Fibers and Polymers最新文献

Aggregation-induced emission (AIE) technology had already been applied in polymer science and provides a deeper understanding on polymer structure and formation processes. Here we prepared a copolymer of (2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene (TPEE) and acrylonitrile (AN) (PTPEE-co-AN), which was utilized as the fluoresce probe for the monitoring of the electrostatic spinning process. Owing to the physical entanglement which restrincted the movement of TPE units, the PL intensity of the spinning solution increased with the increase of PAN in the solution. The viscosity and the concentration of PAN spinning solution was, therefore, could be monitored by PL intensity or by nake eyes. As the main component of fluoresce probes was PAN, the copolymer can be well integrated with spinning components, and has no impact on the electrospinning process. Moreover, the PTPEE-co-AN endowed photoluminescence properties to the formed fibers, as well as the fiber films. This method provides a new observation platform for the electrospinning process, and a variety of probes can be prepared through copolymerization to suit the spinning of different polymers.

This study investigates the mechanical properties of composites focusing on tensile, flexural, compression strength, Izod impact toughness, hardness, fatigue life, creep resistance, and drilling behavior. The approach involves extracting nano-biosilica from sorghum husk and infusing it with silane-treated kenaf fiber under temperature aging conditions to enhance composite materials’ properties. The reinforcement consists of kenaf fibers (34.2–43.2 µm in diameter) and nano-biosilica prepared from sorghum millet husk via a thermochemical method. Silane treatment enhances the adhesive bonding between the matrix (vinyl ester resin and methyl ethyl ketone peroxide in a 10:1 ratio) and reinforcing agents. Composite fabrication employs a hand layup method with varying concentrations of biosilica (1 vol. %, 3 vol. %, and 5 vol. %) and kenaf fiber. Notably, specimens N2 and M2 exhibited superior performance, with N2 achieving tensile strength of 101 MPa, flexural strength of 123 MPa, compression strength of 159.9 MPa, Izod impact toughness of 4.9 kJ/m², and hardness of 98 Shore-D. Even after undergoing aging at 40 °C and 70% humidity for 30 days, M2 demonstrated remarkable durability to the silane treatment of both fiber and filler with tensile strength of 85 MPa, flexural strength of 117 MPa, compression strength of 143 MPa, Izod impact toughness of 4.2 kJ/m², and hardness of 95 Shore-D. SEM analysis revealed uniform dispersion of filler particles in N2 and M2, highlighting the effectiveness of the silane treatment in enhancing microstructural characteristics and durability. This research underscores the potential of silane-treated kenaf-fiber- and nano-biosilica-reinforced vinyl ester composites for applications requiring enhanced mechanical properties and durability.

Nowadays, composite materials are widely used in various industries, including aerospace, automotive, and military sectors. In many of these applications, there is a need to understand the dynamic and vibrational responses due to changes in different parameters for a more precise structural analysis. This study examines the impact of varying fiber types under different boundary conditions on the natural frequency of a three-dimensional woven composite rectangular plate. For this purpose, the Ritz theory has been used to calculate the system’s natural frequency, and to validate the results, the current analysis method has been compared with previous research findings and results from finite element software simulations. The results obtained from the analytical solution and finite element simulation correlate well.

This research study investigates the moisture management properties of woven fabrics produced from banana and bamboo fibers. The moisture management characteristics of three different fabric structures, namely plain, twill, and satin weaves, were examined using varying proportions of bamboo and banana fibers. Results revealed that an increase in the proportion of bamboo fibers led to enhanced maximum wetted radius, spreading speed, AOTI, and OMMC. Furthermore, fabric structure played a significant role in moisture management performance, with satin weave fabric demonstrating excellent moisture management behavior and twill weave fabric exhibiting the least favorable moisture management properties.

Ultrafine particulate matter and airborne microorganisms present in the atmosphere significantly affect human health, leading to serious respiratory diseases. Among these particulates are bioaerosols, which include viruses, bacteria, and fungi. When inhaled, these microorganisms can cause diseases, such as influenza, tuberculosis, and COVID-19. Therefore, the development of bifunctional membranes that can simultaneously filter particulate matter (PM) and inhibit microorganism growth is essential. Electrospun filters, known for their high surface area, are effective in capturing these airborne particles. This study presents a novel approach by incorporating various surfactants into electrospun filters made from 8% polyacrylonitrile (PAN). The surfactants used include cetyltrimethylammonium bromide (CTAB), widely cited in the literature for bactericidal filtering applications, as well as sodium dodecyl sulfate (SDS) and cetylpyridinium chloride (CPC), which are rarely used in electrospun filters for this purpose. The addition of surfactants enhanced the filter performance, capturing particles smaller than 250 nm with over 99% efficiency for particles between 6.38 and 242 nm. The pressure drop across the filters ranged from 111.4 ± 1.2 to 204.4 ± 1.1 Pa. Moreover, the incorporation of surfactants not only improved hydrophobic and hydrophilic properties—where hydrophobic nanofibers performed better for filtration—but also significantly increased antimicrobial activity against Staphylococcus aureus (97.25 ± 0.95%) and Escherichia coli (94.52 ± 2.37%). These filters not only capture particles but also inactivate pathogens, contributing to a healthier environment. Filters with biocidal properties are particularly useful in hospitals, laboratories, and other settings where air sterility is critical.

A series of metalated porous organic polymers (POPs) derived from tetraphenylporphyrin (TPP) was synthesized, and the specific surface areas, selectivities for CO₂ over N₂, and conversion properties of the POPs were investigated. The metallo-tetraphenylporphyrin-based porous organic polymers were characterized using FT-IR, ¹³C-NMR, TGA, XRD, XPS, HR-FESEM, and EDX. Among the five catalysts studied, non-metalated TPP-based POP exhibited the highest BET surface area of 524.04 m²g⁻¹, whereas the Ni(II)TPP-based POP had the greatest CO₂/N₂ selectivity at both 298 and 323 K. In terms of the catalytic efficiency for the conversion of styrene oxide to styrene carbonate using CO₂, 2HPOP exhibited the highest yield of 91.67%, while the yield obtained with the metalated POPs was approximately 20%. This result suggests that the catalytic efficiency for CO₂ conversion is determined by both the selectivity and surface area of the metalated POPs. Moreover, the improvement in the CO₂/N₂ selectivity resulting from metalation did not play a dominant role in counterbalancing and surpassing the decrease in porosity.

This research explores how the structural integrity and geometric configurations of corrugated cores impact the bending characteristics of sandwich panels. The 3-D knitted fabrics were produced on a flat knitting machine to form an integrated structure, while the non-integrated structure was manufactured by conventional 2-D fabrics in the identical parameters. The bonding of the core to the skin in the non-integrated structure was achieved by resin. The both integrated and non-integrated structures were fabricated with nearly identical mass and epoxy resin was injected through a vacuum assisted resin transfer method. The integrated 3D composite structures were manufactured in three distinct corrugated core designs: rectangular, hat-type, and triangular. The bending characteristics of the produced structures were measured in the transverse direction of corrugation by 3-point bending process. The results indicated that under equivalent load conditions for long beams, the 3D integrated structure displayed reduced bending deflections and enhanced bending stiffness compared to the non-integrated structure. Moreover, the non-integrated exhibited higher transverse shear rigidity than the integrated structure. It was also found that in long beams, the load-carrying capacity of the integrated structure is higher than that of the non-integrated structure. This comparison demonstrates some advantages of 3-D fabric as a sandwich panel reinforcement compared to lamination of 2-D fabric. Also, experimental results demonstrated that core geometry cannot significantly influence the flexural stiffness of the corrugated core sandwich panels. Finally, results demonstrated that the highest and the lowest transverse shear rigidity can be associated with the hat-type core sandwich panels and the triangular core sandwich panels, respectively. So, the hat-type corrugated core sandwich panel has the lowest deflection against bending force. Lastly, the experimental findings were evaluated against those from finite element analysis and showed a good correlation between experimental and numerical results.

This paper describes the investigation of the influence of the substitution position of ethynyl groups in benzoxazines on their ring-opening polymerization (ROP) and the thermal stability of the resulting polybenzoxazines. A series of benzoxazines derived from bisphenol A with ethynyl groups at various positions are synthesized and structurally characterized using Fourier transform infrared (FT-IR) spectroscopy and ¹H nuclear magnetic resonance (¹H-NMR) spectroscopy. Monitoring of the curing behavior via in situ FT-IR and differential scanning calorimetry analyses reveals the occurrence of position-dependent effects during curing. Kinetic studies of the curing process, conducted via the Kissinger and Ozawa methods, indicate that the presence of ethynyl groups not only promotes the ROP but also reduces the activation energy required for the process. Compared to conventional ethynyl-free polybenzoxazine, ethynyl-functionalized polybenzoxazines exhibit superior thermal stability, including increased glass transition temperature. In particular, the introduction of the ethynyl groups at the meta position provides the greatest enhancement of the thermal properties, reaching an increase in the char yield of approximately 21%. This position also allows reducing the curing temperature, underscoring its critical role in the development of high-performance polybenzoxazines.

Within the realm of sustainable agriculture, there is a growing focus on the development of biodegradable plastic coverings in response to the adverse environmental impact stemming from contamination by fossil-based plastic film. Herein, a function-integrated cellulose-based composite film was innovatively designed for agricultural insulation applications. Lignocellulosic nanofibers (LCNF) and hollow SiO₂ microspheres are blended to construct LCNF/SiO₂ composite films with multistage nanocavity structures. Meanwhile, the hexadecyltrimethoxysilane modification further promotes the integration of hydrophobic function and the encapsulated function of hollow SiO₂ microspheres in the composite film to form the hydrophobic LCNF/SiO₂ (H-LCNF/SiO₂) composite film. Owing to the small size effect of SiO₂ microspheres and the nanocavity structure, the resulting film exhibits a low thermal conductivity (0.07 ± 0.002 W/(m·K)) and excellent optical properties of the UV–Vis transmission with transparency of over 77% (above 600 nm). Furthermore, H-LCNF/SiO₂ composite film displays acceptable mechanical properties with tensile strength of 56.03 MPa and elongation at a break of 6.10%, respectively. Notably, the composite film acquires excellent flexibility, water-proofing, water vapor permeability, and biodegradable performances, improving agricultural applications. Therefore, this work provides a lignocellulose-based film with functional integration that differs from traditional agricultural films by constructing a hollow structure to achieve thermal protection, with the advantage of being more energy efficient and environmentally friendly, promising potential applications in agriculture.

Aimed at the current problems of low strength and poor toughness in alginate fibers, which limits its large-scale application in the textile field, nano-montmorillonite (MMT) suspension was added into sodium alginate spinning solution during the wet spinning process with CaCl₂ solution as the coagulation and the modified alginate fibers were obtained. The structure of the fibers was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and TGA. The mechanical properties and water regain rate of the fibers were tested, and the mechanism of intermolecular interaction between sodium alginate and MMT was analyzed. The results indicate that the mechanical properties of MMT-modified alginate fibers were significantly improved. The fracture strength of the modified alginate fibers was increased from 1.32 cN/dtex to 3.01 cN/dtex. The elongation at break increased from 9.11% to 16.05%. The preparation of alginate/MMT fibers provides a feasible reinforcement and toughening strategy for alginate fibers, which improves toughness while achieving an increase in fracture strength. The preparation of alginate fibers with high strength and good toughness is beneficial for expanding the application of textiles.