Journal of Coatings Technology and Research最新文献

In this work, the changes in surface roughness and thickness of particles have been investigated after coating with polymers that result in hydrophobicity after a given time period. The study fundamentally investigates the evolution of these surface properties from the instant the particles are coated. Six chemical agents have been used on near-spherical glass beads and the changes in surface profiles monitored. Surface roughness was quantified using the power spectral density method and the surface thickness of the coatings was determined by a new technique which involved calculating the change in the representative radius of asperity. Results showed that the coating process altered the surface roughness and thickness of particles irrespective of chemicals used. The time-dependency of the coating process is illustrated and it was observed that fluctuations in both surface roughness and thickness lessened after a time period of 30 min. Depending on the chemical agent used, either an overall roughening or softening was recorded at 60 min and the values of surface thickness showed increases between 71 and 256 nm. By analyzing the evolution of surface roughness and thickness at the particle level following coating, this study demonstrated the intricate link between surface properties and chemistry in inducing functional properties on particles.

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In this work, h-BN@STPP was successfully obtained by facile co-modification of sodium tripolyphosphate (STPP) and silane coupling agent (KH-550) on h-BN nanosheets, with waterborne epoxy coatings incorporated for metallic substrate corrosion protection. Results showed that the impedance modulus at the lowest frequency (Z_{f = 0.1 Hz}) of h-BN@STPP composite coating increased three orders of magnitude in comparison with neat waterborne epoxy coating, exhibiting outstanding corrosion resistance. The reinforced anticorrosion performances of h-BN@STPP composite coatings could be attributed to the “labyrinth effect” of h-BN and passivation effect of STPP on the metal substrates.

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Synthetic amorphous aluminum silicates-coated titanium dioxides (AS–T nanocomposites) were synthesized by a hydrothermal reaction of aluminum silicate precursors with various chemical compositions and titanium dioxide suspensions. AS–T nanocomposites showed narrow particle size distributions centered between 1.0 and 2.0 μm and their specific surface areas were ranging from 138 to 209 m²/g. Water vapor adsorption isotherms revealed that AS–T nanocomposites with higher Si/Al ratios exhibited high hydrophilicity, as the maximum water adsorption rate reached almost 40 wt%. In methylene blue photocatalytic degradation tests, AS–T nanocomposites with higher Si/Al ratios showed much higher photodegradability than a commercial titanium dioxide, degrading up to 92.7% of methylene blue after 30 min of UV irradiation. A possible mechanism is that a distribution state of Si(Al)–OH and/or Si–OH–Al exposed on the aluminum silicate surface influenced the methylene blue adsorption to the surface, which significantly improved the photodegradation performance. The results of this study indicate that AS–T nanocomposites have the potential to be used as fillers in paints.

In this paper, fully bio-based branched unsaturated polyester (BUPE) oligomers were synthesized by one-step solvent-free polycondensation using itaconic acid, isosorbide and glycerol as feedstocks. The branched structure was confirmed by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (¹H NMR). The effect of the branched structure on the properties of BUPE UV curing coatings was investigated. The results showed that the introduction of a glycerol branched structure was favorable for UV curing. The BUPE UV curing coatings based on the glycerol branched structure showed higher gel content and crosslink density, which enhanced the hardness, solvent resistance and mechanical properties of the coatings. In addition, the BUPE UV curing coatings possessed extremely low surface roughness, excellent heat resistance and light transmission properties.

An aqueous dispersion of carbon black is crucial in industrial coatings. In this manuscript, a hyperdispersant IBOMA-MPEGA-DMAM (IMD) has been synthesized using isobornyl methacrylate (IBOMA), polyethylene glycol monomethyl ether acrylate (MPEGA), and N, N-dimethyl acrylamide (DMAM) as monomers via a free radical polymerization method, which is used to improve the dispersibility of an aqueous dispersion system of carbon black. The molecular structure and performance stability of IMD were investigated through comprehensive characterizations of FTIR, GPC, particle size distribution and TEM. When the molar ratio of the monomers IBOMA:MEPGA:DMAM is 5.5:8.3:9.7, the obtained hyperdispersant shows good dispersibility. When the optimal dosage of dispersant IMD was 8%, the viscosity of carbon black slurry was as low as 18.6 mPa·s and the average particle size of carbon black was 275 nm. Furthermore, the stability of the prepared carbon black slurry was better than that of the two commercial dispersants.

Biofouling is a major issue for many industries including shipping, oil, and gas and can lead to accelerated corrosion, particularly for structures and components in and around salt water. Many efforts are undertaken to lessen its impact and financial losses. One of the promising methodologies is application of antibiofouling coatings to minimize biofouling, and the best results were observed with a superhydrophobic coating. Ample literature reviews on superhydrophobic coating have shown biofouling inhibition on the surface due to high wetting angles similar to the phenomenon on a lotus leaf. The hydrophobic coating can be deposited using multiple techniques such as electroless plating, chemical vapor deposition (CVD), sol–gel, and electrodeposition. In this review, an effort has been made to encompass such experimental work under a single domain and compare the effectiveness of each coating. In addition, mechanical properties and surface characteristics such as wetting angle, surface energy, and morphology were also discussed for various types of polymeric coating. Similarly, the application of nanoparticles such as ZnO, SiO₂, TiO₂, and CeO₂ was found to improve the substrate's mechanical properties, the durability of coatings, improvement in wear properties, adhesion, interlaminar cohesion, and increased wetting angle and above all, improve superhydrophobicity. These improvements are compared for various nanoparticle integrated coatings. In addition, other novel approaches to prevent marine biofouling by various polymer-based coatings such as superhydrophobic, foul-release, and foul-resistant coatings are discussed in this paper.

Since alkyd resins include hazardous solvents, converting alkyds into waterborne hybrid polymers is an essential research topic. Here, alkyd/styrene acrylic waterborne hybrid polymers were synthesized in the presence of monomers, water, emulsifiers, and an initiator by using synthesized alkyd resins at 0%, 5%, 10%, and 15% ratios based on the total monomer ratio. A mini-emulsion technique and a semi-batch polymerization method were used to synthesize the latexes. Two different biosources, tall oil fatty acids (TOFA) and hemp seed oils (HSO), were used to synthesize the alkyd resins. Synthesized waterborne hybrid latexes and their films were analyzed by using FTIR, NMR, particle size, MFFT, TGA, DSC, CA, AFM, and mechanical tests. It was determined that the type and concentration of the alkyds affected the viscosity, particle size, T_g and MFFT values, and appearance. It was also identified that alkyd incorporation took place with grafting and that the alkyd concentration was particularly effective in increasing the particle size. In addition, experiments were carried out on waterborne paint systems for exterior paint by using synthesized hybrid polymer emulsions. It was observed that the alkyd content was not effective in changing the paint color in hybrid latexes. As a result, it is suggested that hybrid waterborne latexes could be used for exterior paints.

A series of two-component UV-curable waterborne CO₂-based polyurethane dispersions (UV-PUDs) with excellent flexibility and mechanical strength were synthesized from poly(propylene carbonate) diol (PPCD), isophorone diisocyanate (IPDI), 2,2-bis(hydroxymethyl) propionic acid (DMPA), 2-hydroxyethyl acrylate (HEA), pentaerythritol triacrylate (PETA) and 1,4-butanediol (BDO). One component was UV-curable waterborne polyurethane terminated by HEA and PETA (molar ratio 1:1), and the other component was linear waterborne polyurethane. The content of the UV-curable component in UV-PUD was 15%, 30%, 45%, 60%, and 100% (weight content). The obtained cured films exhibited superior flexibility without loss of tensile strength, accompanied by excellent acid and alkali resistance. In particular, the dried UV-PUD films without curing showed good mechanical properties.

Metal–organic frameworks (MOFs) have gained interest in recent years for anticorrosion applications owing to their inimitable structures and excellent properties. As a prominent subclass of MOFs, zeolite imidazolate frameworks (ZIFs) exhibited hydrophobicity, corrosion inhibition, and positive water stability, making them frequently appear in the field of metallic anticorrosion. This review presents the establishment and development of a theoretical model for superhydrophobicity, followed by the reported applications of different kinds of ZIFs in the field of metallic anticorrosion with particular emphasis on ZIF-8, which is the most extensively researched structure among ZIFs. In addition, the applications of superhydrophobic coatings in many aspects other than anticorrosion are also summarized. Finally, the existing challenging problems and future development trends of this kind of coating are discussed. It is hoped that this review will contribute to further development in the field of superhydrophobic anticorrosion coatings for metallic materials.

Wind power, as a new type of green energy, can be converted into electric energy through wind turbines. However, the extremely cold and harsh weather makes the blade surface easy to freeze, which seriously affects the capacity of wind power. In this study, a bilayer epoxy-based nanocomposite coating that consists of an electrothermal and superhydrophobic layer has been developed for anti-icing/deicing. The electrothermal layer consists of epoxy/silver-coated copper (Ag–Cu) and epoxy/multi-walled carbon nanotubes (MWCNTs) nanocomposites. Epoxy/Ag–Cu coating showed high electrical conductivity, which can quickly generate heat under voltage. Epoxy/MWCNTs coating exhibited high thermal conductivity, which conducts heat to the whole surface. The superhydrophobic layer was fabricated by epoxy/SiO₂/hexadecyltrimethoxysilane (HDTMS) nanocomposite, which covered the top of electrothermal layer. The designed bilayer epoxy nanocomposite coating displayed electrical power consumption (0.2 W), super hydrophobicity (static and dynamic water contact angle of 156.3° and 3°, respectively), low ice adhesion (0.01 MPa), long icing time (312 s), short deicing time (41 s), and good wear, acid, alkali, and salt resistance, making it promising for industrial application on wind turbine blades.