Resin Coatings Research Articles

Comparative evaluation of surface microhardness and microleakage after application of commercially available G-Coat Plus, nano silver fluoride resin coat and petroleum jelly over glass ionomer cement restoration: an in vitro study

Background Glass ionomer cement (GIC) is a widely used tooth coloured material. However, GIC holds certain undesirable properties. In order to overcoming the major drawback of moisture sensitivity, surface coatings like petroleum jelly, varnish are applied over GIC restoration. Thus, the present study was planned to compare efficacy of newly formulated nano silver fluoride resin coat with G Coat Plus and petroleum jelly on microhardness and microleakage of Type IX GIC. Methods Class V cavities were prepared on the buccal surface of thirty-six non carious premolars and restored with type IX GIC. The restored teeth were divided into 3 groups: Petroleum gel, G Coat plus and Nano silver fluoride resin coat. Protective surface coatings were applied over the restorations, dried for 2 minutes and thermocycled. Teeth were then placed in 1% methylene blue for 24 hours. Longitudinally sections were prepared and were observed under stereomicroscope at 25x magnification for dye penetration. Forty-five blocks of PVC were prepared and restored with GIC. Samples were divided into three groups equally as mentioned earlier and a layer of each coating was applied on all samples according to the groups and dried for 2 minutes. Further, surface microhardness (SMH) of the samples was tested by Vickers microhardness machine under a load of 50 grams for 10 seconds at 3 sites and a mean was calculated. Statistical analysis was conducted using post hoc and one way-ANOVA tests. Results The microleakage scores of three groups were statistically insignificant. The mean microhardness of all samples in the three groups showed no statistically significant difference. The mean surface microhardness of group 1 was 66.44±4.57 whereas for group 2 and group 3 it was 76.15±3.02 and 79.22±4.03 respectively. Conclusions The novel agent containing nano silver fluoride is showed superior results and is intended to augment the properties of GIC.

Robust macroscale superlubricity of multiple base oils achieved on soft epoxy resin coatings

Reducing the friction of base oils to a superlubricity state is highly expected at engineering scale. However, it still is a great challenge for the most of viscous base oils to achieve superlubricity on the conventional tribopairs up to now. Here we report the strategy of solid-oil composited lubrication constructed with an ultra-smooth epoxy resin (EP) coating and base oils for achieving superlubricity. Especially, the frictional results showed that the proposed strategy in this study could be suitable for multiple base oils, including nonpolar and polar base oils as lubricants. The friction coefficient of steel/EP tribopair lubricated by the base oils containing hydroxyl group can be as low as 0.001. Meanwhile, the composited lubrication system did not undergo an obvious running-in stage to achieve the superlubricity state regardless of the type of base oils. The surface hydroxylation of the steel counter ball sliding against EP coating was observed by time-of-flight secondary ion mass spectrometer, even when lubricated by nonpolar base oils without hydroxyl group. This could be a critical factor for the base oils to achieve superlubricity. This finding provides a new and facile approach to realize robust superlubrication for different base oils at engineering scale.

TEOS-modified SiC superhydrophobic nanostructures in epoxy resin coatings for corrosion prevention

Superhydrophobic coatings have been widely studied because of their great potential for application in the field of corrosion protection of metals such as carbon steel. However, expensive production costs, complex manufacturing processes and fragile mechanical properties limit the range of applications. Inspired by the natural phenomenon that oysters grow on reefs to protect themselves, SiC/2-SiO2 particles were synthesized by growing silica nanostructures in-situ on the surface of hard silicon carbide particles, and SiC/2-SiO2 particles were securely fixed on the surface of various substrates by using commercial epoxy resins and PDMS as the adhesive. SEM, XRD test results showed that the silica nanoparticles were successfully synthesized and bonded to the silicon carbide surface. The fabricated SiC/2-SiO2/EP superhydrophobic coating has good mechanical robustness and chemical stability, losing only 13.6 % of its mass after 1000 wear cycles. The chemical breakage leads to the loss of superhydrophobicity, which can be restored with a simple sanding. EIS test results show that the corrosion prevention effect of modified SiC/2-SiO2/EP is superior to that of ordinary EP coatings, and Tafel test results show that the corrosion rate of SiC/2-SiO2/EP coatings is 1143 times slower than that of bare steel, which exhibits good corrosion prevention effect. This method can be prepared on a large scale by spraying method, which is important for promoting the application of superhydrophobic coatings in the field of anticorrosion.

Protection of N80 steel from erosion-corrosion of geothermal water by nanoparticle-modified expoxy resin coatings

In order to investigate the erosion-corrosion resistance of nano-SiO2/EP composite coating and TiO2/EP composite coating in a geothermal environment, the coatings were subjected to potentiodynamic polarization curve tests, AC impedance tests, weightlessness tests, under different immersion time in geothermal water. The micro-morphology of the coating after erosion-corrosion was observed to evaluate the protective effect of the modified EP coating on N80 steel. The result showed that the addition of nanoparticles can improve the corrosion resistance of EP coatings to a certain extent, and the optimum addition amount of nanoparticles is 3%. In geothermal water containing sand, the corrosion inhibition efficiency of EP coatings modified by nanoparticles was above 99.99% except for the 1 wt% SiO2/EP composite coating. When the nanoparticle content is 1 wt%, the protective effect of nano-SiO2/EP composite coating is better than that of TiO2/EP composite coating, but the protective effect is opposite when the nanoparticle content is 3% and 5%, respectively.

Self-lubricating and wear-resistant epoxy resin coatings based on the “soft-hard” synergistic mechanism for rapid self-healing under photo-thermal conditions

Mechanical components made of alloy steel are susceptible to severe surface wear after long periods of operation. The construction of protective coatings with high wear resistance and self-healing properties provides references for solving this problem. Herein, a highly wear-resistant coating (named as C-EP/PFW) that can rapidly self-healing under photothermal conditions was constructed by introducing both a novel phase-change material (polytetrafluoro-wax) and polydopamine-functionalized carbon nanotubes (PDA/CNTs) into the epoxy resin. The melt-phase transition of PFW at approx. 120 °C induces intermolecular phase migration and repair of the damaged area. The PDA/CNTs can act as microscopic bearings to enhance the load-bearing capacity of the composite coating, they can also construct thermal conductivity networks to enhance the thermal conductivity and repair efficiency of the coating. Based on the perfect combination of CNTs' excellent thermal conductivity and PDA's photothermal conversion capability, the average repair rate of the composite coating was increased by 20.7 % than pure EP/PFW coating. Additionally, the C-EP/PFW coatings in both dry and wet friction environments (seawater and sunflower oil) exhibited excellent self-lubricating properties. This is attributed to the synergistic of the soft lubricating phase on the repair of the lubrication transfer film and the microscopic slipping layer constructed by the CNTs at the tribofilm. The C-EP/PFW coatings, which are capable of rapid self-healing in thermal environments, provide a reference for the construction of highly wear-resistant protective layers on the surfaces of steel mechanical components.

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.

Designing a photocatalytic and self-renewed g-C3N4 nanosheet/poly-Schiff base composite coating towards long-term biofouling resistance.

Inhibiting the adhesion and growth of marine microorganisms through photocatalysis is a potentially efficient and environmentally friendly antifouling strategy. However, the undesired "shading effect" caused by resin coatings and microbial deposition reduces the utilization of the catalysts and leads to a failure in the antifouling active substance on the coating surface. Here, we successfully developed a composite coating (DPC-x) combining g-C3N4 nanosheet (g-C-NS) photocatalysts with degradable green poly-Schiff base resins, which integrates the dual functions of enhanced dynamic self-renewal and photocatalytic antibacterial activities towards long-term anti-biofouling. The controllable and complete degradability of the poly-Schiff base polymer chains and the self-renewal mechanism of the DPC-x coating exposed the internal g-C-NS, which provided a constant stream of photocatalytic reactive interfaces for 100% utilization and release of the photocatalysts. g-C-NS were homogeneously dispersed in the degradable resin coating, significantly enhancing and adjusting the self-renewal rate of the poly-Schiff base resin coating in visible light. The degradation reaction rate of DPC-0.2 (20 wt% g-C-NS) was 40 times that of DPC, thus improving the capabilities of surface self-renewal and fouling-release. Due to the synergistic antifouling mechanism of the efficient antibacterial properties and the enhanced degradation/self-renewal, the antimicrobial rates of DPC and DPC-0.2 were 94.58% and 99.31% in the dark, and 98.2% and 99.87% in visible light. DPC-x has excellent all-weather antimicrobial efficacy and could offer a new perspective on eco-friendly marine antifouling strategies.

Effect of Resin Coating on Soft Body Impact Damage of CFRP

Effect of Resin Coating on Soft Body Impact Damage of CFRP

Fabrication of polyaniline/waste sugarcane bagasse composite fillers for excellent anti-corrosion protective coatings

Herein, biomass-based anti-corrosion composite fillers for water-based epoxy resin coatings, epoxy resin powder coatings, and efficient anticorrosive coatings were successfully prepared.

BUBBLE DEFECTS AND CONTROL OF THERMAL CURING OF WATERBORNE RESIN COATINGS

To solve the problem of bubble retention leading to a decrease in the performance of waterborne resin coatings during thermal curing, a rapid thermal curing coating based on an aqueous epoxy-modified acrylic resin containing an amino resin cross linker was synthesized through solution copolymerization. Using a synchronous thermal analyzer, the mass loss and heat flow during the thermal curing process of the coating was measured. In addition, an in situ thermal curing visualization system was used to observe the curing behavior at the easy-open end notches under different heating rates. The results indicated that the curing process is divided into an initial rapid heating stage and a subsequent slower heating stage by the boiling point of water, with a critical temperature range of 126-150°C. The visualization experiments showed that when the temperature reached 100°C, the water quickly evaporated to form bubbles. Increasing the heating rate before this temperature caused the bubbles to rapidly escape. Therefore, an optimal heating profile with a rapid initial heating rate of 3.13°C/s, followed by a slower heating rate of 0.52°C/s in the next stage, is proposed. This discovery is of great significance for optimizing the thermal curing process of waterborne coatings on metal substrates, including those used for easy-open ends.

Surface characteristics of phenolic resin coatings

Phenolic resins are commonly used as polymer binders for metal, paper and mineral wool substrates. For such applications, mechanical, adhesive and thermal properties are considered most important, and the effect of synthesis and structural parameters on such end-use characteristics are well-documented. However, surface characteristics of cured phenolic resins can be equally relevant and are often overlooked. Widely used resins are phenol-urea-formaldehyde (PUF) and phenol-formaldehyde (PF). It is believed that the inherent chemistry and curing procedure of these resins result in coatings with distinct surface properties and wettability. To gain more insight into surface characteristics such as morphology, chemical composition and wettability of cured PUF and PF resins, different binder formulations were applied on glass substrates and subsequently characterised by Scanning Electron Microscopy (SEM), Contact Angle Goniometry (CAG) and X-Ray Photoelectron Spectroscopy (XPS). The effect of catalyst, chemical composition and curing conditions on surface characteristics of various PUF and PF coatings were investigated. The curing temperature was found to have a strong influence on surface properties; curing at 200 °C yields a surface with varying degrees of oxidation, differences in linkages between phenolic and urea species, and a lower overall nitrogen content in case of urea-containing coatings, resulting in stronger fluctuations in water-wettability compared to surfaces hardened at lower temperatures.

Retracted: Synthesis of SiO2 Nanoparticle Epoxy Resin Composite and Silicone-Containing Epoxy Resin for Coatings.

[This retracts the article DOI: 10.1155/2022/8227529.].

Investigation of hydroxyl-terminated polydimethylsiloxane-modified epoxy resin

Epoxy resin coatings are characterized by a high concentration of hydroxyl groups, making them inherently hydrophilic and prone to corrosion. Additionally, the brittleness of epoxy resin limits its practical uses. In this study, epoxy resin (EP-51) was modified using hydroxyl-terminated polydimethylsiloxane (HTPDMS), which possesses a low surface energy due to its -Si-O- bonds, to improve the hydrophobicity and toughness of the coating. The effect of varying HTPDMS concentrations on the properties of epoxy resin was evaluated in terms of mechanical, thermodynamic, and electrochemical properties, as well as contact angle measurements. The findings reveal that as the HTPDMS content increases, the tensile strength of the modified EP diminishes, while the elongation and impact strength are enhanced. However, higher HTPDMS levels lead to reduced compatibility with EP, causing phase separation and the formation of an “island structure”. The glass transition temperature of the EP declines with added HTPDMS, resulting in an increased swelling rate and reduced pencil hardness and adhesion grade of the coatings. Notably, the hydrophobicity of the EP improved significantly, with its contact angle rising from 74.8° to 99.0° post-modification. Electrochemical impedance spectroscopy and polarization curve analyses revealed optimal protective performance of the coating at an epoxy resin to HTPDMS mass ratio of 8:2.

Preparation and Anticorrosion Performance of Double-Layer Epoxy Resin Coatings on Bonded NdFeB Magnets

Preparation and Anticorrosion Performance of Double-Layer Epoxy Resin Coatings on Bonded NdFeB Magnets

Processing of kaolin micro-composite functional fillers for enhancing the near-IR reflective performance of polyurethane resin coatings

Polyurethane (PU) resin products meant for protective coatings are chemically composed of two-phase microstructures; soft ‘polyols’ and hard ‘diisocyanates and chain extenders’. For durable high-performance specialty PU coatings, their surface heat reflectance property is to be enhanced; otherwise, the absorption of solar heat energy eventually generates heat build-up that finally induces microstructural changes and chemical degradation. Hence, in this work, an attempt is made to improve the poor IR reflectance property of PU resin by incorporating kaolin micro-composite functional fillers. In this study, kaolin delamination was first carried out using alumina and zirconia milling media. Delaminated kaolin was treated with colloidal oxides, SiO2, Al2O3, and TiO2, to produce kaolin micro-composite fillers. The filler effect, chemical interaction, heat build-up, scratch resistance, and hydrophobic properties were examined, and results were presented. The study confirmed that when Al2O3-modified kaolin micro-composites improved the scratch resistance, the incorporation of 10 mass% mixed oxide kaolin micro-composite fillers enhanced the NIR reflecting property of PU coats from 4% to 53%. A facile strategy to enhance the solar heat shielding property of PU top coats for obtaining long-life durable protective coatings is presented in this work.

Novel highly efficient ternary ZnO wrapped PPy-NTs/g-C3N4 nanocomposite as an epoxy coating for corrosion protection

The main goal of this study is to develop an epoxy coating coupled with an organic–inorganic hybrid nanocomposite that can be used as a corrosion-inhibiting pigment on carbon steel. Herein, polypyrrole nanotubes (PPy-NTs), polypyrrole nanotubes/g-C3N4 (PPy-NTs/g-C3N4) and novel nano-composite polypyrrole nanotubes/g-C3N4/ZnO (PGZ) were prepared by facile wet impregnation approach. The developed pigments were investigated using XRD, FTIR, FE-SEM equipped EDS. Electrochemical impedance spectroscopy (EIS) and polarization measurements were used to assess the behavior of the prepared pigments on the anticorrosion performance of epoxy resin coatings. EIS experiments revealed that introducing nano-pigments to neat coatings enhanced the epoxy resin and charge transfer resistance. The anticorrosion performance of the three nano-pigments was assessed as follows: PGZ ˃ PPy-NTs/g-C3N4˃ PPy-NTs.

Construction of ammonium polyphosphate-modified halloysite nanotubes on phase change material microcapsules for the enhancement of thermophysical performance and flame retardant properties

Organic microencapsulated phase change materials (MPCMs) are regarded as promising for building energy efficiency while the low thermal conductivity and flammability limit their further application. Aiming at improving the thermal response performance and flame retardancy of the MPCMs, the MPCMs embedded by ammonium polyphosphate-modified halloysite nanotubes (a-HNTs) are developed and then applied in the epoxy resin (EP) coatings. Herein, the ammonium polyphosphate (APP) is grafted onto HNTs as a flame retardant for the first time and the resultant nanotubes are successfully embedded into the shell of traditional MPCMs. As a result, the obtained microcapsules (a-MPCMs) possess a regular spherical morphology and the desired chemical composition. Moreover, the a-HNTs with their unique inorganic tubular structure connect the inside and outside of the original polymethylmethacrylate (PMMA) shell and act as the thermally conductive channel, which greatly facilitates the conversion of external heat to the latent heat of the capric acid (CA) core. The phase change data show that the embedding of a-HNTs has little effect on the encapsulation efficiency of MPCMs, and the latent heat of a-MPCMs is 118.3 J/g. Meanwhile, the a-HNTs/PMMA hybrid shell also significantly improves the thermal stability of MPCMs with the highest residual weight of 24.3%. With the addition of a-MPCMs, the resultant temperature-control coatings (a-MPCMs/EP) hold a high thermal cycle stability and excellent temperature control performance with less temperature fluctuation. In addition, a-HNTs also provide superior flame retardant properties for a-MPCMs/EP. Compared to the EP composites with the same mass fraction of pristine MPCMs added (MPCMs/EP), the pHRR and THR of a-MPCMs/EP are reduced by 30.2% and 4.5%, respectively. Through flame retardant modification of HNTs and incorporating them into the shell material of MPCMs, this work provides a promising approach to the development of multifunctional MPCMs with enhanced thermophysical performance and flame retardant properties.

Preparation of acrylic metal salt resin containing capsaicin derivative structure and study of anti-fouling properties

Modifications of acrylic resins with environmentally friendly compounds often solve the problems of marine fouling. In this work, capsaicin derivatives-modified acrylic acid resins were successfully synthesized via free radical polymerization and condensation reactions of monomeric acrylic acid, capsaicin derivatives, metal salts and benzoic acid and structurally characterized by infrared spectroscopy and nuclear magnetism. The physicochemical properties of the synthesized resin coatings were tested with a rotary viscometer, gel permeation chromatography, video optical contact angle measurements and a laser confocal tester. The self-polishing and antifouling properties of the resins were investigated with dynamic simulation experiments, algae inhibitions, bacterial inhibition experiments and real sea antifouling experiments. By comparing with the acrylic resin without capsaicin derivatives, the acrylic resin with added capsaicin derivatives had good antifouling performance, and the optimal content was 2.5 %. In summary, the capsaicin derivative-modified acrylic metal salt resins have good self-polishing properties and antifouling properties.

Enzyme-mediated and formaldehyde-free formation of phenolic resin coatings

Coatings from phenolic resins are utilized in a wide range of applications and remain a crucial type of thermosetting polymers. Curing at high temperatures and the utilization of formaldehyde, however, are ever more pressing concerns. In this work, a novel approach towards phenolic resin coatings is presented. The rationale follows the concept of Enzyme-Mediated Addressing, a technique for controlled formation of coatings and structures via immobilized enzymes. Employment of Horseradish Peroxidase leads to radical induced coupling of phenol to cross-linked polymers. This well-known polymerization technique is now performed at close proximity to the support surface. Action of the enzyme is shown to lead to formation of nanoparticles from poly phenolic material and their subsequent deposition on the surface. First, important reaction parameters are investigated. From this, largely coalesced films are gained at the ideal reaction conditions. Additionally, some insight into possible process mechanisms is provided. Finally, site-specific coatings are shown to be accessible with this method as well. Due to the applied enzymatic process, formaldehyde-free cross-linking at low temperatures is achieved.

Improved Thermal and Mechanical Properties of Kenaf Fiber/ABS Polymer Composites via Resin Coating Treatment

In developing natural fiber composites (biocomposites), compatibility between natural cellulosic fibers and polymers has always created serious challenges, reducing performance. This study focused on applying a novel approach using epoxy resin as a coating medium to enhance the properties of the fibers and the interface between the hydrophobic polymer and the hydrophilic natural fiber. 10 wt% of uncoated kenaf fibers (KF) and coated kenaf (CKF) fibers were compounded with acrylonitrile butadiene styrene (ABS) thermoplastic polymer in a twin-screw extruder at an optimized temperature of 220°C under the same processing conditions. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) examined the coated and uncoated fibers' physicochemical compositions and surface properties. The developed composites' thermal, mechanical, and microstructural characteristics were also examined, and the results revealed that the CKF/ABS composites had better interfacial bonding and mechanical characteristics than the uncoated KF/ABS composite. Coating natural fibers with epoxy resin is a novel technique for improving interfaces and developing environmentally friendly composites from natural sources.