Search Results (3,470)

To enhance the interfacial bonding between bamboo and the polymer matrix in natural fiber composites (NFCs), vacuum heat treatment was applied to moso bamboo strips at temperatures ranging from 140 to 180 °C with holding times of 4 and 6 h. The effects of treatment conditions on the surface characteristics and chemical composition of bamboo were systematically investigated. Scanning electron microscopy (SEM), contact angle measurements, and Fourier transform infrared spectroscopy (FTIR) were employed to evaluate the changes in microstructure, surface wettability, and the main functional groups including α-cellulose, hemicellulose, and lignin. The results indicate that the severity of heat treatment (temperature–time combination) significantly influences the physicochemical properties of bamboo. Hemicellulose, which exhibited the lowest thermal stability, underwent pronounced degradation above 140 °C and showed the most substantial compositional variation. Although the relative contents of α-cellulose and lignin increased with increasing treatment severity, their absolute contents decreased. The vacuum environment was found to retard the degradation of α-cellulose to some extent. At 180 °C, severe disruption of the cell wall structure was observed, accompanied by the deformation and collapse of cell lumens. In addition, heat treatment increased the surface contact angle, indicating enhanced hydrophobicity, with temperature exerting a more pronounced effect than treatment time. FTIR analysis revealed a marked reduction in the intensity of the C=O stretching vibration of hemicellulose (~1730 cm⁻¹) and the O–H stretching vibration (~3400 cm⁻¹), while the aromatic structure of lignin remained relatively stable. Overall, vacuum heat treatment effectively enhanced the surface hydrophobicity of bamboo, providing a theoretical basis and technical support for the development of bamboo-reinforced natural fiber composites. Full article

The development of phase change materials (PCMs) for window applications with both high optical transparency and effective temperature regulation is crucial for passive energy saving. However, liquid leakage during phase transition and enhanced interfacial light scattering often cause fluctuations in optical transmittance and deterioration of image clarity. To address these challenges, a highly transparent phase change composite was constructed via a microencapsulation strategy. Submicron core–shell microcapsules were fabricated using n-octadecane as the core and silica as the shell, enabling effective encapsulation of the liquid PCM component. The resulting microcapsules exhibited a high melting enthalpy of 155.3 J g⁻¹. They were subsequently homogeneously dispersed within a refractive-index-matched polymer matrix, mitigating light scattering during phase transition by reducing interfacial refractive index mismatch. The composite exhibited favorable thermal energy storage capability and transmittance performance, with a visible light transmittance of 83.75% and a transmittance fluctuation of only ~5% before and after phase transition. After 100 thermal cycles, the optical attenuation remained as low as 0.35%, demonstrating excellent cycling stability. This work provides a new strategy for balancing optical transparency and phase change function, with potential applications in smart windows and flexible electronics. Full article

Carbon fiber-reinforced polymer (CFRP) composites are widely used in engineering applications due to their high strength-to-weight ratio and corrosion resistance. However, their mechanical performance depends strongly on laminate architecture, processing conditions, and environmental exposure. This study investigates the effects of fiber orientation, thermal post-curing, and corrosive SO₂ atmosphere on the mechanical properties of CFRP laminates. Three-layer carbon/epoxy laminates with 90°, 45°, and [90°/45°/90°] fiber orientations were manufactured by vacuum-assisted lamination. Selected specimens were post-cured at 80 °C for 10 h and exposed to sulfur dioxide according to ISO 3231. Tensile and Charpy impact tests showed that the 90° laminate exhibited the highest tensile strength (484 MPa), whereas the 45° laminate showed the lowest value due to shear-dominated load transfer. Post-curing increased tensile strength by approximately 10–30%, while exposure to the corrosive environment reduced both tensile strength and impact toughness. The observed behavior was associated with differences in load-transfer mechanism, possible increased degree of cure and/or residual stress relaxation after post-curing, and degradation of the epoxy–matrix and fiber–matrix interface after SO₂ exposure. The results demonstrate that suitable selection of laminate architecture and thermal treatment can significantly improve the durability of CFRP structures intended for aggressive environments. Full article

Increasing regulatory demands for high-quality plastic recycling create a strong need for novel tracer systems that enable reliable polymer identification and sorting. This feasibility study evaluates germanium nanocrystals (GeNCs) as Raman-detectable tracer materials in polypropylene (PP). The synthesis of GeNC/PP composite materials possessing various GeNC contents via a solvent-based intercalation process followed by compounding and injection molding is reported. Hydride-terminated GeNCs were synthesized and subsequently functionalized with dodecyl ligands to ensure chemical stability, compatibility with the polymer matrix, and processability under conventional melt-processing conditions. The dodecyl-functionalized GeNCs were successfully stabilized and homogeneously integrated into the PP matrix. Raman spectroscopy demonstrates the clear detection of GeNCs within the composites through a characteristic Ge–Ge optical phonon mode at 296 cm⁻¹, which is well separated from the intrinsic Raman bands of polypropylene. The Raman signal intensity increases systematically with increasing GeNC concentration. Raman mapping reveals an overall homogeneous distribution of the nanocrystals within the polymer, while a slight tendency toward agglomeration is observed at higher loadings. These results demonstrate that GeNCs are well suited as optically detectable tracers for polypropylene and can be reliably identified using Raman spectroscopy, highlighting their potential for tracer-based sorting concepts in advanced recycling and digital material passport applications. Full article

Carbon fiber-reinforced polymer (CFRP) composites are widely employed in the aerospace industry due to their excellent properties such as high specific strength and corrosion resistance. However, the delamination and tearing of composites are prone to occur in the machining of CFRP, which significantly affect its performance. The existing laser-assisted cutting model generally simplifies the machining process into high-temperature conventional cutting, and only reflects the thermal effect by modifying the material parameters. The core selective ablation characteristics of laser–CFRP interaction are completely ignored, and the unique mechanical behavior of bare fiber under a large cutting angle is not modeled, and the quantitative correlation between cutting force evolution and machining damage is lacking. In this study, an innovative method of partially exposing fibers is proposed to simulate laser-assisted machining. A micromechanical model is developed to analyze the removal mechanisms of different phases during CFRP processing, and a cutting force prediction model from the micro to macro scale is also established. At the micro-scale, a micromechanical model for fiber cutting in orthogonal machining of CFRP is constructed based on the elastic foundation beam theory. The results show that the proposed cutting force prediction model has high reliability, and the relative error between the predicted value and the experimental measured value is only 7.81%~8.99%. All experiments were repeated three times. Statistical analysis showed that the repeatability of the results was excellent. Compared with conventional cutting, laser-assisted cutting fundamentally changed the failure mode of the fiber from matrix-constrained crushing fracture to controllable free-end large-deflection bending fracture. This transformation leads to a smoother and more regular fiber fracture surface, which effectively inhibits fiber breakage, matrix tearing, and fiber–matrix interface debonding. Quantitative analysis confirms that under laser-assisted processing conditions, the matrix tearing length is positively linearly correlated with the cutting depth, cutting speed, and bare fiber length. Full article

This study systematically investigates the low-velocity impact response of aerospace-grade carbon-fiber-reinforced polymer (CFRP) T-stiffened panels. Through drop-weight impact tests at 20 J and 35 J energies and Cohesive Zone Model (CZM) numerical simulations, a comparative analysis was performed on two composite configurations: the pure CFRP baseline (Configuration A) and the hybrid configuration incorporating surface glass fiber layers (Configuration B). High-fidelity correlation between experimental and numerical results was achieved, validating the progressive damage evolution of the matrix and fiber constituents. The main findings demonstrate that the hybrid Configuration B exhibits significantly superior impact resistance compared to the monolithic CFRP Configuration A. The introduction of surface glass fiber layers produces a synergistic hybrid effect in the composite system. This surface layer acts as a protective buffer, effectively attenuating the impact load before it propagates to the underlying carbon fiber laminate. As a result, the hybrid structure absorbs more energy and effectively suppresses rapid crack propagation. Under 35 J impact energy, Configuration B avoids the brittle failure of the matrix observed in Configuration A, achieving a 24% increase in permanent energy absorption. This surface hybridization strategy provides an effective method for improving damage tolerance and preserving the structural integrity of advanced composite stiffened panels. Full article

Microneedle systems represent a promising minimally invasive approach for transdermal drug delivery; however, their performance strongly depends on the composition and mechanical properties of the polymer matrix. The aim of this study was to select an optimal polymer composition for the fabrication of dissolving microneedle arrays produced by the mold casting method. The study focused on evaluating mechanical strength, dissolution behavior, and penetration efficiency of different polymer systems. Microneedle matrices were fabricated using polyvinylpyrrolidone (PVP K-30), methylcellulose, sodium alginate, and hyaluronic acid at various concentrations, alone and in combination. No active pharmaceutical ingredient (API) was incorporated; the study was performed using blank polymeric systems intended for subsequent drug loading. The microneedles were manufactured using 3D-printed and silicone molds. Their performance was evaluated by in vitro dissolution testing, pH measurement, penetration studies in gelatin gel and Parafilm M models, and mechanical compression testing. Monopolymer systems demonstrated either rapid dissolution with insufficient mechanical strength or improved strength at the expense of prolonged dissolution time. Combined polymer formulations showed superior structural uniformity and balanced performance. In particular, the system containing 5% PVP K-30 and 10% sodium alginate demonstrated the best overall characteristics, achieving high penetration efficiency (up to 96%), uniform dissolution (78%), and appropriate dissolution time (8.5 ± 0.5 min). Addition of hyaluronic acid further improved structural uniformity and handling properties. The results indicate that composite polymer matrices provide an optimal balance between mechanical stability, penetration ability, and dissolution rate. The formulation consisting of 5% PVP K-30 and 10% sodium alginate was identified as the most promising base for further development of drug-loaded dissolving microneedle systems. Full article

The development of durable and practical polymer-supported photocatalytic materials that are suitable for use in continuous-flow systems has become an increasingly pressing issue in the field of water treatment. In this study, FeTiO₃/BiOCl heterojunction structures were synthesized at different ratios and integrated into a poly(vinylidene fluoride) (PVDF) matrix to develop photocatalytic thin-film systems. The resulting materials were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and UV–visible diffuse reflectance spectroscopy (UV-DRS) analyses. In photocatalytic experiments conducted under visible light, a 66.3% removal of doxycycline was achieved for pristine FeTiO₃ within 180 min, whilst the FTO@BiOCl(III) composite reached 74.4%. In the PVDF-based thin-film system, the film catalyst demonstrated a removal efficiency of 68.9%. When the pH effect was investigated, the highest total removal of 90.3% was achieved under pH 6.0 conditions. Radical scavenging experiments revealed that superoxide radicals were the predominant active species (a decrease to 30.5% in the presence of benzoquinone (BQ). In experiments conducted in the air-lift reactor system, the P-FTO@BiOCl(III) film achieved approximately 65% removal after 9 h and maintained its structural stability. The PVDF-supported FeTiO₃/BiOCl heterojunction thin-film system offers a noteworthy alternative for environmental applications due to its suitability for continuous systems, structural stability and effective photocatalytic performance. Full article

Zeolite-based composite nanomaterials represent a versatile and mechanistically rich platform for the removal of organic micropollutants (OMPs)—including pharmaceuticals, endocrine-disrupting compounds, pesticides, and per- and polyfluoroalkyl substances (PFAS)—from contaminated water systems. Although pristine zeolite frameworks provide well-defined microporous architectures, tunable Si/Al ratios, and ion-exchange capacity, their intrinsic hydrophilicity restricts interaction diversity and limits performance toward the structurally heterogeneous OMPs prevalent in real aquatic environments. Composite integration with carbonaceous nanophases, functional polymers and surfactants, and catalytically active metal oxide nanoparticles substantially extends this interaction repertoire, yielding multifunctional materials whose adsorption performance exceeds that of the individual components. Drawing on a systematic survey of peer-reviewed literature published between 2016 and 2026, this review develops a mechanism-oriented, structure–property–performance framework examining five dominant adsorption mechanisms—electrostatic attraction, π–π stacking, hydrogen bonding, hydrophobic partitioning, and micropore confinement—in relation to composite nanoarchitecture, surface chemistry, and structural parameters. The modulating influence of realistic water matrix conditions on adsorption efficiency is critically assessed, alongside challenges of regeneration, long-term stability, metal leaching, and the persistent gap between laboratory-scale synthesis and scalable deployment. Priority research directions are identified, including standardized performance evaluation under environmentally representative conditions and rational design of hierarchical multifunctional nanocomposites from earth-abundant and waste-derived precursors. Full article

Electrochemical sensors have emerged as promising tools for rapid pesticide screening in food and environmental samples because they combine simple instrumentation, fast response, portability, and compatibility with disposable electrodes. This review organizes recent progress through a cross-system framework linking pesticide class, interfacial electrochemical process, and material design. Carbon materials, metal–organic frameworks and their derivatives, metal nanoparticles, metal compounds, conducting polymers, MXene-based composites, and selected emerging materials are compared in terms of enrichment capability, charge-transfer regulation, catalytic amplification, recognition-layer integration, and suitability for real-sample analysis. Emphasis is placed on issues that are often under-discussed in performance-centered surveys, including matrix interference, electrode fouling, batch-to-batch reproducibility, storage stability, scalability, and cost-effectiveness. Representative examples show that the most useful advances arise not simply from lowering the limit of detection but from improving structure–function understanding and translating interfacial design into robust analytical performance. Future work should prioritize standardized fabrication and benchmarking protocols, in situ and operando identification of active sites and interface evolution, matrix-specific antifouling validation, multiresidue and metabolite analysis, and hybrid portable devices coupled with intelligent readout. Full article

Barely Visible Impact Damage (BVID) in heterogeneous polymer-matrix composites remains difficult to detect because subtle damage signatures are often masked by complex architectures, hybrid textures, and overlapping failure morphologies. This study therefore presents an experimentally grounded, physics-aware, and statistically validated vision-based inspection framework rather than a purely detector-centered benchmarking exercise. Real post-impact images were obtained from controlled low-velocity impact experiments on 20 composite architectures and 60 physical specimens, yielding approximately 2000 images across laminated, hybrid, textile-reinforced, and sandwich structures. The dataset was organized using a specimen-disjoint splitting protocol to prevent leakage across training, validation, and test subsets. To improve robustness while preserving physical realism, a physically grounded Albumentations strategy was developed using only physically admissible transformations and explicit exclusion of non-physical operations that could distort damage morphology or surface continuity. Model development was further complemented by a hybrid hardware workflow in which cloud-based GPU training was combined with deployment-oriented inference profiling on resource-constrained edge-like hardware, thereby linking detection accuracy to practical industrial feasibility. In addition, model performance was evaluated under a standardized training budget and validated through repeated runs, Friedman significance testing, and Holm-corrected Wilcoxon signed-rank pairwise comparisons to ensure error-controlled interpretation of inter-model differences. Across the evaluated compact YOLO families, YOLO26s delivered the strongest overall performance, reaching 0.841 mAP@0.5, 0.586 ± 0.004 mAP@0.5:0.95, and an F1-score of 0.809, while YOLO11s achieved the highest precision and YOLO26n remained competitive in recall with nano-level compactness. Overall, the results show that experimentally generated heterogeneous composite data, morphology-preserving augmentation strategy development, leakage-aware dataset design, deployment-oriented computational profiling, and statistically grounded validation together provide a more robust and application-relevant basis for automated BVID detection in polymer-matrix composite structures. Full article

Sodium-ion-based polymer electrolytes have emerged as an essential technology for the next generation of solid-state batteries, offering the possibility of greater safety and mechanical flexibility. This work aimed to prepare eco-friendly ormolytes based on a biohybrid host matrix, which were doped, for the first time, with a wide range of NaTFSI concentrations. The matrix consists of short poly(ε-caprolactone) segments covalently bonded to siliceous domains via urethane linkages. The samples obtained were thin and transparent films. They were characterized by means of thermogravimetric analysis (TGA) and X-ray diffraction (XRD), and the films exhibited an amorphous character over the entire composition range. Ionic conductivity measurements were performed, and at room temperature for n = 10, the ionic conductivity was 2.44 × 10⁻³ mS.cm⁻¹. The highest ionic conductivity value of 1.78 × 10⁻² mS.cm⁻¹ (n = 10) was obtained at 62.0 °C. To access the cation/urethane interactions, Fourier transform infrared (FT-IR) spectroscopy was employed, and it was noted that the global profile was slightly altered with the incorporation of salt, in which more interactions were observed for the more concentrated samples. Thus, the proposed material may be promising in the development of more sustainable and environmentally friendly electrochemical devices with Na ions. Full article

The design of sustainable composite materials requires approaches that integrate performance, durability, and circularity. In this study, jackfruit seed residue (JSR), a starch-rich agro-industrial by-product, is explored as a multifunctional biopolymeric component in cement-based rendering composites within a Safe and Sustainable by Design (SSbD) framework. Despite conventional strategies based on purified polymers or synthetic admixtures, JSR is incorporated in its unprocessed form, preserving its intrinsic chemical and structural heterogeneity and enabling complex physicochemical interactions within the composite matrix. Mortar formulations containing 0%, 3%, 5%, and 7% JSR (by binder mass) were evaluated through fresh-state, mechanical, and durability tests, combined with multiscale characterization (X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray fluorescence). The incorporation of JSR enhanced workability and significantly reduced capillary water absorption (up to 25.83%), while maintaining mechanical performance within the typical range for rendering applications, with strength gains observed at 28 days. The observed behavior is attributed to synergistic mechanisms, including water retention, internal curing, and microfiller effects, as well as ionic contributions from the mineral fraction of the residue. Further, microstructural analysis revealed refinement of the interfacial transition zone and modification of the pore network, indicating reduced transport connectivity rather than a simple decrease in total porosity. These results demonstrate that unprocessed bio-residues can act as effective multifunctional components in cementitious composites, enabling the tuning of structure–property relationships and offering a scalable pathway toward low-impact composite materials aligned with circular economy principles. Full article

This study investigates the influence of nano-alumina (nano-Al₂O₃) on the compressive properties and damage mechanisms of epoxy matrix composites across a wide strain rate range. Composites with varying nano-Al₂O₃ contents (0, 1, 3, 5, 10, 15 wt%) were tested under quasi-static (0.001~0.1 s⁻¹) and dynamic (2500~4800 s⁻¹) conditions using a universal testing machine and a Split Hopkinson Pressure Bar, respectively. The phase, the microstructure, and their effects on macro-mechanical performance and micro-damage were characterized by XRD, SEM, and TEM. Results indicate that the incorporated nano-Al₂O₃ is highly crystalline, single-phase lamellar α-Al₂O₃. Its addition significantly modulates the compressive properties, with effects dependent on both content and strain rate. Under quasi-static compression, yield strength increased monotonically with nano-Al₂O₃ content at 0.1 and 0.01 s⁻¹, reaching a maximum increase of ~9.5% at 15 wt%. However, at 0.001 s⁻¹, optimal strength occurred at 10 wt%, beyond which agglomeration caused degradation. Dynamic tests revealed a positive strain rate effect. The 10 wt% composite exhibited optimal overall performance, combining high peak stress and a stable stress plateau, whereas the 15 wt% sample showed higher peak stress but poor post-peak load-bearing capacity. Microstructural analysis showed that 10 wt% nano-Al₂O₃ dispersed uniformly, enhancing toughness by inhibiting crack propagation via interfacial bonding and microstructural refinement. In contrast, at 15 wt%, particle agglomeration induced interfacial defects, promoting debonding and brittle fracture. This work provides insights into the wide-strain-rate mechanical behavior of nanoparticle-reinforced polymers and supports the design of high-performance, impact-resistant epoxy composites. Full article

The escalating demand for high-performance dielectric energy storage materials in pulse-power systems and portable electronics calls for polymer film capacitors with high discharged energy density and breakdown strength. Conventional polymers, however, suffer severe performance degradation under concurrent thermal and electrical stress, and existing reinforcement strategies—involving inorganic nanofillers or chemical crosslinking—often compromise flexibility, introduce interfacial defects, or involve complex processing. Herein, we demonstrate that incorporating a rigid mechanically interlocked molecule, specifically an octacationic homo[2]catenane, into a polyimide matrix yields robust, crosslink-like networks through strong [π∙∙∙π] electrostatic interaction between electron-rich aromatic units of polyimide and electron-deficient homo[2]catenane. This supramolecular network simultaneously enhances breakdown strength via densified chain packing and suppresses conduction loss by forming deep electron traps derived from the high electron affinity of homo[2]catenane. The optimized PI–HC⁸⁺ composite achieves a high discharged energy density of 7.86 J/cm³ with an efficiency > 80% and sustains stable performance over 10⁵ charge–discharge cycles at 150 °C. This research establishes mechanically interlocked molecules as a new class of functional fillers for high-performance polymer dielectrics, opening an unexplored avenue in the design of next-generation capacitive energy-storage materials. Full article