Search Results (509)

Polyethylene (PE) fibers enable engineered cementitious composites (ECCs) to achieve tensile strain-hardening and multiple-cracking behavior through fiber bridging; however, the relatively large crack widths that can develop in PE fiber-reinforced high-strength ECC (HS-ECC) may limit its autogenous self-healing capability. This study therefore establishes a direct link between PE fiber-mediated crack control, matrix micromechanical tailoring, and autogenous self-healing. The critical crack-width thresholds for reliable self-healing were first determined using water sorptivity tests combined with wet–dry cyclic exposure. The results showed that transport properties could be restored to nearly their original levels when crack widths were below approximately 50 μm in tap water and 60 μm in seawater. Based on these thresholds, waste fly ash ceramsite (FAC) was subsequently incorporated to tailor the matrix fracture characteristics and promote saturated multiple cracking under PE fiber bridging. Replacing 20% of quartz sand with FAC increased the tensile strain capacity from 2.75% to 7.14% and the crack number from 17 to 61, while reducing the average crack width from 110 μm to approximately 49 μm. The refined crack pattern enabled reliable autogenous self-healing under wet–dry cycling, with seawater exhibiting particularly favorable healing behavior. These findings provide a micromechanics-based strategy for designing sustainable PE fiber-reinforced HS-ECC with enhanced ductility, crack control, and intrinsic self-healing capability. Full article

Fiber-reinforced polymer composites are attractive multifunctional material systems for aerospace, defense, and transportation because of their low density, high specific mechanical properties, and tailorable electromagnetic response. This study comparatively evaluated the effects of fiber system, thermoset matrix, and hybridization on the mechanical, thermomechanical, and electromagnetic behavior of Coremat interlayered sandwich composites containing carbon, glass, and aramid fabrics with polyester, vinylester, and epoxy matrices. Eighteen configurations were fabricated by hand lay-up and evaluated by tensile, three-point bending, heat deflection temperature (HDT), Vicat softening temperature (VST), and two-port S-parameter measurements over 4–40 GHz. The carbon/epoxy configuration exhibited the highest tensile strength (231.2 MPa), whereas the glass/vinylester configuration showed the highest flexural strength (160.5 MPa), HDT (128.0 °C), and VST (132.7 °C). The relatively low standard deviations across the tested configurations indicated consistent experimental repeatability and limited within-configuration dispersion. Carbon-containing systems strongly suppressed electromagnetic transmission; however, the single carbon systems were predominantly reflection driven. The carbon/glass polyester hybrid S10 provided the highest total shielding effectiveness (38.45 dB) at an overall laminate thickness of 3.30 mm, corresponding to a normalized shielding effectiveness of 11.65 dB/mm, while the carbon/aramid epoxy hybrid exhibited the highest incident-power absorption ratio (22.4%) together with very low transmission (0.22%). Overall, the results show that fiber system, matrix type, and hybrid architecture should be selected jointly when balancing structural, thermomechanical, and electromagnetic requirements. Full article

Silica-based desiccants are widely used in rotary dehumidification systems but are limited by insufficient water adsorption and mechanical durability. Herein, Al–SiO₂, Ti–SiO₂, and sequentially co-doped TiAl–SiO₂ adsorbents were prepared on glass fiber honeycomb substrates to investigate the effects of metal incorporation and pH regulation on pore structure, adsorption performance, and mechanical strength. Al incorporation under mildly acidic conditions (pH 2.5–2.7) promoted the formation of a homogeneous mesoporous network, whereas Ti incorporation under strongly acidic conditions (pH ≈ 1.0) caused rapid precursor hydrolysis, resulting in the aggregation of Ti-containing species, pore blockage, and deteriorated adsorption performance despite improved mechanical strength. A pH-mediated sequential incorporation strategy was therefore developed by introducing Ti while maintaining the reaction pH at approximately 2.0, effectively suppressing uncontrolled hydrolysis and promoting uniform Ti dispersion within the aluminosilicate framework. The resulting TiAl–SiO₂ exhibited a specific surface area of 460 m² g⁻¹, a pore volume of 0.37 cm³ g⁻¹, a low fractal dimension of 2.60, and an equilibrium water uptake of 23.08%, while maintaining a compressive strength of 1.25 MPa. These findings demonstrate that regulating precursor hydrolysis through pH control provides an effective strategy for tailoring heterometal incorporation, simultaneously optimizing pore structure and mechanical robustness, and highlighting the potential of the prepared materials as candidate desiccants for rotary dehumidification applications. Full article

Peach palm (Bactris gasipaes) heart is a sustainable, fiber- and polysaccharide-rich ingredient with potential for plant-based food structuring. This study investigated peach palm heart powder (PPHP) as a functional co-ingredient in soy protein isolate (SPI)-based inks for extrusion-based 3D food printing, focusing on rheology, printability, microstructure, molecular interactions, texture, and in vitro digestibility. Increasing PPHP concentration enhanced apparent and complex viscosity, storage modulus (G′), deformation resistance, and structural recovery while maintaining strong shear-thinning behavior, improving printing performance; PPHP8 showed the lowest dimensional deviation (0.25%) and highest shape fidelity (100.25%). PPHP was progressively incorporated into the SPI matrix, forming a denser protein–polysaccharide network primarily through non-covalent interactions, as indicated by microstructural and SDS–PAGE analyses. PPHP reduced hardness, gumminess, chewiness, and resilience but maintained springiness, enabling texture modulation, and FTIR/PCA revealed a shift from α-helical toward β-sheet-rich protein conformations, consistent with enhanced hydrogen bonding. Protein hydrolysis during simulated digestion and B. longum subsp. longum viability were not significantly compromised by PPHP incorporation. These findings demonstrate that PPHP can be strategically incorporated to tailor the rheological and textural properties of SPI-based inks for 3D printing without compromising nutritional functionality, supporting its potential as a sustainable structuring ingredient for next-generation plant-based printed foods. Full article

During resistance welding of fiber-reinforced thermoplastic composites (FRTP), lower temperatures are observed at the edge of the welding area that is vertical to the direction of the current (longitudinal edge, L-edge). This paper proposes a perforated heating element (HE) with reduced edge mesh size to increase the temperature in the L-edge, thereby mitigating the edge effect during the resistance welding of FRTPs. By reducing the mesh size in the L-edges of the welding area, a temperature gradient can be created during the heating process, thereby increasing heat generation at the L-edges of the HE. Through experimental and numerical investigations, the influence of this HE on temperature evolution and joint performance during FRTP resistance welding was investigated. A resistance model was proposed to analyze the resistance and heat generation of regions with different mesh sizes. The results show that the tailored HE increased the temperature in the L-edge area. Furthermore, the reduced mesh size decreased the resistance of the HE in the welding area, mitigating the excessive temperature in the transverse edge (T-edge) (parallel to the current direction) of the welding area. The joints welded with the tailored HE achieved a lap-shear strength (LSS) of 26.6 ± 0.8 MPa, which is 31% higher than the LSS of joints welded with unmodified HE. The proposed resistance model could predict the changing trends of resistance and heat generation in regions with different mesh sizes at the qualitative level. Further work needs to be carried out to improve its quantitative prediction ability. Full article

Poly(vinyl alcohol) (PVA) nanofibers have emerged as versatile materials in biomedical science due to the high surface-to-volume ratio enabled by nanofibrous morphologies, together with their biocompatibility, hydrophilicity, low toxicity, water solubility, and ease of chemical modification. Solution blow spinning (SBS) provides an alternative route for producing PVA-based nanofibers and is particularly relevant for PVA because the polymer is commonly processed from aqueous solutions. This review critically examines the fabrication of PVA nanofibers by SBS within the broader framework established for PVA hydrogels and electrospun PVA nanofibers, emphasizing how aqueous processing conditions govern fiber formation and morphology and how these features translate into mechanical performance and functional behavior tailored to biomedical applications. Applications in wound dressings, drug-delivery systems, tissue engineering scaffolds, and biosensors are discussed, highlighting the role of the fillers/additives in modulating biological responses and drug release behavior. Key challenges remain, including water sensitivity and PVA solubility, crosslinking approaches compatible with bioactive payloads, and limitations in mechanical robustness for certain load-bearing applications. Finally, future perspectives on scale-up and eco-friendly PVA nanofibers are outlined to support translation of SBS-derived PVA nanofibers toward clinical applications. Overall, this work positions SBS as a promising route to complement established nanofiber fabrication methods and support the sustainable integration of PVA nanofibers into next-generation biomedical solutions, while providing broader insights into the processing of aqueous polymer systems by SBS. Full article

To use renewable energy and mitigate the greenhouse gas effect on the environment, carbon dioxide (CO₂) separation is crucial. Recent research has shown that using membranes for CO₂ separation is a vital option, but challenges remain with permeability and selectivity. Blend hollow fiber membranes offer a solution to these challenges. In this study, a blend of hollow fiber membranes made of polyether sulfone (PES) and polyvinyl acetate (PVAc) was developed, along with the incorporation of fillers, to overcome the permselectivity challenge. This resulted in the creation of mixed matrix blend hollow fiber membranes by using the phase inversion method. The membranes that were developed were examined using FESEM, FTIR, XRD, TGA, and pure-gas permeation analysis. The polymer blend demonstrated miscibility and preserved strong morphological and structural stability during CO₂ and CH₄ separation tests, exhibiting little deformation and reliable performance across different feed pressures ranging from 2 to 8 bar. The addition of TiO₂ improved the compatibility of the polymer blend and increased the mobility of CO₂. At 8 bar, the optimized PES/PVAc–5 wt.% TiO₂ hollow fiber membrane reached a CO₂ permeance of 92.22 GPU, representing an enhancement of about 24.7% in CO₂/CH₄ selectivity compared to the standard membrane. This emphasizes its potential for effective biogas upgrading under high pressure. Full article

Carbon-based materials exhibit diverse structural responses to irradiation owing to their distinct dimensionality, degree of graphitization, surface chemistry, and pore architecture. Although irradiation has traditionally been regarded as a source of structural damage, increasing evidence demonstrates that controlled irradiation can be deliberately utilized to tailor defects, surfaces, interfaces, and pore structures, thereby enabling desirable functional properties. This review summarizes recent progress in the irradiation-induced structural evolution and functional applications of four representative carbon-based materials, including graphene-based materials, carbon nanotubes, carbon fibers, and activated carbon/biochar. Particular attention is given to the characteristic irradiation responses of different carbon architectures. In graphene, irradiation predominantly induces vacancies, reconstructed defects, and surface functionalization, providing active sites for environmental remediation. Carbon nanotubes additionally undergo inter-tube cross-linking and welding, enabling enhanced mechanical performance and tunable electronic properties. For carbon fibers, irradiation mainly regulates surface chemistry and fiber matrix interactions, facilitating interface engineering in high-performance composites. In activated carbon and biochar, irradiation modifies pore accessibility, structural disorder, and surface functional groups, thereby influencing adsorption and electrochemical performance. These distinct responses demonstrate that irradiation can evolve from a conventional damage process into a controllable materials-engineering strategy when appropriate irradiation conditions are employed. Finally, current challenges associated with optimal irradiation conditions, quantitative defect identification, and irradiation structure–property relationships are discussed. Based on these distinct responses, we propose an architecture-dependent irradiation–structure–function (A-ISF) framework that links the initial carbon architecture and irradiation conditions to dominant energy-deposition mechanisms, structural evolution pathways, property modulation, and ultimately functional applications. Within this framework, irradiation engineering is interpreted as a competition between beneficial structural modification and excessive radiation damage, giving rise to an application-dependent optimal irradiation window. Full article

Electrospinning is a versatile technique for producing membranes composed of submicrometric fibers and possessing high porosity and a large surface-to-volume ratio. These properties make electrospun fiber mats attractive for many applications including filtration, biomedical materials, and sensing. While conventional set-ups readily generate randomly oriented nonwovens, many applications require precise control over fiber organization. Such control can be achieved by manipulating the charged jet and the residual charges retained by deposited fibers, both governed by the electric field that is intrinsic to the electrospinning process. This review examines strategies for electrostatic control of electrospun fiber mat morphology, organized around two principal mechanisms: control of the charged jet in-flight and control of the landing jet. Auxiliary electrode-assisted electrospinning, which aims to suppress or redirect the whipping instabilities, as well as gap-separated and structured collectors that exploit electrostatic template effects, are discussed. Particular attention is given to the underlying mechanisms. Collectively, these methods illustrate how tailoring the electric field allows for the production of membranes with complex, application-specific fiber morphologies. Full article

Carbon-fiber-reinforced polymer (CFRP) composites are widely used in lightweight aerospace structures because their mechanical performance can be adapted to different structural requirements through appropriate manufacturing conditions. This study investigates the influence of curing temperature applied using temperature-controlled heated molds on the mechanical and thermo-mechanical behavior of vacuum-infused CFRP laminates manufactured with an IN2 epoxy infusion resin. Laminates were cured at room temperature (25 °C) and at 40, 50, 60, and 70 °C using heated molds. Their performance was evaluated by tensile testing, three-point bending, and heat deflection temperature (HDT) measurements. The highest tensile strength (675.06 MPa) was obtained for laminates cured at 40 °C, whereas increasing the curing temperature beyond this value did not provide further improvement in tensile performance. The highest flexural stress at the first peak (983.36 MPa) and flexural modulus (67.17 GPa) were obtained for laminates cured at 70 °C, while the highest energy absorption during bending (0.57 J) was measured for laminates cured at 40 °C. The HDT increased from 59.77 °C for room-temperature curing to 87.60 °C for laminates cured at 70 °C, indicating improved thermo-mechanical stability with increasing curing temperature. The results indicate that no single curing temperature simultaneously maximized the tensile, flexural, and thermo-mechanical properties. Instead, the optimum curing temperature depended on the specific mechanical and thermo-mechanical requirements of the intended application. The results further indicate that controlling the temperature of heated molds during manufacturing provided a practical approach for tailoring the mechanical and thermo-mechanical performance of CFRP laminates without modifying the reinforcement architecture, laminate stacking sequence, or constituent materials. Full article

Tailored flax-reinforced composites (TFRC) are being investigated as a sustainable alternative to conventional glass- and carbon-fiber-reinforced composites, having a lower fiber volume than these and the structure of the laminate with two plies (two identical layers of alkali-treated flax yarns) is unidirectional, weakly twisted, oriented at ±45°, and reinforced by stitching; it is also impregnated with bio-resin and has robust reinforcement through controlled lamination. TFRC has shear-dominated behavior under both tensile and compressive loading, due to the off-axis orientation of the fibers, but the damage evolution differs significantly. Under tensile loading, the material exhibits a lower strength (55.2 MPa), whereas under compression loading, the composite achieves a higher apparent strength (99.1 MPa). The paper provides a comprehensive analysis for structural and mechanical characterization using the following: nondestructive evaluation using ultrasound to detect internal discontinuities and assess homogeneity; optical microscopy to evaluate fiber–matrix integration and porosity reduction; and Dynamic Mechanical Analysis to assess thermomechanical transitions and storage modulus stability. Finite element simulations have been used to determine elastic properties and validate the matrix-dominated shear response. The results confirm that the [±45°]_4S sequences of TFRC optimize mechanical response and interfacial adhesion, promoting TFRC as an ecological solution for structural systems where progressive energy dissipation is preferred. Full article

A high-sensitivity fiber-optic hot-wire anemometer based on a liquid-filled leaky-guided fiber Mach–Zehnder interferometer (LGFMZI) with UV-cured polymer/aluminum-microparticle photothermal encapsulation is proposed and experimentally demonstrated. The sensing element consists of a side-polished-fiber-assisted liquid-filled hollow-core fiber structure, in which a refractive-index-selected liquid core is introduced through a microslit to tailor the modal effective refractive-index difference and enlarge the free spectral range. The sensing region is uniformly encapsulated with a UV-cured NOA81 polymer layer containing aluminum microparticles. This encapsulation layer serves as both a photothermal conversion layer under 980 nm LD heating and a mechanical reinforcement layer. Under laser heating, the sensor is subsequently cooled by external airflow, converting wind-velocity variations into monotonic wavelength shifts. Experimental results show that, at an LD current of 80 mA corresponding to an optical power of 16 mW, the single-wavelength-dip sensor achieves a maximum airflow sensitivity of −22.922 nm/(m/s). The device also exhibits a fast transient response, with a rise time of 0.606 s and a fall time of 0.316 s. The proposed liquid-filled LGFMZI combines simple fabrication, photothermal encapsulation, high spectral readability, and stable airflow response, making it suitable for real-time fiber-optic hot-wire anemometry. Full article

High-temperature graphitization inevitably compromises the surface polarity and resin wettability of polyacrylonitrile (PAN)-based high-modulus carbon fibers (HMCFs), creating a long-standing trade-off between fiber modulus and interfacial adhesion that restricts its applications. Here we report a tension–temperature synergy to overcome this limitation. HMCFs were fabricated at 1700–2100 K under axial tensions of 0–70 N, and the resulting microstructures and surface activity were characterized by X-ray diffraction, Raman spectroscopy, dynamic contact angle testing, and microdroplet debond measurements. Temperature dominates crystallite coarsening and surface-active carbon (Sac) concentration, whereas tension enhances axial lamellar orientation without inducing appreciable grain growth. At constant temperature, two competing effects, both slight crystallite growth and radial lamella rearrangement, keep Sac stable under varying tension. Fibers processed at 1900 K with 60 N tension achieve a modulus of ~350 GPa, equivalent to that of the 2100 K/10 N sample, while delivering a 13.5% higher Sac, elevated surface energy (26.3 mN·m⁻¹), and 37.9% stronger interfacial shear strength (IFSS). The Sac parameter exhibits strong correlations with surface energy and IFSS. This one-step in situ thermal strategy eliminates post-treatment and offers an industrially viable route to HMCFs with balanced modulus and intrinsic interfacial bonding. Full article

Recycled glass fiber-reinforced polymer (GFRP) powder from decommissioned wind turbine blades offers sustainable reinforcement for wood–plastic composites (WPCs), but its efficiency is limited by poor interfacial adhesion with the polypropylene (PP) matrix caused by surface epoxy residues. In this study, GFRP/WPCs with a fixed formulation of 15 wt% GFRP, 10 wt% wood flour, and 75 wt% PP were used to compare two modification strategies: MAPP compatibilization (1–7 wt%) and H₂O₂ treatment (5–30%). MAPP modification improved the mechanical properties of GFRP/WPCs, with the optimal concentration varying by property: flexural strength reached its maximum (75.45 MPa, +24.7%) at 1 wt% MAPP, while tensile strength (+9.2%), flexural modulus (+20.7%), and impact strength (+18.9%) were maximized at 3 wt% MAPP. H₂O₂ at 10% achieved higher strength gains (tensile: +23.65%, i.e., 26.7 MPa; flexural: +27.93%, i.e., 77.4 MPa; impact: +35.29%, i.e., 16.98 kJ/m²) but moderately reduced flexural modulus. FTIR confirmed up to 71.7% epoxy removal by H₂O₂, exposing cleaner fibers. Both modifications slightly lowered thermal decomposition temperatures but increased char residues and PP crystallinity via enhanced nucleation. SEM showed that MAPP created a compatible interphase, while H₂O₂ enabled direct mechanical interlocking. Surface free energy analysis revealed that MAPP increased polar components, whereas H₂O₂ increased dispersive components. Overall, MAPP offers simpler processing and balanced properties, while H₂O₂ provides superior strength at the cost of some stiffness—providing practical guidance for tailoring recycled GFRP/WPCs for construction and sustainable applications. Full article