Advanced Composites and Hybrid Materials最新文献

The investigation and understanding of heterointerfaces formation and charge transfer dynamics in two or more semiconductor heterojunctions increased ensuing establishment of S-scheme and dual S-scheme heterojunctions. However, investigations of possible charge transfer at interfaces and their type in four component systems are limited. Herein, a four-component heterojunction was investigated to postulate and demonstrate deviation between quadruple and triple S-scheme heterojunctions possibilities using LaNiO₃, BiOBr, CuBi₂O₄, and Bi₂WO₆. DFT and XPS were used to construct the band structure and support the charge transfer at the interfaces to follow S-S strategy during OTC and SMX degradation under visible light. IEF, bend bending systematically modulated charge transfer, and the core-shell strategy restricted possible junctions’ formation to three to accord triple S-scheme heterojunction. This work demonstrated the construction of Triple S-scheme heterostructures as a promising strategy for efficient charge separation making it a suitable candidate for elimination of pollutants.

The application of adhesives is becoming increasingly widespread, and the requirements for adhesive performance are also increasing. People have been learning to design many high-performance materials using the principles of bionics since a long time ago. The structure and secretions of organisms can provide solutions for bionics. Displaying different shapes and functions under different conditions is a challenging task for adhesives to adapt to different environments. Adhesives can composite different materials together, and the addition of different materials can also enhance the functionality of the adhesive. Although there have been many studies on biomimetic adhesives and intelligent bonding, research on biomimetic intelligent composite materials is scarce. This article explores the biomimetic structures of animals and plants, provides a comprehensive review of biomimetic adhesives, and summarises biomimetic intelligent composite materials.

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Exchange bias has been extensively studied in both exchange-coupled thin films and nanoparticle composite systems. However, the role of non-exchange mechanisms in the overall hysteresis loop bias is far from being understood. Here, dense soft-hard binary nanoparticle composites are used not only as a novel tool to unravel the effect of dipolar interactions on the hysteresis loop shift but also as a new strategy to enhance the bias of any magnet exhibiting an asymmetric magnetization reversal. Mixtures of equally sized, 6.8 nm, soft maghemite (γ-Fe₂O₃) nanoparticles (no bias—symmetric reversal) and hard cobalt doped γ-Fe₂O₃ nanoparticles (large exchange bias—asymmetric reversal) reveal that, for certain fractions of soft particles, the loop shift of the composite can be significantly larger than the exchange-bias field of the hard particles in the mixture. Simple calculations indicate how this emerging phenomenon can be further enhanced by optimizing the parameters of the hard particles (coercivity and loop asymmetry). In addition, the existence of a dipolar-induced loop shift (“dipolar bias”) is demonstrated both experimentally and theoretically, where, for example, a bias is induced in the initially unbiased γ-Fe₂O₃ nanoparticles due to the dipolar interaction with the exchange-biased hard nanoparticles. These results open a new paradigm in the large field of hysteresis bias and pave the way for novel approaches to tune loop shifts in magnetic hybrid systems beyond interface exchange coupling.

This study aims to investigate the properties of boron-modified phenolic resin (BPR) composites reinforced with glass fiber (GF) and mica, SiO₂, and glass powder (MSG) for potential aerospace applications. The BPR/MSG/GF composites exhibited improved mechanical strength, reduced shrinkage, and enhanced insulation properties at high temperatures. Specifically, exposed at 1000 °C, the impact strength increased by 108%, bending strength increased by 113%, shrinkage was reduced by 7.42%, and insulation properties were enhanced by 12.3%. Thermogravimetric analysis (TGA) revealed enhanced thermal stability, with a residue rate of 89.91% at 800 °C. The addition of glass powder, functioning as a fluxing agent, resulted in the densification of the ceramic layer. X-ray diffraction analysis (XRD) demonstrated that mica undergoes eutectic reaction with other fillers and glass powder to form the final ceramic layer. These findings indicate that BPR/MSG/GF composites can be optimized for high-performance applications requiring excellent heat resistance and mechanical strength. Further optimization of filler content and processing conditions can enhance the performance of these composites for specific applications.

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Carbon fibers possess advantages such as light weight, high aspect ratio, and excellent electrical conductivity. However, pure carbon fibers as electromagnetic wave-absorbing materials lack loss capability. Introducing magnetic loss through magnetic materials is an effective strategy. In this study, polyacrylonitrile (PAN) fiber-doped with Prussian blue (PB) cubes are firstly prepared using electrospinning. Afterwards, by adjusting calcination conditions, carbon fibers doped with PB derivatives (PBFC) composites are successfully fabricated. PBFC-3 achieves excellent electromagnetic wave absorbing properties with a reflection loss (RL) of − 47.28 dB at 1.32 mm and effective absorption bandwidth (EAB) of 4.38 GHz at 2.92 mm. Excellent performance comes from electromagnetic coordination of conduction, magnetic, and dielectric losses. Additionally, simulation technology is employed to simulate radar cross section (RCS) absorption for the composites in real-world applications. The reflected signal values of PBFC-3 are less than − 20 dB m² in the angular range of − 100 to 100°, and when θ = 0, it achieves 30.95 dB·m² at 2.42 mm and 24.56 dB·m² at 1.32 mm. This study provides a reference of structural design and performance tuning for electromagnetic wave absorption structures.

This research explores the properties of yellow bamboo (Phyllostachys aurea species) stalks and its composite from Colombia under compression loads. The bamboo pipes were filled with epoxy resin aiming structural applications. Samples included untreated, peroxide-treated, and hypochlorite-treated bamboo, both with and without nodes. For each of these conditions, up to 20 samples were evaluated via Weibull distribution; this is to determine the variability of the compressive properties. For the characterization, scanning electron microscopy was used to analyze the microstructure, while finite element analysis was included for the bamboo stalks to better understanding of the stress–strain relations. Results showed that compressive strength was from 60 to 130 MPa, with nearly 3 times more variability for samples with node than without node, which was accounted for the Weibull modulus. Also, it was seen that bamboo stalks without node showed higher strength than samples with node, in which the node acts as stress concentrator, lowering the strength of the bamboo pipe. For bamboo stalks filled with epoxy resin was found that the resin did not contribute much to reinforce the composite, but increased the elongation at break, a very important property related to ductility and toughness. The resin also was found to increase the Weibull modulus upon the compression loads, which reduced the property variability, a known limitation of natural fiber composites. It was also observed that in both the bamboo stalks and the composites, the failure presents buckling deformation, with cracks along the longitudinal direction, parallel to the pipe axis, although with less damage for those with nodes, since the node can limit the crack growth. The composite bamboo resin could be used in construction or impact applications.

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Developing a multifunctional protection material compatible with infrared (IR) stealth and electromagnetic interference (EMI) shielding is urgently required but challenging to ensure special human safety and maintain the smooth operation of electronic equipment. Herein, it is designed and fabricated a double-layered ANF/MXene film containing a thermally insulated aramid nanofiber (ANF) aerogel and low emissivity MXene coating with integrated long-term thermal camouflage at elevated temperatures and highly efficient EMI shielding capability. In this system, the lower aerogel film can act as a barrier to insulate heat transfer through its novel skin–core structure under ultralow directional thermal conduction, while the upper Ti₃C₂T_x MXene coating can provide a very low emissivity surface and highly conductive network. Owing to its unique double-layer structure, the ANF/MXene film demonstrates a significant EMI shielding effectiveness of 43.6 dB and a remarkably low emissivity of 0.24, delivering excellent IR stealth performance across various ambient temperatures. This research lays the foundation for the creation of versatile protective materials that have great potential for use in both military and civilian contexts.

Flexible wearable heater plays a critical role in maintaining a consistent human body temperature, particularly during outdoor activities in cold environments, where garment elasticity, stretchability, and mechanical strength are paramount. Thus, there is an urgent demand for the development of flexible wearable heaters. In this study, we have successfully engineered a photo-thermochromic elastic fiber with control over its color properties via a continuous wet-spinning process. Through the incorporation of a modest amount (as little as 0.5%) of photothermally active polyaniline (PANI) and polydopamine (PDA) nanoparticles, this fiber exhibits exceptional photothermal conversion performance compared to pure thermoplastic polyurethane (TPU) fiber. Notably, when exposed to 600 W m⁻² irradiation for 600 s, the equilibrium temperature of the photo-thermochromic elastic fiber rises impressively from the ambient 20.0 °C to 53.5 °C. A significant feature of this fiber is its reversible color-changing capability, which can be conveniently controlled by manipulating the light source. This innovative characteristic empowers the user to monitor the fiber’s temperature by observing its color shifts. Furthermore, the fiber boasts exceptional stretchability, with an impressive elongation capacity of up to 500%, and remarkable resistance to washing, enduring up to 25 cycles. Taking this innovation further, we integrate the fiber into a fabric that maintains its superior photothermal conversion performance, mechanical resilience, and the ability to undergo reversible color changes when exposed to sunlight. This stretchable and vibrant photo-thermochromic elastic fiber holds significant promise as an energy-efficient alternative and is poised to find exciting applications in the realm of smart textiles.

In this paper, the recrystallization behavior of 4043 aluminum alloy under the deformation conditions of dwell times of 1 s, 10 s, 30 s, and 90 s between passes was studied. The results show that when the inter-pass dwell time is increased to 10 s, the instability region in the material hot processing map disappears. Additionally, particle-stimulated nucleation (PSN) predominantly occurs at low deformation temperatures and in specimens with short inter-pass dwell times under high deformation temperatures. Importantly, at a deformation condition of 450 °C and a strain rate of 0.01 s⁻¹, when the inter-pass dwell time is increased to 90 s, the alloy texture type changes from a strong Goss texture to a strong rotated cube texture, with the primary recrystallization mechanism shifting from PSN to continuous dynamic recrystallization (CDRX). A longer dwell time of 90 s tends to achieve the maximum static softening rate and a higher recrystallization fraction (8.54%). These findings reveal the impact of inter-pass dwell time on the hot deformation behavior of 4043 aluminum alloy, providing theoretical guidance for industrial production.

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The effect of dwell time on recrystallization behavior and the recrystallization mechanism of PSN were studied.

Here, we report a general strategy for designing a metal/carbon system, via a facile and environmentally friendly one-step approach, from metal acetate as an active electrocatalyst in oxygen evolution reaction (OER) during water decomposition. As a demonstration, a nanostructured Ni/C composite induced from nickel acetate is revealed in great detail. The resulting material is composed of: metallic nickel (Ni), nickel(II) oxide (NiO), and nickel carbide (Ni₃C) coated with a graphitic shell and deposited on a carbon platform. Our findings underscore the prominent role of nickel species, including Ni⁰, Ni²⁺, and Ni³⁺, in driving the catalytic activity. Notably, the catalyst exhibits an overpotential of 170 mV, a Tafel slope of 49 mV·dec⁻¹, an electrocatalytic surface area (ECSA) of 964.7 cm², and a turnover frequency (TOF) value of 52.8 s⁻¹, surpassing RuO₂. The Raman spectra also suggest a graphitic "self-healing" phenomenon post-OER, attributed to the reduction of oxygen-containing groups. Carbon in the system (i) facilitates electron transfer, (ii) allows homogeneous distribution of Ni nanoparticles avoiding their agglomeration, and (iii) promotes durability of the electrocatalyst by serving as a protective barrier, shielding the core metal compounds. What is more, density functional theory (DFT) calculations allowed to optimized geometry of the model cluster Ni₈O₈(OH)₈ describing two different sites on the β-NiOOH surface (001) and two different intermediates, (i)L-OOH and (ii)L-OOH. This facilitated to propose the reaction mechanisms involving both hydroxide ions and water molecules as reducers. Therefore, the chemisorption of OH⁻ and H₂O molecules at the NiOOH active center accompanied by bond breakage and the formation of a lattice hydroperoxide as an important intermediate is presumed. What is more, the proposed fabrication method for electroactive metal/carbon composites was validated with an iron and iron/nickel mixture.