Energy Dissipation Mechanisms Research Articles

Soft, Tough, Antifatigue Fracture Elastomer Composites with Low Thermal Resistance through Synergistic Crack Pinning and Interfacial Slippage.

Soft elastomer composites are promising functional materials for engineer interfaces, where the miniaturized electronic devices have triggered increasing demand for effective heat dissipation, high fracture energy, and antifatigue fracture. However, such a combination of these properties can be rarely met in the same elastomer composites simultaneously. Here a strategy is presented to fabricate a soft, extreme fracture tough (3316J m-2) and antifatigue fracture (1052.56J m⁻2) polydimethylsiloxane/aluminum elastomer composite. These outstanding properties are achieved by optimizing the dangling chains and spherical aluminum fillers, resulting in the combined effects of crack pinning and interfacial slippage. The dangling chains that lengthen the polymer chains between cross-linked points pin the cracks and the rigid fillers obstruct the cracks, enhancing the energy per unit area needed for fatigue failure. The dangling chains also promote polymer/filler interfacial slippage, enabling effective deflection and blunting of an advancing crack tip, thus enhancing mechanical energy dissipation. Moreover, the elastomer composite exhibits low thermal resistance (≈0.12K cm2 W-1), due to the formation of a thermally conductive network. These remarkable characteristics render this elastomer composite promising for application as a thermal interface material in electronic devices.

Hierarchical Supramolecular Aggregation of Molecular Nanoparticles for Granular Materials with Ultra High-Speed Impact-Resistance.

The high-speed impact-resistanct materials are of great significance while their development is hindered by the intrinsic tradeoff between mechanical strength and energy dissipation capability. Herein, the new chemical system of molecular granular material (MGM) is developed for the design of impact-resistant materials from the supramolecular complexation of sub-nm molecular clusters (MCs) and hyper-branched polyelectrolytes. Their hierarchical aggregation provides the origin of the decoupling of mechanical strengths and structural relaxation dynamics. The MCs' intrinsic fast dynamics afford excellent high-speed impact-resistance, up to 5600 s-1 impact in a typical split-Hopkinson pressure bar test while only tiny boundary cracks can be observed even under 7200 s-1 impact. The high loadings of MCs and their hierarchical aggregates provide high-density sacrificial bonding for the effective dissipation of the impact energy, enabling the protection of fragile devices from the direct impact of over 200 ms-1 bullet. Moreover, the MGMs can be conveniently processed into protective coatings or films with promising recyclability due to the supramolecular interaction feature. The research not only reveals the unique relaxation dynamics and mechanical properties of MGMs in comparison with polymers and colloids, but also develops new chemical systems for the fabrication of high-speed impact-resistant materials.

Anelastic and Magnetic Properties of Polycrystalline La0.6Sr0.4Fe1−xCuxO3−δ

Perovskite La0.6Sr0.4Fe1−xCuxO3−δ (x = 0, 0.05, 0.1, and 0.2) polycrystalline samples have been synthesized in air and investigated by X‐Ray diffraction, scanning electron microscope, magnetization, and mechanical spectroscopy. An antiferromagnetic transition is observed around 300 K, while no corresponding anomaly is observed in the mechanical spectrum, indicating the absence of conventional magnetoelastic coupling. For La0.6Sr0.4FeO3, an internal friction peak (P1) presents around 140 K and shifts to lower temperatures with increasing Cu‐doping content. Meanwhile, a magnetic anomaly is also observed around P1 peak temperature. As explained, the P1 peak is related to the freezing of the ferroelastic domain walls, and the mechanical energy dissipation is induced by the lagging variation of the octahedral tilting under the alternating stress. This work suggests a peculiar magnetic property of the octahedra within ferroelastic domain walls.

Development and experimental evaluation of cam-grip type compression-free energy dissipative braces

Recent efforts have focused on developing novel energy dissipation braces that allow only tensile yielding to overcome certain limitations of conventional braces and buckling-restrained braces (BRBs). Such limitations include insufficient information regarding the damaged state of braces in a post-earthquake scenario and the challenges associated with replacing heavy restraints to prevent steel cores from buckling. Generally, the available techniques adopt a saw-tooth mechanism that grips the core and only mobilizes the tensile forces in the brace. However, the discrete nature of saw-tooth systems may result in a slippage at the onset of the tensile loading cycle, thereby reducing the efficiency of the energy dissipation mechanism. This study introduces a novel Direction-based Force Control Mechanism (DFCM) utilizing a cam-type grip that ensures continuous gripping under reversed-cyclic loading. Using this mechanism, a new type of so-called compression-free energy dissipative braces (CEDBs) are developed and tested under reversed-cyclic loading. For this purpose, six CEDB specimens were fabricated and installed in a steel frame sub-assemblage. The frame-brace system was then subjected to quasi-static lateral drifts with increasing amplitudes to test the efficiency of the proposed device. The experimental results demonstrate that the proposed bracing system only mobilizes the tension forces with significantly low slippage with about 1 % drift (Δ ≈ 2 mm). The system also exhibits a stable energy dissipation mechanism and reliable hysteretic properties under multiple cycles of large inelastic deformations. Furthermore, the damaged steel cores can be conveniently observed and replaced after a severe shaking event, while the same DFCM can be repeatedly used. Therefore, the proposed bracing system emerges as a cost-effective option for enhancing the lateral performance of structures subjected to dynamic loadings and strong ground motions. Besides, an idealized hysteretic model for this system was developed and validated; two examples of specimens were conducted as uniaxial elements with the proposed bilinear hysteretic; based on experimental results, it is shown that the proposed bilinear hysteretic model can capture important mechanical properties and energy dissipation of the specimens with reasonable accuracy of both CEDB specimens which the average difference between experiment results and Idealized CEDBs in yield force is about 10.87 %, the ultimate force is about 1.90 %, and the corresponding cumulative energy dissipation is about 6.98 %.

Exploring fracture of H-BN and graphene by neural network force fields

Extreme mechanical processes such as strong lattice distortion and bond breakage during fracture often lead to catastrophic failure of materials and structures. Understanding the nucleation and growth of cracks is challenged by their multiscale characteristics spanning from atomic-level structures at the crack tip to the structural features where the load is applied. Atomistic simulations offer ‘first-principles’ tools to resolve the progressive microstructural changes at crack fronts and are widely used to explore the underlying processes of mechanical energy dissipation, crack path selection, and dynamic instabilities (e.g. kinking, branching). Empirical force fields developed based on atomic-level structural descriptors based on atomic positions and the bond orders do not yield satisfying predictions of fracture, especially for the nonlinear, anisotropic stress–strain relations and the energy densities of edges. High-fidelity force fields thus should include the tensorial nature of strain and the energetics of bond-breaking and (re)formation events during fracture, which, unfortunately, have not been taken into account in either the state-of-the-art empirical or machine-learning force fields. Based on data generated by density functional theory calculations, we report a neural network-based force field for fracture (NN-F3) constructed by using the end-to-end symmetry preserving framework of deep potential—smooth edition (DeepPot-SE). The workflow combines pre-sampling of the space of strain states and active-learning techniques to explore the transition states at critical bonding distances. The capability of NN-F3 is demonstrated by studying the rupture of hexagonal boron nitride (h-BN) and twisted bilayer graphene as model problems. The simulation results elucidate the roughening physics of fracture defined by the lattice asymmetry in h-BN, explaining recent experimental findings, and predict the interaction between cross-layer cracks in twisted graphene bilayers, which leads to a toughening effect.

AlScN-on-SiC microelectromechanical Lamb wave resonators operating at high temperature up to 800 °C

We report on the experimental demonstration of aluminum scandium nitride (AlScN)-on-cubic silicon carbide (3C-SiC) Lamb wave resonators (LWRs) realized via microelectromechanical systems (MEMS) technology, operating at high temperature (T) up to T = 800 °C, while retaining robust electromechanical resonances at ∼27 MHz and good quality factor of Q ≈ 900 even at 800 °C. Measured resonances exhibit clear consistency and stability during heating and cooling processes, validating the AlScN-on-SiC LWRs can operate at high T up to 800 °C without noticeable degradation in moderate vacuum (∼20 mTorr). Even after undergoing four complete thermal cycles (heating from 23 to 800 °C and then cooling down to 23 °C), the devices exhibit robust resonance behavior, suggesting excellent stability and suitability for high-temperature applications. Q starts to decline as the temperature exceeds 400 °C, which can be attributed to energy dissipation mechanisms stemming from thermoelastic damping and intrinsic material loss originating from phonon–phonon interactions.

AlScN-on-SiC microelectromechanical Lamb wave resonators operating at high temperature up to 800 °C

We report on the experimental demonstration of aluminum scandium nitride (AlScN)-on-cubic silicon carbide (3C-SiC) Lamb wave resonators (LWRs) realized via microelectromechanical systems (MEMS) technology, operating at high temperature (T) up to T = 800 °C, while retaining robust electromechanical resonances at ∼27 MHz and good quality factor of Q ≈ 900 even at 800 °C. Measured resonances exhibit clear consistency and stability during heating and cooling processes, validating the AlScN-on-SiC LWRs can operate at high T up to 800 °C without noticeable degradation in moderate vacuum (∼20 mTorr). Even after undergoing four complete thermal cycles (heating from 23 to 800 °C and then cooling down to 23 °C), the devices exhibit robust resonance behavior, suggesting excellent stability and suitability for high-temperature applications. Q starts to decline as the temperature exceeds 400 °C, which can be attributed to energy dissipation mechanisms stemming from thermoelastic damping and intrinsic material loss originating from phonon–phonon interactions.

Controlled Structural Relaxation of Aramid Nanofibers for Superstretchable Polymer Fibers with High Toughness and Heat Resistance.

Polymer fibers that combine high toughness and heat resistance are hard to achieve, which, however, hold tremendous promise in demanding applications such as aerospace and military. This prohibitive design task exists due to the opposing property dependencies on chain dynamics because traditional heat-resistant materials with rigid molecular structures typically lack the mechanism of energy dissipation. Aramid nanofibers have received great attention as high-performance nanoscale building units due to their intriguing mechanical and thermal properties, but their distinct structural features are yet to be fully captured. We show that aramid nanofibers form nanoscale crimps during the removal of water, which primarily resides at the defect planes of pleated sheets, where the folding can occur. The precise control of such a structural relaxation can be realized by exerting axial loadings on hydrogel fibers, which allows the emergence of aramid fibers with varying angles of crimps. These crimped fibers integrate high toughness with heat resistance, thanks to the extensible nature of nanoscale crimps with rigid molecular structures of poly(p-phenylene terephthalamide), promising as a template for stable stretchable electronics. The tensile strength/modulus (392-944 MPa/11-29 GPa), stretchability (25-163%), and toughness (154-445 MJ/cm3) are achieved according to the degree of crimping. Intriguingly, a toughness of around 430 MJ/m3 can be maintained after calcination below the relaxation temperature (259 °C) for 50 h. Even after calcination at 300 °C for 10 h, a toughness of 310 MJ/m3 is kept, outperforming existing polymer materials. Our multiscale design strategy based on water-bearing aramid nanofibers provides a potent pathway for tackling the challenge for achieving conflicting property combinations.

On the effect of strain rate during the cyclic compressive loading of liquid crystal elastomers and their 3D printed lattices

Nematic liquid crystal elastomers (LCEs) are a unique class of network polymers with the potential for enhanced mechanical energy absorption and dissipation capacity over conventional network polymers because they exhibit both conventional viscoelastic behavior and soft-elastic behavior (nematic director changes under shear loading). This additional inelastic mechanism makes them appealing as candidate damping materials in a variety of applications from vibration to impact. The lattice structures made from the LCEs provide further mechanical energy absorption and dissipation capacity associated with packing out the porosity under compressive loading.Understanding the extent of mechanical energy absorption, which is the work per unit mass (or volume) absorbed during loading, versus dissipation, which is the work per unit mass (or volume) dissipated during a loading cycle, requires measurement of both loading an unloading. In this study, a bench-top linear actuator was employed to characterize the loading-unloading compressive response of polydomain and monodomain LCE polymers and polydomain LCE lattice structures with two different porosities (nominally, 62% and 85%) at both low and intermediate strain rates at room temperature. As a reference material, a bisphenol-A (BPA) polymer with a similar glass transition temperature (9°C) as the nematic LCE (4°C) was also characterized at the same conditions for comparing to the LCE polymers. Based on the loading-unloading stress-strain curves, the energy absorption and dissipation for each material at different strain rates (0.001, 0.1, 1, 10 and 90 s-1) were calculated with considerations of maximum stress and material mass/density. The strain-rate effect on the mechanical response and energy absorption and dissipation behaviors was determined. The energy dissipation ratio was also calculated from the resultant loading and unloading stress-strain curves. All five materials showed significant but different strain rate effects on energy dissipation ratio. The solid LCE and BPA materials showed greater energy dissipation capabilities at both low (0.001 s-1) and high (above 1 s-1) strain rates, but not at the strain rates in between. The polydomain LCE lattice structure showed superior energy dissipation performance compared with the solid polymers especially at high strain rates.

Dissipation behaviors in submerged beam-vibrated granular systems

This study investigates intruder dynamics within granular systems, focusing on energy dissipation and phase transitions influenced by beam vibrations. Using a granular-beam experimental setup and discrete element method (DEM) simulations, we explore the dynamic responses of a simply supported beam in a granular medium under various excitation conditions. Our results reveal distinct granular phase states and their evolution pathways, driven by changes in excitation amplitude and frequency, which significantly affect energy dissipation. Key findings include the identification of vortical and disordered fluidization states that correlate with extremes in energy dissipation, underscoring the importance of characteristic lengths and times in characterizing these transitions. Additionally, amplitude-frequency characteristics and mean squared displacement (MSD) analyses link microscale particle behavior with macroscale beam dynamics, providing insights into the mechanisms of energy dissipation and dynamic heterogeneity. This research enhances our understanding of granular system mechanics, offering implications for the design and optimization of engineering applications across various fields.

Development and application of out-of-plane deformable X-shaped brace for energy dissipation and thermal stress mitigation: An experimental and numerical study

Exoskeleton systems are increasingly employed in both new and existing buildings to enhance seismic performance. Addressing the critical challenges of energy dissipation and thermal stress mitigation in these systems, an out-of-plane deformable X-shaped energy dissipation brace (OPD-XEDB), integrating an out-of-plane X-shaped brace with a shear-type metallic damper, was proposed in this study. A seismic design methodology for OPD-XEDB was firstly developed, ensuring effective energy dissipation of the damper before any potential brace buckling. Following this methodology, two specimens, exhibiting distinct failure modes of damper shear fracture and brace buckling, were designed and subjected to quasi-static loadings to explore their energy dissipation mechanisms. Upon these experimental results, a numerical model incorporating buckling and pinching behaviors was proposed and calibrated, effectively capturing the hysteretic responses of the specimens. This model was then employed in a comprehensive numerical analysis, validating the effectiveness of design methodology and determining the optimal specifications for the OPD-XEDB in a prototype building. Ultimately, thermal analysis and nonlinear time history analysis were conducted on the prototype building. The thermal analysis proved the effectiveness of the OPD-XEDB's out-of-plane configuration in mitigating thermal stress by out-of-plane deformation, significantly mitigating thermal stress in braces and interconnected moment frames by 96.59-96.66%. The time history analysis revealed that the dampers in OPD-XEDBs dissipated 11.6-23.2% of total seismic energy, effectively preventing substantial buckling in the X-shaped braces. This energy dissipation mechanism led to a remarkable 79.7% reduction in steel consumption for post-earthquake retrofitting, thereby significantly enhancing the seismic resilience of the primary structure.

The mechanism of internal energy losses in double- suction centrifugal pumps under direct and reverse conditions

The double-suction centrifugal pump has gained extensive application in various hydraulic projects and industrial processes under direct and reverse operating conditions. However, the occurrence of unstable flow phenomena, such as flow separation, vortex and reflux, poses a significant challenge to its hydraulic performance. Therefore, this paper aims to analyze the energy loss and energy dissipation mechanisms in double-suction centrifugal pumps operating in both direct and reverse conditions. By utilizing the entropy production theory, a combination of numerical simulations and experimental methods are employed to investigate the energy loss of double-suction centrifugal pump compared to double-suction centrifugal pumps as turbines. The findings indicate that the turbulent entropy production loss and wall entropy production loss are the principal contributors, accounting for over 57 % and 33 % of the total entropy production loss, respectively, under different flow conditions of the pump and turbine. Conversely, the direct entropy production loss is not more than 1 %. This suggests that the main causes of energy losses are associated with wall effects in the near-wall region and unstable flow in the main flow region. Within the pump conditions, the main components responsible for energy loss are the volute and impeller. Conversely, under turbine conditions, the impeller and draft chamber are the main contributors to energy loss. The presence of a suction chamber rib proves beneficial under pump conditions as it diverts and optimizes internal flow. However, the draft chamber flow divider exacerbates energy losses under turbine conditions. This study not only provides insights into the energy loss characteristics of a double-suction pump operating under direct and reverse conditions but also offers a fresh perspective on the structural optimization of both the double-suction pump and double-suction pump as turbine.

Flow characteristics of a low-head and high-discharge hydraulic turbine under various operating conditions

A low-head and high-discharge hydraulic turbine holds significant potential for energy recovery across various engineering applications, owing to its capacity to manage substantial flows. However, the intricate mechanisms of energy loss within this turbine, particularly concerning its impeller and discharge tube, have received limited investigation. In this study, we present a comprehensive examination of the energy dissipation mechanisms, flow characteristics, and streamwise vorticity of the low-head and high-discharge hydraulic turbine. Utilizing the enstrophy dissipation theory, we conducted analyses under diverse operational conditions. Our findings reveal that energy dissipation predominantly occurs within the impeller and discharge tube. Volume enstrophy dissipation power contributes to over 80% of the total hydraulic loss under three flow rate conditions. Flow separation and intricate turbulence patterns emerge as primary factors contributing to energy loss within the impeller, while backflow and turbulence are that in the discharge tube. The regions with high energy loss in impeller is near the leading and trailing edges and in the discharge tube that is around the entrance.

A metamaterial with enhanced effective stiffness and negative Poisson's ratio for frictional energy dissipation

Unlike traditional energy dissipation structures that dissipate energy through irreversible plastic deformation or collapse, metamaterials based on friction energy dissipation have attracted attention due to their reusability. This article proposed a novel energy dissipation metamaterial by integrating friction energy dissipation mechanism into negative Poisson's ratio (NPR) structures. The integration of friction energy dissipation mechanism can simultaneously enhance the effective stiffness and NPR effect. The mechanical properties of the proposed structure were investigated using theoretical analysis, experiments, and finite element (FE) simulations. The influence of variables such as internal concave angle, friction coefficient, and number of reinforcing ribs was discussed. The results indicate that both unit cell and honeycomb structure can repeatedly dissipate energy within the elastic range. Compared with the traditional concave hexagonal structure, the effective stiffness and NPR effect were enhanced. This work provides a novel idea for the design of NPR energy dissipation structures.

Influence of High Strain Dynamic Loading on HEMA-DMAEMA Hydrogel Storage Modulus and Time Dependence.

Hydrogels have been extensively studied for biomedical applications such as drug delivery, tissue-engineered scaffolds, and biosensors. There is a gap in the literature pertaining to the mechanical properties of hydrogel materials subjected to high-strain dynamic-loading conditions even though empirical data of this type are needed to advance the design of innovative biomedical designs and inform numerical models. For this work, HEMA-DMAEMA hydrogels are fabricated using a photopolymerization approach. Hydrogels are subjected to high-compression oscillatory dynamic mechanical loading at strain rates equal to 50%, 60%, and 70%, and storage and loss moduli are observed over time, e.g., 72 h and 5, 10, and 15 days. As expected, the increased strains resulted in lower storage and loss moduli, which could be attributed to a breakdown in the hydrogel network attributed to several mechanisms, e.g., increased network disruption, chain scission or slippage, and partial plastic deformation. This study helps to advance our understanding of hydrogels subjected to high strain rates to understand their viscoelastic behavior, i.e., strain rate sensitivity, energy dissipation mechanisms, and deformation kinetics, which are needed for the accurate modeling and prediction of hydrogel behavior in real-world applications.

Investigation of soil damping for offshore wind turbine monopile-soil system in stiff clay on elastoplastic-damage model

Damping plays a crucial role in the design of offshore wind turbine (OWT) monopile foundations. The soil damping of the monopile-soil system (MSS) represents the energy dissipation mechanism arising from the interaction between the pile and the soil. It is typically derived by back-calculating from the overall damping measured in the entire OWT structure. However, few studies have independently examined the soil damping in MSS, and the impact of key parameters such as pile diameter, pile embedded depth, cyclic load amplitude, and load eccentricity on the variation of soil damping in MSS remains unclear. This paper introduces an elastoplastic-damage constitutive model for the numerical simulation of the damping ratio variation in seabed soil and MSS. The model is implemented in ABAQUS software and validated against cyclic triaxial tests on stiff clay soil. On this basis, a three-dimensional finite element sensitivity study was conducted to elucidate the effect of these key parameters on the MSS damping ratio. The results of the study reveal that the MSS damping ratio exhibits a nonlinear and asymmetric trend as the loading cycles increase. The MSS damping ratio decreases with increasing pile diameter and embedded depth but increases with increasing lateral cyclic load amplitude and load eccentricity from the mudline.

Experimental and numerical investigation of crashworthiness of multicell metal/CFRP tubes

Metal/CFRP hybrid thin-walled structures combine low-density and high-strength carbon fibre reinforced plastics (CFRP) with low-cost and stable failure form aluminium, which have drawn increasing attention in the transportation industry. A theoretical model was developed to predict the average crushing force of a hybrid multicell under axial compression. The model captures the main energy dissipation mechanism of the hybrid tube under axial compression, and the average crushing force is determined by a quasi-static compression test. The obtained results show that the average crushing force predicted by the theoretical model is in good agreement with the experimental results. However, the geometry size and configuration of multicell thin-walled structures have important effects on crashworthiness. Therefore, it is necessary to study the parametrization of hybrid multicell tubes. First, the simulation model of the multicell tube is established, and quasi-static experiments verify its accuracy. Second, finite element analysis was used to compare the effects of the geometric size of the cell and the multicell structure of different configurations on the energy absorption characteristics. It is clear that with the increase in the thickness of the large aluminium tube, the specific energy absorption (SEA) and crush force efficiency (CFE) both show an upward trend. In addition, with the increase in the ply number of the CFRP tubes, the SEA also shows a minor monotonic increasing trend. Finally, various hybrid tubes with different configurations are designed, and the C-C4-AL tube (the aluminium tube surrounded by four small-size CFRP tubes being placed inside a CFRP tube.) configuration has the most significant energy absorption (EA) and peak crushing force (PCF).

Enhancing dynamic viscoelastic performance of flax fiber/fly ash hollow cenosphere‐reinforced composites coated by in situ fabrication of ultrasonically synthesized nanotitanium dioxide

AbstractThis study demonstrates a novel, single‐step, and low‐energy ultrasonic approach to fabricate lightweight, high‐performance flax fiber‐reinforced composites enhanced by nanotitanium dioxide coating and fly ash hollow cenospheres. This innovative approach leads to a remarkable 23% weight reduction compared with conventional composites, making it ideal for the applications demanding both lightweight and superior mechanical properties. Through dynamic mechanical testing, it is found that the composites' viscoelastic behavior, including storage modulus and damping factor, is significantly influenced by both frequency and temperature. By applying time–temperature superposition principles, the composite's dynamic properties are comprehensively characterized across a wider frequency range. A modified fractional calculus Huet–Sayegh model accurately captures the observed viscoelastic behavior. The combined effect of nanotitanium dioxide coating, which strengthens the fiber–matrix interface, and the inclusion of rigid fly ash hollow cenospheres results in significant improvements in both storage modulus (10% increase at room temperature) and peak loss factor (80% increase) compared with uncoated flax fiber‐reinforced composites. The nanocoating and cenospheres' rigid shells contribute to enhanced stiffness, while the cenospheres' hollow structure provides efficient energy dissipation mechanisms, leading to an improved damping performance. This ultrasonic approach offers a promising and sustainable method for synthesizing natural fiber nanocomposites with superior viscoelastic properties.

2D Tantalum Disulfide Reduction Strategy Customized Ta2O5/rGO Heterointerface Aerogel Toward Boosting Electromagnetic Wave Absorption and Flame Retardancy.

The exceptional and substantial electron affinity, as well as the excellent chemical and thermal stability of transition metal oxides (TMOs), infuse infinite vitality into multifunctional applications, especially in the field of electromagnetic wave (EMW) absorption. Nonetheless, the suboptimal structural mechanical properties and absence of structural regulation continue to hinder the advancement of TMOs-based aerogels. Herein, a novel 2D tantalum disulfide (2H-TaS2) reduction strategy is demonstrated to synthesize Ta2O5/reduced graphene oxide (rGO) heterointerface aerogels with unique characters. As the prerequisite, the defects, interfaces, and configurations of aerogels are regulated by varying the concentration of 2H-TaS2 to ensure the Ta2O5/rGO heterointerface aerogels with appealing EMW absorption properties such as a minimum reflection loss (RLmin) of -61.93dB and an effective absorption bandwidth (EAB) of 8.54GHz (7.80-16.34GHz). This strategy provides valuable insights for designing advanced EMW absorbers. Meanwhile, the aerogel exhibits favorable thermal insulation performance with a value of 36mW m-1 K-1, outstanding fire resistance capability, and exceptional mechanical energy dissipation performance, making it promising for applications in the aerospace industry and consumer electronics devices.

Self-assembly of curdlan molecules for the formation of thermally induced gels

The differences in the self-assembly process between cold-set (CCS) and heat-set (CHS) curdlan gels were investigated using micro-differential scanning calorimetry, atomic force microscopy, and small-angle X-ray diffraction. The results indicate that the triple-helix structure of curdlan dissociated into single helices in its suspension state (C-SUS) at 65 °C. Upon cooling to around 38 °C, these single helices assembled into long, thick fibers with a height of up to 11.50 nm, contributing to the gel structure of CCS. Heating C-SUS from 65 °C to 90 °C caused the single helices to transform into triple helices due to hydrophobic interactions. Subsequent cooling to 25 °C, led to the formation of short, thick bundles with a height of up to 8.78 nm, forming the network structure of CHS gel. As a consequence, CHS gels exhibited higher hardness and elasticity but lower fatigue resistance. This is attributed to an increased degree of physical cross-linking, as evidenced by a reduction in the size (Ξ) and spacing () of high-density domains within the gel structure, and a simpler mechanism of energy dissipation through alignment of the molecular chain segment. These findings are valuable for the design and development of curdlan-based gels with tailored mechanical properties.