Thermal Curing Research Articles

Superhydrophobic surface with good anti-icing properties and high durability

Ice formation is a widespread phenomenon in nature, and superhydrophobic surfaces, due to their excellent hydrophobic properties, are extensively employed in the field of ice prevention. In this study, silane coupling agent (Si69) is used to modify the petal-like SiO2 surface to reduce its surface energy. An epoxy/benzoxazine/Si69-SiO2 ternary mixed superhydrophobic surface is constructed on basalt fiber fabric using a spray and thermal curing method. Examination of the data reveals that a 1:2 proportion of Si69-SiO2 and epoxy/benzoxazine yields a surface whose hydrophobicity is quantified by a water contact angle measuring 165±2°. The water droplet bounces three times on the surface, demonstrating optimal superhydrophobicity. Compared to samples without the addition of Si69-SiO2, the icing time is extended by approximately 4.83 times. Following 30 iterations of freeze-thaw processes, the surface retains its exceptional water-repellent properties, demonstrating excellent ice-phobic stability. Furthermore, the surface maintains its superhydrophobic performance, demonstrating excellent mechanical durability, even after being subjected to friction with SiC sandpaper (220 mesh) for 200 cm under a pressure of 3.2 Kpa and reciprocal friction for 30 minutes under a 50 g load. The surface can withstand over 12 hours of acid and alkali corrosion, and it also possesses excellent self-cleaning capabilities.

Novel Crosslinked Anion Exchange Membranes Based on Thermally Cured Epoxy Resin: Synthesis, Structure and Mechanical and Ion Transport Properties.

Limitations in existing anion exchange membranes deter their use in the efficient treatment of industrial wastewater effluent. This work presents an approach to fabricating novel anion-conducting membranes using epoxy resin monomers like hydrophobic or hydrophilic diglycidyl ether and quaternized polyethyleneimine (PEI). Manipulating the diglycidyl ether nature, the quantitative composition of the copolymer and the conditions of quaternization allows control of the physicochemical properties of the membranes, including water uptake (20.0-330%), ion exchange capacity (1.5-3.7 mmol/g), ionic conductivity (0.2-17 mS/cm in the Cl form at 20 °C), potentiostatic transport numbers (75-97%), as well as mechanical properties. A relationship was established between copolymer structure and conductivity/selectivity trade-off. The higher the quaternized polyethyleneimine, diluent fraction, and hydrophilicity of diglycidyl ether, the higher the conductivity and the lower the permselectivity. Hydrophobic diglycidyl ether gives a much better conductivity/selectivity ratio since it provides a lower degree of hydration than hydrophilic diglycidyl ether. Different mesh and non-woven reinforcing materials were also examined. The developed membranes demonstrate good stability in both neutral and acidic environments, and their benchmark characteristics in laboratory electrodialysis cells and batch-mode dialysis experiments are similar to or superior to, commercial membranes such as Neosepta© AMX, FujiFilm© Type1, and Fumasep FAD-PET.

Thermal curing mechanisms and cross-linking network structure of a novel silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene unit

Silicon-containing arylacetylene resin and its composites have attracted great interest as emerging heat-resistant materials, but their curing mechanisms and products are still elusive. In this work, the influences of the terminal and inner acetylenes on the curing mechanisms of silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene were first identified by density functional theory. Two reaction pathways were proposed and their products include polyenes, anthracene dimers, and benzene trimers. To gain a distinct observation of the cross-linking process, molecular dynamics simulations were used to construct a cross-linking polymerization model. The effects of the temperature on the cured structure were investigated by analyzing the characteristics of the cross-linked network. As expected, higher curing temperature will make the larger proportion of polyene chain and aromatic ring in the terminal alkyne−terminal alkyne route, meanwhile, for the inner alkyne−inner alkyne route, the short chains and a small amount of aromatic rings are major productions. Overall, our cross-linking method may provide an unique guidance for studying the cured structure of other thermosetting resins.

Freeze-Dried β-Glucan and Poly-γ-glutamic Acid: An Efficient Stabilizer to Strengthen Subgrades of Low Compressible Fine-Grained Soils with Varying Curing Periods.

The freeze-drying of biopolymers presents a fresh option with greater potential for application in soil subgrade stabilization. A freeze-dried combination of β-glucan (BG) and γ-poly-glutamic acid (GPA) biopolymers was used to treat low compressible clay (CL) and low compressible silt (ML) soils in dosages of 0.5%, 1%, 1.5%, and 2%. The California bearing ratio (CBR) test for the treated specimens was performed under three curing conditions: (i) thermal curing at 60 °C, (ii) air-curing for seven days followed by submergence for 4 days, and (iii) no curing, i.e., tested immediately after mixing. To investigate the influence of shear strength on the freeze-dried biopolymer-stabilized soil specimens and their variations with aging, unconfined compressive strength (UCS) tests were conducted after thermal curing at 60 °C for 3 days, 7 days, and 7 days of thermal curing followed by 21 days of air curing. The maximum CBR of 125.3% was observed for thermally cured CL and a minimum CBR of 6.1% was observed under soaked curing conditions for ML soils. Scanning electron microscopy (SEM), infrared spectroscopy, average particle size, permeability, and adsorption tests revealed the pore filling, biopolymer adsorption and coating on the soil surface, and agglomeration of the soil along with the presence of hydrogen bonds, covalent amide bonds, and Van der Waals forces that contributed to the stiffening of the stabilized soil. Using three-dimensional (3D) finite element analysis (FEA) and layered elastic analysis (LEA), a mechanistic-empirical pavement design was carried out for the stabilized soil and a design thickness catalog was prepared for the maximum CBR. The cost reductions for a 1 km section of the pavement were expected to be 12.5%.

Radiation-induced cross-linking polymerization: Recent developments for coating and composite applications

Abstract Radiation-initiated cross-linking polymerization of multifunctional monomers is an attractive method used for drying solvent-free liquid coatings, inks, and adhesive as well as for fabricating high-performance composite materials. The method offers a number of advantages compared with thermal curing processes. Free radical and cationic polymerization have been investigated in detail over the past years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors and/or by acting on the process parameters (overall dose, dose rate, dose increment, initial temperature). Several pending issues that require deeper investigations are as follows: (i) the fast polymerization of multifunctional monomers generates micro-heterogeneous networks requiring detailed characterization and quantification by microscopic, thermal, and spectroscopic analyses; (ii) the adhesion and surface properties of radiation-cured coatings are quite sensitive to processing parameters; and (iii) significant enhancement of the toughness is needed to qualify potential matrices based on simple difunctional monomers for high-performance composites. Recent results show that the bulk and surface properties of radiation-cured materials can be improved by advanced formulation of matrix precursors and by a parametric study of the processing factors.

Photoactivated ultralong room‐temperature phosphorescence from epoxy polymer films doped with carbazole derivatives for erasable light printing

AbstractThe development of polymer‐based luminescent materials with efficient and switchable ultralong organic phosphorescence (UOP) under ambient conditions is of great importance but remains challenging. In this work, three new organic luminogens have been developed by attaching the ethyl benzoate to the nitrogen atoms of carbazole, 7H‐benzo[c]carbazole, and 7H‐dibenzo[c,g]carbazole via the Buchwald‐Hartwig coupling reaction, respectively. Subsequently, they are embedded into epoxy polymers through doping into the mixtures of bisphenol A diglycidyl ether and 1,3‐propylenediamine, followed by a thermal curing reaction. It is found that the resulting polymer films EB‐BCz@EP and EB‐2BCz@EP show unique photoactivated UOP properties. After UV light irradiation, their phosphorescence quantum yields are up to 7.6%, and the lifetimes reach 1.84 and 1.18 s, respectively. These observations suggest that it is possible to elevate the UOP lifetime without reducing the phosphorescence quantum yield by tuning the molecular structure of the guest luminogen. Upon thermal annealing, the photoactivated polymer films can recover to the pristine state, demonstrating switchable UOP characteristics of the polymer films in the air. Inspired by these exciting results, the EB‐2BCz@EP has been successfully explored as a transparent polymer film for erasable light printing.

Scalable Jet‐Based Fabrication of PEI‐Hydrogel Particles for CO2 Capture

The capture, regeneration, and conversion of CO2 from ambient air and flue gas streams are critical aspects of mitigating global warming. Solid sorbents for CO2 absorption are very promising as they have high mass transfer areas without energy input and reduce emissions and minimize corrosion as compared to liquid sorbents. However, precisely tunable solid CO2 sorbents are difficult to produce. Here, we demonstrate the high‐throughput production of hydrogel‐based CO2‐absorbing particles via liquid jetting. By wrapping a liquid jet consisting of an aqueous solution of cross‐linkable branched polyethylenimine (PEI) with a layer of suspension containing hydrophobic silica nanoparticles, monodisperse droplets with a silica nanoparticle coating layer was formed in the air. A stable Pickering emulsion containing PEI droplets was obtained after these ejected droplets were collected in a heated oil bath. The droplets turn into mm‐sized particles after thermal curing in the bath. The diameter, PEI content, and silica content of the particles were systematically varied, and their CO2 absorption was measured as a function of time. Steam regeneration of the particles enabled cyclic testing, revealing a CO2 absorption capacity of 6.5 ± 0.5 mol kg−1 solid PEI in pure CO2 environments and 0.7 ± 0.3 mol kg−1 solid PEI for direct air capture. Several thousands of particles were produced per second at a rate of around 0.5 kg per hour, with a single nozzle. This process can be further scaled by parallelization. The complete toolbox for the design, fabrication, testing, and regeneration of functional hydrogel particles provides a powerful route toward novel solid sorbents for regenerative CO2 capture.

Manufacturing of TiO2, Al2O3 and Y2O3 Ceramic Nanotubes for Application as Electrodes for Printable Electrochemical Sensors

This paper describes the process to obtain ceramic nanotubes from titanium dioxide, alumina and yttrium oxide by a feasible, replicable and reliable technology, including three stages, starting from an electrospinning process of poly(methyl methacrylate) solutions. A minimum diameter of 0.3 μm was considered optimal for PMMA nanofibers in order to maintain the structural stability of covered fibers, which, after ceramic film deposition, leads to a fiber diameter of 0.5–0.6 μm. After a chemical and physical analysis of the stages of obtaining ceramic nanotubes, in all cases, uniform deposition of a ceramic film on PMMA fibers and, finally, a uniform structure of ceramic nanotubes were noted. The technological purpose was to use such nanotubes as ingredients in screen-printing inks for electrochemical sensors, because no study directly targeted the subject of ceramic nanotube applications for printed electronics to date. The printing technology was analyzed in terms of the ink deposition process, printed electrode roughness vs. type of ceramic nanotubes, derived inks, thermal curing of the electrodes and the conductivity of electrodes on different support (rigid and flexible) at different curing temperatures. The experimental inks containing ceramic nanotubes can be considered feasible for printed electronics, because they offer fast curing at low temperatures, reasonable conductivity vs. electrode length, good printability on both ceramic or plastic (flexible) supports and good adhesion to surface after curing.

Early-age thermo-hydro-mechanical properties of reinforced concrete bridge piers on the plateau

The reinforced concrete (RC) piers located on the plateau suffer a thermo-hydro-mechanical response at an early age, which severely damages the safety and durability of bridges. In this research, five RC piers were constructed on a plateau (altitude: 4360 m) to explore the development of bridge pier early-age temperature and strain. Thermo-hydro-mechanical finite element analyses were then performed to investigate the early-age temperature, moisture, and deformation properties of the RC pier on the plateau. The findings demonstrate that employing thermal insulation curing, modifying the cement ultimate hydration heat, and minimizing the concrete w/c ratio could mitigate the pier early-age temperature gradient and moisture loss. The concrete hydration degree and compressive strength are often greater around the pier gravity center than in other situations. After 96 h of curing, the compressive strength of the concrete at the pier gravity center is approximately 1.766 times that of the pier surface concrete. The most unfavorable locations for bridge piers are at the arc surface and the bottom of the plane.

From cement to geopolymers: Performances and sustainability advantages of ambient curing

The production of Portland cement results in substantial carbon emissions. Geopolymers are regarded as highly promising alternative binder materials to cement due to their low energy consumption and excellent mechanical properties. However, it should be noted that the thermal curing process of geopolymers diminishes their low-carbon advantage. In this study, ground granulated blast furnace slag (GGBS) was used to replace metakaolin (MK) by the ratio of 10 %, 20 %, 30 %, 40 %, and 50 % to produce geopolymers. The aim was to examine the impact of GGBS content on the thermal curing performance of MK-based geopolymers. The microstructure of the specimens was analyzed using SEM and XRD analysis techniques. Lastly, a comprehensive assessment of their sustainability potential was carried out. As a result, slag may increase flow spread, decrease the setting time, and effectively improve the mechanical properties which curing on ambient temperature. The group with 50 % slag content had the highest compressive and flexural strengths, reaching 55.9 MPa and 8.45 MPa at 28 d, respectively. The drying shrinkage of geopolymers increases as the GGBS content goes up. Notably, owing to the evolution of chemical transformation and gel structure, MK exhibits a significant mitigation on shrinkage. Ultimately, with a 50 % slag content, the carbon dioxide emissions of geopolymer can be reduced to 265.36 kg CO2-eq, which is a 43.6 % decrease compared to that of OPC. With a comprehensive consideration of the performance and sustainability potential of geopolymers, it is recommended to introduce GGBS content in the range of 30 %–40 %.

Stretchable Metal Halide Perovskite Color Conversion Layers with Block Copolymer Dispersant

AbstractStretchable luminescent nanocomposites with metal halide perovskite (MHP) emitters are in high demand as deformable color‐conversion layers (CCLs) for vivid‐colored form‐factor free displays. However, the immiscibility of the MHP crystals with an elastomeric polymer matrix induces particle aggregation with resultant luminescence quenching, hindering the development of MHP‐based CCLs. Herein, a simple method is proposed to produce highly luminescent MHP nanoparticles (NPs) and stably disperse them in an elastomeric poly(dimethylsiloxane) (PDMS) polymer matrix with block copolymer (BCP) dispersant. The nanocomposites are developed through sequential steps of synthesis of MHP‐NP dispersion solution with BCP and blending with PDMS followed by thermal curing. It is revealed that Lewis basic poly(2‐vinylpyridine)‐block‐poly(dimethylsiloxane) (P2VP‐b‐PDMS) BCP added in the synthesis step promotes crystallization of the MHPs as nanocrystals with an average diameter of 5.9 ± 1.2 nm, whereas MHPs with hundreds of nm are produced without BCP. The resultant MHP‐NPs with P2VP‐b‐PDMS exhibit excellent photophysical properties, such as narrow band emission, high photoluminescence (PL) quantum yield, and long PL lifetime. The MHP‐NPs are stably dispersed in the PDMS matrix by P2VP‐b‐PDMS without particle aggregation, leading to highly deformable and stretchable nanocomposites with stable PL emission upon repetitive stretching, and excellent environmental stability.

Polyester-enhanced poly (cyclic carbonate-fluoride)-based polymer electrolyte for stable circulating solid lithium batteries

Polymer solid-state electrolytes have become one of the promising materials for constructing solid-state lithium batteries due to their excellent processability and good compatibility with electrode interfaces. However, their limited electrochemical performance and mechanical strength have hindered their widespread application. Through the adoption of an in-situ thermal curing method, we successfully prepared a poly(carbonate-fluoride) solid-state electrolyte, utilizing a polyester separator with abundant polar groups as a reinforcing framework. The introduction of ionic liquid into the solid polymer electrolyte not only enhances the mobility of polymer chain segments to improve ionic conductivity but also, in synergy with trifluoromethyl, promotes lithium salt dissociation while restricting the migration of lithium salt anions. Additionally, their reaction with the lithium metal anode generates the LiF-rich SEI, regulating the deposition of lithium dendrites. The resulting 31VPIF/OZ exhibited outstanding ionic conductivity (3.58 × 10−4 S cm−1 at 25 °C), Li-ion migration number (0.52), and electrochemical window (5.4 V). Li | 31VPIF/OZ | Li battery cycled for 1000 h at 0.1 mA cm−2 without short-circuiting. Importantly, Li | | LiFePO4 battery demonstrated a high capacity retention rate of 91.5 % after 600 cycles at 0.5C (25 °C). Thus, through the synergistic interplay of polymer structure design and fillers, we have successfully achieved stable cycling in solid-state lithium batteries, providing robust support for their application in rechargeable lithium battery technology.

Ultralight, shapeable, and superhydrophobic polyacrylonitrile/polybenzoxazine aerogel for high oil-water separation capacity

Environmental and human health are significantly threatened by oily wastewater emission and oil spills. Polymeric porous aerogels are ideal materials to absorb oils or organic solvents selectively, thereby mitigating environmental pollution and protecting human health. In this study, a shapeable, super-hydrophobic, polyacrylonitrile fiber/polybenzoxazine (PAN/PBOZ) aerogel with high oil-water separation ability were successful designed. The preparation process of PAN/PBOZ aerogel is as follows: Firstly, PAN micro-nanofibers were prepared by electrospinning, and then benzoxazine was uniformly dispersed into PAN fibers. After freeze-drying and thermal curing, the aerogel was obtained. For comparative analysis, a pure polyacrylonitrile (PAN) fiber aerogel is also presented. The resulting PAN/PBOZ aerogel exhibits ultralight (0.017 g/cm3), remarkable hydrophobicity, as evidenced by a water contact angle of 156°, high adsorption capacity up to 157.7 g/g for oil or organic solvents, and a high water-in-oil emulsion separation flux (9718 ± 45 L m−2 h−1) efficiently. Notably, the rigid cross-linking structure of PBOZ and the toughness structure of PAN make the aerogel exhibit synergistic strengthening and toughening effects. When the PAN/PBOZ fiber aerogel is compressed to 60 %, an outstanding recovery stability of its original size is displayed. While the springback of pure PAN fiber aerogel is poor under the same compression test condition. In conclusion, this study provides a preparation method and design concept of aerogel that can meet the requirements of low density, high toughness and high oil adsorption capacity. The rationally designed PAN/PBOZ aerogel shows significant potential for practical applications in treating oily and organic wastewater.

Improving Mechanical Properties of the Fe/epoxy Composite with a Novel Room Temperature-Thermal Curing Process

A novel room temperature-thermal curing process was proposed to fabricate the Fe/epoxy composite easily and rapidly. The effect of thermal curing on the microstructure and mechanical properties were investigated. The results show that the thermal curing leads to the coarsening of Fe phase and the dense of Fe/epoxy interface. The average diameter of Fe increased from 36.03 μm to 64.91 μm after thermal curing, leading to the microstructure evolved from the island shape to the quasi reticular structure. The voids in the Fe phase and cracks along the phase boundary in the Fe/epoxy composite disappeared under the effect of diffusion. The tensile strength increased from 13.14 MPa to 53.72MPa and the elongation increased from 5.86% to 8.18% after thermal curing, with the improvement of 308.8% and 39.6%, respectively. The combination of brittle fracture in Fe and the crack elongation along the interface of Fe/epoxy improve both the strength and the plasticity of the Fe/epoxy composite. The Fe grains sustain fine with average size of 0.49 μm, contains abundant low-angle grain boundary (LAGBs) and deformed grains, but the density of dislocation and the value of texture are extremely low.

Utilization of Aluminosilicate Industrial Wastes as Precursors in CO2-Cured Alkali-Activated Precast Concrete Pavement Blocks

This research focuses on the utilization of recently investigated aluminosilicate industrial wastes as precursors to produce non-structural precast alkali-activated concrete pavement blocks. For this purpose, conventional blocks (200 mm × 100 mm × 80 mm) were produced using electric arc furnace slag and municipal solid waste incineration bottom ashes as the sole binders. Portland cement and fly ash blocks were produced as references. The blocks underwent a curing regimen comprising thermal, dry, and carbonation curing stages. Control uncarbonated specimens were subjected to dry curing instead of CO2-based curing to evaluate the influence of carbonation on the blocks’ strength development. The specimens were subsequently examined following EN 1338, which is the European standard for assessing and ensuring the conformity of conventional concrete pavement blocks. The carbonated blocks revealed improved mechanical and physical properties in relation to the uncarbonated ones. All blocks met standard dimensions, showed minimal skid potential (most indicating extremely low potential for slip for reporting unpolished slip resistance values exceeding 75), and had enhanced abrasion resistance due to carbonation, showing 30% and 11% less volume loss due to abrasion for fly ash and bottom ash, respectively. Carbonated blocks performed better than non-carbonated ones, displaying lower water absorption (0.58% and 0.23% less water absorption for bottom ash and slag, respectively) and higher thermal conductivity (20%, 13%, and 8% increase in values for fly ash, slag, and bottom ash, respectively). These results confirm the effectiveness of the accelerated carbonation curing technique in improving the block’s performance. Despite the promising outcomes, further optimization of the alkaline solution and carbonation curing conditions is recommended for future research.

Effects of blending poly (polyol sebacate) and poly (polyol adipate) bioelastomers for soft tissue engineering in biomedical applications

AbstractIn this article, the synthesis of four novel bioelastomers known as poly (xylitol sebacate) (PXS), poly (xylitol adipate) (PXA), poly (sorbitol sebacate) (PSS), and poly (sorbitol adipate) (PSA) was carried out through bulk polymerization, followed by their blending using the solution method. Six blends were prepared namely PXS25/PSS75, PXS50/PSS50, PXS75/PSS25, PXS50/PXA50, PSA50/PXA50, and PSS50/PSA50. After blending, a thermal curing process was applied to the samples. The intrinsic viscosity, density, Tg, hydrophilicity, degradation, wound healing, and mechanical properties of polymers and blends were measured to investigate the effects of blending. Analyzing hardness, modulus, stress at breakpoint, degradation, and hydrophilicity data showed that the mechanical properties of bioelastomers are adjustable by blending for tissue engineering. Furthermore, the scratch assay proved the biocompatibility of pure polymers and indicated that blending does not have a negative impact on this matter.

UV-durable self-cleaning coatings for autonomous driving

A key technology to ensure the safety and accuracy of autonomous driving for future transportation is the cleanliness of the sensor surfaces for accurate signal reading. This study focuses on hydrophobic coatings with self-cleaning performances and UV durability, their possible degradation mechanism of static water contact angle (sWCA), and the effect of the hydrophobic surface on camera image quality. The UV-durable hydrophobic coatings are applied by a spray process followed by a thermal curing. The UV-durable hydrophobic coatings are evaluated on a vision camera under lab-simulated weathering conditions such as rain, mud, fog, and bugs, on samples as-prepared and after various hours of Weather-Ometer® weathering. The results indicate that the sWCA degradation of the UV-durable hydrophobic coatings during accelerated weathering is corresponding to the loss of fluorine (F) atomic percentage in the coatings, and the vision camera imaging quality improves significantly with the UV-durable hydrophobic coatings in comparison to an uncoated surface. The self-cleaning performances of the UV-durable hydrophobic coatings, as measured by two metrics using signal-to-noise ratio and modulation transfer function 50 loss (MTF50loss), linearly correlate with sWCA of the coatings. The UV-durable hydrophobic coatings on the sensor surface will significantly benefit autonomous driving specifically for accurate signal reading under inclement weather.

Ultraviolet and thermal dual-curing assisted extrusion-based additive manufacturing of lunar regolith simulant for in-site construction on the Moon

The establishment of a lunar base is crucial for lunar studies, resource extraction, and advancement in deep space exploration. Considering the limitations of rocket capacity and Earth-Moon transportation costs, lunar regolith is regarded as the most practical material for lunar base construction. Consequently, the in-situ additive manufacturing technology for simulated lunar regolith has been widely studied in recent years. This paper proposes a novel additive manufacturing approach for lunar regolith simulants. The simulants and several resins were mixed into a paste with high simulant content of 86 wt%, which was suitable for extrusion-based additive manufacturing process. To fully leverage the lunar environment, the feasibility of the ultraviolet (UV) and thermal curing of the resins was first verified, which was followed by the validation of the lunar regolith paste with the solid content of 86 wt%. After the characterization of the ultraviolet and heat curing properties, the paste was further 3D printed via the extrusion-based device. The extruded paste underwent preliminary curing in a UV environment and was then heated to approximate the daytime lunar conditions, achieving complete curing of the printed component. The cured parts exhibited a compressive strength of 9.83 ± 1.07 MPa, meeting the requirements for infrastructure construction in the low-gravity lunar environment. This work offers significant implications for future in-situ construction on the Moon using extrusion-based additive manufacturing of lunar regolith.

Effects of wheat flour levels on the thermal curing behavior of Urea–Formaldehyde and Phenol–Formaldehyde resins

Urea–formaldehyde (UF) and phenol–formaldehyde (PF) resins are the most prevalent adhesives in the manufacturing of wood composites, and they are cured by hot pressing to build a three-dimensional network structure in the composites. UF and PF resins are typically formulated with organic fillers like wheat flour to control viscosity and reduce costs in the commercial production of plywood. Although this formulation is well established, research on the effect of filler on the curing behavior of UF and PF resins has been insufficient. Therefore, this study used differential scanning calorimetry (DSC) to examine the influence of wheat flour as a filler in varying amounts on the thermal curing behavior of UF and PF resins. The results demonstrated that the viscosity and solid content of the UF and PF resins increased as the filler amount increased. In contrast, the gelation time, which reflected the curing speed of the resins, decreased as the filler content increased. Similarly, DSC results demonstrated that with increased filler amounts, the curing reaction of UF resins accelerated, as evidenced by a decrease in the apparent activation energy (Ea) determined using the Kissinger–Akahira–Sunose and Vyazovkin methods. However, in the case of PF resins, the average Ea increased and subsequently declined when 10% and 20% fillers were added. This demonstrated the complicated interaction between wheat flour and resins, particularly PF resins. Furthermore, the isothermal DSC curves reveal that the highest exothermic peaks of UF resins are observed at different isothermal temperatures as the filler amount increases. In contrast, PF resins maintain an isothermal temperature for the highest exothermic peaks across all filler levels. In addition, FTIR analysis suggested that wheat flour might contribute to the curing reaction of UF and PF resins.

Facile Preparation of Impalement Resistant, Mechanically Robust and Weather Resistant Photothermal Superhydrophobic Coatings for Anti-/De-icing.

Photothermal superhydrophobic coatings hold great promise in addressing the limitations of conventional superhydrophobic anti-icing coatings. However, developing such coatings with excellent impalement resistance, mechanical robustness and weather resistance remains a significant challenge. Here, we report facile preparation of robust photothermal superhydrophobic coatings with all the above advantages. The coatings were prepared by spraying a dispersion consisting of fluorinated silica nanoparticles, a silicone-modified polyester adhesive and photothermal carbon black nanoparticles onto Al alloy plates followed by thermal curing. Thermal curing caused migration of perfluorodecyl polysiloxane from within the coatings to the surface, effectively maintaining a low surface energy despite the presence of the adhesive. Therefore, combined with the hierarchical micro-/nanostructure, dense yet rough nanostructure, adhesion of the adhesive and chemically inert components, the coatings exhibited remarkable superhydrophobicity, impalement resistance, mechanical robustness and weather resistance. Furthermore, the coatings demonstrated excellent photothermal effect even in the -10 °C, 80 % relative humidity and weak sunlight (0.2 sun) environment. Consequently, the coatings showed excellent passive anti-icing and active de-icing performance. Moreover, the coatings have good generalizability and scalability. We are confident that this study will accelerate the practical implementation of photothermal superhydrophobic coatings.