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Investigations on the damage and degradation mechanisms of epoxy resin under a high-energy irradiation and improvement in its stability in irradiation environments are crucial to expand the application of epoxy resin in numerous fields including the aerospace and nuclear industries. In this study, graphene quantum dots (GQDs) were used as free radical scavengers to slow down the degradation of epoxy resin under a γ-irradiation environment, and the anti-irradiation mechanism of the GQDs on epoxy resin was investigated. The results demonstrated that following irradiation, the mechanical properties of epoxy resin exhibited a reduction of 49%, accompanied by a decrease in glass transition temperature by 4.4 ℃. Similarly, the mechanical properties of graphene quantum dots/epoxy resin (GQDs/EP) composites experienced a decline of 35%, along with a decrease in glass transition temperature by 2.2 ℃. Notably, upon the incorporation of GQDs, the generation of free radicals within irradiated GQDs/EP composites was significantly suppressed compared to pure resin. Furthermore, GQDs nanoparticles enhanced both the mechanical properties and thermal stability of epoxy resin prior to and after irradiation. Therefore, GQDs nanoparticles can be used as free radical scavenger to effectively improve the irradiation stability of epoxy resin. The scavenging mechanisms for free radicals mediated by GQDs is closely associated with sp2 carbon domains and surface functional groups. This study provides a novel concept and method to improve the stability of epoxy resin under γ-ray radiation.

Ramie composites have been widely used in automobiles, daily necessities, aerospace, ships, cruise lines, etc., but their flame retardant properties are relatively poor, which is difficult to meet the flame retardant performance requirements of composites for rail transit. In order to improve the properties of ramie reinforced composites, flame retardant treatment is necessary. In this paper, phosphorus flame retardant phytic acid (PA) was used to modify ramie fabric, and then the composites were prepared. The flame retardancy and mechanical properties of ramie reinforced composites were investigated. It was found that the flame retardancy of ramie composites was improved after flame retardant modification with phytic acid, but the mechanical properties were decreased. In order to improve the mechanical properties of PA ramie composites, two kinds of layered PA ramie/glass fiber hybrid composites were prepared by replacing part of ramie with glass fiber. The results show that the addition of glass fiber can improve the mechanical properties and flame retardancy of composites. [ABSTRACT FROM AUTHOR]

This paper investigates the parallel harmonic resonance problem for hybrid compensation systems, consisting of active power filters and thyristor-switched capacitors, and proposes an adaptive composite control strategy for solving the parallel harmonic resonance problem that may arise in practical applications of hybrid compensation systems. In practice, a hybrid compensation system can effectively solve harmonic and reactive power problems, but the equivalent reactance of the thyristor-switched capacitor and the supply line may form a parallel resonant circuit, which may generate parallel harmonic resonance when excited by a harmonic source at the non-linear load side, affecting the quality and stable operation of the system. The adaptive composite control strategy employs a second-order generalized integrator-frequency-locked loop (SOGI-FLL) to extract the harmonic voltage at the point of common coupling (PCC) and generate an adaptive damping current command using an adaptive algorithm, which adaptively adjusts the parameters of the resonance suppression controller through harmonic content limitation. Matlab/Simulink simulations show that the method effectively achieves harmonic resonance suppression of the power supply system under complex operating conditions, thus ensuring the stable operation and power quality of the power supply system. Therefore, the proposed control strategy is feasible and effective. [ABSTRACT FROM AUTHOR]

Aramid fibers and ultra‐high molecular weight polyethylene (UHMWPE) fibers lack active surface functional groups, and the surface is smooth, limiting their practical application in textile composite materials. In this study, zinc oxide nanorods were used to grow on aramid fibers surfaces, and oxygen plasma followed by treatment with a silane coupling agent was used to modify UHMWPE fibers. The effects of surface modification on the surface morphology and composition, and mechanical properties of fibers and composites were investigated. The mechanical response of interlayer hybrid textile composite materials based on modified aramid and UHMWPE fabrics was examined. The results reveal that surface roughness, active surface functional groups, and wettability that can be controlled by treatment conditions and parameters are important for improving interface adhesion. In addition, the interlayer hybridization pattern as a result of using dissimilar layer materials and altering stacking sequence has a great impact on the mechanical behavior of hybrid textile composite materials. [ABSTRACT FROM AUTHOR]

Conductive macroscopic MXene‐based architectures receive tremendous attention for various potential applications. In this paper, the rheology and printing suitability of MXene ink were optimized by ball milling method to ensure good structural integrity and electrical conductivity of the printing structure. Porous CNT/Ti3C2Tx/CS composites were prepared by 3D printing, and the effects of various arrangements on electromagnetic interference shielding (EMI SE) were studied in depth. Since Ti3C2Tx can produce TiO2 under the action of high‐energy ball milling, it provides more heterogeneous interfaces and dipole effects. At the same time, Ti3C2Tx and CNT are evenly dispersed and can construct a complete conductive network, which greatly enhances its conductivity loss. In collaboration with the 3D‐printed framework, it can also extend the propagation path of electromagnetic waves and enhance their multiple reflection losses. The results show that the EMI SE of the composite material can reach 26 dB in X‐band, and EMI SE can be affected by the different arrangement. This work lays a solid foundation for the construction of heterogeneous interfaces by ball milling and the free construction of EMI shielding materials by 3D printing. [ABSTRACT FROM AUTHOR]

Membrane separation technology represented by graphene oxide (GO) membranes has been widely used in lithium extraction from salt lakes. It is extraordinary to study the extraction of Li+ by GO membranes from the perspective of the confined mass transfer effect. This study establishes a GO channel model with the confined mass transfer effect to closely fit the actual mass transfer process. Meanwhile, this study investigates the dynamic fluid characteristics in the separation of Li+/Mg2+ by GO membranes using molecular dynamics simulations. The results showed that the Li+/Mg2+ separation ratio is maximum at 1.0 nm layer spacing and 10% oxidation degree of the GO membrane. Water molecules form a bilayer within the channel at the appropriate interlayer channel (1 nm) and oxidation level (10%), which accelerates the ion transport rate. Furthermore, the GO oxidation group has the weakest hydrogen bonding effect on water which promotes the passage of water. Finally, the maximum separation ratio is reached due to the fact that the binding force of Li+ to water molecules in the channel is lower than that of Mg2+. The results of this study will provide theoretical consideration for the design of high-performance Li+/Mg2+ separation membranes. [ABSTRACT FROM AUTHOR]

Electromagnetic interference (EMI) shielding material with good flexibility and lightweight is an effective way to eliminate electromagnetic pollution sources. Herein, lightweight, flexible, and strong CoFe/C/HCF composites with hierarchical pore structures were constructed by in situ growth, etching/ion exchange reaction, and high-temperature pyrolysis using cotton fabric (CF) as the substrate. The Co-MOF nanosheet was in situ grown on the surface of CF, and CoFe-LDH nanosheets were formed after the etching/ion-exchange reaction. CoFe/C/HCF composites with hierarchical pore structures were obtained after high-temperature pyrolysis. The hierarchical pore structure was verified using small-angle neutron scattering analysis. The unique hierarchical pore structure and strong interfacial interaction make the composites have higher average shielding efficiency (SE) and specific shielding efficiency (SSE), when the thickness is only 0.9 mm, which reached 30.7 dB and 109.64 dB·cm3 g–1, respectively. Meanwhile, ultrafast photothermal performance is also achieved, which can ensure the normal function of the composite material in cold conditions. This work provides possibilities for the potential applications of CoFe/C/HCF composites in flexible sensing and wearable smart electronics. [ABSTRACT FROM AUTHOR]