Fibers and Polymers最新文献

The current work examines the buckling, damping, and vibration characteristics of hybrid sandwich plates reinforced with graphene. The sandwich plate is composed of graphene/epoxy/carbon fiber-reinforced composite skins and graphene/alumina fillers/epoxy reinforced composite core. The graphene/alumina filler-reinforced hybrid composite cores were fabricated using the sonication technique. Experiments were conducted to investigate the hybrid composite cores' microstructure and mechanical properties. The finite element formulation was built based on higher-order theory. The structural characteristics of the sandwich plates derived by the present formulation are compared with those of other authors and show excellent agreement. This paper also examines the impact of graphene, thickness ratio, and end conditions on the damping, buckling, and vibration characteristics of hybrid composites.

The rapid advancement of information technology has led to an increase in electromagnetic interference (EMI) issues, as electronic devices are now widely utilized, requiring materials with greater versatility. This study developed an efficient preparation method utilizing alternating vacuum filtration (AVF) technology to overcome this issue. Through the precise control of the deposition sequence of cellulose nanofibers (CNF)/Na-bentonite (NB) and MXene conductive layers, this study successfully prepared CNF/NB–MXene composite films with a well-structured alternating layered structure. The composite film exhibited a distinctive "brick–mortar" architecture, imparting favorable mechanical properties (i.e., 8.17 MPa tensile strength). Measuring 41 μm thick, the composite film exhibited a conductivity of 189.6 S m^–1, along with EMI shielding effectiveness (SE) of 34.3 dB and SE per unit thickness (SE/t) of 8365.85 dB cm^–1 in the X-band. Furthermore, the composite film demonstrated a high limiting oxygen index (LOI) of 36.5% and a residual carbon content exceeding 70%, which indicated exceptional flame retardancy. Consequently, the alternating layered composite film exhibited superior EMI performance and flame-retardant performance, making it particularly advantageous in harsh environments such as high temperatures.

Due to the smooth and chemically inert surface of poly(p-phenylenebenzobisoxazole) (PBO) fibers, leading to poor interfacial properties in epoxy resin, which severely limits their applications in composite materials. The vast majority of research on PBO fiber interfaces is focused on PBO-HM type, while there is little research on PBO-AS type. Here, a modification strategy of in-situ regeneration of cellulose on PBO-AS fiber surface to enhance its interfacial properties in epoxy resin was proposed for the first time. First, PBO-AS fibers were oxidized and then underwent acyl chlorination, followed by chemical bonding with cellulose molecules. Second, cellulose molecules were in-situ regenerated on the fiber surface in different regeneration solvents. The results show that cellulose molecules were successfully in-situ regenerated on the fiber surface. Due to the physical and chemical properties of PBO-AS itself, the modification process inevitably damaged its mechanical properties, especially the oxidation process. In addition, the oxidation step slightly enhanced its interfacial strength in epoxy resin, while the rougher surface formed by cellulose regeneration was the main reason for the improvement of interfacial performance; the IFSS increased by 38.87% compared with untreated ones.

Medium-density fiberboard (MDF) is highly susceptible to degradation from moisture and chemicals due to the inherent vulnerability of its wood fibers and urea–formaldehyde resin. To mitigate this, we developed a dielectric barrier discharge (DBD) plasma process to deposit a robust, hydrophobic polydimethylsiloxane (PDMS)-like coating on MDF surfaces. A modified three-electrode DBD system, optimized for wood-based materials and operating at 693.5 Hz with a 50% duty cycle, was employed. We systematically investigated the effects of processing time, discharge power, and hexamethyldisiloxane (HMDSO) precursor concentration on coating performance. The optimal treatment achieved a water contact angle of 142° after 20 min, confirming the formation of a highly hydrophobic, silicon-based layer. Analysis of surface morphology and chemical composition revealed the uniform deposition of PDMS-like films. This study not only demonstrates a highly effective method for creating moisture-resistant MDF but also underscores the potential of tailored atmospheric pressure plasma as a versatile tool for sustainable wood product manufacturing.

In this study, two synthesized pyrimidine derivatives (2a and 2b) were employed as modifiers for two textile substrates: 100% “Cotton” gauze (C) and 50/50% “Cotton/PET” (C/PET) to prepare filters for crude milk. The fabrics were modified using the pad/dry/curing technique. The effect of filtration on the shelf life of raw milk stored at temperatures of 20 and 5 °C was investigated using fabric filters. The chemical composition analysis of raw and filtered milk, including fat, protein, lactose, and solid non-fat content, was assessed. Similarly, a clot-on-boiling test, pH, and microbial content were investigated. The shelf life of the milk was extended from 8 to 20 h and from 4 to 6 days by filtration for samples stored at 20 and 5 °C, respectively, without any significant differences in chemical composition. Antibacterial activity of all treated fabrics and filtered milk was evaluated against pathogenic bacteria, Coliform, “E. coli”, and total molds, and the results showed high antimicrobial activity. The cytotoxicity of treated fabrics, as well as pyrimidine derivatives, was tested and displayed no cytotoxicity performance.

The fiber-reinforced polymer composites obviously find inventive practice as modern materials for several structural and functional applications due to their high specific strength and stiffness. The interply hybrid composites are designated for their versatile performance in structural applications, replacing the conventional materials and offering more stable and durable alternatives. The importance of these hybrid composites lies in their ability to provide tailored mechanical, thermal, and electrical properties, which makes them an ideal substitute for harnessing a wide range of applications across diverse industries such as aerospace, automobiles, construction, etc. Nevertheless, ongoing improvements are required in hybrid composites, particularly in addressing deficiencies at the fiber-matrix interface. Further attention is required to investigate the delamination resistance and failure modes. The present work is an effort to develop hybrid fiber composites with both E-glass and S-glass incorporating the fibers of carbon and Kevlar. The study profoundly analyzes the effect of stacking sequences and Mode II delamination characteristics of the hybrid composites by using end-notched flexure specimen test. The study reveals that hybrid fibers made by using both E-glass and S-glass fibers have similar outcomes. There is no significant deviation between the two types of glass fibers. It is found that the inclusion of carbon fiber with glass fiber increases the stiffness nearly 100%, whereas the inclusion of Kevlar with glass increases only about 50% for both glass types. Glass–carbon fiber doubles the interlaminar toughness, shear strength, and stiffness, whereas glass–Kevlar fiber significantly lowers the toughness of the hybrid composite.

Incorporating conductive materials into flexible fibers can be woven into comfortable wearable electronic devices catering to a convenient life. However, conventional conductive fibers, are constructed by dispersing or coating conductive materials in matrix fibers with unstable, abrasion-resisting, and unbendable electrical conductivity. Different from the preparation of traditional conductive fibers, we report a conductive fiber-inspired household wire structure with high electrical stability, which is formed by twisting integration that a carbon fiber core is wrapped into an insulating shape memory polyurea (PU) fibrous membrane by twisting together to form a conductive composite fiber with high stable conductivity against large deformation. A bionic spider silk β structure contributes to the high toughness of shape memory PU fibers that are capable of high output energy to trigger the rotation of a windmill and can wrap high-strength carbon fibers without breaking. Each meter of fiber possesses 800 Ω of resistance and enables reaching 40 ℃ under a 2 V voltage despite the condition of bending and knotting, which is also woven into wearable textiles for thermotherapy. The advantages are evident in the preparation of any core–shell structure functionality fibers, and we explain with demonstrations the shape memory effect, the thermal stability of conductive fibers, and thermotherapy textiles.

A novel aliphatic and aromatic waterborne polyurethane (WPU) compounds were synthesized by incorporating phosphorus and nitrogen into the WPU as flame-retardant and antimicrobial agents in leather finishing. A spirocyclic pentaerythritol bisphosphorate disphosphoryl dihydrazone (SPDPDH) as a novel compound and as a source of phosphorus–nitrogen was prepared by reacting hydrazine hydrate with spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPCl). The structure of SPDPDH was characterized using FTIR, ¹H NMR, and ¹³C NMR spectroscopy. The process of creating water-based polyurethane (WPU) involves a poly-addition polymerization reaction. This reaction relies on a few different variables, such as the polyethylene glycol (PEG, 300), isophorone diisocyanate (IPDI) used for aliphatic PU, or toluene diisocyanate (TDI) used for aromatic PU, in conjunction with 1,4-butanediol (BDO) with dimethylolpropionic acid (DMPA) and along with SPDPDH. Subsequently, an aqueous polyurethane coating containing SPDPDH compound was applied to the leather and compared to the uncoated. The physical properties, water absorption %, and water vapour permeability % were investigated. The surface structure morphology and element composition of leather before and after treatment were examined using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The mechanical properties, tensile strength, and elongation % of coated leather were considered. The limited oxygen index (LOI) can achieve 30.8%, and the vertical burning test UL-94 was adopted to estimate the flame-retardant property. The antibacterial activities of the samples were evaluated using Gram-negative bacteria (Pseudomonas aeruginosa (ATCC 27853)), Gram-positive bacteria (Micrococcus luteus (ATCC 10240) and Staphylococcus aureus (ATCC 6538)), and pathogenic fungi such as Candida albicans ATCC 10231 test methods, proving a high synergistic antimicrobial efficiency of the modified leather. Results indicated an improvement in leather characteristics; this may be due to satisfactory dispersion and strong interfacial interaction of waterborne phosphorus–nitrogen polyurethane with the leather matrix. These treatments improved thermal stability, physical morphology, surface mechanical properties, and flame retardancy with obvious results.

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This study presents the first report on the development of a Karaya gum (KG)/chitosan-based nanocomposite embedded with silver nanoparticles (AgNPs) for multifunctional applications in wastewater treatment, uniquely combining the complementary properties of two biopolymers to stabilize and enhance AgNP performance. Structural characterization via SEM, TEM, XRD, and FTIR confirmed a porous nanocomposite matrix with homogeneously embedded crystalline AgNPs, stabilized by interactions between biopolymer functional groups (–COOH, –NH₂) and uniformly dispersed AgNPs (25–100 nm, average 60 nm). The material exhibited high adsorption capacity for methylene blue (MB) dye (91 mg/g at pH 6), following pseudo-second-order kinetics and Langmuir isotherm behavior. The thermodynamic results confirmed spontaneous, endothermic adsorption with increased entropy at higher temperatures. The incorporation of AgNPs significantly enhanced antimicrobial efficacy, producing a pronounced inhibition zone against Escherichia coli. The nanocomposite retained 64% adsorption efficiency after five regeneration cycles, underscoring its reusability. By synergizing the unique functional group chemistry of KG and chitosan with the antimicrobial and catalytic effects of AgNPs, this work introduces a novel, biodegradable platform for integrated dye adsorption and pathogen control, offering promising implications for sustainable wastewater remediation.

Electrospun polyvinylidene fluoride (PVDF) piezoelectric membranes exhibit inherent mechanical fragility, particularly inadequate elongation at break and fracture toughness, which severely limits their reliability in flexible sensing applications. To overcome this limitation, we incorporated calcium sulfate oligomers (CSOs) as multifunctional nano-additives into the PVDF electrospinning system. The resulting composite membranes achieve concurrent breakthroughs in mechanical robustness and piezoelectric performance: the elongation at break increases to 157% (vs. 89% for pure PVDF), while the piezoelectric output voltage reaches 6.24 V, approximately six times that of pure PVDF. This dual enhancement originates from ionic coordination between sulfate groups in CSO and PVDF dipoles, which simultaneously facilitates energy dissipation during deformation and promotes piezoelectric β-phase nucleation. The composites maintain uniform hydrophobic fiber morphology with refined diameter (362 vs. 807 nm for pure PVDF), ensuring excellent processability for sensing applications. Functionality tests confirm exceptional dynamic performance with strain-dependent voltage output and reliable signal generation during biomechanical motions such as finger tapping. This work demonstrates that CSO incorporation effectively overcomes the traditional trade-off between mechanical durability and electromechanical sensitivity in piezoelectric polymers, establishing a promising strategy for developing high-performance flexible sensors.