Search Results (111)

The escalating climate change and extreme weather conditions have highlighted the limitations of conventional textiles in body temperature regulation Phase-change thermoregulatory fibers can maintain constant temperature when environmental conditions fluctuate, effectively meeting human comfort requirements. To investigate the temperature-regulating properties of TempSolution viscose/cotton thermoregulatory yarn in seamless knitted fabrics, this study examined three different knitted fabric structures along with varying blend ratios and linear densities of TempSolution viscose/cotton yarn as experimental variables. According to a full factorial experimental design, eighteen fabric samples and corresponding garment prototypes were produced on a seamless circular knitting machine. Differential scanning calorimetry (DSC) and thermal manikin tests were conducted to compare the thermoregulatory performance and thermal comfort of seamless knits with different yarn compositions and structures. The results demonstrated that among the fabric structures, the 1 + 3 mock rib configuration exhibited superior thermal resistance and comfort properties. Regarding yarn types, the 50/50 TempSolution blend with 50 s yarn count showed relatively superior performance across all test parameters, providing a theoretical foundation for developing phase-change knitted fabric. Full article

This research highlights the issue that large amount of sweat generated by metabolism cannot be discharged from the internal environment of traditional fire suits when firefighters are intensively operating in high-temperature environments. This is highly prone to bacterial growth, which brings much harm to their health. Therefore, this study aims to present a new fire-retardant fabric with both antibacterial and high hygroscopic properties. Blended fibers were used including aramid 1313 fibers with excellent flame retardancy and flame-retardant viscose fibers. By uniformly embedding antibacterial nanofibers into the microfiber aggregates and controlling the adhesion behavior at the cross-scale interfaces of micro–nano fibers, the fire-retardant yarns were endowed with both antibacterial and moisture-transporting properties. The bacterial inhibition rate was calculated by comparing colonies cultured on EF fabric versus NF fabric. Additionally, the antibacterial and moisture-wicking properties of the fabrics were verified through tests such as placing the fabrics vertically in liquid to measure the height of absorbed moisture. This prepared functionally integrated fabric has excellent antibacterial properties even after 50 washing cycles. Its antibacterial rate against Escherichia coli and Staphylococcus aureus kept a preferred result of 99%. Its moisture-transporting performance has also been significantly improved. Based on the above, this study has not only successfully developed a flame-retardant fabric with high antibacterial and moisture-wicking properties, but more importantly, the method demonstrates a degree of universal applicability. Full article

High-performance spun bionanocomposite fibers, composed of high-molecular-weight chitosan (HMW), low-molecular-weight chitosan “oligomers” (LMW), and cellulose nanofibers (CNFs), were successfully fabricated via gel spinning of viscous aqueous chitosan (CHI) based formulations into a NaOH coagulation bath. The X-ray diffraction (XRD) analysis revealed that the incorporation of cellulose nanofibers contributed to enhance crystallinity of chitosan in spun fibers. The spinning process, which comprised sequential acidic solubilization, basic neutralization, stretching, and drying steps, produced chitosan/CNF composite fibers with high crystallinity, further enhanced by the incorporation of low molecular weight chitosan. The cellulose nanofibers seem to promote CHI crystallization, by acting as nucleation sites for the nucleation and growth of chitosan crystals, with those latter of LMW further enhancing crystallization and orientation due to higher mobility of shorter polymer chains. Two-dimensional XRD patterns demonstrated the preferential alignment of both CNFs and chitosan crystals along the fiber axis. Increasing the proportion of short-chain chitosan led to a reduction of the viscosity of collodion, facilitating the spinning of solutions with higher polymer concentrations. The X-ray diffraction (XRD) analysis revealed that the addition of low-molecular-weight chitosan (LMW), with an intermediate molecular weight Mw of ~4.4 × 10⁴ g/mol, produced the most significant improvements in the crystallinity index (CrI) and orientation. This structural enhancement corresponded to superior mechanical properties like Young’s modulus, yield stress σ_y, and stress-at-break σ_b of the processed composite fibers. By incorporating that intermediate molecular weight chitosan, a Young’s modulus as high as 20 GPa was achieved for the spun composite fibers, which was twice higher than the modulus of around 10 GPa obtained by adding the lowest molecular weight chitosan of Mw ~ 2.9 × 10⁴ g/mol in the composite, and largely above the modulus of around 5 GPa obtained for fiber just spun with chitosan without incorporation of cellulose nanofibers. Full article

The main aim of this study is to produce TEOS-based fibers using the electrospinning method with solutions without carrier polymers, unlike most TEOS-based fibers that are produced with polymer additives. This study provides fundamental insights into the production and characterization of TEOS-based fibers and offers a general overview of their potential applications. We investigate the production and overlaying of their morphological, chemical, thermal, and electrochemical properties. The effects of electrospinning parameters such as voltage, flow rate, and solution viscosity on fiber morphology were examined, revealing a strong dependence of fiber diameter and structural uniformity on these parameters. Furthermore, TEOS-based fibers containing nickel–manganese–cobalt oxide (NMC) were fabricated, and their electrochemical behavior was investigated. The analyses indicate that the addition of NMC enhances the electrochemical properties of the TEOS fibers; however, the system still requires further improvement to be effective in energy-storage applications. To investigate how the flow properties of the solution affect fiber generation during electrospinning, viscosity measurements were conducted on the TEOS-based solution. Differential thermal analysis (DTA) was applied to assess the thermal behavior and stability of the fibers at elevated temperatures. The produced fibers were analyzed using various characterization techniques. As a result, thin fibers were successfully produced. Full article

A multimode magneto-optical fiber based on Tb³⁺-containing borogermanate glass was designed, fabricated, and characterized, aiming at potential sensing applications. There are continuing challenges in the development of single-mode (SMF) or multimode (MMF) optical fibers doped with rare-earth (RE) ions and exhibiting high Verdet constants, related to devitrification of the precursor glass. Most RE-doped glass compositions are not suitable as precursors for core-cladding fiber production due to devitrification processes and consequent poor optical quality. Application as Faraday rotators is limited by the intrinsically low Verdet constant of silica (~0.589 rad T⁻¹ m⁻¹ at 1550 nm and 0.876 rad T⁻¹ m⁻¹ at 1310 nm). Borogermanate glasses are good candidates for manufacturing optical fibers due to their excellent potential to solubilize high concentrations of Tb³⁺ ions as well as satisfactory thermal stability. In this work, a magneto-optical core-cladding borogermanate fiber with a 227 μm diameter was fabricated, with characterization using differential scanning calorimetry (DSC), thermomechanical analysis (TMA), viscosity measurements, M-lines spectroscopy, UV-Vis-NIR absorption spectroscopy, the cut-back technique, and magneto-optical measurements. The measured numerical aperture (NA) was 0.183, with minimum attenuation of 13 dB m⁻¹ at 1270 nm. The Verdet constant (V_B) reached −6.74 rad T⁻¹ m⁻¹ at 1330 nm. Full article

This study explores the challenge of using anthocyanin-rich natural deep eutectic solvent (NADES) extracts to produce electrospun nanofibers for biodegradable freshness indicators. Red cabbage was extracted with two choline chloride-based NADESs (with citric or lactic acid), modified with 10–50% ethanol to lower viscosity, and compared with a standard 50% ethanol-water solvent. The citric acid NADES with 30% ethanol gave the highest anthocyanin yield (approx. 0.312 mg/mL, more than 20 times higher than the ethanol extract at approx. 0.014 mg/mL). For fiber fabrication, a polymer carrier blend of poly(ethylene oxide) (PEO) and sodium alginate (Alg) was employed, known to form hydrogen-bonded networks that promote chain entanglement and facilitate electrospinning. Despite this, the NADES extracts could not be electrospun into nanofibers, while the ethanol extract produced continuous, smooth fibers with diameters of approximately 100 nm. This highlights a clear trade-off; NADESs improve anthocyanin recovery, but their high viscosity and low volatility prevent fiber formation under standard electrospinning conditions. To leverage the benefits of NADES extracts, future work could focus on hybrid systems, such as multilayer films, core-shell fibers, or microcapsules, where the extracts are stabilized without relying solely on direct electrospinning. In storage tests, ethanol-extract nanofibers acted as effective pH-responsive indicators, showing visible color change from day 4 of meat storage. At the same time, alginate films with NADES extract remained unchanged after 12 days. These results highlight the importance of striking a balance between chemical stability and sensing sensitivity when designing anthocyanin-based smart packaging. Full article

Compared with traditional continuous plant fiber-reinforced thermoplastic composites, their 3D-printed counterparts offer distinct advantages in the rapid fabrication of complex geometries with integrated forming capabilities. However, the impregnation process of continuous plant fiber yarn with thermoplastic resin presents greater technical challenges compared to conventional synthetic fibers (e.g., carbon or glass fibers) typically employed in continuous fiber composites, owing to the yarn’s unique twisted structure. In addition, low molding pressure during 3D printing makes resin impregnation more difficult. To address the impregnation difficulty within plant fiber yarn during 3D printing, we employed two low-viscosity resins, liquid thermoplastic resin (specifically, reactive methyl methacrylate) and thermosetting epoxy resin, to pre-impregnate flax yarns, respectively. A dual-resin prepreg filament is developed for 3D printing of flax fiber-reinforced composites, involving re-coating pre-impregnated flax yarns with polylactic acid. The experimental results indicate that liquid thermoplastic resin-impregnated composites exhibit enhanced mechanical properties, surpassing the epoxy system by 39% in tensile strength and 29% in modulus, attributed to improved impregnation and better interfacial compatibility. This preparation method demonstrates the feasibility of utilizing liquid thermoplastic resin in 3D-printed continuous plant fiber composites, offering a novel approach for producing highly impregnated continuous fiber filaments. Full article

Developing high-performance bio-based epoxy resins as sustainable alternatives to petroleum-derived bisphenol A (BPA) epoxies for recyclable carbon fiber-reinforced polymers (CFRPs) is pivotal in materials research. Herein, the bio-based bisphenol monomer BDEF was synthesized from the lignin derivative 4-propylguaiacol. The derived epoxy monomer BDEF-EP was cured with adipic acid to form a bio-based vitrimer. Stress relaxation synergistically accelerates through intrinsic dynamic carboxylic acid ester exchange and enhanced chain mobility from the flexible propyl structure. At 220 °C, this vitrimer shows rapid stress relaxation (τ* < 30 s) and repairs ~90% of surface scratches in 30 min. It exhibits tensile and flexural strengths of 69 MPa and 105 MPa, respectively. BDEF-EP’s low viscosity reduces diluent needs in composite fabrication, lowering costs and improving efficiency. The resulting bio-based CFRP achieves tensile and flexural strengths of 543 MPa and 414 MPa, respectively, which are comparable to commercially available petroleum-derived CFRP. In addition, CFRP containing dynamic crosslinked networks demonstrates degradable recyclability in ethylene glycol solvent, preserving the surface morphology and chemical structure of recovered carbon fibers. The results demonstrate that this bio-based epoxy vitrimer has promising potential for developing sustainable, degradable, and recyclable CFRP composites. Full article

The aim of this study is to identify the textile materials used to make Bulgarian folk costumes and to support the process of conservation and restoration of ethnographic objects. In the 18th and 19th centuries, folk costumes were made almost exclusively of natural materials, while in the first half and middle of the 20th century, they included contemporary synthetic and regenerated cellulose materials, as well as blends of these materials with natural fibers. A series of historical textiles and contemporary industrial fabrics were studied using a variety of analytical approaches, including micro-chemical staining and solubility tests, optical microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and infrared (IR) spectroscopy. IR measurements were carried out in attenuated total reflectance (ATR) and external reflectance (ER) modes using a portable IR spectrometer, which enabled non-invasive analysis. The analysis revealed that the composition of the industrial fabrics and historical textiles encompassed synthetic fibers, such as polyester and polyamide, while others were made of regenerated cellulose fibers like viscose. Additionally, some textiles had a mixed composition of cotton and polyester or silk and viscose. The combined analytical approach provided reliable identification of both the synthetic and natural textile materials. Full article

Electrospun nanofibrous mats from bovine, porcine, and fish gelatin were systematically fabricated at varying concentrations (15, 20, 25, and 30 wt.%) to investigate the influence of molecular characteristics on morphology, crystallinity, mechanical properties, thermal behavior, and solubility. Optimal ranges of viscosity (0.08–1.47 Pa·s), surface tension (35–50 mN·m⁻¹), and electrical conductivity (0.18–1.42 mS·cm⁻¹) were determined to successfully produce homogeneous fibers. Bovine and porcine gelatin, characterized by higher molecular weight and greater proline/hydroxyproline content, exhibited thicker (up to 725 ± 41 nm at 30 wt.%) and less uniform nanofibers due to higher viscosity and surface tension, restricting polymer jet stretching. Conversely, fish gelatin, with lower molecular weight and limited proline/hydroxyproline content, produced significantly thinner (as low as 205 ± 28 nm at 20 wt.%) and more uniform nanofibers. X-ray diffraction analysis revealed distinct crystallinity transitions associated with triple-helix and amorphous structures, dependent on gelatin type and concentration, including the emergence of peaks near 7.9° and 20.1° (2θ) for bovine gelatin. Mechanical tests demonstrated superior tensile strength for bovine gelatin (up to 2.9 MPa at 30 wt.%), balanced properties for porcine gelatin, and exceptional elasticity for fish gelatin. Thermal analysis indicated concentration-dependent shifts in viscoelastic behavior and damping performance. Solubility studies showed rapid dissolution of low-concentration fish gelatin fibers, moderate stability for intermediate-concentration porcine gelatin, and excellent structural retention for high-concentration bovine gelatin. These results demonstrate the potential for tailored gelatin nanofiber design to meet specific functional requirements in biomedical applications. Full article

The increasing depth of coal mine construction has led to complex geological conditions involving high ground stress and elevated groundwater levels, presenting new challenges for water-sealing technologies in rock microfissure grouting. This study investigates ultrafine cement grouting in microfissures through systematic analysis of slurry properties and grouting simulations. Through systematic analysis of ultrafine cement grout performance across water–cement (W/C) ratios, this study establishes optimal injectable mix proportions. Through dedicated molds, sandstone-like microfissures with 0.2 mm apertures and controlled roughness (JRC = 0–2, 4–6, 10–12) were fabricated, and instrumented with fiber Bragg grating (FBG) sensors for real-time strain monitoring. Triaxial stress-permeation experiments under 6 and 7 MPa confining pressures quantify the coupled effects of fissure roughness, grouting pressure, and confining stress on volumetric flow rate and fissure deformation. Key findings include: (1) Slurry viscosity decreased monotonically with higher W/C ratios, while bleeding rate exhibited a proportional increase. At a W/C ratio = 1.6, the 2 h bleeding rate reached 7.8%, categorizing the slurry as unstable. (2) Experimental results demonstrate that increased surface roughness significantly enhances particle deposition–aggregation phenomena at grouting inlets, thereby reducing the success rate of grouting simulations. (3) The volumetric flow rate of ultrafine cement grout decreases with elevated roughness but increases proportionally with applied grouting pressure. (4) Under identical grouting pressure conditions, the relative variation in strain values among measurement points becomes more pronounced with increasing roughness of the specimen’s microfissures. This research resolves critical challenges in material selection, injectability, and seepage–deformation mechanisms for microfissure grouting, establishing that the W/C ratio governs grout performance while surface roughness dictates grouting efficacy. These findings provide theoretical guidance for water-blocking grouting engineering in microfissures. Full article

The precursor-derived ceramic route is recognized as an advanced and efficient technique for fabricating ceramic matrix composites, particularly suitable for the development and microstructural tailoring of continuous fiber-reinforced ceramic matrix composites. In this work, octamethylcyclotetrasiloxane and tetravinylcyclotetrasiloxane were employed as monomers to synthesize a branched siloxane via ring-opening polymerization. A subsequent hydrosilylation reaction led to the formation of polyvinylsiloxane with a three-dimensional crosslinked structure. The precursor exhibited excellent fluidity, adjustable viscosity, and superior thermosetting characteristics, enabling efficient impregnation and densification of reinforcements through the polymer infiltration and pyrolysis process. Upon pyrolysis, the polyvinylsiloxane gradually converted from an organic polymer to an amorphous inorganic ceramic phase, yielding silicon oxycarbide ceramics with a high ceramic yield of 81.3%. Elemental analysis indicated that the resulting ceramic mainly comprised silicon and oxygen, with a low carbon content. Furthermore, the material demonstrated a stable dielectric constant (~2.5) and low dielectric loss (<0.01), which are beneficial for enhanced thermal stability and dielectric performance. These findings offer a promising precursor system and process reference for the low-cost production of high-performance, multifunctional ceramic matrix composites with strong potential for engineering applications. Full article

Despite the strength and ductility of steel reinforcing bars, their susceptibility to corrosion can limit the long-term durability of reinforced concrete structures. Fiber-reinforced polymer (FRP) reinforcing bars made with a thermosetting matrix offer corrosion resistance but cannot be field-bent, which limits flexibility during construction. FRP reinforcing bars made with fiber-reinforced thermoplastic polymers (FRTP) address this limitation; however, their high processing viscosity presents manufacturing challenges. In this study, the Continuous Forming Machine, a novel pultrusion device that uses pre-consolidated fiber-reinforced thermoplastic tapes as feedstock, is described and used to fabricate 12.7 mm nominal diameter thermoplastic composite rebars. Simple bend tests on FRTP rebar that rely on basic equipment are performed to verify its ability to be field-formed. The manual bending technique demonstrated here is practical and straightforward, although it does result in some fiber misalignment. Subsequently, surface deformations are introduced to the rebar to promote mechanical bonding with concrete, and tensile tests of the bars are conducted to determine their mechanical properties. Finally, flexural tests of simply-supported, 6 m long beams reinforced with FRTP rebar are performed to assess their strength and stiffness as well as the practicality of using FRTP rebar. The beam tests demonstrated the prototype FRTP rebar’s potential for reinforcing concrete beams, and the beam load–deformation response and capacity agree well with predictions developed using conventional structural analysis principles. Overall, the results of the research reported indicate that thermoplastic rebars manufactured via the Continuous Forming Machine are a promising alternative to both steel and conventional thermoset composite rebar. However, both the beam and tension test results indicate that improvements in material properties, especially elastic modulus, are necessary to meet the requirements of current FRP rebar specifications. Full article

This study aimed to evaluate the nanomechanical surface properties and water uptake of a flowable short-fiber-reinforced composite (SFRC) using various restorative techniques in order to assess its potential as a standalone restorative material. Nanoindentation and compressive creep testing were employed to characterize material performance. Three resin composites were examined: a flowable SFRC (everX Flow), a bulk-fill particulate filler composite (PFC), and a conventional PFC. Five experimental groups were established based on the restorative technique: layered PFC, layered SFRC, bulk SFRC, bulk PFC, and a bi-structure combining SFRC and PFC. Ninety standardized specimens (n = 18/group) were fabricated. Static and creep nanoindentation tests were conducted to assess surface properties, and water uptake was measured over a 30-day period. Data were analyzed using one-way ANOVA and Bonferroni post hoc tests. Nanoindentation revealed significant differences in hardness, with bulk PFC exhibiting the lowest values (p < 0.001). Creep testing indicated changes in modulus and viscosity following water storage. Notably, bulk SFRC showed the lowest water absorption (p < 0.001). Overall, bulk-applied SFRC demonstrated favorable nanomechanical properties and reduced water uptake, demonstrating its suitability as a standalone restorative material. Further clinical investigations are recommended to validate its long-term performance. Full article

Additive manufacturing (AM) has the potential to revolutionize the fabrication of continuous carbon fiber-reinforced polymer composites (CCFRPCs). Among AM techniques, direct ink writing (DIW) with ultraviolet (UV) curable resin shows promise for creating CCFRPCs with high manufacturing speed, high fiber volume fraction, and low energy consumption. However, issues such as incomplete curing and weak interfacial bonding, particularly in dense fiber bundles, limit the mechanical performance. This study addressed these challenges using pre-impregnated systems (PISs), which is a process developed to impregnate dry fiber bundles with partially cured resin before being used for DIW printing, to enhance resin-fiber adhesion and fiber–fiber bonding within fiber bundles. By optimizing resin viscosity and curing conditions in the PIS process, samples treated by PIS achieved improved mechanical properties. Tensile and bending tests revealed significant performance gains over non-PIS treated samples, with tensile stiffness increasing by at least 39% and bending stiffness by 45% in 3K fiber bundles. Tensile samples with thicker fiber bundles (6K and 12K) exhibited similar improvements. On the other hand, while all samples exhibit enhanced mechanical properties under bending deformation, the improvement of flexural stiffness and strength with thicker fiber bundles is shown to be less significant than those with 3K fiber bundles. Overall, composites made with PIS-treated fibers can enhance mechanical performance compared with those made with non-PIS-treated fibers, offering the scaling capability of printing thicker fiber bundles to reduce processing time while maintaining improved properties. It emphasizes the importance of refining the pre-processing strategies of large continuous fiber bundles in the AM process to achieve optimal mechanical properties. Full article