Search Results (14,287)

Carbon nanotube yarns (CNTYs) have received more consideration recently due to their excellent specific mechanical, electrical and thermal properties, making them promising materials for different applications. Until now, the axial properties of the yarn have been thoroughly investigated; however, the transverse or radial properties, orthogonal to the fiber axis, remain relatively unknown due to the challenges associated with their measurement. In this study, the transverse or radial response of the CNTY including its elastic modulus was determined using Atomic Force Microscopy (AFM) and Raman Spectroscopy. Determining transverse properties in fibrous materials presents challenges owing to their geometry, inherent anisotropy, whereby mechanical characteristics exhibit directional disparities; i.e., the properties in the transverse direction may be several orders of magnitude smaller than those in the axial direction. To overcome these difficulties, AFM was utilized to perform nanoindentation experiments, where a tipless flexible cantilever probe was used to apply a controlled force to the CNTY surface. The resulting indentation depth was then analyzed to determine the transversal elastic modulus. Preliminary findings indicate that the transverse elastic modulus of the CNTYs ranges from 10–54 kPa for strain levels below 3%. Complementary Raman spectroscopy provided insight into the bulk-scale mechanical behavior of CNTYs. Incremental compressive loading between microscope slides induced nonlinear upshifts in the 2D Raman band (from ~2686.6 to 2691.4 cm⁻¹), indicating nanoscale tube realignment, inter-tube densification, and compaction. From lateral diameter measurements under load, a stress–strain curve was constructed, revealing three distinct regimes: one with an initial elastic modulus of 3.12 MPa (0.3–11.2% strain), another one with an elastic modulus increasing to 8.46 MPa (11.2–14.4%), and finally one with an elastic modulus peaking at 16.86 MPa beyond 14.4% strain. Together, these methods delineate the hierarchical and anisotropic nature of CNTYs, validating the importance of multiscale mechanical characterization for their deployment in piezoresistive sensors and multifunctional composites. This study establishes a robust framework for quantifying the transverse mechanical response of CNTYs. Full article

For the first time, hybrid nanocomposites based on poly(2,5-dichloro-3,6-bis(phenylamino)-p-benzoquinone) (PCPAB) and multi-walled carbon nanotubes (MWCNTs) were obtained and the influence of the preparation method on their structure and functional properties was demonstrated. The nanocomposites were obtained both by ultrasonic mixing of PCPAB and MWCNTs, and via in situ oxidative polymerization of CPAB in the presence of MWCNTs or MWCNTs with the addition of ZnO. The formation of hybrid nanocomposites occurs due to non-covalent interaction (π-stacking) between the graphene structures of the MWCNT surface and the phenyl rings of PCPAB. It was found that during the in situ oxidative polymerization of CPAB in the presence of MWCNTs, the growth of polymer chains occurred in close proximity to the filler surface, which led to the formation of a polymer coating. ZnO particles, localized on MWCNTs, on the one hand, prevent their aggregation, and on the other hand, create additional polymerization reaction centers due to the coordination of the Zn-O bond at the H and O atoms of the monomer. An increase in the concentration of reaction centers as a result led to a 2–2.5-fold reduction in the induction polymerization period. According to SEM data, in this case, a more ordered and denser polymer layer is formed due to intermolecular complexation between the main and side chains of the growing polymer with the participation of Zn²⁺ ions formed as a result of the transformation of ZnO to ZnCl₂ in the acidic reaction medium of polymerization. The results of the study of the frequency dependences of conductivity indicate a hopping mechanism of conductivity of nanocomposites. The electrical conductivity of nanocomposites depends on their production method and the MWCNT content and varies between 0.5 and 1.1 S∙cm⁻¹, which is 6–12 times higher than the conductivity of the original polymer. Thermogravimetric analysis revealed that the nanocomposites exhibit enhanced thermal stability compared to PCPAB. The best results were shown by nanocomposites with a higher content of MWCNTs, for which the residual mass at 450 °C was 51–53%. Full article

Crosslinked polyethylene (XLPE) is a widely used cable insulation material for power cables at various voltage levels, offering excellent electrical, mechanical, and thermal stability. However, during the continuous extrusion moulding process, prolonged shear action and localized temperature accumulation can easily induce premature crosslinking. This leads to a decline in melt rheological properties and reduced processing stability, as well as having an adverse effect on the microstructure and overall performance of the formed insulation layer. This study systematically investigated the impact of shear-induced pre-crosslinking on the mechanical properties and dielectric characteristics of XLPE cable insulation materials through experimental testing methods. The experimental results demonstrate that, while premature crosslinking has a minimal effect on mechanical properties, it significantly deteriorates dielectric performance, as evidenced by increased conduction current, reduced breakdown strength, and compromised microstructural integrity. These findings suggest that, to improve the quality and reliability of XLPE cable production, engineering designs should prioritize controlling the pre-crosslinking process to ensure stable dielectric performance. Full article

In recent years, two-dimensional (2D) materials have attracted growing attention for their application in chemoresistive gas sensors. Among these materials, graphene stands out due to its exceptional electrical, mechanical, and chemical properties. A simple and low-cost method for producing graphene involves the use of a laser to induce its formation on carbon-rich substrates, such as polyimides. This technique, first introduced in 2014, has been successfully applied in the fabrication of various types of sensors, including pressure sensors, temperature sensors, biosensors, and gas sensors. For chemoresistive gas sensors, laser-induced graphene (LIG) has been used either as an electrode or as part of the nanocomposite forming the active sensing layer. Moreover, this technology has allowed the use of heating elements. Sensing performance, including sensitivity and selectivity, can be tailored by incorporating different materials into the nanocomposite, such as metallic nanoparticles, metal oxides, or conductive polymers. These modifications can be implemented using low-cost and scalable fabrication methods, making this approach highly suitable for the development of affordable and efficient gas sensors. In this contribution, we present a comprehensive overview of the contributions, reported from the proposal of LIG technology in 2014 to 2025, about the use of this fabrication process in the development of chemoresistive gas sensors. Full article

Copper-based hybrid metal matrix composites reinforced with graphene and zinc were developed to achieve a balanced combination of mechanical strength, corrosion resistance, wear performance, and electrical conductivity. In this study, Cu matrix composites containing a constant graphene content of 1 wt.% and varying Zn contents (0, 5, 10, and 15 wt.%) were fabricated through mechanical alloying followed by Spark Plasma Sintering (SPS). The effects of zinc content on microstructure, densification, hardness, corrosion behavior, tribological performance, and electrical conductivity were systematically investigated. Microstructural analyses revealed that the combined use of graphene and Zn significantly influenced grain refinement, interfacial stability, and densification behavior. The composite containing 10 wt.% Zn exhibited the highest relative density (~90.5%) and maximum hardness (62 HB), indicating an optimal reinforcement level. Corrosion tests conducted in 3.5 wt.% NaCl solution demonstrated that the 10 wt.% Zn composite showed the most noble corrosion potential and the lowest corrosion current density, which was attributed to reduced porosity and improved microstructural homogeneity. Tribological results confirmed that graphene contributed to a self-lubricating effect, while Zn enhanced load-bearing capacity, leading to improved wear resistance under increasing normal loads. Electrical conductivity measurements showed a gradual decrease with increasing Zn content, mainly due to solid-solution-induced electron scattering in the Cu matrix; however, the fixed graphene addition and effective SPS consolidation helped preserve conductive pathways, allowing all composites to retain acceptable conductivity levels. The results indicate that the hybrid Cu–graphene–Zn composites exhibit a balanced combination of mechanical, corrosion, tribological, and electrical properties, with 10 wt.% Zn emerging as the optimal composition. Full article

In the fragile Loess Plateau ecosystem, straw return is a key measure to improve its low soil organic matter. However, the short-term carbon retention efficacy of straw return, which depends on the initial balance between carbon mineralization and sequestration, remains unclear across different soil textures. This study investigated the short-term impacts of straw return on organic carbon fractions in three soils with varying textures via laboratory incubation. Results showed that while straw return universally increased active organic carbon pools, its accumulation in the mineral-associated organic carbon (MAOC) pool was texture-dependent. Straw incorporation, especially maize straw, effectively promoted MAOC formation in clayey soils (Phaeozems and Anthrosols) with large specific surface areas. Conversely, in Arenosols, carbon was retained in active pools, limiting long-term retention potential. The mechanism involves a combined regulation by soil physicochemical properties, where clay content and specific surface area are fundamental physical drivers for MAOC accumulation, synergistically influenced by chemical factors like pH and electrical conductivity through processes such as cation bridging. These findings provide critical scientific evidence for developing texture-specific straw return management strategies for the Loess Plateau. Full article

Single memristive nanowire networks have emerged as a promising pathway for energy-efficient neuromorphic computing, owing to their intrinsic nonlinearity, high dimensionality, fading memory and volatile switching dynamics relevant to physical reservoir computing. While prior works focused on oxide- or silver-based network systems, these approaches face trade-offs between operating voltage, cost, stability, and scalability. This work presents a proof-of-concept demonstration of stochastic polyvinylpyrrolidone (PVP)-coated nickel nanowire networks as low-cost and scalable memristive platforms, exhibiting low-voltage resistive switching (1–2 V). The electrical characterization reveals predominantly volatile resistive switching combined with nonvolatile behavior, consistent with a filamentary conduction mechanism at nanowire junctions. The switching dynamics are governed by the polymer coating thickness, with an intermediate PVP concentration (Ni@PVP = 1:25) showing optimal performance, with a resistance ratio of ~200, stable retention over 1 h, and a reproducible endurance of over 45 cycles. These results establish Ni@PVP nanowire networks as promising memristive platforms for neuromorphic hardware applications and physical reservoir computing, with relevant properties such as fading memory and nonlinear dynamics. Full article

This study aims to develop high-performance hybrid nanocomposites for solid-state energy conversion. We achieved this by improving charge transport and thermoelectric efficiency through the interaction of polymers, nanoparticles, and ionic liquids. Nickel oxide nanoparticles (NiO NPs) were synthesized via a sonochemical route using a novel ionic liquid, 1,2-(propan). In our recent work, this approach enabled the formation of a hybrid [NiO NPs + IL] system, which was subsequently incorporated at different loadings (8, 15, and 30 wt.%) and coated with polyethylene glycol (PEG). The resulting nanocomposites were investigated to elucidate charge-transport mechanisms and assess the influence of the polymer coating on their optical, electrical, and thermal transport properties. Optical measurements showed a shift in the band gap due to π–π* electronic transitions. This effect indicates strong interface interactions. The PEG-coated [NiO NPs + IL] nanocomposites exhibited significantly enhanced charge-carrier mobility, resulting in improved electrical conductivity. Remarkably, a high Seebeck coefficient of 720 μV/K and an electrical conductivity of 0.35 S/cm were achieved, resulting in a maximum power factor of 24.74 μW/m·K², surpassing many recently reported polymer-based nanocomposites. PEG-coated [NiO NPs + IL] systems offer tunable optical properties and superior thermoelectric performance. Consequently, they are a promising alternative to conventional nanocomposites for sustainable energy conversion. Full article

Ground tire rubber (GTR) is composed of high-quality components; therefore, searching for new technologies for GTR recycling and upcycling is fully justified. In this work, the effect of micronized ground tire rubber content on the rheological, mechanical, thermal, and morphological properties, electrical conductivity, and electrochemical behavior of thermoplastic polyurethane/carbon black was investigated. The application of micronized ground tire rubber in the range of 5–20 wt% reduces the manufacturing cost by 5.6–22.6% and improves the electrical conductivity and electrochemical properties of composites. The results showed that higher contents of ground tire rubber increased the electrical conductivity of the studied materials from 11.7 to 33.8 S/m. This phenomenon is due to two factors: (i) additional carbon black present in GTR and (ii) phase separation that promotes local carbon-rich domains and facilitates conductive pathway formation. Electrochemical analysis revealed that the studied composites after laser activation can be used as flexible sensors. This research work confirms that using a ground tire rubber as a low-cost and valuable source of raw materials is a promising approach for the sustainable development of soft electronics. Full article

Wide bandgap (WBG) semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) have revolutionized modern power electronics by enabling devices that operate at higher voltages, temperatures, and switching frequencies than their silicon counterparts. This paper reviews the material properties, device architectures, fabrication techniques, and thermal management strategies that underpin the performance of GaN and SiC technologies. We highlight key trade-offs between GaN and SiC in terms of voltage blocking capability, switching efficiency, and thermal robustness and discussed their application in electric vehicles, renewable energy systems, and power converters. Market adoption trends and manufacturing challenges are also analyzed, with attention to cost-performance dynamics and packaging innovations. Finally, we address the critical role of thermal boundary resistance and emerging reliability solutions, providing a perspective on the future trajectory of WBG device research and commercialization. Full article

This research aims to investigate the modifications of the structural, dielectric, and sensing properties of CaFeO_3−δ ceramics produced by solid-state reaction induced by varying sintering temperatures in the range of 1000–1200 °C. A single crystallographic orthorhombic (Pcmn) structure was revealed by X-ray diffraction with Rietveld analysis, both for the powders and sintered ceramics, irrespective of the sintering temperature. The increase in the sintering temperature induces better densification and a larger grain size. Dielectric measurements reveal a pronounced enhancement of the relative permittivity, reaching 2 × 10⁵ at 1 kHz and 330 °C for the sample sintered at 1200 °C/4 h. This composition also displays the highest electrical conductivity, 0.4 S/m at 1 MHz. Cole–Cole analysis indicates a clear deviation from ideal Debye behavior, while the relaxational features of the dielectric permittivity suggest a strong correlation between the dielectric response and Fe-related conduction mechanisms. Gas sensing tests show that the ferrite ceramics exhibit consistent ethanol response trends. The ceramic sintered at 1200 °C/4 h achieved the highest sensitivity, of 56.28%, which can be attributed to its higher density, larger ceramic grains, and reduced low-frequency conductivity. The CaFeO_3−δ ceramic sintered at 1200 °C/4 h shows a combination of high permittivity, enhanced conductivity, and strong ethanol sensitivity, making it a promising material for dielectric components, capacitive devices, and gas sensing applications. Full article

Polyester resin composites containing expanded graphite often exhibit reduced mechanical strength due to the porous structure of the filler. The aim of this study was to enhance mechanical performance without compromising electrical behaviour. Although carbon fibre and expanded graphite are chemically identical carbon allotropes, their distinct morphologies motivated the use of carbon fibre to reinforce expanded graphite-filled polyester composites. To examine the role of expanded graphite porosity, ultrasonicated EG was used to produce exfoliated, lower-porosity particles, while vacuum processing was applied to remove entrapped air prior to curing. Adding 0.5–5 wt% milled carbon fibre increased electrical conductivity by up to three orders of magnitude relative to neat polyester while maintaining 70–80% of the original specific strength at moderate fibre contents. Ultrasonicated EG reduced tensile strength by more than 50% at 5 wt% loading and decreased conductivity due to additional grain boundary formation. Vacuum-processed EG not only provided slight mechanical enhancements but also significantly improved electrical properties by lowering surface resistance by 6–10 orders of magnitude, reaching the tens-of-Ω range at 3–5 wt% EG. This performance is comparable to previously reported conductive EG/polymer systems, which exhibit surface resistances of 10–10² Ω at 5 wt% EG. This systematic comparison offers practical guidelines for balancing conductive percolation and mechanical reinforcement in expanded graphite polyester composites. Full article

In this work, the electrochemical behavior of potassium jarosite-type solid solutions synthesized via a controlled hydrothermal method was evaluated. Structural characterization by X-ray diffraction (XRD) confirmed the formation of potassium jarosite. FTIR spectra complemented these findings, revealing bands characteristic of Fe–O metal coordination (625 and 505 cm⁻¹). Voltammetric tests evidenced redox processes attributable to the Fe³⁺/Fe²⁺ couple, suggesting that iron within the jarosite framework contributes electrochemically to the observed conductivity. The assembled galvanic cells demonstrated the capability for electrical energy microgeneration, and the presence of jarosite was found to enhance ionic transport within the system. Overall, these results suggest an intergranular ionic-conduction mechanism, possibly facilitated by the mineral matrix, which would act as a structural medium enabling the mobility of charged species. Full article

Wetlands play a vital role in the global carbon cycle and serve as critical carbon sink systems. However, increasing human disturbances and land-use changes have led to widespread wetland degradation, severely weakening their carbon sequestration capacity. This study investigated the Huixian Wetland in the Li River Basin of Southwest China to examine the impacts of wetland degradation on soil physicochemical properties, organic carbon fractions, and carbon fluxes. Based on vegetation and environmental conditions, the wetland was classified into four degradation gradients: non-degraded (ND), slightly degraded (SD), moderately degraded (MD), and heavily degraded (HD), and their spatial differences were systematically analyzed. The results showed that with increasing degradation, soil moisture, total nitrogen, and total phosphorus significantly decreased, whereas soil bulk density and electrical conductivity exhibited an increasing trend. Total organic carbon and active organic carbon fractions, including readily oxidizable organic carbon, light fraction organic carbon, microbial biomass carbon, and dissolved organic carbon, exhibited a pronounced decreasing trend along the degradation gradient, with the decline being most evident in the HD area. Among the labile carbon fractions, microbial biomass carbon (MBC) and light fraction organic carbon (LFOC) exhibited the most drastic declines in heavily degraded areas, indicating their high sensitivity as early warning indicators of wetland degradation. Observations of CO₂ fluxes revealed that from April to September, the net ecosystem exchange (NEE) was negative across all areas, indicating that the wetland functioned as a carbon sink overall. However, NEE values increased with higher degradation levels, suggesting a progressive decline in the carbon sequestration capacity of the wetland; ecosystem respiration (ER) peaked in July and increased with the degree of degradation. The findings indicate that wetland degradation leads to soil environment deterioration, reduction in organic carbon storage, and enhanced CO₂ emissions, ultimately weakening its carbon sink function. To enhance carbon sequestration capacity and maintain ecological functions, sustainable management strategies such as hydrological restoration and vegetation reconstruction are recommended. This study provides a scientific basis for wetland ecological conservation and carbon management in the context of climate change. Full article

Textile materials represent a versatile class of engineering substrates widely used in apparel, domestic products, and medical protective systems. Despite their extensive application, large-scale textile production has seen limited integration of fundamentally new functionalization strategies. In recent years, however, advances in materials science have enabled the development of textiles with tailored electrical, adaptive, and biological functionalities. This review summarizes recent progress in the functionalization of textile materials with a focus on approaches relevant to engineering and industrial implementation. Particular attention is given to conductive textiles designed for operation under extreme environmental conditions, including low-temperature climates. Methods for integrating electrically conductive elements into fibrous structures are discussed, highlighting their potential for sensing, thermal regulation, and energy-related applications such as powering portable electronic devices. Inkjet printing is presented as a scalable technique for high-resolution deposition of conductive patterns while preserving the mechanical integrity and aesthetic properties of textile substrates. In addition, adaptive and stimuli-responsive textile systems are reviewed, including materials capable of responding to thermal, optical, or chemical stimuli, with applications in camouflage, wearable systems, and multifunctional surfaces. The review further addresses the development of bioactive textiles, emphasizing antibacterial functionalization using organic and inorganic agents to mitigate the spread of pathogenic microorganisms. The relevance of such materials has been underscored by recent global viral outbreaks. Overall, this work aims to provide a materials science perspective on emerging textile functionalization strategies and to facilitate the transition of these technologies from laboratory-scale research to practical engineering applications. Full article