Lightweight and broadband microwave absorbing materials are essential for advanced stealth applications. In this study, RPUF composites incorporating multi-component microwave-absorbing fillers were prepared. A functionally graded structure was designed by integrating GFRP as the panel and CFRP as the backing layer. The optimized composite demonstrated excellent mechanical properties and effective absorption performance, achieving a reflection loss below −10 dB across the 8–18 GHz band. Experimental results closely aligned with simulation predictions, confirming the effectiveness of the structural design. This work offers a viable strategy for developing high-performance, lightweight absorbing materials suitable for such applications.
Ulcerative colitis (UC) is a chronic inflammatory bowel disease associated with oxidative stress and mucosal inflammation. Curcumin (Cur) shows promise for UC management, but its poor aqueous solubility and instability in the gastrointestinal tract lead to low oral bioavailability and limited therapeutic efficacy. In this study, curcumin-loaded ROS-responsive nanoparticles (HSNPs@Cur) were developed based on diselenide-modified hyaluronic acid (HA-Se) to improve the stability and oral delivery of Cur. HSNPs@Cur exhibited good stability under different temperatures, pH, and storage conditions, indicating that nanoencapsulation effectively protected Cur under non-oxidative conditions. In the presence of H2O2, HSNPs@Cur showed ROS-responsive behavior and rapidly released Cur within 8 h. In addition, HSNPs@Cur demonstrated significant antioxidant and anti-inflammatory activities in vitro, likely owing to the combined contribution of Cur bioactivity and diselenide-bond-mediated ROS responsiveness. HSNPs@Cur exhibited good hemocompatibility, cytocompatibility, and in vivo biocompatibility following oral administration, with no obvious systemic toxicity or histopathological abnormalities observed in major organs. These results provide preliminary evidence that HSNPs@Cur represents a stable and biocompatible ROS-responsive oral nanocarrier with potential to improve the stability and oral delivery of Cur for UC-related applications.
A novel polyol Poly-PDM was synthesized via polycondensation of Phenyl phosphoryl dichloride (PPDC), Dipropylene glycol (DPG), and N-Methyldiethanolamine (MDEA), and adopted to prepare modified rigid polyurethane foams (RPUF). The addition of Poly-PDM refined cell morphology without significantly altering density. Compressive strength and energy absorption performance initially increased then decreased with higher Poly-PDM content. The RPUF containing 50 parts Poly-PDM achieved a limiting oxygen index (LOI) of 22.3 %. Cone calorimetry tests verified that appropriate Poly-PDM addition greatly decreased the peak heat release rate (PHRR), total heat release (THR) and other heat release parameters. In terms of flame-retardant mechanism, Poly-PDM can produce phosphorus radicals to quench active free radicals and cut off combustion chain reactions, and its pyrolysis products promote the formation of dense char layers for physical barrier effect. Meanwhile, the released inert gases dilute flammable volatiles, thus jointly restraining combustion and flame propagation.
Biodegradable materials have garnered significant attention due to their environmental friendliness and renewability. However, inadequate crystallization properties may occur during the molding process, affecting product appearance, mechanical properties, thermal stability, and shelf life, thereby limiting their industrial development and application. Nucleating agents, as crucial polymer additives, can significantly alter the crystallization behavior of polymer materials. This study provides an exhaustive review of the properties, impacts on material properties, and mechanisms of action of various nucleating agents. It also describes upcoming development trends and examines difficulties that arise in real-world applications. The goal is to provide more reference for researchers.
Polylactic acid (PLA) is a sustainable food packaging polymer, but its limited mechanical and barrier properties restrict its use for light- and moisture-sensitive products. PLA films containing 1–5 % chemically modified microfibrillated (MMFC) and nanofibrillated cellulose (MNFC) were prepared via solvent casting and characterized. FTIR confirmed successful chemical modification with maleic anhydride, while the main PLA peaks remained unchanged. XRD showed a slight increase in matrix crystallinity for MMFC/MNFC films compared to control PLA; however, no apparent trend was observed across the different fiber loadings. FE-SEM observations suggested relatively smooth surfaces at lower filler concentrations, whereas some degree of aggregation appeared to occur at 5 % loading. DSC results suggested a slight increase in glass transition temperature and a decrease in cold crystallization temperature, which may indicate reduced chain mobility and a potential influence on crystallization behavior. Incorporating 1–3 % MMFC increased tensile strength to 42.41 MPa while maintaining flexibility, whereas 5 % loading reduced performance due to fiber aggregation. Thermal adhesion strength improved at low filler contents, with MNFC showing better heat-seal performance. WVTR decreased from 4.44 to 3.93 g/m2·24 h with 1–3 % fillers. UV-C transmittance decreased from 78.3 % in neat PLA to 56.7 % and 66.0 % for 5 % MMFC and MNFC films. These results demonstrate that low loadings of chemically modified MFC and NFC enhance physical, mechanical, barrier, and photoprotective properties of PLA films for sustainable food packaging.
Cis-1,4-polyisoprene is a persistent environmental threat, particularly when present as microplastic debris due to its resistance to natural degradation processes. The oxidative enzyme horseradish peroxidase (HRP) can initiate oxidative chain modification of polyisoprene and thus represents a promising approach for the conversion of elastomeric microplastics into more bioavailable products in technical treatment processes. However, the use of HRP for the degradation of polyisoprene is still not ready for technical applications and requires a better understanding of the reaction conditions that maximize enzymatic activity. Therefore, we systematically investigated the influence of temperature, buffer concentration, pH, and the stoichiometric ratios of HRP, hydrogen peroxide, and mediator on the HRP-catalyzed oxidation of cis-1,4-polyisoprene. Optimal conditions were identified and validated through the enzymatic degradation of polyisoprene latex emulsion as a model system for microplastic particles, with carbonyl-containing oligomers confirmed qualitatively by colorimetric assays. Overall, the results provide experimentally supported guidelines for maximizing HRP activity toward polyisoprene oxidation and establish a technical foundation for further development of enzymatic treatment strategies targeting elastomer-based microplastic contaminants.
Polyvinyl alcohol (PVA) is a promising material for flexible electronics but suffers from flammability and electrical insulation. Here, we fabricate a flame-retardant and conductive PVA-based composite film using a one-pot solution casting method. A phosphorus-containing ionic liquid, [Asp][H2PO4], servers as both a plasticizer and a flame retardant, while a hybrid network of Ti3C2TX-MXene and hydroxylated multi-walled carbon nanotubes (MWCNTs) imparts electrical conductivity. The electrical conductivity of the prepared film is 9.58 × 10−3 S/m, which is 795 % higher than that of the pure MXene film and 510 % higher than that of the pure MWCNTs film. It also exhibits stable strain sensing for human motion monitoring, with enhanced sensitivity after water soaking. This work offers a simple strategy for fabricating multifunctional PVA composites for wearable electronics.
Chronic wounds represent a significant clinical challenge, characterized by persistent infection, inadequate angiogenesis, and impaired tissue regeneration. To address these issues holistically, we developed a multifunctional hydrogel dressing by incorporating umbilical cord mesenchymal stem cell-derived exosomes (UCMSC-Exos) into a robust, physically crosslinked polyvinyl alcohol/ε-polylysine (PVA/EPL) network. The resulting composite hydrogel exhibited an ideal wound dressing microstructure with high porosity, enhanced mechanical strength, excellent moisture retention, and potent broad-spectrum antibacterial activity. Functioning as an effective exosome reservoir, the hydrogel enabled a sustained release profile that potently stimulated the proliferation, migration, and tube-forming capacity of human umbilical vein endothelial cells (HUVECs) in vitro. In a murine full-thickness wound model, the exosome-laden hydrogel significantly accelerated wound closure, promoted re-epithelialization, and enhanced the deposition of well-organized collagen. Most importantly, transcriptome sequencing analysis revealed 36 differentially expressed genes and identified modulation of immune response and cell motility as key underlying processes. The marked upregulation of critical skin repair genes Epcam and Ang2 was further validated by qRT-PCR. This study demonstrates that our UCMSC-Exos-PVA/EPL hydrogel synergistically integrates the physical advantages of a polymeric matrix with proactive biological signaling, offering a promising and comprehensive strategy for advanced wound management.
The effect of the mechanical and moisture absorption properties of two types of plywood-based composites, glass/plywood/polyester (WGP) composites and carbon/plywood/polyester (WCP) composites, was investigated. In addition, the inorganic fillers, including blue nitrile powder, graphite powder, marble dust, and color pigment, were added to the composites. Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy analyses were performed to identify the functional groups of the composites and confirm the presence of the filler. The results revealed that the WCP composites had excellent mechanical properties such as tensile strength (79.6 MPa) and compressive strength (48.6 kN). The impact strength of WGP (8 J) composites slightly decreased in the WCP (7.8 J) composites. Furthermore, the WCP composites showed lower moisture absorption (0.39 %) and thickness swelling (1.6 %) properties. The exceptional mechanical properties and water resistance of the WCP composites make them optimal for application in sports industry, especially high-performance snowboards.
This work developed thermosetting materials with antibacterial and flame-retardant properties for protective coatings and medical components where simultaneous hygiene requirements and fire safety are necessary. Hydrophilic hyperbranched polyethyleneimine reacted with salicylaldehyde to form a Schiff base, then with diphenylphosphine oxide (DPPO) to create a flame-retardant hydrophobic shell. Based on host-guest chemistry, the photosensitizer indocyanine green (ICG) was encapsulated into the amphiphilic core-shell polymer to obtain the ICG@HPEIDPP complex (0.06 g ICG per 1 g host). The residual secondary amines allowed curing with epoxy resins. At only 1.1 wt% ICG, the thermoset achieved antibacterial rates of 96.48 % against E. coli and 96.46 % against S. aureus. The material also reached a V-0 vertical burning rating and a limiting oxygen index above 26 %. This integration approach imparts photodynamic antibacterial activity via host-guest encapsulation, while preserving the intrinsic flame-retardant properties of the hyperbranched host, and can be extended to incorporate other functional molecules.
Soft interlayered rock slopes with gently dipping bedding planes are highly susceptible to deformation accumulation, local strain concentration, and instability during dynamic excavation and construction. However, conventional stability analysis and monitoring methods are mainly based on static mechanical models or external sensing devices, which are insufficient for capturing real-time deformation evolution under repeated disturbance. Therefore, highly flexible, sensitive, and cyclically stable intelligent sensing materials are required for dynamic deformation monitoring and support optimization. In this study, graphene (GR) and multi-walled carbon nanotubes (MWCNTs) were incorporated into thermoplastic polyurethane (TPU) through a dual-carbon synergistic strategy to construct a highly stable conductive strain-sensing composite. The mechanical, electrical, morphological, rheological, and viscoelastic properties of the composites were systematically characterized by tensile testing, cyclic resistance-strain measurements, current–voltage (I–V) analysis, scanning electron microscopy (SEM), rubber process analysis (RPA), and dynamic mechanical analysis (DMA). The results showed that the two-dimensional GR framework and one-dimensional MWCNT bridges formed a multiscale “plane-line” conductive network, which improved filler dispersion, enhanced interfacial load transfer, and promoted reversible reconstruction of conductive pathways. Consequently, the optimized MGTPU composite achieved a high gauge factor of 9,462.56, a low resistive hysteresis area of 11.29 %, excellent cyclic durability, and stable resistance response under large deformation. Molecular dynamics (MD) simulation was further conducted in parallel with the experimental investigation to reveal the molecular origin of the enhanced electromechanical stability, which cannot be directly identified from macroscopic tests alone. The MD analysis focused on mean square displacement (MSD), radial distribution function (RDF), fractional free volume (FFV), and interfacial binding energy. Compared with the single-filler systems, MGTPU exhibited the lowest molecular chain mobility, the strongest interfacial atomic ordering, the lowest FFV of 7.62 %, and the highest absolute binding energy of approximately 3.6 × 104 kcal/mol. These simulation results confirm that the GR-MWCNT synergistic network restricts TPU chain motion, strengthens filler-matrix interfacial bonding, reduces free volume, and suppresses conductive network relaxation during cyclic deformation. Therefore, the combined experimental and MD results demonstrate that the dual-carbon strategy enhances strain sensitivity and cyclic stability by simultaneously stabilizing the conductive network at the microscopic scale and reinforcing molecular-level interfacial confinement. This study provides a material design strategy and molecular-level mechanism for developing high-performance TPU-based flexible strain sensors for intelligent deformation monitoring in slope engineering and other structural health monitoring applications.
Physical (thermal and non-thermal) modification of native starch (NS) offers an environmentally friendly strategy to tailor wall-material functionality for microencapsulation. This study systematically compares heat moisture treatment (HMT), annealing (ANN), ultrasonication (US), microwave treatment (MW), and high-pressure processing (HPP) for modifying sago starch and evaluates their effects on physicochemical, structural, morphological, and encapsulation performance toward butterfly pea (Clitoria ternatea) phenolic extract. Apparent amylose content remained relatively stable across treatments (23–30 %), although US and HPP increased apparent linear-chain fractions by approximately 30 % and 26 %, respectively. Water absorption capacity increased significantly from 1.67 g/g (NS) to 1.89 g/g (US) and 1.94 g/g (HPP). Correspondingly, solubility increased from 5 % (native) to 5.5 % (HPP), while swelling power increased from 11.5 g/g to 12.1 g/g (US) and 15.1 g/g (HPP). X-ray diffraction confirmed that all samples retained the native C-type polymorph in all samples, while relative crystallinity decreased from 63 % in NS to 62 % and 45 % after US and HPP treatments, respectively. Fourier-transform infrared spectroscopy revealed no new functional groups, indicating preservation of chemical structure, whereas scanning electron microscopy showed localized surface disruption in US and HPP samples. Spray-dried powders prepared using modified starch wall materials demonstrated enhanced encapsulation efficiency, with US and HPP achieving approximately 32 % and 33 % EE, respectively compared to 26 % for NS. The improved performance is attributed to increase linear-chain availability and enhanced starch–phenolic interactions, facilitating stronger hydrogen bonding and matrix entrapment. Overall, ultrasonication and high-pressure processing emerged as the most effective solvent-free modification techniques for engineering sago starch-based wall materials for spray-dried bioactive delivery systems.
Carbon fiber reinforced polymers (CFRPs) are promising materials for tubular structures in wind energy systems. Although their torsional behavior has been widely studied, the coupled influence of diameter and ply orientation under different loading rates remains insufficiently understood. This study addresses this gap through static and dynamic torsion experiments using a custom-designed fixture that converts impact forces into controlled torsional loading, thereby overcoming the inability of conventional setups to measure dynamic torsional responses. In dynamic tests, ply orientation produces a pronounced effect; for example, the peak force of the 25-90-40 specimen is 17.2 % higher than that of the 25-45-40 specimen due to circumferential fiber alignment, which enhances hoop constraint and rate-dependent shear stiffness. Analysis of response histories and failure modes further reveals a clear rate-dependent diameter effect: smaller-diameter tubes show better stability under low incident energy, whereas larger-diameter tubes exhibit higher dynamic torsional resistance as the incident energy increases. These findings provide new insight into the torsional behavior of CFRP tubes under multi-rate loading.
The preparation of polyurethane-based porous materials from waste sources for the selective separation of oil from contaminated water has attracted significant attention. In this study, a hydrophobic and oleophilic porous thermoplastic polyurethane (TPU) monolith was fabricated via a thermally induced phase separation (TIPS) method. The optimal preparation conditions, determined through orthogonal experiments, were as follows: a TPU concentration of 2.8 g per 40 mL of solvent, a solvent ratio of 1,4-dioxane to water at 11:1 (v/v), and a freezing temperature of -20 degrees C. The resulting TPU monolith exhibited excellent adsorption performance, capable of absorbing oils and organic solvents up to 6-55 times its own weight. Moreover, it maintained stable adsorption capacity under harsh conditions, including exposure to strong acids, strong bases, and a wide temperature range. The material also demonstrated effectiveness in removing trace organic pollutants from oil-in-water emulsions.
The ambiguity of the effect of applying pro-oxidant additives to polyolefins aroused interest in its actual biodegradability. A sample of a commercial package with pro-oxidant additive, a sample of pure low-density polyethylene (LDPE) and a sample of LDPE with d2W additive were studied. For the complete biodegradation of polyethylene with pro-oxidant additives, the samples were first subjected to abiotic exposure under ultraviolet light and then placed in a biologically active medium. Biodegradability at the second stage was determined by the release of carbon dioxide. For 100 days, polyethylene with 5 wt% d2W decomposed by 7.5 %, a commercial package with an additive - 6 %, pure polyethylene - 3 %. The supramolecular structure and the chemical composition of polyethylene with additives changed significantly. It was concluded that polyethylene with pro-oxidant additives can be biodegraded to carbon dioxide after two-step degradation. However, the rate of biodegradation is low, and the intermediate product is microplastics.
Tertiary fatty amide, N,N-dibutyldodecanamide (DBDA), has been synthesized and evaluated as a new environmentally friendly plasticizer for polyvinyl chloride (PVC). Homogeneous PVC/DBDA films containing from 10 to 40 wt% fatty amide were prepared by solvent casting. Infrared analysis of PVC/DBDA compositions indicates molecular interactions between the -CH-Cl group of PVC and the amide carbonyl group. Differential scanning calorimetry analysis revealed the plasticizing efficacy of DBDA toward PVC. Thus, the introduction of DBDA (20 % and 30 %) into PVC significantly reduced its glass transition temperature by 67.4 degrees C and 80.4 degrees C, respectively. According to the results of thermal gravimetric analysis, the thermal degradation point of PVC/DBDA compositions is higher than the actual processing temperature of plasticized PVC. DBDA plasticizer was also found to have a high resistance to migration from PVC films, similar to that of common green plasticizer ESO. Microbiological analysis indicates that PVC/DBDA films are not toxic for the biofilm-forming bacterial strains Klebsiella pneumoniae and Staphylococcus aureus. The biodegradability of DBDA plasticizer, determined by a primary biodegradation test CEC L-33-A93, was found to be 96.5 % after 21 days. Overall, tertiary fatty amide DBDA can be considered as a new promising plasticizer for PVC, alternative to common toxic phthalate esters.
This study employs molecular dynamics (MD) simulations to systematically investigate the effects of the degree of polymerization (DP 10, 20, and 35) on the mechanical and tribological properties of nitrile butadiene rubber (NBR) against a copper (Cu) probe. Mechanical property analysis reveals that increasing the DP from 10 to 35 enhances the Young’s modulus and shear modulus by 11.9 % and 16 %, respectively, establishing a more rigid structural foundation. Tribological simulations demonstrate that increasing DP significantly optimizes performance, yielding a 44.3 % reduction in the coefficient of friction (COF) and a 36.9 % relative decrease in the wear rate. Microscopic analysis of atomic concentration, velocity distribution, and radial distribution functions (RDF) indicates that higher DP promotes a denser network of physical entanglements, which effectively mitigates adhesive shearing and restricts molecular migration at the friction interface. Energy evolution profiles further confirm that high-DP matrices suppress potential energy surges and local heat accumulation, thereby enhancing thermal stability and structural integrity. These findings demonstrate that increasing DP significantly strengthens the internal physical entanglements and intermolecular interactions within the NBR matrix, providing a theoretical basis and molecular design strategy for developing high-performance, wear-resistant materials for water-lubricated bearings.
Elastomeric conductive textiles are promising for wearable electromagnetic shielding, requiring maintained performance under stretch. Herein, weft-stretch conductive woven fabric integrating silver-plated elastic wrapped yarns were fabricated, achieving tunable electromagnetic shielding effectiveness (EMSE). The fabrics show excellent reversible stretchability (similar to 85 % elongation, full recovery) and stable cyclic tensile performance. Their EMSE over X-band can be modulated by key structural factors: fabric placement (determing the orientation of silver-plated yarns relative to electric field; horizontal approximate to 19 dB > vertical, negligible; due to structural anisotropy); weft density (increasing conductive content per unit area; from 6 to 10 picks/cm double shielding); applied strain (tightening the conductive network; 0-50 % strain improves EMSE by similar to 44.4 %); and an optimized double-layer design where tuned spacing forms a resonant cavity, boosting peak EMSE via wave interference and coupling. This work provides a viable strategy for designing adaptive textile-based shields with precisely tailorable shielding performance through integrated material and structural engineering.
Epoxidized natural rubber (ENR), a renewable derivative of natural rubber (NR), was investigated as an effective compatibilizer to enhance the crystallization behavior of stereocomplex polylactide (stPLA) blends. Neat stPLA and blends containing NR or ENR (5-20 wt%) were prepared via melt blending. Differential scanning calorimetry showed that ENR exhibited better compatibility with PLA than NR, promoting stereocomplex crystallization while suppressing homocrystalline formation. At 10 wt% ENR, the stereocomplex crystallinity increased to 42.3 %, more than twice that of neat stPLA. Polarized optical microscopy revealed an earlier crystallization onset in ENR-containing blends (similar to 140 degrees C) compared with stPLA and stPLA-NR (similar to 120 degrees C). Water contact angle measurements indicated enhanced surface hydrophilicity, reaching an optimum of similar to 70 degrees at 10 wt% ENR. Non-isothermal crystallization kinetics analysis demonstrated that ENR accelerated crystallization and reduced the activation energy barrier, confirming its role as an effective compatibilizer facilitating stereocomplex crystallization via enhanced miscibility.
A library of co-initiators for Type II photoinitiating system was discovered, which was characterized by alpha-aminoketone structural units. This alpha-aminoketone derivative library encompassed a broad spectrum of compounds, including peptides, glycine ester derivatives, piperazinone derivatives, piperidone derivatives, and others. When combined with camphorquinone under aerobic conditions, these co-initiators demonstrated versatile radical photopolymerization initiation capabilities across various pH conditions. Among them, 1-methyl-3-oxopiperazine demonstrated significantly superior performance compared to the benchmark ethyl 4-dimethylaminobenzoate (EDB). Moreover, 1-methyl-3-oxopiperazine demonstrated superior biocompatibility relative to EDB in L929 fibroblast assays, exhibiting minimal cytotoxicity across all tested concentrations. This optimal alpha-aminoketone derivative displayed broad compatibility with both hydrophobic and hydrophilic monomers, as well as diverse photosensitizers. Notably, when paired with camphorquinone, it effectively initiated the photopolymerization of formulations containing black pigment - a challenging condition for conventional systems - highlighting its robust reactivity and significant potential for application in advanced photocuring technologies, including dental restorative materials and biohydrogel fabrication. Static photolysis, cyclic voltammetry analysis, ESR spectroscopy, free energy calculations and computational chemistry analysis collectively elucidated the photoinitiating mechanisms.
