查看更多>>摘要：Transparent conductive fibers play a pivotal role in developing advanced smart textiles for the future. Due to high flexibility and transparency, ionic hydrogel fibers have attracted great attention. Among them, the physically cross-linked hydrogel possesses non-volatility and low cost, which makes it an attractive transparent conductive material. However, the current physical cross-linked hydrogel suffers from low conductivity, transparency, and weak mechanical strength. A novel hybrid cross-linking strategy for ionic hydrogel through wet spinning has been proposed to address these issues. In this study, polyvinyl alcohol (PVA) crystallizes to form a homogeneous and robust polymer network with deep eutectic solvents (DESs) that substitute for water. Simultaneously, sodium alginate (SA) also interacts with metal ions in DESs to further form a crosslinked network, which enhances both the mechanical and conductivity. The as-prepared hydrogel fiber exhibited great all-around performances, including remarkable conductivity (2.28 S/m), transparency (92 %), high strength (3.01 MPa), and toughness (5.65 MJ/m3). Furthermore, we demonstrated a 3 x 3 electroluminescent textile display matrix woven with luminescent fibers as warp and the prepared hydrogel fibers as weft yarns, which exhibited the potential value of the hydrogel fibers in textiles.
Laura SimoniniMarkus KakkonenRoyson DsouzaMikko Kanerva...
110991.1-110991.16页
查看更多>>摘要：The aim of this study was the development and characterization of a continuous poly(e-caprolactone) (PCL) coating, which was applied on glass fibers by a fluid coating method, in order to tailor the interfacial properties in glass fiber-epoxy microcomposites. Scanning electron microscopy revealed that a uniform coating was formed without noticeable discontinuities or irregularities, and its thickness increased with the deposition speed. To achieve consistent results with this approach, it is essential to consider the homogeneity of the coating thickness, which is influenced by the viscosity of the solution. The PCL-coated fibers were used for the preparation of microcomposites combined with epoxy resin (EP). The samples were tested in the microdebonding configuration to determine the interfacial shear strength (IFSS) and to assess their interfacial self-healing capability. For all deposition speeds, no significant degradation of interfacial adhesion was observed indicating the applicability of PCL coating on glass fibers. However, a decrease in self-healing efficiency was observed after multiple self-healing stages. The possible cause was identified in the progressive alteration of the EP droplet's shape after repeated microdebonding tests. This phenomenon altered the stress distribution along the fiber-matrix contact area and, therefore, underestimated the values of interfacial adhesion and self-healing efficiency. Hence, the experimental results from microdebonding tests were presented along with a finite element analysis of the interfacial region, in order to provide a comprehensive understanding of the debonding and self-healing mechanisms after multiple repairing steps.
查看更多>>摘要：Cellular structures incorporated in conductive polymer composites (CPC) are gaining recognition as a promising alternative to traditional metal materials for electromagnetic interference (EMI) shielding applications, owing to their outstanding properties and lightweight nature. In this study, the polylactic acid (PLA)/carbon nano-structure (CNS) composite foam with a multilayered gradient structure was prepared by supercritical carbon dioxide (CO2) foaming technology. The original size of the sample, saturation pressure, and foaming temperature had obvious effects on the foaming behavior of the PLA/CNS composite. In the prepared multilayered gradient-structured sample, the CNS content increased layer by layer (from 1 wt% to 7 wt%), and its density could be as low as 0.22 g/cm3. In addition, the EMI SE value of the prepared sample could be as high as 51.8 dB with an absorption coefficient of 0.85, thus providing superior EMI shielding performance. This result indicated that high-performance and lightweight polymer-based shielding materials could be obtained by preparing multilayered gradient-structured foam samples, which have broad application prospects in aerospace and electronics.
查看更多>>摘要：With the widespread application of highly integrated and high-frequency power devices in the electronics field, traditional electronic packaging materials can no longer effectively resist the harm caused by electromagnetic interference and heat accumulation to electronic equipment. To address these challenges, we have successfully constructed a heterostructure-rich dual-level three-dimensional (3D) network framework (M0S2/CMF) by effectively integrating molybdenum disulftde (M0S2) with carbonized melamine foam (CMF). These fillers were then composited with epoxy resin (EP) to develop M0S2/CMF/EP composites exhibiting both electromagnetic wave absorption (EMA) and enhanced thermal conductivity. Specifically, two-dimensional (2D) M0S2 nanosheets with a lT/2H-phase structure uniformly grew on the surface of CMF, improving the poor impedance characteristics of the 3D carbon structure and increasing heterointerfaces and multiple scattering abilities. Owing to the synergistic effects of attenuation performance and impedance matching, the EP-based M0S2/CMF-I composite demonstrated an impressive reflection loss value of -64.80 dB and an effective absorption bandwidth of 8.48 GHz, achieved with only a 5 wt% loading. Correspondingly, CST simulation results indicated that when electromagnetic waves are vertically incident on M0S2/CMF-I/EP samples, the radar cross-section (RCS) attenuation value can reach up to 35.4 dBm2. Moreover, the highly interconnected 3D carbon structure of CMF provides broad pathways for phonon transport, resulting in the thermal conductivity of MoS_2/CMF-l/EP reaching 0.41 W/mK at room temperature, a nearly 141 % improvement compared to pure EP. This multifunctional EP-based composite, with its high-efficiency EMA and thermal management performance, shows great potential for application in the packaging of highly integrated electronic devices.
查看更多>>摘要：In space exploration, lightweight multifunctional materials capable of shielding neutron radiation, dissipating heat, and providing damping are essential. Polymer composites reinforced with boron nitride (BN) nano-materials-specifically one-dimensional boron nitride nanotubes (BNNTs) and two-dimensional boron nitride nanoplatelets (BNNPs)-offer promising solutions. This study investigates how BN nanomaterial morphology influences the performance of high-temperature (HT) epoxy composites. We developed ultralightweight, three-dimensional BN foams comprising ID BNNTs, 2D BNNPs, and hybrid ID BNNT/2D BNNP structures via freeze-drying, then infiltrated them with HT epoxy to form dense composites. The BNNT foam exhibited the highest neutron radiation shielding, with a mass absorption coefficient of 26.64 cm~2 g~(-1), outperforming the hybrid foam (18.18 cm~2 g~(-1)) and the BNNP foam (11.12 cm~2 g~(-1)). A similar trend was observed in the HT epoxy composites; incorporating these foams at least doubled the mass absorption coefficient compared to the neat polymer. In terms of thermal conductivity, the BNNT/BNNP foam-epoxy composite achieved the highest value of 0.34 W m~(-1) K~(-1), a 2.13-fold increase over neat HT epoxy. The BNNT/BNNP foam-epoxy composites also improved by 1.88 and 1.75 times, respectively. Mechanical testing revealed that BNNP foams withstood the highest loads during nanoindentation (3.53 kN), followed by BNNT/BNNP foams (1.93 kN) and BNNT foams (1.56 kN). All BN foam-epoxy composites exhibited enhanced damping properties, with tan 8 increasing by at least 30 % compared to neat HT epoxy. These findings elucidate the impact of BN nanomaterial morphology on the multifunctional performance of HT epoxy composites, offering insights for developing high-performance, tailorable materials for demanding environments.
H.F.M. de QueirozN.V. dos SantosJ.S.S. NetoM.D. Banea...
110996.1-110996.13页
查看更多>>摘要：This research focuses on the fabrication and analysis of novel natural fibre hybrid composites using two different reinforcement techniques: intralaminar reinforcement (2D) and orthogonal-through-the-thickness reinforcement (3D-OTT). Jute bidirectional fabric served as the main fibre phase, while secondary reinforcement phases (sisal, curaua, and glass fibres) were woven unidirectionally through the jute fabric for the 2D architecture (intralaminar reinforcement). For the 3D architecture, a transverse fibre phase was additionally woven orthogonally through the thickness of the fibre preforms. Pure jute and glass fibre-reinforced composites were also fabricated and tested for comparison. Tensile, flexural, and impact tests were performed to assess how the innovative 3D-OTT architecture influences in-plane composite properties. SEM analysis and X-ray microtomography were used to examine failure modes, interfacial quality and void volume fractions. The results support the viability of the novel composite materials for partial or complete substitution of glass fibre-reinforced materials (GFRP) in specific applications. For instance, curaua-reinforced specimens demonstrated comparable tensile and flexural stiffness to synthetic composites, while 3D-reinforced sisal specimens exhibited exceptional energy absorption during impact testing. Additionally, the simple fabrication process resulted in very low void fractions, making these composites suitable for the automotive industry.
查看更多>>摘要：Aerogel, a lightweight and highly porous material with a network structure, has found extensive applications in sound absorption. To effectively enhance the acoustic properties, it is crucial to design appropriate pore structures within the aerogel. In this study, a novel composite aerogel (named ACQ) that incorporates aramid nanofibers (ANFs), cellulose nanofibers (CNFs), and quartz fibers (QFs) to achieve a synergistic effect is proposed. By precisely controlling the content of these ternary components, ANFs and CNFs establish directional channels that are further reinforced by the penetration of rigid QFs. The resulting ultra-light density (5 mg/cm~3) hybrid ACQ aerogels exhibit exceptional broadband sound absorption performance with an average sound absorption coefficient of 0.367. Finite element simulation elucidates the acoustic energy dissipation mechanism as follows: (1) the directional channel architecture formed by ANFs/CNFs enhances the absorption of acoustic waves and effectively impedes their outward propagation; (2) penetration of QFs significantly increase pore density, causing multiple reflection and diffraction of acoustic waves within the channels; (3) vibrations of pore walls and QFs induced by sound waves dissipate acoustic energy as heat, further enhancing the aerogel's acoustic absorption capacity. Additionally, the hybrid ACQ aerogel demonstrates excellent compressive resilience and fatigue resistance as it maintains a 90 % retention rate in compression strength even after undergoing 50 cycles of compression at a strain level of 50 %. These findings highlight the aerogel's promising prospects for applications in aerospace, marine and transportation fields.
查看更多>>摘要：Existing methods of incorporating flame-retardant fillers to improve the fire resistance of epoxy-matrix based carbon fibre composites often significantly reduce their mechanical properties. To address this issue, this study introduces a novel method for synthesizing nano-sized ammonium polyphosphate (APP) particles by reacting them with amine-containing hardener and applying probe sonication, resulting in nano-sized APP particles (SHF-APP). This treatment reduces the particle size from 14μm to 0.12 μm. A systematic investigation of the impact of particle size and the hardener treatment reveals that the SHF-APP nanoparticles can simultaneously improve flame-retardancy and mechanical properties of the composites. The concurrent improvements in fire resistance and mechanical properties highlight the significant potential of this novel approach, enabling carbon fibre reinforced epoxy composites to withstand extreme environments and meet stringent fire safety standards while maintaining high mechanical and fracture properties, a feat previously unattainable with conventional methods.
查看更多>>摘要：The design and fabrication of piezoelectric materials with exceptional thermal stability for application in harsh environments remains a challenging. Herein, a three-dimensional porous fluorine-containing polyimide (PI) and zinc oxide (ZnO) composite self-powered piezoelectric sensor with high sensitivity and high-temperature resistance is prepared via the water vapor-induced fast phase separation method. The increased interface area within the PI film can produce enhanced piezoelectric properties by introducing a porous structure. The piezoelectric coefficient (d_(33)) of pure porous PI-0 film reached 3.3 pC/N. In addition, the addition of ZnO nanoparticles significantly improved the piezoelectric properties and thermal stability of composite porous films. The as-prepared sensor exhibits good piezoelectric characteristics with a voltage output of 4 V, excellent piezoelectric sensitivity (0.75 V·N~（-1）), fast response (15 ms), recovery time (20 ms) and outstanding durability (>9000 times). Furthermore, the composite porous PI films exhibit high flexibility, hydrophobicity, excellent high-temperature resistance with T_(d5%) up to 500℃. This study represents a novel kind of piezoelectric substrate for the design of high-performance self-powered piezoelectric sensors in aerospace and microelectronics.
查看更多>>摘要：The incorporation of nanoparticles into epoxy resin constitutes a highly effective strategy for the development of high-performance adhesives. Biobased spherical cellulose nanocrystals (SCNCs), which exhibit renewability and high specific surface area, are constantly plagued by aggregation structures during the blending modification process for enhancing and toughening epoxy nanocomposite adhesives. Here, a universal strategy to manufacture solvent-free spherical cellulose nanocrystalline fluids (SCNCs-F) was reported by covalent grafting of flexible organic chains. As expected, SCNCs-F, showing good fluidity and dispersion stability at room temperature due to the barrier function of organic chains, was expected to address the aggregation issue of SCNCs in epoxy adhesives. In addition, we successfully prepared various SCNCs-F by changing the kind of flexible organic chains, demonstrating the feasibility of this universal strategy. As a proof of concept, the modification effect of incorporating SCNCs-F as a single component filler into epoxy adhesives was studied. The uniform dispersion of SCNCs-F and its robust interfacial interaction with the matrix qualified the epoxy adhesives with excellent adhesive strength (lap shear strength of 20.64 MPa) and decent toughness (work of debonding of 19027 N/m). This work is expected to facilitate the development of novel solvent-free nanofluids and establish a pathway for the application of biomass cellulose materials in epoxy nanocomposite adhesives.
NETL
NSTL
Elsevier