Fibers and Polymers最新文献

We report a systematic investigation into the optimization of ZnO nanofiber-based NO gas sensors through precise control of structural parameters. By employing electrospinning technique, we fabricated ZnO nanofibers with controlled diameters (160–310 nm) and thicknesses (19–25 μm), enabling detailed analysis of structure–property relationships in gas sensing performance. The sensors exhibited optimal performance at 200 °C operating temperature, with the thinnest membrane (160 μm) and smallest fiber diameter (9.52 μm) demonstrating superior sensing capabilities. Under these optimized conditions, the sensor achieved a remarkable sensitivity of 25 (Ω/Ω) toward 500 ppb NO gas with a notably fast recovery time of 191 s. Structural characterization revealed that reducing membrane thickness by 30% enhanced sensitivity by 96%, attributed to increased pore area accessibility. In addition, decreasing nanofiber diameter by 90% resulted in a twofold improvement in NO gas sensitivity. The sensing mechanism was elucidated through energy band analysis, revealing the critical role of electron depletion layer modulation at the gas–solid interface. The sensors demonstrated excellent selectivity against common interferents including ethanol, isopropanol, and acetone, with NO response approximately 84 times greater than these compounds. This study provides crucial insights into the rational design of metal oxide nanofiber architectures for enhanced gas sensing performance, offering potential applications in both industrial and biomedical monitoring systems.

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EMI shielding films are increasingly in demand for wireless networks, wearable electronics, and navigation control systems. Given the flammability of polymers and their prolonged high power operation, it is imperative to consider the environmental and human health impact arising from fire incidents during usage. Consequently, there is a strong need to develop easily manageable and highly scalable flame-retardant EMI shielding films. Herein, we present a viable approach for fabricating a series of flexible and flame-retardant films with a sandwich structure that offers adjustable EMI shielding performance. This approach involves coating plating silver nanowires (AgNWs) assisted by polydopamine (PDA) on a commercially available nylon mesh (PA6 mesh), followed by applying a flame-retardant polyvinyl alcohol/guanidine phosphate (PVA/GP) coating. When sprayed coating 0.6 mg/cm² AgNWs, the films exhibit an EMI shielding effectiveness (SE_T) up to 55.11 dB, capable of blocking 99.999% of EM waves. Besides, such film possesses remarkable self-extinguishing property and a high thermal diffusion coefficient of 3.54 mm²/s. Therefore, the highly lightweight sandwich film holds great promise for multifunctional applications in EMI shielding on a large scale.

In recent years, there has been a growing interest in smart textiles, and photochromic compounds are well-established colorants in the manufacturing of UV-sensing smart textiles. This study investigated the optimal dyeing conditions for photochromic spiroindolinonaphthoxazines dyes, specifically trimethylspiroindoline-2,3′-3H-naphth[2,1-b][1,4]oxazine (SNO) and 9′-hydroxy-1,3,3-trimethylspiro{indoline-2,3′[3H]naphtho[2,1-b][1,4]oxazine} (SNO–OH), on polyester fabric using an aqueous exhaust dyeing method. The results revealed that the optimal conditions for dyeing polyester fabric with spiroindolinonaphthoxazines dyes are pH 8, 100 °C, and 20 min. Liquid chromatography–mass spectrometry analysis demonstrated the susceptibility of these dyes to degradation at higher dyeing temperatures and acidic pH. Notably, the singlet oxygen quencher 1,4-diazabicyclo[2,2,2] octane enhanced photochromic performance by protecting the dyes from degradation during the dyeing process. Polyester fabrics dyed with SNO exhibited superior photochromic behavior compared to those dyed with SNO–OH, including higher color build-up, exhaustion, fatigue resistance, and color fastness properties. Overall, the optimization of the dyeing conditions and the use of a singlet oxygen quencher are crucial for achieving optimal photochromic performance and dye stability on polyester fabrics.

This study presents an entirely experimental and mathematical analysis of extrusion and melt spinning to obtain polyethylene terephthalate (PET) fibers. In addition, results concerning the design and construction of a quench system were investigated. PET fibers were obtained from two raw materials: postconsumer PET thermoform packaging (R-PET) and virgin PET (V-PET). The mathematical analysis part for the extruder contemplated a melt flow model based on the Navier–Stokes constitutive equations for a rectangular coordinate in the z-direction to predict the extruded mass flow depending on processing conditions (temperature and extrusion speed) and physical properties of raw material (intrinsic viscosity and density). Concerning the spinning process, a rheological model based on the Phan–Thien and Tanner (PTT) constitutive equations was used for the simulation of the dynamic flow of postconsumer PET thermoform packaging, including the combined effects of material flow, filament cooling, air drag, surface tension, and gravity to determine the necessary quench system length to cooling melt PET fiber down to their glass transition temperature (T_g), as well as axial velocity, filament diameter, and filament temperature profiles along all draw region of the spinning process. For this, it was necessary to fabricate and evaluate three different quench system designs to ensure a uniform air velocity profile along all cooling systems. The experimental analysis contemplated all critical steps for PET fiber fabrication, such as extrusion and spinning processes. This physical and chemical characterization of raw material, extruded PET, and fabricated PET fibers were obtained. Finally, the experimental data were used to validate both mathematical models. Proper sorting of PET thermoforms, removing impurities, and appropriately operating conditions for the extrusion and spinning processes allowed us to obtain elongation at yield, Young’s modulus, and tenacity values of 4.18%, 5568.1 Kg_f/cm², and 0.94 g_f/den for V-PET fibers and 7.11%, 4795 Kg_f/cm², and 0.7 g_f/den for R-PET fibers, respectively.

Surgical site infection is a prevalent complication that significantly impacts patient survival. The use of antimicrobial sutures can effectively reduce the risk of infection in surgical patients. Surgical sutures were prepared by knitting polylactic acid fibers using a biomedical knitting machine, and drug-loaded slow-release microspheres were prepared by the emulsification-solvent evaporation method. Finally, dopamine was utilized to construct a secondary reaction platform for the sutures, which led to the successful loading of drug-loaded microspheres onto the surface of the sutures with minimal changes in diameter and weight. The suture exhibited a knotless strength of 32.88 N and knotting strength of 32.34 N, respectively. The initial release of the drug-loaded microspheres of each specification was modest, and the release rate of the microspheres of each specification exhibited variability, thus achieving the desired control of the release. In addition, the finishing sutures demonstrated effective antimicrobial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The drug release pattern of the suture fits well with the Higuchi equation, and the drug release cycle can be up to about 17 d. Consequently, the microsphere-loaded surgical suture material prepared in this experiment exhibits favorable mechanical properties, along with remarkable antimicrobial properties. Additionally, the drug release rate can be precisely regulated.

Yarn-based strain sensors are breaking the boundaries between flexible wearable electronics and smart clothing due to their unique functionality and weavability. The sensing strain range of most flexible strain sensors is less than its tensile range, and it is easy to exceed its sensing strain range during use, resulting in unstable performance and failure of the sensor. An effective-strain-range-controllable and wear-resistant yarn strain sensor was developed with a core-sheath braided structure with the sensing yarn as the core and the braided yarn as the shell. This design strain allows for control over the effective strain range by adjusting the core sensing yarn’s pre-stretch ratio and the outer braided layer’s structure. This prevents damage to the conductive network and sensor failure caused by excessive stretching during use. The sensitivity, linear sensing range, and hysteresis of the braided strain sensors are effectively adjusted by changing the braiding yarns’ braiding angle and the sensing yarn’s pre-stretch ratio. Additionally, the sensors’ appearance and texture can be customized by changing the colour and material of the braiding yarns, allowing these sensors to integrate seamlessly with the garment and enhance their aesthetics. Furthermore, when combined with elastic fabric bands, these sensors can be attached to various parts of the human body to monitor physiological information, such as respiration and movement. The braided structure design presents a versatile strategy that could be applied to other types of strain sensors, achieving stability, durability, and aesthetics simultaneously.

In this paper, the ballistic impact performance of the single and multi-layer 2D woven fabric system is simulated at filament level. A dynamic approach implementing the elasto-plastic fiber transversal behaviour is proposed to statistically investigate the probabilistic impact response and failure mechanism at filament level. A convergence study is carried out first to determine the resolution of discretization. The simulated impact performance of the single layer fabric is validated by the experiment’s upon impact velocity ranges from 38 to 346 m/s. The probabilistic velocity response (PVR) curve is derived utilizing the Langlie (one-shot) method. Then, the 1- to 6-layer fabric are simulated under the impact velocity of 518 m/s. The deflection and stress level of a filament in principal yarn in each layer is plotted over time. It revealed that filaments failed at random location due to statistical defect upon impact. The variation between the numerical and experimental reaches the most when impact velocity is in between V₀ and V₁₀₀. Yarns are subjected to tensile dominate failure. Partial yarn failure, yarn decrimping, slippage, and filament transverse movement happened during the projectile perforation process. The stress level in the filament in principal yarns of all layers is almost the same, it propagates from the impact center to the edge and doubles its value, which leads to filament failure near the clamped edge.

In the purification of oily wastewater, polyvinylidene fluoride (PVDF) nanofiber membranes have attracted widespread attention for their excellent water–oil separation performance. And chitosan (CS), as a natural polymeric alkaline polysaccharide containing many functional groups interacting with heavy metal ions, such as –NH₂ and –OH, has been widely used to treat heavy metal ions in wastewater. However, a few studies have been conducted on superhydrophilic and underwater hydrophobic PVDF composite membranes for the simultaneous removal of heavy metal ions and oil from wastewater. In this paper, PVDF/PVP composite membranes were used as the substrate of separation membranes, and PVDF/PVP-modified membranes were prepared by surface coating with PDA and CS in turn. Among them, CS can be coated on the surface of PVDF/PVP composite membrane by cross-linking the amino group on the molecule with the quinone structure in the PDA molecule to form a stable CS/PDA gel layer. Compared with other modified membranes, CS/PDA-PVDF/PVP has better hydrophilicity and underwater oleophobicity. The underwater OCA of dichloromethane could reach 161°, and the OCA of other oils were above 140°. The water flux was 14,171 L m⁻² h⁻¹. After 15 mixture and emulsion separation tests, the separation efficiency was higher than 99% and 98%, respectively. The adsorption efficiency for Cu²⁺, Pb²⁺, and Cr³⁺ aqueous solutions with concentrations of 10–60 mg/L reached more than 80%. Therefore, this method has great potential in treating oily wastewater.

The airborne particulate matter (PM) poses a severe risk to human health worldwide, and developing high-temperature resistant material with high filtration performance is crucial for the effective removal of industrially generated PM. In this study, a novel double-layered composite nonwoven (CN) constructed with one layer of polyphenylene sulfide (PPS) needle-punching felt (NF) and one layer of polysulfone-amide (PSA) nanofiber mat (NM) was designed and implemented for potential high-temperature filtration application. In details, an electrospinning strategy was first employed to fabricate PSA NMs with adjustable fiber diameters. Then, a thermal-pressing post-treatment was utilized to realize the combination of PSA NM and commercial PPS NF, to generate a PSA/PPS CN. The electrospun PSA nanofibers were found to be uniformly covered on the PPS microfibers after the thermal-press process, resulting in a stable micro-/nano-fibrous structure. It was found that the PSA/PPS CN with the 120 μm thickness of nanofiber mat possessed 100% filtration efficiency to both of the DEHS PM and NaCl PM with the particle sizes ranging from 0.225 to 7.25 μm. In addition, the CN also presented high thermal stability. In all, this study provides a simple and easily-handling strategy for fabricating a high-temperature resistant nano-/micro-fibrous CN with high filtration performance, which shows huge potential for high-temperature air filtration application.

Spacer fabrics are unique three-dimensional structures, which are used in various applications due to their specific features. Spacer fabrics are exposed to constant compressional strain in some applications. Consequently, the fabric’s performance will change due to the stress relaxation phenomenon in the fabric structure. This study aims to investigate the effect of spacer fabric’s structure on the compressional stress relaxation of the fabric. To this end, weft-knitted spacer fabrics with different spacer yarn lengths were produced, and their compressional stress relaxation was studied compared to polyurethane (PU) foam. The results reveal that by increasing the length of spacer yarns, the stress relaxation of the fabric decreases, while the maximum energy absorption efficiency increases. Based on the findings, the performance of the spacer fabrics compared to foam depends on the stress level, and all considered spacer fabrics exhibited more energy absorption and efficiency than foam at low-stress levels (lower than 100 cN/cm²). Eventually, knitted spacer fabrics’ compressional and stress relaxation behavior can be precisely estimated using the three-parameter model with nonlinear spring, and the three-parameter Maxwell model with nonlinear spring, respectively.