Composites Communications最新文献

Smart footwear plays a vital role in walk correction, with mechanical behavior and shape memory effect (SME) being essential aspects. To create personalized smart insoles, we developed a novel blend of polylactic acid (PLA), thermoplastic polyurethane (TPU), and carbon nanotubes (CNT) via melting-extrusion for a continuous-fiber 3D printer. Diverse insole support unit-cell structures (triangular, rhombus, grid) were fabricated with PLA/TPU/CNT filaments, incorporating continuous carbon fibers (CFs) in the front, middle, and back parts of a particular orthopedic insole. The compressive strength and modulus of samples unexpectedly decreased upon CNT incorporation. However, CNT in the TPU phase improved the shape memory performance, shortening the recovery time by 58 %. CF-reinforced composites exhibited excellent mechanical properties and SME; the front triangular structure showed a 13.4 times increase in compressive strength and a 22.6 times increase in modulus compared to free-fiber composites. The printed samples demonstrated remarkable electro-induced shape memory properties due to the dual conductive network formed by CF and CNT. Our PLA/TPU/CNT/CF (nano-) composite is well-suited for personalized shape-memory insole applications, offering enhanced mechanical performance and electro-induced shape-memory capabilities.

Non-ablative thermal protection materials are subjected to localized high-density heat flux, facing extreme temperatures and uneven temperature distribution. Heat dredging is expected to enhance thermal protection efficiency and alleviate its resistance to temperature pressure. In this study, the function of in-plane (IP) heat leading is innovatively incorporated to increase the thermal-protection efficiency of carbon-bonded carbon fiber (CBCF) composites. The modified composite is prepared by a one-step integrated filter press process in which continuous flexible graphite paper (FGP) is used as the heat-leading layer. The typical micromorphology, mechanical response, thermal-insulation and heat-leading performance are determined. The CBCF/FGP composites with a 0.1 mm thick heat-leading layer exhibits a density of 0.22 g/cm³. The compressive strength increased by 160 % in the IP direction while remaining consistent in the through-the-thickness direction relative to that of the pure CBCFs. The thermal conductivity in the insulation and heat-leading directions at room temperature are 0.061 W/mK and 21.14 W/mK, respectively, indicating significant anisotropy with an approximately 350-fold difference. The incorporation of FGP effectively enhances the IP heat-leading capabilities of CBCF composites, potentially improving their thermal-insulation efficiency when combined with different matrix materials.

Nacre-like graphene composite films (GCFs) with high strength have been highly developed. However, the GCFs usually exhibit relatively poor toughness and poor flame resistance, seriously limiting their applications as structural materials. Here, reduced graphene oxide (rGO), halloysite nanotubes (HNTs), and flame-retarding modified lignin (F-lignin) were compounded to fabricate the rGO-HNTs-(F-lignin) film. In the rGO-HNTs-(F-lignin) film, the F-lignin binds the rGO sheets and HNTs, enhancing the entanglement of HNTs and the interactions between HNTs and rGO sheets, and the macromolecular F-lignin also improves the ductility of the rGO-HNTs-(F-lignin) film, while the entangled HNTs conversely reinforce the F-lignin to prevent the F-lignin from fracture when the rGO-HNTs-(F-lignin) film is under stress, further increasing the ductility of the rGO-HNTs-(F-lignin) film. The HNTs and F-lignin promote each other to enhance the strengthening and toughening effect on the rGO-HNTs-(F-lignin)-film, and endowing the rGO-HNTs-(F-lignin)-film with the superior mechanical properties of the tensile strength of 634 ± 38 MPa, tensile fracture strain of 8.17 ± 0.59 %, and toughness of 25.35 ± 2.95 MJ/m³, respectively. The rGO-HNTs-(F-lignin) film also exhibits improved flame-retardant properties due to the high flame retardancy of HNTs and F-lignin. These excellent integrated properties of the rGO-HNTs-(F-lignin) film will promote its potential applications as structural materials.

The natural Caprinae horn sheaths possess excellent mechanical properties due to the synergistic effects of the porous and corrugated lamellar structure. However, research on bioinspired designs based on this structure remains absent. In this work, we attempted to integrate hollow glass microspheres modified by silane coupling agents into A. pernyi silk fabric, and finally fabricate a horn sheath-inspired composite using the vacuum-assisted resin transfer molding. The impact strength of the horn sheath-inspired composite reaches up to 150 kJ m^-2 with a low density of 1290 kg m^-³. Fracture morphology analysis and finite element simulation confirmed the toughening mechanisms, including crack deflection and interfacial bonding due to the synergistic effects of the porous structure and the corrugated silk fabrics. This study provides a bioinspired strategy to lightweight and tough composites, with significant potential in impact-critical applications.

Superhydrophobicity exhibited by several natural surfaces has broad application prospects due to their excellent self-cleaning and low adhesion properties. However, designing a robust superhydrophobic coating via design strategy using amorphous polymers is allimportant for industrial applications, yet rather challenging. Here, we report a scalable strategy based on the phase separation and swelling treatment to construct an ultra-durable superhydrophobic coating with hierarchical micro-/nanostructures formed by two amorphous polymers (e.g. hydrophilic and lipophilic polymers). The controlled phase separation of two amorphous polymers creates uniformly distributed microprotrusions on the coating surface and the following swelling process produces submicro-/nanobumps on the microprotrusions. Notably, when both types of polymers achieve the hierarchical micro-/nanostructures, hydrophilic polymers exhibit strong adhesion with the substrates, whereas lipophilic polymers reduce the surface energy of the system. Benefitting from the self-similar structure and the adhesive effect, the polymer-based superhydrophobic coating displays superior mechanical and chemical robustness. Furthermore, our strategy will boost the practical application of robust superhydrophobic coatings for anti-corrosion application.

To address the increasingly serious environmental pollution and energy crisis, there is an urgent need to develop multi-source-driven energy storage materials, the field of new energy sources, such as solar thermal power generation, but electromagnetic pollution has become a primary problem that needs urgent resolution. Therefore, the development of multifunctional phase change composites (CPCMs) with multi-source drive capabilities and excellent electromagnetic shielding integration is crucial. In this study, polypyrrole (PPy)-coated conductive fibers were crosslinked with polyvinyl alcohol (PVA) to form a three-dimensional network, which was then combined with metal foam to prepare Ni–F/PPy@CNF-PVA (PCN) dual-network carriers with high electrical conductivity by vacuum-assisted adsorption and freeze-drying methods. Polyethylene glycol (PEG) was subsequently encapsulated via vacuum impregnation to get the shape-stable PEG/Ni–F/PPy@CNF-PVA (PPCN) phase change composites. The PPCN exhibited good stability and high energy storage density (melt enthalpy up to 126.18 J/g, relative enthalpy efficiency over 99 %). Benefiting from its outstanding electrical conductivity (186680 S/m for PPCN-3), light-absorbing properties, and magnetism, the PPCN also exhibits highly efficient photothermal, electrothermal, and magnetothermal conversion capabilities. The electromagnetic interference shielding efficiency reaches up to 110.37 dB within the X-band frequency range (8.2–12.4 GHz). In conclusion, PPCNs are significant for multi-source-driven energy storage and electromagnetic shielding.

The development of structures and devices with enhanced acousto-mechanical properties is a topic of interest in engineering, especially in the biomedical field. A case study is the reconstruction of the tympanic membrane after partial or complete damage, such as from chronic suppurative otitis media, which is the leading cause of infectious diseases in children. In this work, we developed graphene-oxide (GO) nanocomposite polymeric scaffolds fabricated via electrospinning to assess their potential suitability as substitutes of the eardrum. To evaluate the structural influence of GO on the fibrous mesh, we performed a characterization in terms of wettability, mechanical properties, and surface morphology. Moreover, a finite-element model of the middle ear was employed to assess the acousto-mechanical behavior of the eardrum upon application of the developed scaffolds. We observed that GO influenced the morphology of the fibrous scaffolds by increasing the mean diameter of the fibers, their stiffness and strength, while decreasing the water contact angle, thus making the structures more hydrophilic. From the acoustic standpoint, the simulations showed that GO does not significantly affect sound transmission, except for PVDF-based structures, for which GO slightly improves the behavior only up to 2 kHz, but with a suboptimal performance at higher frequencies. Our results open to the development of fibrous nanocomposite polymeric scaffolds with an enhanced acoustic behavior for structural applications not limited to bioengineering.

The crystalline-amorphous interfaces play vital roles in affecting martensitic transformation, shear band nucleation and interface stability. Though both quasi-static and dynamic mechanical behaviors of shape memory enhanced bulk metallic glass composites have been studied via experiments, the atomic-level interactions among martensitic transformation, localized shear softening and interfacial strain concentration imposed by strain rate remain elusive. We employ molecular dynamics simulations to study strain rate effect on uniaxial compression behavior of transformable B2–CuZr enhanced bulk metallic glass composite. As strain rate increases, the proportion of martensitic transformation accelerates. During the competition among martensitic transformation induced-hardening, shear induced-softening and interface debonding, a two-stage work-hardening is observed, which is in agreement with experimental findings.

Mantis shrimps use their robust claws to repeatedly strike and break the shells of bivalves during predation without sustaining damage themselves. It appears to be a confrontation between the bouligand microstructure and the brick-and-mortar microstructure of the nacre layer. In the daily struggle for survival, defects are inevitably introduced. To elucidate the mechanical mechanisms exhibited by the two microstructures in the struggle for survival, thus a bold conjecture was proposed: the bouligand structure exhibits less sensitivity to random defects compared to the brick-and-mortar structure, enabling mantis shrimps to survive in the battle for existence. To verify this hypothesis, numerical models of bouligand and brick-and-mortar microstructures were established considering interfacial random defects. The results indicated that for various defect volume fraction, the bouligand structure demonstrates superior mechanical performance compared to the brick-and-mortar structure. In terms of peak load and damage dissipation energy, the bouligand structure exhibits higher tolerance to interfacial random defects than the brick-and-mortar structure, delaying the occurrence of damage in the Bouligand structure while prematurely inducing damage in the brick-and-mortar structure. This study not only reveals the mechanical mechanisms behind the advantages of biological microstructures in the struggle for survival but also provides technical references for future biomimetic microstructure designs.

Biomass carbon-based flexible sensors have shown significant potential in various applications. Indeed, biomass carbon-based flexible sensors, such as carbonized cotton fabrics, exhibit limitations in terms of sensitivity and response speed. Herein, a kind of biomass carbon nanosphere-based flexible pressure sensor was proposed and developed by embedding biomass carbon nanospheres on the skin-hair structures of the polydimethylsiloxane surface. The carbon nanospheres were obtained through the carbonization of cuttlefish ink. Owing to the skin-hair structures fabricated on the surface of the composite films, the sensors achieve a sensitivity of 135.2 kPa⁻¹ in the pressure range of 0–1 kPa. In addition, the sensors exhibit a short response (43 ms) and recovery time (23 ms). With these properties, the sensors can capture and monitor various motions as well as the characteristic waveforms of the wrist pulse, such as the percussion wave (P wave), tidal wave (T wave), and diastolic wave (D wave).