Fibers and Polymers最新文献

Enhancing vehicle crashworthiness is critical for improving passenger safety during collisions. Subsequently, this research seeks to explore both the deformation characteristics and the crashworthiness behaviors of square tubes made from 3D-printed polylactic acid (PLA). For this reasons, three printing parameters are examined, each at four different levels: infill pattern structure (gyroid, honeycomb, Schwarz P, and Schwarz D), infill density (5, 10, 20, and 30%), and layer height (0.15, 0.20, 0.25, and 0.30 mm). The structures were exposed to quasi-static axial compression loading to assess their performance. During the testing of these tubes, data were systematically gathered on crashing load, absorbed energy, and displacement responses. In addition, the failure histories of each tube were accurately documented. The evaluation of crashworthiness involved the measurement of several critical indicators: the initial peak crash load (({F}_{text{ip}})), the total energy absorbed (U), the mean crash load (({F}_{text{m}})), the specific absorbed energy (SEA), and the crash force efficiency (CFE). To identify the optimal configuration, a multi-attribute decision-making (MADM) approach was employed. This analysis revealed that the combination of honeycomb pattern structure, 30% infill density, and a layer height of 0.20 mm (denoted as H30/0.20), which achieved ({F}_{text{ip}}), U, ({F}_{text{m}}), SEA, and CFE of 26.35 kN, 1440.73 J, 24.01 J/g, 33.54 kN, and 0.911, respectively, offered the best performance in terms of crashworthiness.

This study examines the effects of the coupling agent maleic anhydride-grafted polypropylene on the thermal and dielectric properties of areca–polypropylene composites. Test specimens of both uncoupled and coupled composites were prepared using injection molding methods in accordance with ASTM standards, with filler percentages ranging from 20 to 50%. Dielectric characteristics were evaluated across frequencies ranging from 10 Hz to 10 MHz and temperatures from 30 °C to 120 °C at 10 °C intervals. The results showed enhanced dielectric properties in the maleic anhydride-grafted polypropylene composites due to improved fibre dispersion and polarization mechanisms. These composites, with their high dielectric constants, have potential applications in gate dielectrics, actuators, sensors, and more. The morphology and chemical composition were analyzed using scanning electron microscopy and Fourier transform infrared spectroscopy, while thermogravimetric analysis and water diffusion coefficient tests confirmed the successful grafting of the coupling agent onto the fibres.

Tea polysaccharide (TP), as a naturally occurring bioactive polysaccharide derived from tea leaves, exhibits diverse pharmacological activities, which extensively utilized in healthcare products. However, previously reported applications did not include wound repair until now. In this study, TPs isolated from Tibetan tea was compound with bacterial cellulose (BC) via a novel membrane–liquid interface (MLI) culture resulted in obtained a novel TP-based dressing. The results of SEM and AFM confirmed successful attachment of TPs onto the surface of BC fibers. The obtained TP/BC composite exhibited robust thermal stability, excellent water absorption, acceptable water retention, and improved mechanical properties. The introduction of TP also conferred the dressing notable antioxidant properties (DPPH clearance rate was up to 85%), acceptable antibacterial properties (the antibacterial rate against S. aureus and E. coli were above 80%), and potent anti-inflammatory activity (the secretion of pro-inflammatory factor TNF-α was inhibited, while the secretion of anti-inflammatory factor TGF-β was promoted). Furthermore, the TP/BC composite exhibited improved cytocompatibility to promote NIH3T3 cells proliferation and spread compared with BC. All results indicated that the obtained TP/BC composite has an enormous potential for wound dressing, and the application of TP will be broadened.

In the present study, we hypothesized that the presence of gallic acid as an additive antioxidant agent and alendronate can improve the osteogenic differentiation potency of human adipose mesenchymal stem cells, cultured on the scaffolds with fiber-microparticle structures. For this purpose, a combination of electrospinning and electrospraying techniques was employed to prepare a fiber-microparticle structure, composed of polycaprolactone (PCL)–alendronate (ALN) fibers/gallic acid-loaded chitosan nanoparticles (GNP) @ polyvinylpyrrolidone (PVP) microparticles. GNPs were fabricated by a cross-junction microfluidic device. By adjusting the gallic acid concentration, three types of GNPs were fabricated. The morphology of fabricated nanoparticles was quasi-sphere. %Loading efficiency increased by employing higher concentrations of gallic acid. According to dynamic light scattering results, the average hydrodynamic diameter of nanoparticles was between 213 and 217 nm. The impact of ALN concentration on the size and morphology of PCL electrospun scaffolds was separately investigated by SEM in which PCL/ALN 2.5% was selected for the next steps. The % porosity of all samples was around 62–68%. The release profile of ALN was slower than gallic acid. The % 1,1 diphenyl-2-picrylhydrazyl (DPPH) inhibition analysis showed that the presence of gallic acid could effectively improve the additive antioxidant properties of fabricated scaffolds. According to the MTT results, the presence of ALN could significantly improve the proliferation of human adipose mesenchymal stem cells. The alkaline phosphatase (ALP) activity and calcium deposition assessments on days 7, 14, and 21 and the evaluation of mRNA levels of ALP and osteopontin on days 7 and 14 confirmed the synergistic impact of gallic acid and ALN on osteogenic differentiation.

Graphical abstract

A series of five azo dyes derived from the diazonium salt of 4-aminoantipyrine and α- and β-naphthols and naphthalenediol were synthesized, and their chemical structures were identified by spectral measurements such as UV, FT-IR, and NMR, as well as elemental analysis. The chemical descriptor parameters of the synthesized dyes were computed using the B3LYP/6-31G(d,p) level. The dyes were classified as disperse dyes and were used to dye polyester fibers at high temperature and pH 4.0–5.0, utilizing acetic acid, while dispersing agents were added to enhance the stability and dispersion of the dyes. The color fastness properties of the dyed fibers were tested, and their color strength, reflectance, and dye exhaustion were measured. Finally, a plausible mechanism for the dyeing process was suggested.

Oil spills and marine pollution caused by oil spills have a serious effect on environment and human life. The efficient removal of oils, petroleum-based products, and organic solvents from water is important for protecting the environment. Oil-absorbent nanofiber mats with high oleophilicity were prepared by electrospinning in the present work. Nylon 6,6 is chosen as a crystalline polymer with oleophilic hydrocarbon chains that are linked by hydrophilic functional amides. There has been little research into using electrospun Nylon 6,6 as an oil absorbent to remove oil from water. Two different organically modified montmorillonites (o-MMT, with trade names Tixogel VP and Cloisite 20A—C20A) are separately incorporated into Nylon 6,6 polymer to produce nanofiber mats with more oleophilic properties. To achieve efficient dispersion and exfoliation of organoclays in Nylon 6,6/formic acid solution, ultrasonication is applied for 30 min, followed by mixing for 24 h with a magnetic stirrer. After reaching a more homogenous solution, Nylon 6,6-organoclay nanofiber mats were then successfully electrospun by the electrospinning technique and characterized by using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), and water contact angle measurement (WCA). The mechanical properties of the mats were also evaluated. The absorption behavior of the mats for motor oil and other domestic oils was investigated and the absorption capacity calculated in terms of weight gain. Differences in the absorption capacity of these three types of oil were found to be due to the surface tension of the solvents in the oil and viscosity. It has been found that the nanofibers produced have a very high oil absorption capacity in the case of a 2% loading of organoclay. These newly produced mats demonstrated excellent motor oil absorption of 60–80 times their own weight in motor oil. It can be concluded that these novel oil-absorbing materials are promising candidates for the treatment of wastewater containing oil.

Polylactide (PLA) composites containing a flame retardant, ammonium polyphosphate (APP), and short rayon fiber were prepared by direct melting compounding in a brabender. The limiting oxygen index of the neat PLA sample was only 20.5%, which was increased to 29% by adding 15 wt% APP and 15% rayon to the PLA matrix (sample A15R15) as an example. During the UL-94 vertical flammability test, flame dripping was further avoided by adding the rayon fiber, and a V-0 rating was achieved. The char residue determined by thermogravimetric analysis increased with increasing APP content in the PLA composites. However, the PLA composite revealed a loss in mechanical tensile modulus and strength due to the APP addition, which was improved when rayon fiber was added to replace a portion of APP.

Elium^® liquid thermoplastic resin, with room-temperature curing and recyclability, enables large-scale production. However, limited research exists on the fiber–matrix interface, and understanding micro-scale interactions is key to influencing the composite^’s macro-scale mechanical properties. This study investigates the interfacial adhesion of glass, carbon, basalt, and aramid fibers-reinforced liquid Elium^® thermoplastic matrix composites at micro-, meso-, and macro-scales. Contact angle measurements show 53-56º for glass fibers, indicating superior wettability with the Elium^® matrix, while carbon, aramid, and basalt fibers exhibit 58-62º, 73-74º, and 79-86º, respectively. Micro-bond tests demonstrate the highest load-carrying capacity in the interface between glass fibers and the matrix, with glass fibers carrying 11.4% more load than carbon fibers and 25.8% more than basalt fibers. Fiber bundle tests, including transverse and 45° fiber bundle tests, highlight the superior load-carrying performance of glass fibers, with all fiber types showing increased load-carrying capacities in the 45° tests. The micro-scale and meso-scale data obtained from micro-bond and fiber bundle tests corroborated the results of the macro-scale interlaminar shear stress (ILSS) tests, confirming the significant influence of the fiber–matrix interface on the mechanical integrity of the composites. The shear strength at the glass/Elium^® interface was 47.54 MPa, which was 8.5% higher than carbon, 20.3% higher than aramid, and 25.9% higher than basalt interfaces. These findings advance our understanding of the mechanical behavior and interfacial adhesion in thermoplastic matrix composites. They underscore the crucial role of the fiber/matrix interface in determining the mechanical properties of composites and offer insights into the compatibility of diverse fiber reinforcements with the innovative Elium^® matrix.

There is a growing trend toward the use of natural fibers as reinforcing materials, with flax being a significant part of this market. The mechanical properties of these polymer composites, like those of synthetic fibers, are governed by parameters and material invariants. The challenge is to minimize these parameters, and to reveal these invariants to make stiffness and strength easily comparable with each other and with other composites, while avoiding excessive complexity. To this end, a simple methodology has been developed using the following parameters: Tsai’s modulus or the trace of the stiffness tensor and the area of the Omni Failure Envelope in stress space. Based on the analysis of significant published experimental data on flax composites, new insights were found. The trace-normalized longitudinal Young modulus is a material property that were found to be 0.77 for tension and 0.67 compression with a coefficient of variation of 5.6% and 15%, respectively. The area of the Omni Failure Envelopes and the strength are linearly related. The use of the proposed parameters and some invariants has been discussed and they are used to compare and rank them with each other and with other composites, including carbon, aramid, and glass fiber-reinforced polymer composites.

This study evaluates the moisture management properties of multilayered knitted fabrics for sportswear, incorporating blends of polyester, modal, bamboo, nylon, and Kooltex. The goal is to improve athletic garment comfort and performance by optimizing moisture transport away from the skin. The research investigates 24 multilayered knitted structures created from yarns such as 40Ne modal, bamboo, nylon, and 150 denier polyester including recycled and micro polyester variants. The study finds that absorption rates are significantly affected by fiber type, yarn structure, and fabric density. Higher porosity in the top layer of the fabric generally facilitates more efficient moisture transport. Results show that, in most cases, the top layer's absorption rate exceeds that of the bottom layer, although some structures display exceptions due to differences in stitch density and fabric thickness. Fabrics that combine polyester for moisture transfer with cotton or wool for absorption enhance comfort by effectively wicking sweat away from the body. Statistical analysis reveals a significant correlation (p < 0.05) between stitch density and moisture transport efficiency, with higher stitch densities potentially impeding moisture movement. The results suggest that fabrics combining effective moisture transport, high absorption rates, and suitable structural properties are optimal for sportswear, enhancing comfort and performance during physical activities.