the optimum effect on physical performance. The water absorption was 12.4%, and the toughness was 3 mm. In addition, the anticorrosive properties of the coating were studied by sodium chloride (NaCl) solution immersion test, wet–dry cyclic test, salt spray test, and electrochemical test. In sodium chloride (NaCl) solution immersion, wet–dry cycle, and salt spray test, a reduction of 43.8%, 50.6%, and 74.2% in corrosion area ratio, respectively, were achieved with a coating of 8% ZnO filled as compared with pure geopolymer coatings. The results indicated that the addition of ZnO enhanced the anticorrosion performance of the coating. The macroscopic test results were verified by SEM. This study lays a foundation for the subsequent research and performance improvement of metakaolin-based geopolymer anticorrosive coatings.

Sol–gel based coatings are used to protect metals from corrosion. They offer a barrier to the electrolyte penetration, but they do not provide active corrosion protection. Therefore, corrosion inhibitors are often added to sol–gel formulations to improve the overall corrosion behavior. Sol–gel-based coatings typically require relatively high temperatures to be properly cured, which supposes high energy consumptions and might damage some of the precursors of the formulation, including corrosion inhibitors incorporated to improve the coating’s properties. In this study, the effect of diethylenetriamine (DETA) as a curing agent, and yttrium 4-hydroxy cinnamate [Y-(4OHCin)₃] as corrosion inhibitor, on the chemistry and corrosion performance of a hybrid silica-epoxy formulation are investigated. Solid nuclear magnetic resonance and attenuated total reflectance Fourier transform infrared spectroscopy are carried out to analyze the influence of the curing agent and the corrosion inhibitor on the chemical structure of the coating. The corrosion performance is assessed by means of electrochemical impedance spectroscopy, and the results are evaluated considering the chemical study and the interaction between the different compounds.

In this study, we utilized nanocomposites prepared from nanosilica (SiO₂) and various polythiophene derivatives as enhancement additives for acrylic coatings. The nanocomposites were synthesized in a nitrogen environment using FeCl₃ as a catalyst in a chloroform solvent. The weight ratio of nanosilica to monomers was 2/1, specifically for the compounds (5-benzo[d]thiazol-2-yl)-7-methoxy-2-(thiophen-3-yl)benzo[d]oxazole (P1), 3-(2-benzothiazolyl)thiophene (P2), and 5-(benzo[d]thiazol-2-yl)-2-(thiophene-3-yl)benzo[d]oxazole (P3). Analysis techniques including IR, TGA, SEM, and UV–Vis were employed to demonstrate the formation of polythiophenes on the surface of the nanosilica. The presence of polythiophenes on the nanosilica broadened the UV absorption region. Upon adding the nanocomposites to acrylic coatings, the UV absorption intensity of the coatings was increased. Notably, the coating containing SiO₂-P3 nanocomposite exhibited the highest abrasion resistance among all the investigated samples. By varying the content of SiO₂-P3 nanocomposite, we observed enhanced abrasion resistance, adhesion, pencil hardness, and gloss of the acrylic coating. The maximum values were achieved when the content of SiO₂-P3 nanoparticles was 2 wt.%. The SiO₂-P3 nanoparticles were uniformly dispersed in the acrylic coatings, leading to an improvement in the coating's sunlight-reflective ability. Consequently, the acrylic/SiO₂-P3 nanocomposite coatings exhibited potential for outdoor applications, particularly as UV-resistant coatings.

Traditional polyurethane (PU) catalysts, especially dibutyl tin dilaurate, face scrutiny over toxicity concerns, leading to interest in safer alternatives. In an unexpected turn of events, research into a commercially available antibacterial agent revealed that it drastically reduced the pot life of PU coatings. Experiments show that when PU coatings were formulated with the antibacterial agent as catalyst, drying time and solvent resistance were improved as compared to traditional tin and zirconium catalysts. Further analysis showed that this was the result of copper compounds and it could be shown that a similar catalytic effect was achieved through Cu(II)-sulfate and Cu(II)-acetate. Such copper salts are not yet commonly known as replacements for tin catalysts. Possible mechanisms such as heterogenous catalysis or in-situ formation of the active compound were discussed.

In this study, coated fabrics were developed using waterborne polyurethane (WPU) containing pomegranate peel (PoP) powders of varying particle sizes. The objective of this research is to diminish the synthetic polymer content by adopting a sustainable approach through the utilization of food waste and functionalized fabrics by using PoP powders with antibacterial properties. In the initial phase of the study, PoP powders were characterized based on parameters such as particle size, moisture content, water activity, water absorption capacity, total phenolic content, and antioxidant activity. Secondly, cotton fabrics were coated with WPU containing PoP powders (10 wt%). While it was observed that the particle size of PoP powders did not make a significant difference in the color and stress-strain values, antibacterial analysis showed that the coatings containing powders with the lowest particle distribution (18.2–81.7 µ, D₅₀: 42.77 µ) resulted in larger inhibition zones. Consequently, functional fabrics with antibacterial properties against both S. aureus (Gram-positive) and P. aeruginosa (Gram-negative) bacteria were composed by incorporating PoP powders as fillers into WPU-coated cotton fabrics.

This work explores how cenospheres (hollow microsphere) can provide a flame-retardant ability to the waterborne acrylic coating. For this purpose, the intumescent fire-retardant coating was prepared on the steel surface, from the acrylic emulsion polymer, flame-retardant additives (ammonium polyphosphate, melamine, pentaerythritol), and flame-retardant fillers (TiO₂, Al(OH)₃). The experimental results showed that after 60-min fire resistance test under burning torch of 900–1000 °C, the backside temperature of coated steel was in the range of 200–250 °C. Addition of cenosphere into the acrylic polymer coating (at 2–10 wt%) enhanced its fire resistance performance by reducing the backside temperature of coated steels from 27 to 76 °C, as compared to the pure coating without FACs. Data from the furnace test showed that the presence of FACs in coating reduced its intumescent factor (from 14.9 to 33.5%) but produced the denser char layer with a better heat shielding ability. XRD analysis confirmed the interaction between cenosphere and coating matrices at high temperatures by forming the heat-stable compounds. TGA data demonstrated that increasing the content of FACs in coating increased its char weight residue at high temperatures and enhanced its thermal stability and fire resistance. Data from the mechanical test indicated that the presence of cenosphere in the acrylic polymer coating did not affect its hardness but decreased its adhesion to the steel surface (from 5.3 to 23.8%).

Graphical abstract

Fluorocarbon surfactants are widely used, especially in the emulsion polymerization of fluoropolymers, due to their high surface activity, excellent stability, and excellent compatibility. However, the long-term environmental pollution of perfluoroalkyl and polyfluoroalkyl groups in fluorocarbon surfactants has made them banned. Here, we designed and prepared an environmentally friendly zwitterionic fluorocarbon surfactant (PFSC) through shortening fluorocarbon chains and covalent bonding them with the zwitterionic groups, and further demonstrated the effect on the emulsion polymerization of fluoropolymers. The results showed that the surface tension of the emulsion after adding PFSC reached 12 mN/m at a concentration above 0.05%, which is significantly superior to that of perfluorooctanoic acid (PFOA). The study also examined the reaction kinetics, emulsion particle size, and emulsion stability during the emulsion polymerization reaction. The results demonstrated that the fluorinated surfactant exhibits excellent emulsification effects and can serve as an alternative to PFOA. This work presents the synthesis strategy of a new environmentally friendly zwitterionic fluorocarbon surfactant for high-efficiency emulsion polymerization of fluoropolymers.