Fibers and Polymers最新文献

Activated carbon (Ac) prepared from Thapsia transtagana was combined with a different ratio of aniline to synthesize Ac/PAni composites. Various characterization techniques, such as XRD, FESEM-EDX, TEM, and ATR-FTIR, were conducted to confirm the structure, surface morphology, and chemical characteristics of the composites. The materials were tested for eriochrome black T (EBT) adsorption. Batch results exposed that the Ac/PAni6 with the highest ratio of aniline displays the highest EBT removal efficiency. The kinetics of EBT adsorption over the Ac/PAni6 composite followed the Elovich model, and the equilibrium data suited the Redlich–Peterson and Toth isotherm models. The adsorption was spontaneous, feasible, and endothermic. The statistical physics equations have also been investigated. Four models have been proposed as one layer and two layers with one and two energies. The adsorption of EBT on the Ac/PAni6 composite correlated to the one layer two energies model. The statistical physical parameters, including the number of adsorbed molecules per site (({n}_{1}), ({n}_{2})), the receptor sites density (({N}_{1M}), ({N}_{2M})), the adsorption capacity at saturation (({Q}_{1}), ({Q}_{2})), and the energy of adsorption (({E}_{1}), ({E}_{2})) have all been considered. The total capacity at saturation is enhanced with temperature, which approves the endothermic nature of the process. The interpretation of the calculated energies ({E}_{1}) and ({E}_{2}) (< 40 kJ/mol) suggested that the EBT interaction with the Ac/PAni6 surface was mainly a physisorption process.

Waste cotton fibers are an ideal raw material for extracting nanocellulose crystals (CNCs), benefitting from  their high cellulose content. In this study, the waste cotton fibers from the calendering finishing process were used to extract CNCs by sulfuric acid, TEMPO oxidation, and phosphoric acid methods, aiming to create a new way to reutilize the waste cotton fiber and also to verify the practicability that the phosphoric acid method can replace sulfuric acid and TEMPO oxidation methods. The CNCs obtained from the three methods are all in cellulose I state with an average length of 200-500nm and diameter of 15-20nm, indicating that the waste cotton fiber can extract CNCs. However, the CNCs from the phosphoric acid method showed the highest thermostability but the lowest crystallinity, while the ones from the sulfuric acid and TEMPO oxidation methods had higher crystallinity but lower thermal stability. Overall, the three methods are all acceptable for preparing CNCs, but the phosphoric acid method has more significant potential due to its low cost, environmental friendliness, and safety.

Graphical abstract

In weight-sensitive applications, the widespread use of honeycomb composites underscores the significance of enhancing their specific strength and energy absorption capacity. In this pursuit, various hybrid honeycomb structures have been developed, with a particular focus on their cell wall buckling behaviour. This study involved testing six different specimen types, incorporating intralayer hybridization with materials namely, Kevlar, Glass, Dyneema, Sisal, Hemp, and Jute. The incorporation of the intralayer hybrid technique examined various aspects of honeycomb structures, leading to improvements in mechanical performance. In addition, the effects of specific energy absorption and crush force efficiency on the compressive and flexural strength were investigated. Among all the samples, the honeycomb core with a height of 15 mm demonstrated the highest compressive strength and specific energy absorption values. This enhancement is attributed to the synergistic effects of intralayer hybridization, emphasizing the potential for utilizing natural alternatives such as sisal, hemp, and jute, which may offer pronounced advantages in impact stress propagation within hybrid composites.

Graphical Abstract

The optimization of geotextile mechanical properties is crucial for enhancing their performance in civil engineering applications such as soil reinforcement and stabilization. This study focuses on the influence of manufacturing parameters on the static puncture (CBR) properties of polyester geotextiles. Polyester geotextile samples were manufactured using various parameters, including needle-punching density, penetration depth, calendering temperature, and speed. The mechanical properties of the samples, specifically strength and elongation, were evaluated using the CBR test according to EN ISO 12236. The data were analyzed using multivariate analysis of variance, followed by statistical analysis to determine the influence of the manufacturing parameters on the mechanical properties. Furthermore, the relationship between these parameters and the mechanical properties was modeled using artificial neural networks (ANN) and regression analysis. The results indicated that all manufacturing parameters significantly impacted the strength and elongation of the geotextiles. The ANN models, employing two hidden layers, predicted the strength and elongation with errors of 1.43% and 1.26%, respectively.

The functional group distribution and skin–core structure of polyacrylonitrile (PAN) pre-oxidized fibers have been evaluated by solid-state ¹³C-NMR, electron probe micro-analysis, element analysis, nano-infrared spectroscopy atomic force microscopy, and optical microscopy. The pre-oxidized fibers exhibited a skin–core structure with high optical density (OD) values in the skin and low OD values in the core. As the heat treatment temperature was increased, the OD of the pre-oxidized fibers increased, which is because of the formation of C = O, C = N, C = C, and their conjugated structures of C = N with C = C. The difference in the OD values between the pre-oxidized fiber skin and core became increasingly apparent as the heat treatment temperature increased, with the OD difference increasing from 0.045 at 220 °C to 0.085 at 260 °C. The OD difference is closely related to the oxygen element and C = O functional groups in the fiber. The contents of the oxygen element and C = O in the pre-oxidized fiber skin were higher than those in the pre-oxidized fiber core. At a heat treatment temperature of 260 °C, the relative content of C = O in the skin was 0.454, whereas that in the core was 0.313, which was consistent with the trend of the OD value change. In comparison, C = C and C = N formed during pre-oxidation were not substantially distributed in the radial direction of the fibers. The radial inhomogeneity of the pre-oxidized fiber was mainly affected by the radial difference of the carbonyl content.

This study examined the natural dyeing properties of hemp fabrics using a mixed mordant consisting of aluminum potassium sulfate (10 and 20 g/L) and tannic acid (5 and 10 g/L). The natural dye was derived from jackfruit wood (Artocarpus heterophyllus) and then processed into a powder via spray drying. The fabrics were dyed using 10% owf dye, at a pH of 5, temperature of 80 °C, for 50 min, with a liquor ratio (L:R) of 1:30. Prior to dyeing, mordanting was applied to improve dye uptake. The mordanting process compared three distinct heating techniques: infrared heating (IRH), ultrasonic heating (USH), and microwave heating (MWH). The X-ray diffraction results showed that MWH was the only heating technique that maintained the crystallinity index ((CI)) of the fibers. However, it produced slightly lower color strength ((K/S) of 1.01 ± 0.01) compared to IRH ((K/S) of 1.36 ± 0.04) and USH ((K/S) of 1.32 ± 0.04). IRH exhibited the most significant reduction in the (CI), followed by USH. The sample treated with IRH had the highest aluminum content (0.88 ± 0.02%), whereas the MWH-treated sample had the lowest (0.75 ± 0.02%), which is consistent with the results concerning (CI) and (K/S). The ratings for color fastness to washing, light, and rubbing were generally favorable. Mordanting enhanced both the color fastness and the color strength of the fabric, but it did not affect the tensile properties of the fabrics. Mordanting and dyeing slightly enhanced the ultraviolet protection efficiency of the fabrics. However, all samples, including the pristine hemp fabric, provided excellent protection against ultraviolet radiation.

Graphical Abstract

Thermoplastic polyurethane (TPU) is a highly favored polymer for 3D printing materials due to its excellent impact and abrasion resistance, superior mechanical properties, and flexibility at low temperatures. Enhancing TPU with conductivity considerably broadens its application range, paving the way for its use in advanced flexible electronics, wearable technologies, and improved industrial components. The addition of electrically conductive fillers such as multi-wall carbon nanotubes (MWCNTs) can improve the conductivity of TPU. In this study, we synthesized TPU with a bio-based polyol (polytrimethyleneether glycol) and chain extender (1,3 propanediol) and improved its conductivity by adding a small amount of CNTs via in situ polymerization without using any harmful solvents. The CNT content was varied from 0.75 to 3.75 wt% and to achieve a tensile strength of 13.45 ± 0.3 MPa, a maximum elongation at break of 859% ± 6%, a hardness of 77 ± 2 Shore A, and the highest conductivity (2.26 × 10⁻⁴ S/cm) with 3.75 wt% of CNTs. Because these physical properties are sufficient for 3D printing, the TPU/CNT composites developed herein can be promising in applications requiring conductive materials.

Several effective methods to precisely evaluate the comfort of hygroscopic cooling fabrics transitioning from a wet to dry state were previously lacking. This study employed the heated plate method to mimic bare skin. We integrated a refitted YG606 II Thermal Resistance Tester with a heating control unit to simulate the human body’s thermoregulation following light activity at a basal metabolic rate. This apparatus recorded the heating curves of hygroscopic cooling fabrics in their wet state to monitor temperature variations during drying. We introduced five objective evaluation parameters (Area, FWHM, K₁, K₂, WCI) based on the temperature differences between the heated plate and wetted fabric samples to differentiate levels of wet comfort among various fabrics. Twelve types of hygroscopic cooling fabrics, varying in material, structure, and hygroscopic properties, were selected from the market to assess the reliability of these parameters. The findings confirmed that these parameters effectively discern variations in wet comfort across the fabric samples. The parameters for cooling capacity (Area) and cooling rate (K₁, K₂) are critical in evaluating the role of liquid water in fabric on wet comfort, while cooling duration assesses the impact of the fabric’s drying process on human comfort. Furthermore, the wet comfort index (WCI) correlated significantly with perceptions of dampness and coldness; a higher WCI value indicated a sharp, transient discomfort due to dampness and coldness, whereas a lower value suggested a mild, sustained sensation of wetness and coldness. The preference for these contrasting sensations varies by context. This research could facilitate the development of predictive models for wet comfort by evaluating the cooling capacity and wet comfort index of textiles in their wet state, thereby aiding fabric researchers and manufacturers in enhancing the thermal–wet comfort of hygroscopic cooling fabrics.

With the rapid development of the economy, new imitation methods are keeping emerging and posing a huge challenge to anti-counterfeiting technology. Due to the advantages such as good concealment, high recognizability, water repellency, and dirt resistance, fluorescent fiber has attracted great attention from researchers. To impart good fluorescence to chitosan (CS) for the preparation of anti-counterfeiting fiber, various amounts of fluorescent molecules — carboxyl-containing spiropyran (SP)—were used to label CS to prepare a series of CS–SP with different degrees of labeling (DL). Then, nanofiber membranes were produced by electrospinning using the CS–SP/PVA blend spinning solutions. Effects of the DL on application performance of the CS–SP were studied. It was found that, labeling appropriate amounts of SP units onto CS was an effective way to endow the CS with good fluorescence property. With the increase in the DL of the CS–SP, its fluorescence intensity increased initially, reached the maximum when the DL was 0.499 mol%, and then decreased. At the DL of 0.499 mol%, the CS–SP/PVA nanofiber membrane could emit bright fluorescence, of which the color was able to change dynamically along with the irradiation time of UV light. Meanwhile, the labeling of SP unit would not bring about adverse effects on surface morphology of the electrospun CS–SP/PVA nanofiber membrane. The fluorescent CS–SP nanofibers have overcome many shortcomings of the commonly used fluorescent fibers and shown great application potential in the anti-counterfeiting field.