Advanced Composites and Hybrid Materials最新文献

Balancing the thickness and bandwidth of electromagnetic wave–absorbing materials has been a challenging task. In this study, a thin and broadband metamaterial absorber consisting of a frequency selective surface (FSS) layer compounded with a magnetic dielectric layer was proposed. The changes in the wave absorbing properties of the absorbers with different numbers of openings in the open circular structure and combinations of open circular rings were analyzed. After obtaining the optimum combination of patterns, the effect of parameter variations on the microwave absorption properties of metamaterial wave absorbers was investigated. The test results show that the optimized metamaterial absorber has a thickness of 1.7 mm, a simulated absorption bandwidth of up to 10.0 GHz, and a microwave reflection loss of less than − 10 dB in the frequency band of 8.0–18.0 GHz. The absorber was prepared and its reflection loss was measured. It is found that these test results have the same trend as the simulation results, which verifies the feasibility of the metamaterial absorber structure design; the proposed two-layer magnetic dielectric composite FSS structure improves the overall impedance matching, avoids the electromagnetic wave being reflected in the surface, and makes the electromagnetic wave enter the interior more; when the resonant absorption peak generated by the introduction of FSS is close to the absorption peak generated by the magnetic dielectric layer, continuous absorption will be achieved, which is the reason for the wide absorption band of the metamaterial absorber. This novel structure takes into account the characteristics of thin layer, broadband absorption, and polarization insensitivity, which has a potential application prospect in stealth technology.

Pulsed DC plasma-liquid interaction was used to prepare Ag-doped Fe₃O₄@SiO₂@TiO₂ (PP-FST) core–shell in a very short time compared to conventional methods. Tetraethyl orthosilicate (TEOS) and Ti(IV) isopropoxide precursors were employed as sources of SiO₂ and TiO₂, respectively, under the influence of plasma-liquid interaction using silver metal electrodes. TEM images and EDS mapping proved the successful formation of Fe₃O₄@SiO₂@TiO₂ core–shell structure without the detection of Ag NPs on the PP-FST surface. This proposed the dispersion of Ag NPs within TiO₂ lattice during the synthesis process using the plasma-liquid technique. The XRD patterns show an increase of the crystallinity of the sample after exposure to plasma. Furthermore, structural and optical properties were studied using XPS and UV–Vis, respectively. The synthesized FST core–shell exhibited outstanding light absorption capabilities which may be attributed to the strong surface plasmon resonance (SPR) effect at the interface of the Ag nanoparticles and the TiO₂ semiconductor. This interaction lowers the energy band gap of PP-FST to 2.05 eV, compared to 2.73 eV for FST. The specific surface area determined by BET analysis was 53.9 m²/g for PP-FST, whereas it was 34.1 m²/g for FST. Moreover, the activity of both the plasma-prepared and conventionally synthesized FST core–shell nano-catalysts was evaluated for the removing of toxic dyes such as Acid Orange 142 (AO). The degradation efficiency significantly increased to 99.6% for PP-FST compared to 80% for FST, highlighting the effect of plasma treatment.

Reinforcing the performances of cemented backfill materials to recycle gangue and tailings is crucial for the sustainable development of mineral resources and mining waste management. However, under practical constraints of low cost, high waste ratio, low carbon emission, and low binder consumption, solidifying upcycles of mining wastes with toxicity, porosity, and mollification to cemented backfill materials with superior properties are inherently contradictory and challenging. This study reported a waste-to-wealth pathway that improves cemented gangue backfill materials by cellulose nanofibers to recycle mining wastes and partially replace cement. Mechanical compression, X-ray diffraction, thermogravimetry, mercury intrusion porosimetry, scanning electron microscopy tests, fractal quantitative analyses of microstructures, and molecular dynamics simulations were carried out to reveal the action mechanism of TEMPO-modified cellulose nanofibers on cemented gangue backfill materials. The difference in the contribution of TEMPO-modified cellulose nanofibers and mechanical cellulose nanofibers to the strengths of cemented gangue backfill materials was analyzed. The results show a series of microscopic improvements of cellulose nanofibers on cemented gangue backfill materials, including regulating cemented gel polymerization, increasing hydration nucleation, inhibiting carbonization, densifying pore structure, enhancing Ca-O connections and H bonds, and preventing C-S–H fracture along interlayer water. Excessive cellulose nanofibers are also found to be harmful to this composite mainly by delaying hydration crystallization and increasing pores by entrapping air, while it still exhibits improvements in deformation resistance and energy absorption despite strength deterioration. The strength and energy absorption reinforcements of this cemented hybrid materials induced by cellulose nanofibers with optimal dosage can reach up to 30 ~ 50%.

Microstructural engineering has been an effective way to modulate the performance of electromagnetic wave absorption (EMA) materials. However, there are still severe challenges in how to design and regulate the microstructure effectively and further elucidate its mechanisms. Here, three-dimensional (3D) bio-derived N-doped carbon fibers anchored by CoNi nanoparticles (N-C_f@CoNi) nanocomposites were successfully prepared using biomass cotton and ZIF-67 precursor as raw materials by a two-step impregnation-carbonization method. By ingeniously adjusting the mass ratio of the ZIF-67 precursor, the surface morphology of balsam pear-like fiber was induced by crystal surface energy to achieve a transition from a “nanotube-assembled nest-like” structures to “rice-shaped nanosheets” to “nanoparticles.” The unique microstructural engineering strategy endows the N-C_f@CoNi nanocomposites with an abundant conductive network, enhanced multiple reflection and absorption, polarization, and magnetic loss, thereby leading to distinguished EMA performance, especially ultrawide EAB values. The optimized N-C_f@CoNi nanocomposites display a minimum reflection loss (RL_min) of − 59.43dB and an effective absorption bandwidth (EAB) of 8.5 GHz at a matching thickness of 2.16 mm. The result underscores the potential of microstructural engineering induced by crystal surface energy in optimizing the microwave absorption of N-C_f@CoNi nanocomposites, laying the foundation for the development of efficient EMA materials with controllable micro-morphology.

Tungsten oxide (WO₃) thin films were deposited on flexible stainless steel (SS) substrates via low-cost chemical bath deposition (CBD) method by varying concentration of sodium tungstate precursor (0.05–0.2 M). Also, tungsten oxide/reduced graphene oxide (WO₃/rGO) nanocomposite thin films were deposited (0.15 M sodium tungstate precursor concentration) at different rGO concentration variations (0.5, 1, and 1.5 mg mL⁻¹). The effect of precursor concentration and rGO addition on the physicochemical properties of electrodes was studied. The thin films of WR2 (deposited at 0.15 M sodium tungstate and 1 mg mL⁻¹ rGO concentration) nanocomposites exhibited a hexagonal crystal structure along with a surface morphology resembling nanorods. The appearance of rGO in WO₃/rGO was proved from the FT-IR, RAMAN, and EDAX studies. WR2 nanocomposite thin film exhibited 1060 F g⁻¹ specific capacitance at scan rate of 5 mV s⁻¹. The flexible WR2//PVA-H₂SO₄//activated carbon asymmetric (ASC) device was fabricated using WR2 as a negative electrode and activated carbon as a positive electrode which showed a specific capacitance of 175 F g⁻¹ with energy and power densities of 19.1 Wh kg⁻¹ and 0.43 KW kg⁻¹, respectively, with 81.3% capacitive retention over 5000 CV cycles.

The development of a multifunctional therapy nanoplatform is of crucial importance to tackle the complex challenges associated with cancer. Despite significant advancements in tumor treatment, the efficacy of these traditional approaches remains insufficient. Recurrence and metastasis following tumor treatment continue to represent a significant contributor to tumor-related mortality. This paper presents an improved, facile, and relatively green fabrication of (5-mercapto-1,3,4-thiadiazol-2-ylthio) acetic acid (TMT)-coated luminescent gold nanoparticles (L-AuNP@TMT), which exhibit highly membrane-targeting capacity and superior photodynamic properties. Furthermore, in vivo tumor-bearing mouse model experiments indicated that the L-AuNP@TMT could be used as a two-photon excited nanomedicine via pyroptosis-mediated anti-tumor immunity for effectively eliminating colorectal cancer (CRC), the third most common malignancy and the second deadliest cancer, without evident toxic side effects or tumor metastasis/recurrence. According to its facile and green fabrication approach, near-infrared light-activatable highly efficient photodynamic cancer therapy, and noninvasive imaging mode, this multifunctional nanoplatform offers significant advantages over traditional monotherapy techniques, providing an alternative for the precise clinical treatment of cancer.

Electrotherapy devices used for pain relief and muscle recovery often face challenges because traditional electrode materials are not biodegradable, causing environmental issues and being less compatible with the body. While current conductive hydrogels show potential, they usually lack the combination of good electrical performance, biodegradability, and body-friendliness needed for sustainable medical devices. To address these challenges, this study presents a novel, eco-friendly, electrically conductive double-layer nanocomposite bio-hydrogel developed using tragacanth gum (TG) and polyvinyl alcohol (PVA), enhanced with carboxylated graphene (Gr_F) and polypyrrole (PPy). The innovative double-layer design represents a significant advancement over single-layer hydrogels, demonstrating reduced impedance and a substantial increase in conductivity (up to 4.99 × 10⁵ times) at frequencies relevant to electrotherapy applications. Specifically, the tragacanth gum/polyvinyl alcohol/carboxylated graphene@polypyrrole (TPG@PPy) bio-hydrogel exhibited a AC conductivity enhancement of up to 1.5 times compared to the tragacanth gum/polyvinyl alcohol@polypyrrole (TP@PPy) bio-hydrogel at frequency of 80 Hz. Additionally, the material’s high biodegradability, with up to 49% mass loss over 60 days in soil, confirms environmental safety. These results show that the double-layer bio-hydrogel could be a better, eco-friendly option for future electrotherapy devices, making it different from current conductive hydrogels.

Graphical Abstract

Combining different materials in a thermally activated manufacturing process into a hybrid composite can lead to residual stresses if there is a difference between the adhesion temperature T_AD and the application temperature T_AP. If such hybrid composites are subjected to high cyclic loads, residual stresses may influence their durability. While residual stress analysis has been extensively studied in the context of metal-plastic hybrids, the residual stress condition is unknown for thermoset-thermoplastic hybrids produced by injection molding. Therefore, we firstly apply a calculational model to estimate the residual stress for the investigated material combination of glass fiber-filled polyamide (PA6.6 GF30) and a unidirectional glass fiber-reinforced plastic (UD-GFRP) with a polyurethane acrylate matrix. Secondly, these results are compared to a corresponding computational simulation model. Integrating Fiber-Bragg-Grating (FBG) sensors in the UD-GFRP allows for the determination of residual strain in the thermoset component at different temperatures and thereby both the calculational and computational simulation methods could be validated against experimental results. The results show that process-related residual stresses occur in the hybrid composite and are not negligible. Normal stresses of − 39.6 MPa have been observed in thermoset material. Furthermore, the calculational determined normal stresses are in accordance with the experimentally determined values.