Formulation Of Coatings Research Articles

Unveiling the potential of dual-extrinsic/intrinsic self-healing lignin-based coatings for anticorrosion applications

The development of self-healing ecofriendly coatings for anticorrosion applications provides stronger protection than passive coatings and mitigates the environmental pollution resulting from petroleum-derived coatings. Due to its intrinsic anticorrosion characteristics, lignin is a viable precursor for the formulation of self-healing anticorrosion coatings. However, the structural rigidity of lignin and the lack of self-healing functionalities in pristine lignin-based coatings hinder the comprehensive application of lignin in this field. Accordingly, we introduced Diels-Alder (DA)-based self-healing functions in the lignin-based coatings and meanwhile, the coatings were chemically conjugated with corrosion inhibitors to further improve the anticorrosion performance. A thin layer (16 μm) of the coating increased the Ecorr from −481 mV (for bare steel) to +91 mV and reduced the corrosion rate (CR) >4000 times. The dual self-healing properties of the coating are attributed to the synergistic action of the DA adduct and the conjugated corrosion inhibitor. Practically, in response to the emergence of microcracks in the coating structure, trace amounts of the corrosion inhibitor are released into the microcracks to form a protective layer on the unveiled metal surface. Simultaneously, DA adducts undergo reversible reactions at specific temperatures (80–120 °C) promoting complete restoration of the microcrack.

Development and Application of Mucilage and Bioactive Compounds from Cactaceae to Formulate Novel and Sustainable Edible Films and Coatings to Preserve Fruits and Vegetables-A Review.

The accelerated ripening and senescence of fruits and vegetables is characterized by various biochemical changes that hinder the maintenance of their postharvest quality. In this context, developing edible films and coatings formulated with natural and biodegradable materials emerges as a sustainable strategy for preserving the quality parameters of these products in replacement of conventional petroleum-based packaging. Recently, plant-based polymers, including mucilage from different cactus species and/or their bioactive compounds, have been investigated to develop edible films and coatings. As the available literature indicates, the Opuntia genus stands out as the most used for mucilage extraction, with the cladode being the most exploited part of the plant. Conventional extraction methods are widely employed to obtain mucilages, which are applied to fruits and vegetables after being combined with plasticizing and cross-linking agents. In general, these films and coatings have proven effective in prolonging the shelf life and maintaining the nutritional, physical, and sensory quality of fruits and vegetables. Given their preservation potential, combining cactus mucilages with bioactive compounds, probiotics, and prebiotics represents an emerging trend in developing functional films and coatings. However, some limitations have been identified, such as the underutilization of different species and parts of the plant, the lack of standardization in extraction methods, and the absence of studies on the effects of the physicochemical properties of mucilages in the formulation and characteristics of films and coatings. Therefore, overcoming these limitations is essential for developing edible films and coatings with enhanced techno-functional properties and greater commercial viability.

Synthesis of Stearyl Alcohol/Polyethylene Glycol Hybrids as Water-Repellent Finishes for Cotton/Polyester Blended Fabric

Nowadays, developing and innovation of new finishing agents that are cost effective, efficient, durable, and safe for the consumer as well as the environment are greatly required by the textile manufactures. In that concern, new stearyl alcohol/polyethylene glycol (SA/PEG) hybrids were synthesized, characterized, and applied as textile finishes to impart cotton/polyester fabric with water repellency. Such hybrids were synthesized by reaction of SA with PEG of molecular weight 1000 or 4000 Da in the presence of ammonium persulfate (APS) as initiator. The optimum conditions of the synthesis reaction are: APS/PEG, 20%; PEG/SA, 15%; reaction temperature, 80 °C and reaction time, 45 min. The synthesized hybrids are self-water dispersible that form oil-in-water stable emulsions. The results indicated that treating cotton/polyester fabric with easy-care finishing formulation containing 60 g/L of dimethyloldihydroxyethylene urea as a cross-linker, and 60 g/L of any of such hybrids emulsions imparts the treated fabric with water repellency, softness, and stiffness properties. Moreover, increasing the PEG molecular weight from 1000 to 4000 Da leads to a reduction in extents of softness and contact angle along with an enhancement in stiffness of treated fabric. Furthermore, the prepared hybrids emulsions-treated fabric samples are durable up to five washing cycles. The FTIR analysis confirmed the chemical structure of the synthesized SA/PEG1000 hybrid. The transmission electron microscope (TEM) revealed that the particles size of SA/PEG4000 hybrid emulsion is in the range of 34–70 nm and reaches to 185 nm in case of the SA/PEG4000 hybrid emulsion. The surface of SA/PEG1000 hybrid emulsion-treated fabric was characterized via scanning electron microscope (SEM).

Standardization of Hormone-Based Seed Coating Formulation for Coriander Dosage and Formulation Optimization

Aims: This study aimed to standardize the dosage of hormone-based seed coating formulations to enhance germination and seedling growth in coriander seeds. Study Design: Completely Randomized Design. Place and Duration of Study: Department of seed science and technology, Tamil Nadu Agricultural University, Coimbatore, India. During the year of 2023-2024. Methodology: Coriander seeds were coated with different concentrations of seed coating polymer and germination study was conducted in laboratory using rolled towel method with four replications. Data were analyzed by ANOVA with significance at p ≤ 0.05. Results: The hormone-based seed coating formulation has recorded significantly higher germination% (69%), root length (16.75 cm), shoot length (7.9 cm), dry matter production (0.058 g/10 seedlings), Vigour Index I (1706) and II (3.9) at 10 g polymer/kg of seed and 290 mL of water. Conclusion: Seed Coating with 10 seed coating formulation dissolved in 290 mL of water enhanced the seed germination and seedling growth.

Optimizing epoxy asphalt tack coat formulations for improved adhesion and working performance of ultrathin wearing course

Insufficient adhesion between ultrathin wearing courses (UTWCs) and substrate layers can result in pavement distress. Epoxy asphalt exhibits potential as a tack coat due to its high bonding strength and thermal stability. However, its rapid curing may pose challenges to construction schedules. This study aimed to optimize the formulations of epoxy asphalt tack coats (EATCs) to enhance the interfacial adhesion and working performance of UTWCs. The adhesion of EATCs was evaluated through rotational viscosity and tensile tests. Design parameters were optimized using analysis of variance and microscopic tests. Road performance was assessed via interlayer shear and tensile testing on three pavement structures. The results indicated that the curing agent strongly influenced the properties and curing kinetics of EATCs. Formulations containing complex polysebacic polyanhydride (CPSPA-EA) exhibited superior bonding while meeting construction schedules. Microscopic analysis of CPSPA-EA revealed a stable crosslinked network formed at 30% binder dosage. The amount of spraying significantly impacted the adhesion in UTWC structures. The optimal spraying amounts were 0.60 kg/m2 for asphalt concrete (AC-13), 0.55 kg/m2 for stone matrix asphalt (SMA-13), and 0.40 kg/m2 for cement concrete substrate layers. These findings presented an optimization framework for designing EATCs to enhance UTWCs working and long-term performance through balanced tack formulations and application parameters.

Formulation and analysis of acrylic emulsion coatings with chrome yellow, phthalocyanine blue, and red oxide pigments using high speed disperser and bead mill techniques

A major commercial problem is achieving stable and fine particle pigment dispersion, especially for aqueous pigment dispersions. It is essential to optimize dispersants in order to moisten, disperse, and stabilize pigments throughout the milling process. This study focuses on formulating acrylic emulsion coatings using chrome yellow, phthalocyanine blue, and red oxide pigment concentrates. The formulations were developed using both high-speed dispersers (HSD) and bead mills. A quality evaluation of the products from the two milling techniques was carried out. Formulations made with chrome yellow, phthalocyanine blue, and red oxide pigment concentrates in a water-based, binder-free system using bead mills, Tween-80, SLS, and cocosulphosuccinate surfactants showed narrower particle size distributions and stronger color than those made with HSD. Specifically, formulations prepared with bead mills and the aforementioned surfactants demonstrated superior color strength compared to those prepared with HSD. The color shade of acrylic emulsion coatings formulated with phthalocyanine blue and red oxide pigment concentrates, along with Tween-80 and cocosulphosuccinate surfactants using HSD, matched the standard color shade formulations prepared in bead mills. However, formulations using phthalocyanine blue pigment concentrates with SLS and oleylsulphosuccinate surfactants in HSD did not match the standard color shade prepared in bead mills.

Enhancing Electrical Conductivity in Cellulosic Fabric: A Study of Bio‐Based Coating Formulations

Enhancing Electrical Conductivity in Cellulosic Fabric: A Study of Bio‐Based Coating Formulations

Waterborne Liquid-like Coatings with High Transparency, Superior Scratch Resistance, and Antismudge Properties.

The aqueous formulation of antismudge coatings is a crucial step for environmental protection and pollution reduction. However, the inferior mechanical durability of waterborne antismudge coatings poses challenges for their practical application. Herein, we developed a fully waterborne antismudge coating with excellent scratch resistance by preparing hyperbranched amine-rich polysiloxane (HySPx) for antismudge ability and epoxy-rich zirconium-based aqueous solution (ZAS) for mechanical performance. The former is obtained by combining SPx, polydimethylsiloxane modified by 3-isocyanatopropyltriethoxysilane (IPTS), with 3-aminopropyltriethoxysilane (KH550), and the latter is synthesized using zirconium propoxide solution (TPOZ) with 3-glycidyloxypropyltrimethoxysilane (KH560). This report investigates the effects of the chain length and content of SPx on the performance of the coating. The results indicate that the coating exhibits optimal comprehensive performance when the molecular weight of polydimethylsiloxane is 4.5 kDa, and the mass fraction of SPx in HySPx is 1.5%. The coating possesses high transparency similar to glass, good adhesion (≈3 MPa) to various substrates, high hardness (8H), flexibility (2.5 mm bending radius), and exceptional antismudge property. More importantly, the coating can still maintain excellent antismudge property even after enduring 400 cycles of abrasion with steel wool. Furthermore, the rapid enrichment of polydimethylsiloxane on the coating surface endows the coating with excellent lubrication ability, allowing most common liquid stains to slide off the coating surface. Moreover, the rewritability of the coating remains stable even after writing traces that have persisted on its surface for several weeks. This coating is anticipated to be utilized for protecting foldable electronic screens, vehicles, and other fields.

Facile route for processing natural polymers for the formulation of new low-cost hydrophobic protective hybrid coatings for carbon steel in petroleum industry

This research helps with the creation, assessment, and characterization of a new hybrid protective coating for carbon steel alloy in acid conditions. The findings of this study will be useful for both chemical and petrochemical companies as well as scientists. This study aims to protect C-steel in acid pickling solution 1.0M HCl and formulate new hydrophobic protective hybrid organic–inorganic coatings from biopolymers chitosan and plant resin guar gum. Eight coating samples of chitosan in the absence and the presence of guar gum, silica and two heterocyclic compounds are prepared at feasible operational conditions using hot melt method. The aiding additives improved compatibility between coating constituents as confirmed by using different methods of analysis. This new processing approach has addressed the problems of using chitosan in corrosion control such as solubility in acid media and low mechanical strength. Coating samples of chitosan and its composites with the heterocyclic compounds (2-Hydrazinyl-6-methyl-4, 5-dihydro pyrimidine-4-on) or (2-Hydrazinyl-6-phenyl-4, 5-dihydro pyrimidine-4-on) are potent biocides. Coating shifts corrosion potential of carbon steel by 30 mV to more noble direction relative to the active potential 520 mV of bare carbon steel surface. Impedance and polarization measurements indicate that coating samples protect metal surface as mixed-type inhibitor by adsorption mechanism. There is a good agreement between percentages protection %P of coating calculated using the values of charge transfer resistance, Rct, and corrosion current density, icorr. All %P values are above 99% for all coating samples. Guar gum plant resin increases gloss of the coating film. Silica fills the pores in the polymeric film and increases the stuffiness of the polymeric coating film by modifying the particle size. All coated samples have high contact angle ranging from 150° to 165° indicating low wettability and high hydrophobicity of coating film on the metal surface.

Towards a zero-waste chemcycling of thermoset polymer composites: Catalyst assisted mild solvolysis for clean carbon fiber liberation and circular coating development

Thermoset materials and their reinforced composites are widely employed in the aircraft, wind energy and construction sectors. Their 3D-crosslinked network and their chemical and physical heterogeneity make them particularly difficult to be recycled. Nowadays, the management of composite scraps and end-of-life waste is still based on landfilling or incineration practices, which are clearly non-compliant with the principles of the circular economy. In this work, a catalysed solvolysis process in mild conditions (T = 180 °C, t = 1–3 h, catalyst 1–7 wt%) was applied for the chemical recycling (chemcycling) of anhydride-cured epoxy resins and their carbon fiber reinforced composites. The selection of the hydroxylated solvents followed thermodynamic considerations (Hansen solubility parameters) and green chemistry principles. The quality of the liberated fibers was studied through thermogravimetric analysis, scanning electron microscopy and single-fiber micromechanical testing, highlighting high surface purity and 100% retention of their pristine mechanical properties (Young's modulus, elongation at break and ultimate strength). The organic recyclates were characterized through gel permeation chromatography, Fourier-transform infrared spectroscopy and chemical titration, and directly reused as hydroxylated binders for the formulation and application of bicomponent polyurethane protective coatings. The resulting coatings were characterized by high chemical resistance (> 100 double rubs at methyl-ethyl ketone test), high surface scratch hardness (3H to 5H), good substrate adhesion (1.5–4 MPa), and excellent optical clarity and surface gloss. These results demonstrate the potential zero-waste reusability of all fractions derived from the chemical recycling of carbon fiber reinforced composites, in line with the principles of the circular economy.

Thermomechanical and physicochemical evolution of meat‐analogue based fried foods

SummaryThis study aimed to get mechanistic insights on the evolution of major quality attributes of meat‐analogue (MA) based batter‐coated fried products. Wheat and rice flour‐based batter systems were used to coat a MA. The products were deep‐fried at 180°C for 4 min in canola oil and their post‐fry quality changes at room environment (RE, 25°C) and under IR‐heating (65 °C) were investigated. Results showed that in addition to moisture‐fat profile, batter coating substantially (P < 0.05) influenced the development of thermal, textural, colour and microstructural traits of MA. Post‐fry colour changes (ΔE value: 3.1 to 10.4) in MA‐based coated product continued under IR‐heating (65 °C). Evolution of the thermal, textural and colour attributes of MA‐based coated products were significantly (P < 0.05) influenced by the formulation of outer batter coatings. Moisture migration occurred from high moisture (ranged from 1.07 to 1.25 g g−1 dry matter) containing core to dry (moisture ranged from 0.15 to 0.59 g g−1 dry matter) crust region of MA‐based coated fried product, where the moisture migration was interlaced with batter formulations. Holding environment and duration substantially (P < 0.05) impacted the textural properties (hardness, brittleness and crispiness) of MA‐based coated fried product. Glass transition temperature (Tg) of coated fried products were ranged between −20.4 to −23.0 °C, that explains quality changes at RE and under IR‐heating. Scanning electron microscopic image analysis (surface openings: 5.7 to 27.31%; fractal dimension: 2.555 to 2.702) revealed the impact of surface microstructure and mass‐transfer modulated textural development in MA‐based coated products. FTIR spectroscopy revealed surface chemical profile in relation to colour evolution of MA‐based fried products. Principal component analysis outcome (PC1: 52.9.% and PC2: 25.8%) revealed varying extent of correlation between studied thermomechanical and physicochemical attributes.

Acute toxicity of petroleum asphalt seal coat leachates to Ceriodaphnia dubia is linked to polymer preservatives

Low-VOC waterborne asphalt-emulsion (AE) seal coat is considered more sustainable than solvent-based coal-tar emulsion seal coat because asphalt emulsions contain negligible amounts of carcinogenic PAHs and release fewer harmful volatile organic compounds. Yet, many low-VOC coatings leach water-soluble substances under outdoor conditions. To investigate the chemical composition of seal coat leachates, three AE formulations were cured under natural weathering conditions and exposed to simulated runoff over a 10-day field trial. Runoff was collected and concentrated using ion-exchange solid-phase extraction (SPE) and analyzed using gas chromatography/mass spectrometry (GC–MS). Leached compounds included hydrocarbons, esters, amines, siloxanes, plasticizers, biocides, polyethylene glycol (PEG) ethers, urethanes, and toluene diisocyanate (TDI). Glycol ethers comprised 29–97 % of the measured leachate mass. Two seal coat formulations contained isothiazolinone biocides, methylchloro- and methylisothiazolinone (CMIT/MIT; 0.5 mg/L in runoff), while a third seal coat formulation continuously leached TDI, a reactive polyurethane (PU) precursor (0.7 mg/L in runoff). Biocide-containing leachates showed acute toxicity to the freshwater water flea, Ceriodaphnia dubia after 48 h, while TDI-containing leachate showed no acute toxicity, suggesting that leachate toxicity was due to in-can polymer preservatives. As biocides are implicated in impaired reproductive signaling, these results support the use of alkaline pH to avoid biofouling and reinforce the goal of reducing and/or avoiding the use of biocides altogether, especially for environmentally friendly products.

Selection of Crosslinking Agents for Acrylic Resin Used in External Coatings for Aluminum Packaging in the Beverage Industry

Paints and coatings are widely used in various applications such as walls, cars, packaging, and food products. The quality of food packaging is essential due to its direct or indirect contact with food. The demand for high-quality food packaging is increasing due to the higher production and consumption rates. However, containers used in the beverage industry often face problems like scratches and abrasions during transportation. This study aimed to investigate different formulations of external coatings for beverage cans to improve their physical resistance properties and prevent corrosion and surface damage problems. The study involved reacting an acrylic resin with six different amino resins, including methylated melamine, butylated melamine, glycoluril, methylated urea, butylated urea, and benzoguanamine, in various proportions. The results of 25 formulated samples were compared based on properties such as adhesion, durability, and chemical resistance. The outcomes of the study showed significant differences among the crosslinking agents. Among all the crosslinking agents, methylated melamine showed the most favorable results in the analyses, proving to be effective in almost all tests.

Metronidazole mediated potassium iodide as high-performance deterioration retardant for mild steel in an acidic media

As corrosion scientists all over the world struggle to discover new metal deterioration retardant which can close the performance gap created by the legislative banned toxic inhibitors, we present in this research work an azole based drug and its mediation performance with a synergistic agent as ‘green’ metal degradation retardant. The anti-deterioration performance of the azole-based drug, metronidazole (MTN) and its different concentration combinations with potassium iodide (KI) were examined with materials degradation analysis tools such as functional group, nanoindentation, weight loss and electrochemical techniques. MTN alone performed well as an anti-deterioration retardant exhibiting retardation efficiencies (η%) in the range between 73 to 85% at different temperatures and analytical techniques. However, with the introduction of KI, an escalation in (η%) was obtained in the region of 92 to 97%. In addition, improved polarization resistance of chemical retardants on substrate cross sections was achieved, manifested by the resultant elevation in values of polarization resistances (Rp) from 1.54 Ω.cm2 of the blank to 30.61 Ω.cm2 of the optimum concentration, charge transfer resistances, (Rct) improved likewise from 6.03 to 144.07 Ω.cm2 and depreciation in the values of corrosion current densities (Icorr) from 8863.86 to 228.89 µA.cm2. This work describes a method of improving the metal deterioration retardation potentials of an azole compound, bringing out new knowledge on the degradation inhibition properties of MTN and the adsorption process taking place between the substrate and the belligerent environment. We hope it opens the door for the utilization of a mixture of MTN and KI as additives for the formulation of sealants, paints, conversion coatings and primers for ferrous alloys. It also encourages more investigations, to find additives such as suitable activating and accelerating agents for MTN to make It exercise the same or more anti-corrosion potents possessed by the banned hexavalent chromium (vi), benzothiazoles (BTA) and others. Some of these potents are the ability of MTN to function at a wide region of pH and in the moment of coating failure, what can enable an azole-containing coating, to undergo some chemical activities and still maintain the substrate surface integrity?

ANN-NSGA-assisted investigation of tribo-performance of lead-free nickel boron coating

In recent times electroless Ni-B coatings free of lead are being investigated with an aim to replace the lead stabilized bath. Traditional formulations of Ni-B coatings often rely on the use of heavy metal/lead-based stabilizers. However, the environmental and health concerns associated with these stabilizers have prompted the exploration of stabilizer-free formulations. The tribological behavior and wear mechanisms of heat-treated heavy metal-free Ni-B coatings were investigated systematically by varying load (10–50 N), speed (0.5–1.5 m/s) and distance (400–1000 m) in accordance with Taguchi's L27 orthogonal array. An artificial neural network (ANN) combined with genetic algorithm is proposed to investigate and optimize wear rate and coefficient of friction (COF) of heat-treated Ni-B coatings. Globular morphology was obtained for the coatings with crystalline peaks of Ni, Ni3B and Ni2B for coatings heat treated at 350°C for 1 h. The mean absolute percentage error of ANN model for wear rate and COF was 5.2846% and 2.0572%, respectively. The multiobjective optimization showed 30.325 N load, 0.50007 m/s speed and 759.2959 m distance corresponding to simultaneous minimum wear rate and COF of 0.005297 × 10−6 g N−1 m−1 and 0.25238 respectively. The worn surface of optimized conditions coatings exhibited oxidized flattened nodules and debris that act as load bearing area leading to lower wear rate and COF.

Cocoa butter and replacement in compound coatings and effect on the coatings rheological profile

Cocoa butter is a crucial component in chocolate and compound coatings, significantly influencing their physicochemical properties, which, in turn, affect the viscosity and cooling rate of the coatings. This impact is vital in the formulation and storage of coatings, affecting their flow behavior, texture, and stability. Research has shown that the inclusion of coconut oil as a cocoa butter substitute in chocolate results in a reduction in the chocolates viscosity. This is attributed to the lower viscosity of coconut oil, primarily due to its lauric acid content. This experiment utilized the Brookfield viscometer to measure the viscosity of chocolate. Three representative types of chocolate were selected: milk chocolate, white chocolate, and dark chocolate, all containing the same ingredient: coconut oil. The analysis of the measurement results allows the determination of the viscosity characteristics of chocolate, providing insights into which type of chocolate exhibits the most significant improvement in viscosity due to the presence of coconut oil. Experimental results indicate that milk chocolate with the addition of 4.5% coconut oil exhibits optimal physical characteristics, including gloss, texture, and overall acceptance by participants. In contrast, dark chocolate with coconut oil has higher viscosity and slower cooling rates, requiring more time to complete the coating or product preparation, which may affect production efficiency. White chocolate with coconut oil typically falls between milk chocolate and dark chocolate in terms of viscosity. This study delves deep into the impact of cocoa butter substitutes on various chocolate coatings, offering valuable insights into the application of coconut oil as a cocoa butter alternative in chocolate production.

Formulation and optimization of a single-layer coat for targeting budesonide pellets to the descending Colon

The current budesonide formulations are inadequate for addressing left-sided colitis, and patients might hesitate to use an enema for a prolonged time. This study focuses on developing a single-layer coating for budesonide pellets targeting the descending colon. Pellets containing budesonide (1.5%w/w), PVP K30 (5%w/w), lactose monohydrate (25%w/w) and Avicel pH 102 (68.5%w/w) were prepared using extrusion spheronization technique. Coating formulations were designed using response surface methodology with pH and time-dependent Eudragits. Dissolution tests were conducted at different pH levels (1.2, 6.5, 6.8, and 7.2). Optimal coating formulation, considering coating level and the Eudragit (S + L) ratio to the total coating weight, was determined. Budesonide pellets were coated with the optimized composition and subjected to continuous dissolution testing simulating the gastrointestinal tract. The coating, with 48% S, 12% L, and 40% RS at a 10% coating level, demonstrated superior budesonide delivery to the descending colon. Coated pellets had a spherical shape with a uniform 30 µm thickness coating, exhibiting pH and time-dependent release. Notably, zero-order release kinetics was observed for the last 9 h in colonic conditions. The study suggests that an optimized single-layer coating, incorporating pH and time-dependent polymers, holds promise for consistently delivering budesonide to the descending colon.

Unravelling the role of TiO2 nanoparticles on the optical performance of dark colourants for coatings

The growing concern on energy savings in buildings, particularly related with cooling needs, has led to the search of new constructive solutions. Frequently, darker colour coatings are used in buildings for aesthetics purposes. However, such coatings have low reflectance, absorbing a large portion of the solar radiation. The associated heat gains enhance the building cooling demand and may reduce the service life of renderings owing to the increased thermal stresses in comparison to light colour coatings. The aim of this study was to assess the influence of size (30–5000 nm), optical band gap energy and concentration (0–20%) of TiO2 nanoparticles in a conventional black colourant for building applications. We confirm that the use of TiO2 nanoparticles increases the reflectance of the colourant and demonstrate that 50 nm is the most adequate nanoparticle size for reflectance enhancement. Furthermore, the colourimetric parameters are also affected by TiO2 incorporation, with the colour difference becoming increasingly noticeable to the human eye with increasing TiO2 concentration. Such results can lead to new formulations of solar reflective coatings are able to reduce the overall cooling load, particularly in warm climates with high cooling demands.

Preparation of Bio-Based Polyurethane Coating from Citrullus colocynthis Seed Oil: Characterization and Corrosion Performance.

In this study, a new epoxidized oil from Citrullus colocynthis seed oil (CCSO) was obtained for a potential application in the formulation of polyurethane coatings. Initially, the fatty acid composition of CCSO was determined by gas chromatography-mass spectrometry (GC-MS). Subsequently, the epoxidation of CCSO was performed with in situ generated peracetic acid, which was formed with hydrogen peroxide (30 wt.%) and glacial acetic acid and catalyzed with sulfuric acid. The reaction was continued at a molar ratio of 1.50:1.0 of hydrogen peroxide to double bond (H2O2:DB) for 6 h at a controlled temperature of 60 °C. The resulting epoxidized oil was then used to produce a bio-based polyol by hydroxylation. The molar ratio of epoxy groups to methanol and distilled water was maintained at 1:11:2, and the reaction was carried out for 2 h at a controlled temperature of 65 °C. The major functional groups of the epoxidized oil and its polyol were validated by Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopies. A polyurethane (PU) coating was produced from the synthesized polyol and 3HDI isocyanurate, keeping the molar ratio of NCO:OH at 1:1. The resulting PU coating was then applied to glass and aluminum panels (Al 1001). After the film was cured, the properties of the PU coating were evaluated using various techniques including pencil hardness, pendulum hardness, adhesion, gloss, chemical resistance, and EIS tests. The results show that the PU coating obtained from CCSO is a promising new raw material for coating applications.

Effect of Phenolic Resin Coating Thickness on Mechanical Properties and Corrosion Resistance of Metal Materials

In the realm of petrochemical and other industries, metal materials face threats such as impact and high-temperature electrochemical corrosion. Consequently, there has been significant attention towards organic coatings that effectively attenuate impact forces while simultaneously providing a barrier against corrosive agents. The thermosetting phenolic resin 2130, known for the facile curing process, exceptional thermal stability, water resistance, corrosion resistance, and superior mechanical properties post-curing, finds extensive applications in the field of coatings. To address the challenge of depositing a complete and uniform resin coating on complex workpieces, coatings with varying thicknesses on the surface of 304 stainless steel were deposited via rotary evaporation combined with long-term low-temperature drying. The relationship between coating thickness and mechanical properties, as well as corrosion resistance, was investigated and analyzed through a comprehensive approach involving mechanical testing, electrochemical analysis, and long-term service weight loss assessment. The results demonstrated that the coatings deposited on the metal surface exhibited excellent integrity and compactness. Moreover, an increase in coating thickness led to a significant reduction in material corrosion rate. The coatings exhibited excellent substrate adhesion and flexibility, thereby providing effective protection against impact on the metal substrate. The relationship between the thickness of the coating and the surface roughness was evident, while the flexibility of the coating first increased and then decreased with the increase of coating thickness. When the coating thickness was 7 μm, the maximum surface roughness of the coating measured 0.44 μm. Under these conditions, the impact toughness of the coating reached the peak, exhibiting a ductile fracture mode and showcasing superior comprehensive mechanical properties. The findings of this study will offer theoretical support for the investigation and formulation of resin coatings in subsequent industrial production.