Search Results (70)

Environmentally friendly coated urea prepared using a waterborne polymer coating material is essential for promoting green and sustainable practices in modern agriculture. However, significant efforts are still urgently needed to address the undesirable properties of waterborne polymer coatings, i.e., poor hydrophobic properties and numerous micropores. Herein, dual nano-SiO₂ and siloxane-modified waterborne-polymer-coated urea was successfully developed. The characteristics of waterborne-polymer-coated urea before and after modification were compared. The results demonstrate that nano-SiO₂ and siloxane modification improved the hydrophobicity (water absorption decreased from 119.86% to 46.35%) and mechanical strength (tensile strength increased from 21.09 to 31.29 MPa, and the elongation at break exhibited an increase of 22.42%) of the waterborne polymer coatings. Furthermore, the –OH number of the modified coatings was decreased, while the coating surface formed a nano-scale rough structure, prolonging the nitrogen (N)-controlled release period from 7 to 28 days. Overall, the proposed novel dual-modification technique utilizing waterborne polymer coatings highlights the significant potential of eco-friendly coated urea with renewable coatings in modern agriculture. Full article

The superhydrophobic coatings for outdoor use need to be exposed to sunlight for a long time; therefore, their UV-aging resistances are crucial in practical applications. In this study, the primary product of titanium dioxide (P-TiO₂) was used as the raw material. Nano-silica (SiO₂) was coated onto the surface of P-TiO₂ by the acid precipitation method to prepare P-TiO₂-SiO₂ composite particles. Then, they were modified and sprayed simply to obtain a superhydrophobic P-TiO₂-SiO₂/HDTMS coating. The results indicated that amorphous nano-SiO₂ was coated on the P-TiO₂ surface, forming a micro–nano binary structure, which was the essential structure to form superhydrophobic coatings. Additionally, the UV-aging property of P-TiO₂ was significantly enhanced after being coated with SiO₂. After continuous UV irradiation for 30 days, the color difference (ΔE*) and yellowing index (Δb*) values of the coating prepared with P-TiO₂-SiO₂ increased from 0 to 0.75 and 0.23, respectively. In contrast, the ΔE* and Δb* of the coating prepared with P-TiO₂ increased from 0 to 1.68 and 0.74, respectively. It was clear that the yellowing degree of the P-TiO₂-SiO₂ coating was lower than that of P-TiO₂, and its UV-aging resistance was significantly improved. After modification with HDTMS, the P-TiO₂-SiO₂ coating formed a superhydrophobic P-TiO₂-SiO₂/HDTMS coating. The water contact angle (WCA) and water slide angle (WSA) on the surface of the coating were 154.9° and 1.3°, respectively. Furthermore, the coating demonstrated excellent UV-aging resistance. After continuous UV irradiation for 45 days, the WCA on the coating surface remained above 150°. Under the same conditions, the WCAs of the P-TiO₂/HDTMS coating decreased from more than 150° to 15.3°. This indicated that the retention of surface hydrophobicity of the P-TiO₂-SiO₂/HDTMS coating was longer than that of P-TiO₂/HDTMS, and the P-TiO₂-SiO₂/HDTMS coating’s UV-aging resistance was greater. The superhydrophobic P-TiO₂-SiO₂/HDTMS self-cleaning coating reported in this study exhibited outstanding UV-aging resistance, and it had the potential for long-term outdoor use. Full article

Recycled wood fiber (RWF) obtained through the multi-stage processing of waste wood serves as an eco-friendly green construction material, exhibiting lightweight, porous, and high toughness characteristics that demonstrate significant potential as a cementitious reinforcement, offering strategic advantages for environmental protection and resource recycling. In this study, high-performance sulfoaluminate cement (SAC)-RWF composites prepared by modifying RWFs with nano-silica (NS) and a silane coupling agent (KH560) were developed and their effects on mechanical properties, shrinkage behavior, hydration characteristics, and microstructure of SAC-RWF composites were systematically investigated. Optimal performance was achieved at water–cement ratio of 0.5 with 20% RWF content, where the KH560-modified samples showed superior improvement, with 8.5% and 14.3% increases in 28 d flexural and compressive strength, respectively, compared to the control groups, outperforming the NS-modified samples (3.6% and 8.6% enhancements). Both modifiers improved durability, reducing water absorption by 6.72% (NS) and 7.1% (KH560) while decreasing drying shrinkage by 4.3% and 27.2%, respectively. The modified SAC composites maintained favorable thermal properties, with NS reducing thermal conductivity by 6.8% through density optimization, whereas the KH560-treated specimens retained low conductivity despite slight density increases. Micro-structural tests revealed accelerated hydration without new hydration product formation, with both modifiers enhancing cementitious matrix hydration product generation by distinct mechanisms—with NS acting through physical pore-filling, while KH560 established Si-O-C chemical bonds at paste interfaces. Although both modifications improved mechanical properties and durability, the KH560-modified SAC composite group demonstrated superior overall performance than the NS-modified group, providing a technical pathway for developing sustainable, high-performance recycled wood fiber cement-based materials with balanced functional properties for low-carbon construction applications. Full article

This study aimed to improve the mechanical properties and water resistance of calcined gypsum from phosphogypsum (CGP) by incorporating organic additives and inorganic admixtures. The effects of the dosage of these additives—including kaolin, nano-SiO₂, polycarboxylic acid superplasticizer, and sodium methyl silicate—on the properties (flexural strength, compressive strength, water absorption, and softening coefficient) of CGP composites (CGPCs) were investigated. A high water resistance of the CGPCs was achieved using nano-SiO₂ and sodium methyl silicate modification, superplasticizer addition, and the partial replacement of gypsum with mineral admixtures. The results showed that the flexural and compressive strength of the composites hit 4.61 MPa and 19.54 MPa, respectively, while the softening coefficient was 0.70 and the water absorption rate was 19.85%. Microstructural investigation confirmed that the combination of nano-SiO₂ and kaolin led to the formation of calcium silicate hydrate. Additionally, the superplasticizer played a crucial role in reducing the water-to-cement ratio, while unhydrated mineral particles had a filling effect, thereby enhancing the density of the hardened paste. The sodium methyl silicate formed a hydrophobic film on the surface of the hardened paste, increasing the contact angle to 109.01° and improving the water resistance of the CGPCs. Full article

Polydimethylsiloxane (PDMS) with good hydrophobicity and nano-SiO₂ with excellent thermal stability and mechanical properties are used as a composite coating for cellulose insulating paper in oil-immersed transformers, which effectively reduces the moisture generated by the thermal aging process, thus prolonging each transformer’s service life. This study employed molecular dynamics simulations to investigate the effects of surface-modified nano-SiO₂ with different silane coupling agents (KH570 and KH151) on the thermodynamic properties and hydrophobicity of PDMS. Four groups of anhydrous models were constructed, namely, PDMS, P-SiO₂, P-570, and P-151, as well as four corresponding groups of water-containing models: PDMS/H₂O, P-SiO₂/H₂O, P-570/H₂O, and P-151/H₂O. The results demonstrate that incorporating silane-coupled nano-SiO₂ into PDMS enhances mechanical properties, FFV, CED, MSD, diffusion coefficient, interaction energy, and hydrogen bond count, with KH570-grafted composites exhibiting optimal thermomechanical performance and hydrophobicity. At a temperature of 343 K, KH570 modification increased the bulk modulus and CED by 26.5% and 31.0%, respectively, while reducing the water molecular diffusion coefficient by 24.7% compared to that of unmodified PDMS/SiO₂ composites. The extended KH570 chains occupy additional free volume, forming a larger steric hindrance layer, restricting molecular chain mobility, suppressing hydrogen bond formation, and establishing a low energy surface. Full article

To enhance the mechanical properties and low-carbon characteristics of industrial solid waste concrete, this paper proposes a synergistic modification strategy using nano-SiO₂ and sodium silicate. The nano-SiO₂ sol and sodium silicate activator were prepared using magnetic heating and stirring technology, and a quadratic regression model (R² = 0.9575, p < 0.0001) for compressive strength with three factors and three levels was established using the response surface method (RSM-CCD). The modification mechanism was verified through optimization of the mix ratio using a desirability function, along with microscopic characterization via SEM and XRD. The results indicate the following: (1) the content of nano-SiO₂ (2.4%) contributed the most to the compressive strength of the concrete, and its interaction with sodium silicate (2.1%) significantly promoted the formation of C-S-H gel; (2) the optimized fly ash substitution rate (21.7%) can achieve a 28-day compressive strength of 34.8 MPa, with the model prediction error controlled within 5%; (3) microscopic analysis showed that the synergistic effect of multiple components lowered the volume porosity of the cementitious phase, forming a densified network structure. The multi-factor synergistic optimization approach for nano-SiO₂-modified alkali-activated concrete (NS-AAC) proposed in this study offers a reference for multi-objective mix design optimization of industrial waste-based concrete. Full article

During oilfield production, organic substances such as asphaltenes and resins present in crude oil are prone to adsorb onto the surfaces of reservoir rocks. This adsorption process can lead to the conversion of hydrophilic rock surfaces into more oleophilic interfaces, which in turn reduces the permeability and porosity of the reservoir, ultimately affecting the overall recovery efficiency. Consequently, targeted modification of reservoir wettability presents a promising strategy for enhancing recovery rates. In this study, a polymer layer comprising large molecular side chains and hydroxyl groups was synthesized on the surface of nano-SiO₂ to enhance the thermal stability of the polymer. Additionally, the hydroxyl groups were employed to improve the wettability of the core material and reduce interfacial tension. The polymers were characterized using techniques such as FTIR and TG, and the results revealed that the modified SiO₂ exhibited superior performance in reducing both interfacial tension and contact angle when compared to the SiO₂. Injection of a 0.4 wt% EP-HMTA-SiO₂ solution resulted in an increase in recovery rates by 16.4% and 13.2% in medium- and low-permeability cores, respectively. Full article

Asphalt modified with treated waste tires has good environmental protection and application value. However, the nano-modification mechanism of crumb rubber (CR) with asphalt is still unclear. This research investigates the mechanism, aging, and interfacial interaction with the aggregate of CR modification asphalt (CRMA). The base asphalt and CRMA (original and aged) and two typical aggregate models were constructed. The accuracy of the model was verified through multiple indicators. The effects of CR and aging on the physical properties (density, compatibility, and diffusion coefficient), mechanical properties, component interaction behavior, and interfacial interactions with aggregates of CRMA were systematically analyzed. The results showed that the CR reduced the diffusion coefficient of asphalt by about 31%. The CR inhibited the movement of the components of asphalt (especially saturate and aromatic), which significantly improved the mechanical properties of asphalt. The compatibility between asphalt and CR significantly deteriorated after aging. The difference in the solubility parameter was about four times that before aging. It is instructive for the regeneration of CRMA. Aging led to a decrease in the shear modulus and Young’s modulus of both base asphalt and CRMA, which verified and quantified the adverse effects of aging on the mechanical properties. Comparing the two aggregates, CaCO₃ had a greater adhesion with asphalt than SiO₂. The difference ranged from 22.5% to 39.9%, which quantified the difference in the adhesion properties of acid base aggregates with asphalt. This study can provide theoretical guidance for the modification and application of CRMA. Full article

Adhesive modification with nanoparticles affects multiple adhesives properties, making it essential to evaluate and compare changes across all key characteristics—existing positive and limiting properties. This study investigates the impact of silica (SiO₂) and titanium dioxide (TiO₂) nanoparticles on the elasticity and aging resistance of PVAc adhesive. Tensile properties were determined according to ISO 527-3:2018, with Young’s moduli of elasticity $\left({\rm E}\right)$, and stress–strain curves for neat PVAc, nano-SiO₂ PVAc, and nano-TiO₂ PVAc adhesive. Material toughness ($U_T$), failure stresses $\left({\sigma }_f\right)$, and failure strains $\left({\epsilon }_f\right)$ were also calculated. After UV exposure (0, 48, and 96 h), according to ISO 9142:2003, samples were characterized by Fourier-transform infrared spectroscopy (FTIR). Analysis of variance (ANOVA) was performed to determine if there is a statistically significant difference in material toughness between neat PVAc and nano-modified PVAc adhesives, as well as changes in FTIR spectra of paper–adhesive samples before and after UV exposure. The Bonferroni post hoc test was used to identify specific group differences. The results showed that SiO₂ nanoparticles improved PVAc elasticity by 9.15%, while TiO₂ nanoparticles reduced elasticity by 44.47%. FTIR analysis revealed similar behavior in both nano-modified and neat PVAc adhesives after UV exposure, indicating that aging resistance was preserved with the addition of SiO₂ or TiO₂. Full article

In order to further improve the corrosion resistance of 7075-T6 aluminum alloy after shot peening, corrosion-resistant superhydrophobic coatings (EP-HDTMS@SiO₂) containing epoxy resin (EP), cetyltrimethoxysilane (HDTMS), and nano-silica (SiO₂) were prepared by a simple spraying method on the surface of shot-peened AA 7075-T6 aluminum alloy. The effects of different EP/SiO₂ mass ratios on the micro-morphology, surface wettability, and corrosion resistance of the superhydrophobic composite coatings were analyzed. Due to the combination of microstructure and the modification of low surface energy organics, the contact angle of EP-HDTMS@SiO₂ coatings reached the superhydrophobic level (152.6°). The electrochemical tests showed that the corrosion current densities (I_corr) of the EP-HDTMS@SiO₂ composite coatings were both significantly lower than those of the EP-HDTMS coatings and matrix aluminum alloys. The addition of SiO₂ nanoparticles could improve the hydrophobicity and corrosion resistance of epoxy-based composite coatings. Due to the increase in surface roughness and epoxy resin, the shot-peened AA 7075-T6 alloy coating had high adhesion after the peel test. The prepared coatings also showed excellent corrosion resistance in the neutral salt spray test. This study provides a simple method for preparing stable superhydrophobic coatings on metal surfaces, which is expected to expand the application of 7075 aluminum alloy in harsh environments. Full article

This study investigates the structural and optical responses of silica glass to femtosecond (fs) laser irradiation followed by high-energy electron (2.5 MeV, 4.9 GGy) irradiation. Using optical microscopy and spectroscopy techniques, we analyzed retardance, phase shifts, nanograting periodicity, and Raman D₂ band intensity, which is an indicator of local glass densification. S-SNOM and nano-FTIR measurements further revealed changes in the Si–O–Si vibrational bands, indicating partial relaxation of the densified nanolayers under electron irradiation. Our findings reveal significant optical modifications due to subsequent electron irradiation, including reduced retardance and phase values, which are in agreement with the relaxation of the local densification. SEM analysis confirmed the preservation of nanogratings’ morphology including their periodicity. Apart from revealing fundamental aspects related to glass densification within nanogratings, this study also underscores the potential of combined fs-laser and electron irradiation techniques in understanding silica glass behavior under high radiation conditions, which is crucial for applications in harsh environments. Full article

In this study, vinyl triethoxysilane (VTES), KH-560 and trimethylchlorosilane (TMCS) were used to modify the surface groups of commercially available nano-silica (SiO₂, 50 nm), and ethylene vinyl acetate copolymer (EVA) was used as a film-forming agent. EVA/SiO₂, EVA/V-SiO₂, EVA/K-SiO₂ and EVA/T-SiO₂ coatings were prepared, respectively. The coatings were characterized by SEM, FTIR, TG and contact angle. It was found that when the mass percentage of SiO₂ was 66 wt%, the hydrophobicity performance of the coating could be significantly improved by silica modification. Compared to the EVA/SiO₂, the water contact angle (WCA) of the EVA/V-SiO₂, EVA/K-SiO₂ and EVA/T-SiO₂ were increased by 24.0%, 14.4% and 24.6%, respectively. The FTIR results indicated that VTES, KH-560 and TMCS could effectively replace the -OH groups on the surface of the SiO₂ after hydrolysis, resulting in the presence of water transport groups on the SiO₂ surface. The TG results certified that TMCS had the highest substitution rate (24.6%) for the -OH groups on the SiO₂ surface after the hydrolysis. Additionally, the SEM results indicated that T-SiO₂ was more easily dispersed in the EVA film-forming agent, leading to a uniform micro–nano surface rough structure, which aligned with the Cassie–Wenzel model. The durability test had demonstrated that the EVA/T-SiO₂ maintained its hydrophobic properties even after enduring 40,000 drops of water and the impact of 200 g of sand. Furthermore, it exhibited excellent resistance to acid corrosion, along with superior self-cleaning properties and an anti-fog performance. It also provided outstanding protection against high temperatures and UV radiation for outdoor applications. Full article

In this study, the feasibility of using bamboo bark fibers as modifiers to enhance asphalt mortar performance was investigated. Bamboo bark fibers were modified with NaOH, KH570 silane coupling agent, and nano-SiO₂, and their preparation methods were established. The modified fibers were assessed for their oil absorption, thermal stability, and hydrophobicity. The asphalt mortar was evaluated for three key indicators: rutting resistance, deformation resistance, and durability at high temperatures. The microscopic morphology and modification mechanisms of the fibers were also studied. The results showed that modification with NaOH increased fiber porosity and surface roughness, while KH570 and its hydrolysis products enabled nano-SiO₂ grafting onto the fibers, improving their adsorption to asphalt. The NaOH-KH570-nano-SiO₂ ternary-composite-modified bamboo bark fiber (NKSBF) demonstrated superior hydrophobicity, oil absorption, and thermal stability at the asphalt mixing temperature. Among the modified fibers, asphalt mortar containing 3% NKSBF showed the best performance based on three key indicators, increased the shear strength by 96.4% and the softening point by 7.1% compared to the base asphalt, and increased the ductility by 1% compared to lignin fiber asphalt mortar. The incorporation of 3% bamboo bark fibers improved the rutting resistance, deformation resistance, and durability of short-term-aged asphalt mortar, with NKSBF showing the most significant improvement. Full article

This paper proposes a method of enhancing public filler (PF) with nano-SiO₂ (NS) to prepare modified recycled aggregate mortar (RAM). The improvement effect of NS solution at different concentrations and immersion times on the macroscopic physical properties of recycled public fine aggregates (PFA) was investigated. Moreover, the effect of NS on the basic physical properties and durability of recycled mortar (RM) and the reinforcement mechanism of NS on recycled mortar was analyzed through various techniques. Results indicated that the modification effect of NS could remove loose cement mortar from the surface of PFA. It reacted with calcium hydroxide and calcite to generate nano-particles that could fill pores in PFA. The water absorption rate of PFA decreased to 9.3% when immersed in 2% NS solution for 72 h. There was no significant improvement in the mechanical properties of RM when the solution concentration and immersion time were increased. However, the compressive strength of RM prepared by modifying PFA with 2% NS was increased by about 21.9%, and the capillary water absorption and electric flux were reduced by 56.3% and 15.1%, respectively. Micro-analysis results showed that the volcanic ash effect of NS enabled it to react with Ca(OH)₂ adhered to the surface of PFA, generating C-S-H and improving the interfacial bonding of PFA. Moreover, NS adsorbed on the surface of PFA dispersed into the freshly mixed cement slurry, which further enhanced the internal structure of PFA. Full article

Membrane distillation (MD) is considered a promising technology for desalination. In the MD process, membrane pores are easily contaminated and wetted, which will degrade the permeate flux and salt rejection of the membrane. In this work, SiC ceramic membranes were used as the supports, and an Al₂O₃ micro-nano structure was constructed on its surface. The surface energy of Al₂O₃@SiC micro-nano composite membranes was reduced by organosilane grafting modification. The effective deposition of Al₂O₃ nanoflowers on the membrane surface increased membrane roughness and enhanced the anti-fouling and anti-wetting properties of the membranes. Simultaneously, the presence of nanoflowers also regulated the pore structures and thus decreased the membrane pore size. In addition, the effects of Al₂(SO₄)₃ concentration and sintering temperature on the surface morphology and performance of the membranes were investigated in detail. It was demonstrated that the water contact angle of the resulting membrane was 152.4°, which was higher than that of the pristine membrane (138.8°). In the treatment of saline water containing 35 g/L of NaCl, the permeate flux was about 11.1 kg⋅m⁻²⋅h⁻¹ and the salt rejection was above 99.9%. Note that the pristine ceramic membrane cannot be employed for MD due to its larger membrane pore size. This work provides a new method for preparing superhydrophobic ceramic membranes for MD. Full article