Search Results (121)

With rapid development of 5G/6G communication and high-power electronic devices, electromagnetic interference (EMI) shielding textiles are urgently required to mitigate electromagnetic pollution. Traditional metallic shielding suffered from heavy weight, poor corrosion resistance, and secondary electromagnetic reflection, while continuous basalt fibers (CBFs) exhibit excellent mechanical strength, lightweightness, thermal/chemical resistance, and electrical insulation, which makes CBFs ideal substrates for EMI devices. Herein, a multifunctional waterborne polyurethane (WPU) sizing agent (coating emulsion) integrated with Mn-Zn spinel ferrite was developed for in situ lubrication on the as-spun CBFs. The composite sizing agents consisted of a WPU matrix, water-soluble epoxy, mineral oil lubricant, CTAB surfactant, KH-570 coupling agent, and micro-sized Mn-Zn ferrites. Characterizations including particle size distribution, thermogravimetric analysis, water contact angle (WCA), water absorption, FTIR, XRD, and SEM were conducted to verify uniform anchoring of ferrites on the CBF surfaces. Increasing ferrite dosages induced slight particle aggregation, elevated surface hydrophobicity (WCA = 42.4° → 99.43°), and reduced water absorption (65% → 35%), which greatly improved the moisture resistance of the CBFs. The X-band EMI shielding tests revealed that the total shielding effectiveness (SET) of modified CBF fabrics increased from 0.11 dB (pristine fiber without ferrite) to 58.57 dB at a loading of 8.0 g/L ferrite. The absorption loss (SEA) dominated the shielding performance over reflection loss (SER). The low-to-moderate contents (1.5–3.0 g/L) of ferrite achieved ultra-high absorption, while higher ferrite loading (5.0–8.0 g/L) intensified the impedance mismatch and enhanced surface reflection. This work establishes a scalable fabrication of absorption-prioritized lightweight CBF shielding, which provides a feasible pathway for flexible EMI shielding textiles. Full article

Solid–solid phase change materials integrate high heat storage, leak-proof performance, and dimensional stability, thereby positioning them as optimal candidates for thermoregulating textile applications. This study effectively synthesized PEG-based crosslinked waterborne polyurethane phase change materials (WPU-SSPCMs) with polyethylene glycol (PEG) as the soft segment, hexamethylene diisocyanate (HMDI) as the diisocyanate, and glycerol (GL) as the multifunctional chain extender. The effects of PEG molecular weight, diisocyanate type, chain-extension temperature, and monomer molar ratio on the phase transition behavior and thermal stability of WPU-SSPCMs were systematically investigated. The results indicate that at a PEG molecular weight of 2000, a chain-extension temperature of 70 °C, and a monomer molar ratio of n(PEG:HMDI:GL) = 1:2:0.67, the synthesized WPU-SSPCMs exhibited optimal comprehensive performance. The material demonstrated a melting temperature of 33.38 °C with a high enthalpy of 80.31 J/g. It displayed characteristic solid–solid phase transition behavior without evidence of liquid leakage during heating. Following 100 thermal cycles, the enthalpy variation remained below 1 J/g, indicating exceptional thermal and cycling stability. When applied to cotton fabric, the resultant thermoregulating textile displayed a buffering plateau during both heating and cooling processes, demonstrating a pronounced temperature-regulating effect relative to untreated fabric. The developed WPU-SSPCM holds considerable promise for applications in intelligent temperature regulation. Full article

3D-printed continuous carbon fiber-reinforced polylactic acid (CF/PLA) composites combine the high load-bearing capability of continuous fibers with the structural design freedom of additive manufacturing, showing broad application prospects in lightweight complex structures. However, the chemically inert surface of carbon fibers and their insufficient interfacial compatibility with the PLA matrix lead to inefficient interfacial load transfer, thereby limiting the mechanical performance of the composites. In this study, a waterborne polyurethane (WPU)-based sizing treatment was applied to carbon fibers to enhance the fiber–matrix interface of 3D-printed continuous CF/PLA composites. The WPU sizing layer increased fiber-bundle cohesion and introduced a transition region between CF and PLA through possible hydrogen bonding, dipolar interactions, and physical adhesion. When the nominal WPU concentration was 5 wt%, the apparent interfacial shear strength reached 1.31 MPa, representing an improvement of approximately 65% compared with ACF/PLA. The three-point flexural strength reached 69.76 MPa, which was 55.3% higher than that of the ACF/PLA composite. These results indicate that WPU sizing is an effective and scalable interfacial regulation strategy for improving the mechanical properties of 3D-printed continuous CF/PLA composites. Full article

Driven by the growing demand for functional textiles featuring excellent waterproofness, moisture permeability and mechanical robustness in outdoor sportswear, medical protection and technical apparel, traditional pongee—despite its desirable softness, high wrinkle resistance and good stability as an ideal substrate fabric—is severely restricted in further application by its intrinsically poor hydrostatic pressure resistance in extremely wet environments. Accordingly, we developed a modified waterborne polyurethane (WPU) coating for pongee substrates to fabricate functional textiles that maintain high hydrostatic pressure resistance while possessing good mechanical properties and increased UV absorption. In this study, by using the sol–gel method, an amorphous silicon dioxide (SiO₂) coating layer was constructed on the surface of titanium dioxide (TiO₂) particles, forming silica-modified titania particles (SiO₂/TiO₂). These SiO₂-modified particles were subsequently physically blended with an anionic waterborne polyurethane system that had been previously modified with a polyester-type modifier A to enhance its hydrostatic pressure resistance. The resulting composite coating was designed to combine the high hydrostatic pressure resistance inherited from the modified WPU matrix, the mechanical reinforcement and increased UV absorption contributed by SiO₂/TiO₂, and satisfactory water repellency on fabric substrates. The results indicate that the incorporation of an appropriate amount of modifier A into the prepolymer system significantly enhances hydrostatic pressure resistance while maintaining high elongation at break. At a SiO₂/TiO₂ loading of 0.2 wt%, the composite film exhibits optimal comprehensive performance, characterized by superior mechanical properties, low water absorption, and static water contact angles exceeding 100° for coated fabrics. SiO₂/TiO₂ composite WPU coatings substantially improve hydrostatic pressure resistance across various fabrics, with 380T polyester taffeta demonstrating the best performance. This resistance remains remarkably stable after standard washing, indicating excellent wash fastness and practical applicability. Full article

The conventional production of waterborne polyurethane (WPU) typically relies on organic solvents to regulate viscosity; additionally, traditional ionic WPU systems still utilize volatile neutralizers, raising environmental and health concerns. To overcome these limitations and reduce dependence on petrochemical resources, this study presents a solvent-free approach for WPU synthesis using isophorone diisocyanate (IPDI), polytetrahydrofuran (PTMG), and the nonionic PEG derivative Ymer^TM A-130. In addition, castor oil (CO), a renewable and hydroxyl-rich bio-based material, was incorporated as a partial substitute for PTMG to improve both sustainability and material performance. The effects of varying substitution ratios of castor oil on the physical properties of the resulting dispersions, dried films, and coatings were initially investigated. The results indicate that increasing the castor oil content from 0 wt% to 11.8 wt% led to an enhancement in tensile strength, rising from 1.45 MPa to 2.40 MPa. Concurrently, the temperature at 5% weight loss (Td_5%) shifted upward from 263.84 °C to 285.36 °C, indicating a favorable trend in thermal stability. Furthermore, the preliminary solvent resistance, surface wetting characteristics, and environmental durability of the prepared coatings were evaluated and discussed. Full article

To enhance flame retardancy of waterborne polyurethane (WPU) coatings, this paper proposes a co-modification method using modified graphene oxide (SiO₂@GO) and a phosphorus flame retardant (P-). SiO₂@GO refers to graphene oxide (GO) with an attached silicon dioxide (SiO₂) layer, while the phosphorus flame retardant (P-) in this work is THPO, a reactive flame retardant used as a chain extender. The influence of component additions on flame retardancy was systematically investigated. Modified WPU coatings (P-SiO₂@GO/WPU) were prepared using THPO and SiO₂@GO as flame-retardant chain extenders. The morphology, structure, and thermal stability of P-SiO₂@GO/WPU were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). At 2% SiO₂@GO, coatings showed enhanced hydrophobicity (water repellency) and thermal stability. With 4% phosphorus flame retardant (P-), the limiting oxygen index (LOI, a measure of flame retardancy) reached 32.2%, and the heat release rate was 32.4% lower than before modification. A continuous, dense P/Si-containing carbonaceous ceramic-like barrier layer was formed, effectively blocking the release of combustible gases and the transfer of heat, thereby demonstrating excellent flame retardancy. This synergistic P-SiO₂@GO/WPU modification offers theoretical support and practical guidance for optimizing and enhancing the flame-retardant performance of WPU coatings. Full article

Waterborne epoxy resin emulsified asphalt (WEA) is often used as a preventive maintenance material for asphalt pavement due to its excellent mechanical properties and high-temperature stability. However, its relatively poor toughness and low-temperature crack resistance limit its broader application. To address this issue, a PPG-IPDI-based waterborne polyurethane/epoxy resin (WER/PU) emulsion was synthesized via the prepolymer dispersion method using polypropylene glycol (PPG), isophorone diisocyanate (IPDI), 2,2-bis(hydroxymethyl)propionic acid (DMPA), and epoxy resin (E-44) as the main raw materials. Fourier transform infrared (FT-IR) spectroscopy confirmed that flexible polyurethane segments were successfully grafted onto the epoxy resin. This WER/PU emulsion was then incorporated as a modifier into emulsified asphalt to prepare waterborne polyurethane/epoxy resin composite-modified emulsified asphalt (WER/PU-CMEA). A series of laboratory tests were conducted to compare the compatibility, conventional properties, mechanical performance, high temperature rheological properties, low-temperature crack resistance and aging resistance of ordinary emulsified asphalt (OEA), WEA, and WER/PU-CMEA. Scanning electron microscopy (SEM) was employed to analyze the modification mechanism of WEA by WPU. The results show that WER/PU exhibits good compatibility with emulsified asphalt, and the synergistic effect of WER/PU significantly enhances the overall performance of the emulsified asphalt. Compared with WEA, WER/PU-CMEA shows a slight decrease in tensile strength and high-temperature stability, but it notably improves material compatibility, flexibility, bond strength, elongation at break, high-temperature creep-recovery performance, and low-temperature crack resistance. This study provides a promising approach for developing high-performance emulsified asphalt materials, which have strong application potential in pavement maintenance, waterproof coatings, and tack coats. Full article

The self-formed rust layer is significant for weathering steels because their corrosion resistance in a marine atmospheric environment mainly relies on the stability, uniformity and compactness of the rust layer. However, the initial stage of rust formation is vulnerable and prone to being disturbed by the external environment, compromising the protectiveness of the rust layer at a later stage. Therefore, weathering steel often requires the application of rust stabilization techniques. This study has developed a waterborne polyurethane (WPU)-based coating incorporated with mesoporous/hollow SiO₂ nanoparticles, acting as the primary components for the construction of pathways for gaseous H₂O and O₂, as well as for Cl⁻ dissolved in moisture, while blocking liquid water. Salt spray was applied to accelerate the rust formation process, and rust can form beneath the coating, which provides shelter for rust formation against the external environment. Hexamethyldisilazane (HMDS) was applied to further hydrophobize the nanoparticles, and a hydrophobic surface with self-cleaning properties was achieved. The hydrophobized and non-hydrophobized coatings with different thicknesses (10–80 µm) were systematically compared: the morphology of the rust layer and coating surface after salt spray was investigated, the ability of the rust layer to inhibit chloride ingress was compared, and the electrochemical behaviors were analyzed. This study presents a new strategy for weathering steel rust stabilization that features maneuverability, environmental friendliness and low cost. Full article

Waterborne polyurethane (WPU) is widely used in flexible films and textile finishing, but its intrinsic flammability, severe melt dripping, and sensitivity to polar additives restrict its fire-safe applications. Herein, a phosphorous acid-protonated chitosan (PCS) was designed as an emulsion-adaptable bio-based modifier and incorporated into cationic WPU via a facile aqueous blending route, yielding transparent multifunctional composite films and flame-retardant textile coatings. Unlike conventional flame-retardant WPU systems that rely on reactive monomers or suffer from poor emulsion compatibility, this work proposes an emulsion-compatible strategy based on PCS, enabling the simultaneous integration of dispersion stability, flame retardancy, and antibacterial functionality within a single system. PCS could be stably accommodated in the WPU latex without visible precipitation or demulsification after centrifugation, and the resulting films preserved a continuous matrix structure with uniformly distributed PCS-rich nanodomains. Rheological analyses revealed that the polar groups of PCS established strong intermolecular associations with urethane segments, strengthening the physical network. The char residue at 700 °C increased from 0.7 wt% for neat WPU to 32.7 wt% for WPU/PCS-5. Meanwhile, WPU/PCS-5 achieved a limiting oxygen index of 35.4% and a UL-94 V-0 rating, while its peak heat release rate and total heat release were reduced by 73.4% and 41.8%, respectively. The composite films also showed nearly complete antibacterial efficiency against Escherichia coli and Staphylococcus aureus. As a textile coating, WPU/PCS-5 enabled immediate self-extinguishing of cotton fabric, increased the limiting oxygen index from 18.5% to 27.2%, and reduced the damaged length from 30.0 to 11.0 cm. This work demonstrates that an emulsion-compatible strategy based on PCS can effectively integrate dispersion stability, fire safety, multifunctionality, and coating applicability into WPU materials. Full article

With the demand for high-voltage electrical insulation systems increasing, the development of environmentally friendly anti-corona materials with reliable nonlinear electrical properties has become essential. In this work, a waterborne polyurethane/epoxy (WPU/EP) composite coating was fabricated using micron-sized SiC (α-SiC), nano-sized SiC (β-SiC), and n-ZnO as multi-scale fillers. Its microstructure, nonlinear conductivity, flashover characteristics, and electro-thermal aging performance were systematically investigated. The results indicate that the incorporation of α-SiC significantly enhances conductivity under high electric fields by forming conductive pathways, while β-SiC further improves nonlinear behavior through interfacial bridging effects. The addition of n-ZnO modifies interfacial characteristics and contributes to improved electrical response. Moreover, the flashover performance is strongly dependent on filler composition, showing a critical role of nano-fillers in charge trapping and transport regulation. Electro-thermal aging tests on simulated stator bars reveal that the developed coating exhibits improved resistance to degradation compared with conventional materials. These findings demonstrate the effectiveness of multi-scale filler design in tailoring the electrical and insulation performance of waterborne anti-corona coatings. Full article

To address the trade-off between storage stability and curing reactivity in NCO-terminated waterborne polyurethane (WPU) systems, a solvent-free WPU emulsion with dual-curing characteristics was developed using vanillin (VAN) and 2-hydroxyethyl acrylate/pentaerythritol triacrylate (HEA/PETA). Hexamethylene diisocyanate (HDI) and 2,2-bis(hydroxymethyl)butyric acid (DMBA) were used as the isocyanate component and internal hydrophilic moiety, respectively, to prepare a self-dispersible polyurethane prepolymer. VAN was introduced as a latent isocyanate-related component, while HEA/PETA served as acrylate-bearing reactive modifiers, followed by self-emulsification to form a stable aqueous dispersion. The prepolymer structure, curing behavior, and adhesive performance on bamboo substrates were systematically investigated. The results supported the successful introduction of VAN-derived structures into the polyurethane chains and the retention of polymerizable C=C bonds from HEA/PETA. Thermal analysis suggested dual-curing behavior with two distinguishable thermal events, involving lower-temperature polymerization of unsaturated groups and a VAN-related higher-temperature reaction. The resulting WPU exhibited dry and wet shear strengths above 23 MPa and 9 MPa, respectively. These findings demonstrate a feasible strategy for integrating emulsion stability, staged curing, and adhesive performance in solvent-free WPU systems. Full article

Wind turbine blades are exposed to multiple coupled stressors requiring protective coatings with ultra-low volatile organic compound (VOC) content, thick-film capability, and long-term durability. This review critically evaluates waterborne polyurethane (WPU) coatings as a sustainable solution, benchmarking five synthesis routes—prepolymer emulsification, acetone process, melt dispersion, ketimine/ketazine chemistry, and self-emulsification—with prepolymer emulsification identified as the most industrially mature method. Key modification strategies are systematically compared, including nano-reinforcement, surface energy control, self-healing chemistries, and bio-based approaches. Based on a synthesis of laboratory, wind-tunnel, and field studies, three critical bottlenecks—thick-film formation, nanofiller dispersion, and long-term weatherability—are identified. To address these, a layered coating architecture is proposed, integrating a low-surface-energy topcoat, a lamellar-barrier mid-coat, and a post-crosslinked primer. This framework aims to guide the industrial deployment of WPU thick-film blade coatings in offshore and other extreme environments. Full article

Resin and interlayer properties play significant roles in the resistance to impact of fibre-reinforced polymer composites (FRPCs). To investigate the contribution of each factor within the coupled variables to the impact resistance ability of FRPCs, in this work, waterborne polyurethane (WPU) with different tensile elastic modulus, tear strength and bonding strength was obtained. To systematically evaluate the impact resistance and failure mechanisms of the composite materials under varying external loads, impact resistance tests, numerical simulations, and relative weight analysis were conducted. The relative weight analysis results quantified the individual contributions of these three factors to the overall energy absorption capacity across diverse loading conditions. The results indicated that with the increasing rate of the external loading, the resin modulus consistently contributed more significantly to energy absorption than tear strength of resin and interlayer strength, reaching up to 44.3%. In ballistic penetration tests, with the increase in resin modulus, the ballistic performance of PE/WPU laminates demonstrated an S-shaped downward trend. Composites prepared with more rigid matrix could lead to unsatisfactory interlayer damage. A more robust structure could result in fibre pull-out and breakage to a greater extent at the point of forced impact while less in the secondary affected area, presenting comparatively lower impact resistant performance. Full article

Biofouling has a detrimental effect on marine infrastructure and poses a severe challenge to the global marine industry. Therefore, developing efficient and environmentally friendly anti-fouling coatings to protect those facilities has become extremely necessary nowadays. To address marine biofouling, a series of photocurable degradable waterborne boron-containing polyurethane acrylate (WPU-PTPBx) anti-fouling coatings were prepared by grafting pyridine-triphenylborane (PTPB) onto polyurethane side chains and UV curing. FTIR and ¹H NMR confirmed the successful grafting of PTPB. The WPU-PTPBx aqueous dispersions had a particle size of 30~75 nm with excellent thermal storage stability. DSC and XRD characterizations revealed the amorphous structure of the coatings, which favored biodegradation. All coatings exhibited adhesion strength over 2 MPa, meeting marine application requirements. Antibacterial and anti-algal tests showed that PTPB content positively correlated with anti-fouling performance: the coating achieved a 99.66% inhibition rate against Escherichia coli and reduced the adhesion density of Nitzschia closterium to only 36.9 cells/mm². With favorable degradability and outstanding anti-fouling performance, WPU-PTPBx coatings are promising green anti-fouling materials for marine applications. Full article

To tackle the long-standing issue of inadequate corrosion protection in waterborne coatings, this study innovatively incorporates hollow glass microspheres (HGB) into waterborne epoxy zinc-rich primers through physical blending, constructing a dual-layer synergistic anticorrosion system comprising an HGB-modified primer and a zirconium phosphate/urushiol titanium polymer (UTPCZrP)-modified waterborne epoxy topcoat. Optimal performance is achieved with 2 wt% HGB addition: the dual-layer coating retains favorable physicochemical and mechanical properties while enhancing anticorrosion performance by 1–2 orders of magnitude, boasting an impedance of 3.2 × 10⁶ Ω, a corrosion rate as low as 5.71 × 10^–6 mm/year, 99.98% protection efficiency (stable after 25-day immersion), and 720 h salt spray resistance without corrosion diffusion. This method exhibits universality in waterborne polyurethane (WPU) and polyester (WPE) systems, yielding impedance values of 3.57 × 10⁶ Ω and 2.7 × 10⁶ Ω, respectively, with over 90% improved anticorrosion performance and long-term stability. By optimizing components and synergistic system design, this work significantly enhances waterborne coatings’ anticorrosion efficiency, reduces raw material costs, and provides a scalable technical pathway for high-performance, eco-friendly anticorrosion coatings. Full article