Latest Issue

2024, Volume 41,  Issue 6

Research progress of bacterial cellulose and its composites for electrochemical energy storage and sensing
WANG Jing, LI Caiyun, WAN Yizao
2024, 41(6): 2745-2760. doi: 10.13801/j.cnki.fhclxb.20240003.006
Bacterial cellulose (BC) is a green and renewable material with abundant sources. BC has outstanding physical and chemical properties and is considered to be a biopolymer material with diverse application potential. With the continuous deterioration of energy and ecological environment, it is urgent to develop advanced energy storage technology. BC shows broad application prospects in the fields of electrochemical energy storage, sensing and energy conversion, and has gained a lot of attention. In this review, BC is briefly introduced. Based on the types of BC and its composites in the field of electrochemical energy storage and sensing, as well as the effects of different treatments and modification methods on the structure and properties of BC, the application progress of BC in the field of electrochemical energy storage and sensing is systematically summarized. In addition, in terms of the composite matrix and reinforcement concept, the construction process of BC and its composites was systematically introduced. The application status of BC in the field of electrochemical energy storage and sensing is mainly reviewed, and the strengths and weaknesses of its application are analyzed and summarized. Meantime, the different applications of BC in new electronic devices and energy conversion are also involved. Finally, the existing challenges and prospects of BC in electrochemical energy storage and sensing are summarized.
Preparation, modification and application of laser-induced graphene
LI Zhao, LIU Cui
2024, 41(6): 2761-2774. doi: 10.13801/j.cnki.fhclxb.20230912.002
Laser-induced graphene (LIG) is a novel graphene preparation technique, which is a process for the rapid transformation of three-dimensional network-structured graphene by irradiating carbon-containing substrates with high-energy beams. Compared with the conventional graphene preparation process, LIG has attracted broad research interest because of its rapid preparation, designable patterning, environmental friendliness, controlled microscopic morphology, and controlled composition. This review summarizes the synthesis process of LIG, including the composition of precursors, the selection of light sources, and the structural modulation of LIG. It also explores the in-situ and non-in-situ modification methods of LIG in recent years, describes the applications of LIG in the field of flexible electrodes and sensors, and provides an outlook on the development of LIG in the direction of integrated energy, sensing, and detection devices.
Research progress on microwave absorption stealth technology of honeycomb sandwich structure composites
LI Xuguang, WU Xuemeng, SHI Junxi, YANG Jin
2024, 41(6): 2775-2788. doi: 10.13801/j.cnki.fhclxb.20231108.001
With the rapid development of detection technology and the demand for operational performance, higher requirements have been put forward for radar stealth technology, honeycomb sandwich structure as a classical structural wave-absorbing material has made great development in recent years, this paper aims to comprehensively analyse and summarize the characteristics, research status and application of honeycomb sandwich structure composites in the field of wave-absorbing stealth technology at home and abroad. This paper focuses on the key factors affecting the wave-absorbing performance of honeycomb sandwich structures, including the performance of absorbers, the design of honeycomb structures and the wave-transparent performance of skins, etc. It also analyses the advantages and disadvantages of different honeycomb sandwich structure wave-absorbing materials with respect to the key indexes of wave-absorbing bandwidth and absorption rate. In addition, this paper summarises the current development trend of honeycomb sandwich structure wave-absorbing stealth composites, summarises the current status of development, and gives an outlook on the future development direction.
Research progress on wood-based porous materials for dye wastewater treatment
MEI Zekai, DING Yi, FENG Shu, YANG Weisheng, HAN Jingquan
2024, 41(6): 2789-2800. doi: 10.13801/j.cnki.fhclxb.20231204.003
Dyes are extensively utilized in various industries, such as textiles, leather, plastics, and paper, and are currently one of the major sources of water pollution. Dye wastewater is characterized by its complex composition, high toxicity, and significant amounts of organic pollutants and heavy metals, which poses a serious threat to the ecological environment. Consequently, the removal of water-soluble organic dyes from water bodies has become a crucial challenge in wastewater treatment. Wood is a renewable, biodegradable, and environmentally friendly natural material that possesses a well-structured and hierarchically organized multiscale structure, as well as abundant pore structures. This porous hierarchical structure serves as a natural basis for the creation of new materials and devices intended for removing dyes. The physicochemical adsorption and catalytic degradation of dyes by wood-based composites can be promoted by loading active substances such as graphene, metal-organic frame (MOF), noble metal nanoparticles (Ag, Au, Pd) and polyoxometalates on the surface of the internal lumen of the wood, which can lead to the effective removal of dyes from wastewater. In this paper, the characteristics of dye wastewater and its hazards are firstly outlined, and the special microstructure of wood and its advantages in dye wastewater treatment are introduced in detail. Subsequently, the principles and research status of wood-based porous materials loaded with active substances for the two treatments of adsorption and catalytic degradation of dye wastewater are overviewed, and the future development prospects of wood-based porous materials for the treatment of dye wastewater are also prospected and summarized.
Research progress of electrospinning flame retardant nanofiber
BAO Yan, ZHAO Haihang, GAO Lu, ZHANG Wenbo
2024, 41(6): 2801-2814. doi: 10.13801/j.cnki.fhclxb.20231127.002
Electrospinning nanofiber exhibits several advantages, such as adjustable fiber diameter and distribution, interconnected pore structure, high porosity, high specific surface area, and controllable fiber packing density, which is a prominent research hot spot in recent years. Flame-retardant is an important characteristic of polymer materials, and flame-retardant fibers have the characteristic of higher safety in use compared to ordinary fibers. The development of nanofibers with flame-retardant properties is of great significance. Electrospinning technology refers to the jet spinning of polymer solutions or melts under strong electric fields, providing technical support for constructing nanofibers with special functions. It not only provides the possibility of combining functional fillers into polymers, but also provides the possibility of uniform dispersion of functional fillers within the polymer, which helps to more conveniently produce nanocomposites with special properties in situ. Based on this, this review introduced the development of flame-retardant nanofibers via electrospinning technology. Specially, the structure of electrospinning flame-retardant nanofibers was discussed, mainly including blend structure, core-shell structure, side-by-side structure, and porous structure. Their advantages and disadvantages were also emphasized. Moreover, the application status of flame-retardant nanofibers in lithium-ion battery separators, air filtration systems, fire alarm sensors, and protective materials were introduced. Finally, the future development directions of electrospinning flame-retardant nanofibers were foreseen.
Research progress of MXene materials in the application of heavy metal electrochemical detection
LI Shangshang, WANG Hongmei, HE Kaiyu, WANG Liu, LAN Hangzhen, XU Xiahong
2024, 41(6): 2815-2828. doi: 10.13801/j.cnki.fhclxb.20231212.001
Detecting heavy metal pollution has become an essential technical guarantee in risk prevention and control, agricultural green development, food safety, and ecological protection. At present, there are many technologies to detect heavy metal ions, among which electrochemical detection methods have the advantages of high sensitivity, fast analysis, and simultaneous detection of a variety of metal ions, which have become a research area in the field of rapid detection of heavy metals. MXene is a transition metal-carbon/nitride material with a graphene-like structure with good hydrophilicity, electrical conductivity, and rich adjustable surface terminations. The focus of this study is the research progress of MXenes in the electrochemical detection of heavy metal ions. The sources, hazards, and detection methods of heavy metal contaminants are briefly described. Secondly, the synthesis methods of MXene are summarized, and the research progress of MXene in the electrochemical detection of heavy metals in recent years is reviewed, including the sensing mechanism and detection performance analysis. Finally, the challenges and prospects of MXene materials in the electrochemical detection of heavy metals are discussed.
A review of the effect of ceramic wastes on mechanical properties and mechanisms of cementitious composites
ZHANG Liqing, XIAO Zhenrong, LIU Sha, WANG Yunyang, XU Kaicheng, HAN Baoguo
2024, 41(6): 2829-2844. doi: 10.13801/j.cnki.fhclxb.20231201.002
As one of the solid wastes, ceramic wastes have a hard texture, and their main chemical composition are SiO2 and Al2O3. These characteristics make properly treated ceramic wastes have the potential to replace natural sand, gravel aggregates and act as admixtures. Application of ceramic wastes into cementitious composites will contribute to alleviate the problems of environmental pollution caused by the overexploitation of natural sand and gravel, high energy consumption and pollution in cement production, and the accumulation of ceramic wastes. This paper first briefly describes the physical and chemical properties of various types of ceramic wastes. Then, from the different application forms of ceramic wastes in cementitious composites, this paper comprehensively reviews the research status of the effect of ceramic waste aggregates and ceramic waste powders on the basic mechanical properties of cementitious composites, reveals the influencing mechanisms of ceramic wastes on the basic mechanical properties of cementitious composites. Finally, suggestions for further application and research of cementitious composites with ceramic wastes, especially in green and ultra-high-performance concrete and mechanical property retention after high temperature refractory concrete, are put forward based on the problems existing in the current research.
Research progress of specific structural composites derived catalysts in dry reforming of methane
XIE Xuanlan, LU Zhiheng, LI Wenzhi
2024, 41(6): 2845-2862. doi: 10.13801/j.cnki.fhclxb.20240002.001
Specific structural composites such as perovskite, spinel and hydrotalcite have attracted widespread research interest in catalytic applications due to their flexible composition, controllable structure, and better thermal stability. Dry reforming of methane is a technology with great application prospect for converting CH4 and CO2 into syngas with low H2/CO molar ratio simultaneously. Conventional supported catalysts are susceptible to face the challenge of catalyst deactivation caused by carbon deposition and active component sintering under high-temperature reforming conditions, whereas supported catalysts derived from specific structural composites have attracted much attention owing to their superiority in terms of catalytic activity and stability. In this paper, the characteristics of dry reforming of methane, the challenges faced and the current research status of the reaction mechanism are first briefly outlined, and then elaborates on the structural characteristics of perovskite, spinel and hydrotalcite these three composites, the advantages and disadvantages of applying them as catalyst precursors in this reaction, their performance and the current status of research on the catalytic pathway. Perovskite structure is relatively more stable, but high calcination temperatures may easily lead to a lower surface area of its derived catalyst. Hydrotalcite-derived catalysts usually have a high specific surface area and can restore partially ordered layered structures when calcined under certain circumstances. Hydrotalcite and spinel are relatively more sensitive to temperature, and the presence of inverse spinel structure is beneficial for improving the reducibility of the derived catalysts. Additionally, the catalytic mechanisms of these three specific structural composites derived catalysts are summarized. The clear one is that CH4 is activated at the active metal sites, and due to the influence of catalysts and operating conditions, researchers have not reached a clear consensus on the details of the reaction mechanism at the catalyst surface for the time being. Finally, some advice is put forward on the application of these specific structural composites derived catalysts in dry reforming of methane.
Research progress in fluorescent transparent functional wood composite materials
LONG Shoufu, ZHANG Ming, AN Congcong
2024, 41(6): 2863-2873. doi: 10.13801/j.cnki.fhclxb.20231129.004
With the continuous development of society, there is an urgent need for a green composite material with environmental protection, low cost, good toughness, high strength, and high added value-functional fluorescent transparent wood composite material, to replace traditional glass doors and windows, building and home materials. Functional fluorescent transparent wood composite materials have advantages such as green, high transmittance, high strength, good toughness, excellent fluorescence effect, good UV shielding, antibacterial, and good mechanical properties, and have broad application fields. This article summarizes the luminescence principle and influencing factors of fluorescent materials, various preparation methods of wood substrates, and the application of functional fluorescent transparent wood composite materials. It also introduces the applications of functional fluorescent transparent wood composite materials in LED lamps, sensors, encryption and anti-counterfeiting, UV conversion, and formaldehyde detection. Finally, it looks forward to future application scenarios and proposes the urgent problems to be solved at present.
Research progress in biomass-based monolithic catalytic microreactors
YAO Sisi, GUO Dengkang, LI Jingpeng, JIANG Zehui
2024, 41(6): 2874-2899. doi: 10.13801/j.cnki.fhclxb.20231213.001
Natural biomass materials are favored in the field of heterogeneous catalysis due to their wide resources, strong carbon sequestration capacity, high mechanical strength, renewability, environmental friendliness, as well as their unique fine structure and chemical composition. The inherent pore channel system and chemical compositions of biomass materials can not only improve the chemical reaction rate, but also participate in the heterogeneous catalytic reaction as the catalysts carrier. The resource, structural and chemical advantages of biomass such as bamboo, wood and rattan as catalyst carriers were briefly introduced in this paper. The basic concepts, types of catalysts, construction strategies and mechanisms, catalytic activity and failure mechanism of biomass-based monolithic catalytic microreactors were reviewed, as well as the research progress in advanced functional fields such as water treatment, energy generation, chemical synthesis, Fischer-Tropsch synthesis, and bioanalysis. Finally, in view of the limitations and existing problems of the current research, the future development trend of biomass-based monolithic catalytic microreactor is prospected in terms of construction strategy optimization, functional catalyst design, structure regulation improvement and stability performance improvement, in order to provide new scientific ideas and technical references for the construction and efficient utilization of functional interfaces of biomass materials under the strategic goals of carbon peak and carbon neutrality.
Resin Polymer Composite
Preparation of carbon fiber heating elements and their effects on the properties of resistance welding joints in thermoplastic composite materials
YAO Xin, HUO Hongyu, AN Xuefeng, ZHANG Baoyan
2024, 41(6): 2900-2908. doi: 10.13801/j.cnki.fhclxb.20231113.004
This paper presents the preparation of two types of thin-layer carbon fiber stretched-width cloth heating elements using the suspension impregnation process with polyether-ether-ketone (PEEK) powder and the melt impregnation process with PEEK resin film. The resistance welding technology for carbon fiber reinforced polyether-ether-ketone composite laminates was experimentally investigated. The results demonstrated that employing an “embedded type” electrode arrangement effectively mitigates the “edge effect” caused by exposed heating elements during resistance welding. Moreover, it was found that the heating time significantly influences the strength of welded joints, which initially increases and then decreases, reaching a maximum value of 28.1 MPa at 120 s. Additionally, the fracture failure mode has changed from initial adhesive failure to a mixed failure mode of implant and fiber. Furthermore, compared to melt impregnation, powder suspension impregnation process enhance joint strength by 15% under identical welding conditions.
Experimental and simulational study on tensile mechanical property of carbon nanotubes/epoxy resin composite
ZENG Lijian, LI Renfu, CHEN Yuxuan
2024, 41(6): 2909-2922. doi: 10.13801/j.cnki.fhclxb.20231024.001
Due to the excellent mechanical, electrical and thermal properties, carbon nanotubes (CNTs) are widely used in the research and preparation of high-performance composite. However, with the high aspect ratio, high specific surface energy and strong van der Waals force, CNTs intend to form agglomeration during the preparation process, causing a decrease in the mechanical property of the composite material at high concentration. In order to accurately characterize the tensile mechanical property of CNTs enhanced epoxy nanocomposite (CNTs/EP) nanocomposite, the tensile mechanical properties of different kinds of CNTs/EP were characterized by experiment and finite element analysis. Considering the influence of agglomeration on the material parameter of epoxy, a method for reducing the materials parameter of epoxy in the agglomeration region was proposed to improve the numerical analysis method of agglomeration distribution model. The results show that the uniform distribution numerical analysis method can accurately predict the tensile strength and elastic modulus of CNTs/EP at a low content of 0.5wt%. The agglomeration analysis method accurately predicts the tensile mechanical property, the error of elastic modulus and tensile strength of CNTs/EP are no more than 5% at a high concentration of 1.5wt%.
Study on interfacial compatibility and resilient creep resistance of silane-modified collagen fiber/polyvinyl chloride composites
LEI Chao, XU Weixing, ZENG Yunhang, SHI Bi
2024, 41(6): 2923-2934. doi: 10.13801/j.cnki.fhclxb.20231019.002
The three-dimensional hierarchical structure of collagen fiber (CF) has the natural advantage of resilient creep-resistant modification of polyvinyl chloride (PVC), but the hydrophilic CF is difficult to be compatible with the hydrophobic PVC effectively, which limits the modification efficacy of PVC by CF. Modified CF (M-CF) was prepared with amino-silane coupling agent (APTES). The structural transformation pattern of M-CF, and the structure, creep behavior, and fracture behavior of M-CF/PVC were investigated by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and dynamic mechanical analysis. The results show that APTES improves the hydrophobicity of CF and formed ionic and covalent bonds with PVC chains, thereby greatly improving the compatibility between CF and PVC. In addition, APTES modification fully opens the three-dimensional hierarchical structure of M-CF, which allows PVC to better penetrate into theM-CF phase region and form more blocking sites between PVC and M-CF. As a result, the movement of PVC chains is obviously inhibited, the deformation activation energy of M-CF/PVC is increased by 30.7% compared with that of pure PVC, the creep lifetime of M-CF/PVC is extended to 80.5 times than that of pure PVC and 2.3 times that of CF/PVC, and the reversible deformation (11.50%) of M-CF/PVC is increased to more than 1.4 times than that of the conventional modified PVC. In summary, the improved compatibility between CF and PVC endows M-CF/PVC with ideal resilient creep-resistance.
In-plane compression properties of foam-filled anti-tetrachiral structure and re-entrant structure
SHI Nannan, ZHANG Weichen, LI Zhenbao, WANG Lihui, LIU Han, ZHANG Lei, XIA Yang
2024, 41(6): 2935-2946. doi: 10.13801/j.cnki.fhclxb.20231027.001
Negative Poisson's ratio honeycomb structure has excellent mechanical properties including indentation resistance, impact resistance and energy absorption. In order to better study the mechanical properties of negative Poisson's ratio structure, this paper selects two kinds of negative Poisson's ratio structure: Anti-tetrachiral structure and re-entrant structure for comparative analysis. In order to improve the mechanical properties of honeycomb structure, polyurethane foam was filled in the structure. The deformation modes and mechanical properties of the foam-filled anti-tetrachiral structure and re-entrant structure were experimentally studied. In addition, through the parametric study of the foam-filled anti-tetrachiral structure, the effects of wall thickness t and node radius r on the energy absorption and Poisson's ratio of the structure were analyzed. The results show that the energy absorption and bearing capacity of anti-tetrachiral structure is better than that of the re-entrant structure. After filling the two kinds of structures respectively, the structure has higher stiffness and energy absorption, but the ‘auxetics’ effect is weakened. With the increase of wall thickness t and node radius r, the stiffness and energy absorption capacity of the foam-filled anti-tetrachiral structure increase, the Poisson's ratio increases, and the "auxetics" effect decreases. However, the brittle failure of the structure is enhanced and its specific energy absorption is weakened when the wall thickness is too thick. In addition, the compaction strain of the four-ligament backhand structure decreases with the increase of the wall thickness t and the decrease of the node radius r.
"Forming-bending" coupling numerical model for the carbon fiber reinforced polypropylene composite tube
WANG Zhen, REN Haoqian, CAO Xi'ao, MEI Xuan, ZHU Guohua, CHEN Yisong, GUO Yingshi
2024, 41(6): 2947-2958. doi: 10.13801/j.cnki.fhclxb.20231016.002
Currently, composite automotive body components still face the challenge of isolated analysis of manufacturing process and structural performance in the research and development process, developing the "forming-performance" coupling model for woven fabric reinforced thermoplastics (WFRTPs) shows great significances to promote the industrial application of WFRTPs in the field of new energy vehicles. In this study, using the carbon fiber reinforced polypropylene (CF/PP) prepregs as the raw materials, two kinds of thin-walled CF/PP tubes with different fiber angles were manufactured by hot molding process, and the quasi-static bias-extension tests for CF/PP prepregs and CF/PP laminates, and the three-point bending tests for CF/PP tubes were preformed, and experimental results show that the increase in fabric fiber angle caused by the forming process leads to the decrease in shear strength and the increase in failure strain of the CF/PP laminates, which further results in the reduction in peak force and the increase in failure displacement of CF/PP tubes. Then, the hypoelastic forming constitutive model for CF/PP prepreg, the progressive damage bending constitutive model for CF/PP laminate and the "forming-bending" coupling constitutive model for CF/PP tube were developed and validated. The numerical results indicate that the shear plastic strain of the non-orthogonal CF/PP tube manufactured with restraints of blank holding force is 69% higher than that of the orthogonal sample without blank holding force, and the increase in fiber angle results in the significant increase in shear plastic strain, which further significantly increases the bending failure displacement of the non-orthogonal CF/PP tube.
Functional Composite
Preparation of graphene (carbon nanotubes)-cellulose/keratin composite sensing films
SUN Zeying, JIANG Dawei, SUN Caiying
2024, 41(6): 2959-2967. doi: 10.13801/j.cnki.fhclxb.20230927.001
Cellulose (CE) and keratin (FK) are abundant natural materials. Cellulose has been used in various fields of production and life, while keratin, which is the main component of feathers, has mostly been discarded. Compounding keratin into cellulose can make good use of waste materials and improve the properties of cellulose materials. Firstly, cellulose and keratin were dissolved with ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), and epichlorohydrin (ECH) was used as a crosslinking agent to connect CE and FK into a network. The ionic liquid can shield the π-π deposition of graphene or carbon nanotubes, so that the carbon nanotubes or graphene can be well dispersed into the cellulose/keratin cross-linked network composite system to improve the electrical and mechanical properties of the material. The tensile strength and strain of the prepared composite film can reach 64.5 MPa and 58.0%, respectively. When bending 30°, 60° and 90°, the resistance would increase by 10%, 14% and 35%. The change of human motion behavior can be monitored by the change of resistance caused by the deformation of the film. Therefore, the composite film is very promising to be applied to wearable electronic devices that monitor motion, for sports, medical and other fields.
Ti3C2Tx MXene-modified domestic high-modulus high-strength carbon fibers based on electrophoretic deposition method
CAO Hongshuo, HUANG Ling, LIU Zhe, TIAN Yanhong, ZHANG Xuejun
2024, 41(6): 2968-2979. doi: 10.13801/j.cnki.fhclxb.20231030.001
In order to improve the surface properties of domestic high-modulus high-strength carbon fibers and the interfacial properties of their composites, Ti3C2Tx MXene nanosheets were constructed on the surface of domestic high-modulus high-strength carbon fibers (BHM5 carbon fibers) using a continuous electrophoretic deposition process. The surface morphology, surface element content, surface wettability of BHM5 carbon fibers and the mechanical properties and cross-section morphology of their composites before and after modification were characterized by SEM, XPS, dynamic contact angle, and INSTRON universal material tester, and the interfacial enhancement mechanism of the Ti3C2Tx MXene-modified BHM5 carbon fiber composites was investigated. The results show that the surface roughness and specific surface area of the Ti3C2Tx MXene-modified BHM5 carbon fibers increase, possessing a good mechanical interlocking ability with the epoxy resin matrix. The content of polar groups on the surface of the carbon fiber increases significantly, and the surface wettability is enhanced. After treating the BHM5 carbon fibers at 15 V for 2 min, the interlaminar shear strength of the composites reaches 82.54 MPa, which is enhanced by 28.2% compared with the composites made of untreated carbon fibers.
Preparation and performance of PVDF/PPy flexible DC nano-generator
LI Jinhui, LIU Xiaodong, JIN Xin, SHI Shanjing, WANG Wenyu
2024, 41(6): 2980-2990. doi: 10.13801/j.cnki.fhclxb.20231122.001
To address the difficulty of high integration, flexibility and low power density caused by the traditional nanogenerators with alternating current (AC) output and still need to use external rectifiers for direct current (DC) conversion, in this paper, poly(vinylidene fluoride) (PVDF) electrostatically spun film was used as a substrate and polypyrrole (PPy) was gas-phase polymerized on the surface of the film to produce a composite nanofibrous film of PVDF/PPy, and based on the Schottky collation principle, a DC nanogenerator was constructed by this composite nanofibrous film. The composite nanofiber membrane was used to construct a DC nano-generator based on Schottky finishing principle. The effects of oxidant concentration on the morphology of PVDF/PPy composite nanofiber membrane and the electromechanical performance of DC nano-generator were investigated under different polymerization time. The results show that when the oxidant concentration is 2 mol/L and the polymerization time is 90 min, the electrical output performance is optimal, corresponding to a peak voltage output of 1.23 V, a peak current output of 210.55 μA, and a theoretical power density of 28.77 μW/cm2. In this study, this PVDF/PPy DC nano-generator was demonstrated, and the energy conversion mechanism originates from the piezoelectric effect of piezoelectric polymer and the rectification effect of Schottky junction. These DC nano-generators are flexible, integrated and self-rectifying, and can be flexibly used in various places to provide power directly to electronic devices.
CsPbBr3 quantum dots passivated by acetylacetone indium and their room-temperature methanol gas sensitivity
HUANG Sheng, WEI Tianle, GU Xiuquan, HUO Yumeng, WAN Zixin, WANG Yanyan
2024, 41(6): 2991-3000. doi: 10.13801/j.cnki.fhclxb.20231011.002
Methanol gas is toxic gas that can harm the human nerve system and blood circulation system. Developing devices capable of detecting methanol gas is of great significance. The use of sensors to detect methanol gas has the advantages of low cost, high sensitivity, and real-time monitoring. However, the mainstream methanol gas sensors mainly rely on metal oxides, which have the drawback of high operating temperatures. Therefore, we synthesized perovskite quantum dots CsPbBr3 through a simple solution synthesis method, and passivated their surface defects using an acetylacetone indium ligand (In(Acac)3), obtaining a material with good gas sensitivity to methanol gas at room temperature. The sensitivity to a volume fraction of 80×10–6 methanol gas at room temperature is 0.25, and the response/recovery time is 11.0 s/17.0 s, gas sensitivity is further improved under ultraviolet light irradiation. It also has good reproducibility and stability, the sensitivity of the sensor has been maintained at around 0.25 after multiple tests at a volume fraction of 80×10–6 methanol gas, and the sensor sensitivity has remained at a high level for 15 days. At the same time, it still has a good response to methanol gas under harsh conditions such as high humidity and no light. Considering that the structure of metal halide perovskite can easily adjust its properties by changing elements, this research method and experimental process can be applied to the detection of other gases.
Preparation of honeycomb porous carbon nanofibers via electro-blowing spinning and investigation of their supercapacitor performance
ZHU Lin, WANG Yifan, HAN Lu, ZHOU Xinghai, SHAN Xiya, CUI Wenqi, GAO Yuan, LYU Lihua
2024, 41(6): 3001-3010. doi: 10.13801/j.cnki.fhclxb.20231120.003
One-dimensional porous carbon nanofibers have become a popular choice for supercapacitor electrode materials due to their high specific surface area, large aspect ratio, and efficient electron transport. In this study, honeycomb porous carbon nanofibers were synthesized using electrospinning technique, where polyvinylpyrrolidone (PVP) served as the carbon precursor and polytetrafluoroethylene (PTFE) emulsion acted as the pore-forming agent, followed by a high-temperature carbonization process. The morphology and structure of the prepared electrode materials were characterized using SEM, TEM, Raman spectroscopy, XRD, and Brunauer-Emmett-Teller (BET) analysis. Furthermore, the influence of pore-forming agent content on the fiber morphology, pore structure, and electrochemical performance was investigated. The results reveal that when the mass ratio of PVP∶PTFE in the spinning solution is 1∶10, the resulting electrode material exhibites the maximum specific surface area of 165 m²/g. Moreover, at a current density of 0.5 A·g−1, it achieves a high specific capacitance of 277.5 F·g−1. In a two-electrode system, the power density reaches 250 W/kg, resulting in an energy density of 31.6 W·h/kg. Additionally, after 10000 charge-discharge cycles, the capacitance retention remains as high as 98.4%, indicating excellent capacitive and cycling performance of the fabricated electrode material. Such a unique porous carbon nanofibers electrode material with its high porosity and honeycomb-like structure can offer abundant active sites for charge storage and provide convenient pathways for fast electron/ion transport, which holds significant reference and guidance for the development of high-performance supercapacitor electrode materials.
Preparation and properties of anisotropic cellulose nanofiber/aramidnanofiber composite foam
LIN Xu, MAI Xueyan, WANG Jun, YU Yan, ZHANG Xuexia
2024, 41(6): 3011-3020. doi: 10.13801/j.cnki.fhclxb.20231101.003
Cellulose nanofibers (CNF) foam has gained attention in the field of thermal insulation due to its lightweight, biodegradable, renewable nature, and excellent insulation properties. However, CNF foam suffers from drawbacks such as poor mechanical properties, flammability, and limited thermal stability, which restrict their practical applications. This study prepared anisotropic CNF/ANF composite foam by introducing aramid nanofibers (ANF) into nanocellulose fibers, using ice templating method combined with freeze-drying technique. The effects of ANF content and the introduction of anisotropic structure on the microstructure, mechanical properties, thermal stability, and thermal insulation performance of the composite foam were investigated. The results show that,when the mass ratio of CNF to ANF is 2∶1, the CNF/ANF composite foam exhibits an ultra-low density (12.25 mg/cm3), good mechanical strength (axial compressive strength of 74.56 kPa), and excellent thermal insulation performance (25.2 mW/(m·K)). Additionally, this composite foam also possesses good thermal stability and flame retardant properties, which endow it with broad prospects for applications in areas such as insulation and self-extinguishing property.
Lubrication-reinforcement microcapsules reinforce UHMWPE material
XIAO Yang, WEI Bin, CHEN Yanyan, LI Ling
2024, 41(6): 3021-3031. doi: 10.13801/j.cnki.fhclxb.20231113.002
Lubrication-reinforcement bifunctional microcapsules PTFE@Al(OH)3 using polytetrafluoroethylene (PTFE) as the core material and Al(OH)3 as the shell material were prepared by in-situ polymerization of sodium bicarbonate and aluminum sulfate solutions. Its surface was treated with vinyl trimethoxysilane (VTMS) and used as a reinforcing filler for ultra-high molecular weight polyethylene (UHMWPE). After it was evenly mixed, processed into composite materials using spark plasma sintering (SPS). The dispersion properties of microcapsules in the matrix, tribological properties and mechanical properties of composite materials were characterized by SEM, TEM, FTIR, universal micro tribometer (UMT-5), three-dimensional white light interferometer and methods of tensile compression testing machine. It is demonstrated that the addition of microcapsules effectively improve the tribological properties (friction coefficient decreased by 35%, wear amount decreased by 20%) and mechanical properties (compression strength increased by 2.5 times) of the composites. In addition, the dispersibility of the microcapsules is also greatly improved by surface modification.
Photocatalytic reduction and cyclic adsorption of Cr(VI) by nanocellulose-polyethylenimine-polypyrrole composite aerogel
YANG Mingyan, CAI Xiaodan, CHEN Xinyue, AN Linyu, XING Jianyu
2024, 41(6): 3032-3041. doi: 10.13801/j.cnki.fhclxb.20231030.003
The combined method of adsorption-reduction is a promising method for chromium pollution control. In this paper, nanocellulose-polyethylenimine-polypyrrole (CPP-F) photosensitive composite aerogel was prepared by in-situ oxidation polymerization of pyrrole using nanocellulose-polyethylenimine aerogel (CPA) as skeleton. The aerogel was characterized by SEM, FTIR, UV-vis and XPS. The adsorption, in-situ reduction and cyclic adsorption properties of CPP-F composite aerogel on Cr(VI) were studied by comparing the dark and light conditions, and the cyclic adsorption mechanism was analyzed. The results show that CPP-F is a black porous aerogel with uniform and stable structure, and has strong light absorption effect in ultraviolet, visible and near infrared region. After light treatment, Cr(III) content in Cr(VI) loaded CPP-F increase from 29.76wt% under dark conditions to 72.33wt%, and its reduction rate is 2.43 times that of dark conditions, indicating that polypyrrole (PPy) has excellent photocatalytic performance, and light treatment can promote the in-situ reduction of Cr(VI). After 6 cycles of adsorption, the cyclic adsorption capacity of Cr(VI) by CPP-F under light treatment is 64.97% higher than that under dark treatment, indicating that photocatalytic reduction of Cr(III) provides a new adsorption site for Cr(VI) and realizes the cyclic adsorption of Cr(VI). The combination of adsorption-photocatalytic reduction-cyclic adsorption has more advantages than adsorption method, and has great application potential in Cr(VI) pollution control.
Preparation of CQDs-rGO/ZnO composites and photocatalytic degradation of metronidazole
YE Hongyong, YANG Yanju, WANG Minghui, ZUO Guangling, DU Jia
2024, 41(6): 3042-3052. doi: 10.13801/j.cnki.fhclxb.20240306.003
The low visible light activity, low photogenerated carrier mobility and easy recombination of ZnO limit its practical application in the field of photocatalysis. To overcome these limitations, a carbon quantum dots (CQDs)-reduced graphene oxide (rGO)/ZnO ternary composite catalyst was prepared by an ultrasonic-assisted impregnation method and characterized for its crystal structure, morphology, and photoelectric properties using XRD, SEM, TEM, X-ray energy dispersive spectrometry (XEDS), XPS, BET, UV-Vis DRS, valence band (VB)-XPS, photoluminescence (PL), transient photocurrent response (TPR), and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of CQDs-rGO/ZnO composite catalyst was investigated with simulated antibiotic wastewater metronidazole (MTZ) as degradation object. The results show that the introduction of rGO and CQDs can optimize the band structure of ZnO and enhance its absorption of visible light. The strong electrical conductivity of rGO and CQDs can promote the rapid transfer and separation of photogenerated carriers, and effectively improve the photocatalytic activity of CQDs-rGO/ZnO composite catalysts. The quenching experiments show that hydroxyl radical (•OH) and superoxide radical (\begin{document}${\text{•}}{\rm{O}}_2^ - $\end{document}) are the main active substances in the reaction process. When the recombination amount of CQDs is 1%, the photocatalytic activity of CQDs-rGO/ZnO is the best, and the degradation rate of MTZ can reach 87.8% under visible light irradiation for 2.5 h. After four cycles, 75.2% of MTZ can still be degraded, indicating that the physicochemical properties of the CQDs-rGO/ZnO composite catalyst are stable.
Preparation and anisotropic conduction behavior of polyethylene/carbonfiber composites
SHI Suyu, LYU Jiansheng, ZHANG Chenhui, REN Zhilin, XU Qiankun, ZHENG Guoqiang
2024, 41(6): 3053-3059. doi: 10.13801/j.cnki.fhclxb.20231031.004
The anisotropic conductive polymer composites (ACPCs) have great application potential in integrated circuits, sensors, thermal management and other fields because of their unique anisotropic conductive and thermal properties. In this experiment, the carbon fiber (CF) and high-density polyethylene (HDPE) films were used as raw materials. The CF was pretreated at high temperature firstly and then used to make a carbon fiber network by ultrasonic dispersion and vacuum filtration technology. Subsequently, the HDPE/CF composites with anisotropic conductivity were fabricated by hot-pressing molding technique. DSC, SEM, TG and conductivity tests were performed to analyze the microstructure, thermal and conductive properties of composites. Then the anisotropic conduction behavior of HDPE/CF was monitored by the integrated circuits and IR thermal camera. HDPE layer and CF web layer are arranged alternately and closely combined. The alternating multilayer structure endows HDPE/CF composites with special intra layer conductivity and interlayer insulation, showing typical anisotropic conductivity. HDPE/CF composites exhibit excellent electrical conductivity in the X and Y directions (with conductivity up to 85.71 S/m), which is 5-7 orders of magnitude higher than the Z direction. The introduction of alternating multilayer structure and CF web significantly improves the thermal stability of HDPE/CF composite, and its initial thermal decomposition temperature is increased by about 35℃ compared with that of HDPE film. It exhibits excellent current-carrying capability and remarkable conductive anisotropy, exhibiting great application potential in circuit connection, directional conduction, thermal management and other fields.
Designed growth of hollow WO3/PEDOT bilayer hybrid nanosphere arrays film with superior electrochromic and capacitive performance
SHI Yingdi, MA Kai, FAN Mengxiang, WANG Lirong, TANG Kai, KE Xiang, LIU Taikang, LIAO Zhaoying, DONG Yingchun
2024, 41(6): 3060-3069. doi: 10.13801/j.cnki.fhclxb.20231026.002
In this work, hollow WO3/poly(3, 4-ethylenedioxythiophene) (PEDOT) bilayer hybrid nanosphere arrays film was constructed by template-assisted magnetron sputtering combined with electrochemical deposition. The hollow nanosphere arrays could provide large contact area with electrolyte to benefit ion exchange. The prepared WO3 layer was responsible for offering a lot of ions binding sites due to the large capacity of amorphous WO3 for small ions, and the PEDOT layer was prepared to construct a unique conductive network which could effectively facilitate electron transportation and connect separated color centers. The obtained hollow hybrid nanosphere film exhibits outstanding electrochromic performance with high contrast (77.4% at 633 nm), fast response speed (3.2 s for coloring and 4.2 s for bleaching), good cycling stability (lose 14.5% optical modulation after 2000 cycles) and decent coloring efficiency (116.2 cm2·C−1) at low colored/bleached potentials (−1.0/1.0 V). The hollow hybrid nanospheres also display high areal capacitance (54.6 mF/cm2), superior rate capability and cyclic stability (areal capacitance remains 79.6% after 2000 cycles).
Surface amination modification of g-C3N4 and enhancement mechanism study
LI Xiaoli
2024, 41(6): 3070-3078. doi: 10.13801/j.cnki.fhclxb.20231026.003
The research of hydrogen production from water decomposition and pollutant degradation using g-C3N4 as photocatalyst has been widely concerned, but how to prepare efficient, stable and good photothermal stability catalyst by a simple and easy method is the research hotspot and difficulty. A simple hydrothermal method was used to introduce more amino groups on the surface of g-C3N4. The influence of surface amination on the surface morphology of g-C3N4 was studied by SEM and TEM, and find that amination has a great influence on the morphology of edge position. XRD, FTIR, UV-vis, XPS analysis show that the surface amination reaction dose not damage the main structure of g-C3N4. Studies on photocatalytic water hydrogen production and rhodamine B (RhB) degradation performance show that the highest hydrogen production rate of g-C3N4 when treated with 15wt% ammonia (180.24 μmol·g−1·h−1), which is 1.46 times higher than that of g-C3N4 (123.04 μmol·g−1·h−1). At the same time, the photocatalytic degradation performance of RhB also reaches the optimum. The degradation rate of RhB is 98.12% in 90 min duration irradiation, which is 1.55 times higher than that of g-C3N4 (63.28%). Neither too high nor too low ammonia concentration can make the photocatalytic performance reach the optimum. The photoelectric performance test results show that the mechanism of the enhancement of photocatalytic performance after surface amination can be attributed to the fact that the amino group is an electron donor group. After excitation, the increase of amino content is conducive to the occurrence of photocatalytic reaction, and excessive amination leads to the destruction of the delocalized triazine ring structure, and the photocatalytic performance is greatly reduced.
Civil Construction Composite
Microstructure and self-repairing performance of granular loaded graphene oxide composite cement-based materials
HU Dexin, SHAN Yuxi, WANG Hailiang, LI Dongxu, ZHANG Yi
2024, 41(6): 3079-3091. doi: 10.13801/j.cnki.fhclxb.20231025.002
To improve the dispersion performance of graphene oxide (GO) in the cement materials, nano SiO2 and CaCO3 powder were used as support of the GO and the SiO2-GO (SG) and SiO2-CaCO3-GO (SCG) were prepared. The effects of the SG and SCG on the mechanical strength, self-repairing performance, hydration products and microstructure of the cement materials were studied. The results show that the mechanical strength of the cement material is improved as the addition of SG and SCG, the flexural strength and compressive strength of the cement-based materials with SCG at 28 days are improved by 7.3% and 18.7%, respectively. The self-repairing performance of SCG composite cement is also improved which shows a higher compressive strength repairing rate of about 110.6% and a higher water permeability repairing rate of 100%. The crack area testing shows that SCG has a more significant repair effect on cracks in the cement materials. XRD analysis shows that the early stage cement hydration is accelerated as the addition of SG and SCG, especially for the SCG, the hydration degree at 3 days is obviously improved. TG analysis shows that with the extension of hydration age, a higher reaction degree of Ca(OH)2 and SiO2 is achieved in the SCG composite cement, compared with the early 3 days hydration stage, the Ca(OH)2 content of SCG composite cement at 28 days reduces to 14.90%. Microstructure analysis shows that the SCG has better compatibility with the cement, more hydrate calcium silicate (C-S-H) gels in the late hydration stage is generated and the microcracks of cement could be filled, which makes the excellent self-repairing performance of the SCG composite cement.
Experimental investigation on discreteness of quasi-static and dynamic compressive strength of recycled aggregate concrete
WANG Xiaojuan, LI Runlin, ZHOU Hongyuan, MU Chongyuan, QIAO Qiyun
2024, 41(6): 3092-3102. doi: 10.13801/j.cnki.fhclxb.20231113.001
To explore the influence of the substitute rate of recycled coarse aggregate (RCA) and strain rate on the discreteness of the compressive strength of recycled aggregate concrete (RAC), RAC specimens with three different RCA substitute rates were prepared for both quasi-static compression and split Hopkinson pressure bar (SHPB) tests. The test results show that despite the limited change in the discreteness of compressive strength of RAC with increasing RCA substitution rate, it still tends to initially increase and then decrease as the RCA substitution rate increases. The results of the SHPB test indicate that both the RCA substitute rate and the strain rate exert a significant influence on the variability of the dynamic compressive strength of RAC. The dynamic compressive strength discreteness of RAC with the same RCA substitute rate gradually decreases with increasing strain rate, while it increases with increasing RCA substitute rate under the same strain rate. In addition, the traditional Weibull distribution model was modified by introducing the parameters of RCA substitute rate and strain rate, and a dynamic compressive strength prediction formula for RAC with different RCA substitute rates at any given probability level was proposed.
Effect of sulfate corrosion on the fracture properties of PVA fiber reinforced cement-based composite materials with steel slag powder
SU Jun, FAN Zikang, CAI Xinhua
2024, 41(6): 3103-3114. doi: 10.13801/j.cnki.fhclxb.20231117.001
In order to study the fracture characteristics of cement-based composite materials under the solid waste steel slag and erosion of sulfate solution, the polyvinyl alcohol fiber reinforced cement-based composite materials (PVA/ECC) were prepared by adding different mass fractions of steel slag powder. Three-point bending performance test was conducted on prefabricated initial crack beam specimens after sulfate erosion. Combined with the apparent morphology and microstructure characteristics of steel slag powder PVA/ECC in Na2SO4 solution (mass fraction of 5wt%), the effect of sulfate corrosion on the fracture performance of steel slag powder PVA/ECC was investigated. The results show that when the content of steel slag powder without sulfate attack is 20wt%, the cracking load and instability load of the specimen are the best, with an increase of about 61% and 110% compared to the specimens without steel slag powder, respectively. The fracture toughness of PVA/ECC first increases and then decreases with erosion time, reaching its peak after 60 days of erosion. After 120 days, the S80 group shows the most obvious degradation, with the initiation toughness \begin{document}$ K\mathrm{^{ini}} $\end{document} and instability toughness \begin{document}$ {K}^{\mathrm{u}\mathrm{n}} $\end{document} decreasing by about 23% and 13%, respectively. The addition of an appropriate amount of steel slag powder can effectively alleviate the erosion damage of PVA fiber reinforced cement-based composite materials. When the amount of steel slag powder does not exceed 60wt%, there is no significant deterioration of the material within the age range of the experimental study. On this basis, the durability life of the specimens was predicted using a Weibull distribution model, PVA/ECC with a 20wt% steel slag powder content having the longest service life, reaching around 444 cycles.
Compressive performance of bamboo scrimber and concrete-filled steel tube columns
WEI Baoxing, WEI Yang, WANG Gaofei, XING Ze, LIN Yu
2024, 41(6): 3115-3128. doi: 10.13801/j.cnki.fhclxb.20231024.002
The light and high strength bamboo scrimber was buried in the core of concrete-filled steel tube column (CFST) to form bamboo scrimber and concrete-filled steel tube column (BCFST), which was expected to give full play to the compressive strength of the bamboo scrimber and delay its crushing and splitting. In order to study the axial compression performance of BCFSTs, on the basis of three groups of axial compression tests, the corresponding model was established by using ABAQUS finite element software and the nonlinear finite element analysis wascarried out. The reliability and applicability of the finite element model were verified by comparing the failure forms and load-displacement curves of the specimens. Based on the verified finite element model, the two key design variables of bamboo scrimber dimension and diameter to thickness ratio of steel tube were parameterized. The analysis results show that: For CFSTs with the same wall thickness, increasing the dimension of bamboo scrimber can inhibit the decline of load-displacement curve after peak point. Compared with CFSTs, the peak load of BCFSTs is increased by more than 8%, and the maximum increase is 16%. The ultimate load of the specimens show a clear growth trend, and the ultimate bearing capacity of the specimens with built-in bamboo scrimber could reach 33.2% compared with that of the CFSTs. With the increase of wall thickness of steel tube, the circumferential constraint of bamboo scrimber and concrete is strengthened, and the core section strength is improved. When the wall thickness of steel tube changes from 4.5 mm to 6.0 mm, the ultimate load of the specimen is increased by 18.2%.
Axial compression performance of precast UHPC-RAC composite short column
QIN Chaogang, DU Jinlin
2024, 41(6): 3129-3142. doi: 10.13801/j.cnki.fhclxb.20231020.002
The combination design of ultra-high performance concrete (UHPC) and recycled aggregate concrete (RAC) forms the precast UHPC-RAC composite columns. Seven precast UHPC-RAC composite short columns were designed and fabricated with the parameters of stirrup position, UHPC thickness and UHPC-RAC interface roughness. The failure form, material strain, load-displacement curve, bearing capacity, Poisson's ratio and damage were analyzed through the axial compression experiments. The results show that the precast UHPC-RAC composite short columns improve the failure pattern, which can be divided into strong confining shear collapse failure and weak confining of UHPC splitting due to the difference in the binding effect of the combination of external UHPC and stirrup on internal RAC. The increase thickness of hooped UHPC ensures the enhancement of external UHPC restraint. The restraint effect of the outer UHPC is enhanced with the increase of the hoop UHPC and its thickness. The axial compressive stiffness and compression capacity of the prefabricated UHPC-RAC short column are increased by 93.3% and 97.4% at the maximum, and the Poisson's ratio and damage index are decreased, with the Poisson's ratio varying from 0.26 to 0.18. The roughness of UHPC-RAC bonding surface has little difference on the favorable influence of axial compression performance parameters. The strong constraint effect can make full use of the mechanics of high performance materials. Based on the superposition principle, the calculation formula of the compression capacity of the strongly constrained precast UHPC-RAC composite column is established, and the design requirements of the precast UHPC-RAC composite short column are proposed to improve the utilization rate of the material.
Constitutive model of recycled brick aggregate geopolymer concrete under compression before and after elevated temperature
WANG Huailiang, OU Rui
2024, 41(6): 3143-3153. doi: 10.13801/j.cnki.fhclxb.20231012.001
Recycled brick aggregate geopolymer concrete (RBGC) is a sustainable building material with great potential, but there are few studies on the performance of RBGC before and after high temperatures. Firstly, the influence of the amount of cementitious material and the type of coarse aggregate on the axial compression constitutive model of geopolymer concrete was explored. It is found that with the increase of cementitious material, the compressive strength, split tensile strength, elastic modulus and peak compressive strength of RBGC decrease. The change amplitude of strain is smaller than that of ordinary aggregate geopolymer concrete (NAGC). The linear section of the rising section of the stress-strain curve of RBGC is longer, and the stress decreases faster in the falling section. Secondly, the mechanical properties of RBGC and NAGC after high temperature were studied. At 800℃, the strength and stiffness loss of RBGC are 22.1% and 18.3% smaller than that of NAGC respectively. And it is found that RBGC shows better high temperature resistance, and different models should be used to calculate the mechanical performance indicators of the two concretes. This is because the temperature expansion coefficient of brick aggregate is close to that of geopolymer mortar, and the internal temperature gradient of RBGC is small at high temperatures. Finally, by correcting the shape parameters of the descending section, the stress-strain relationship model of RBGC and NAGC before and after high temperature is determined, and the model is in good agreement with the test results.
Effect of interfacial agents on the mechanical properties of the interface between full lightweight ceramsite concrete and ordinary concrete
ZHU Hongbing, FU Zhenghao, WANG Ye, CHEN Jingyi
2024, 41(6): 3154-3167. doi: 10.13801/j.cnki.fhclxb.20231101.002
Five types of full lightweight ceramsite concrete and ordinary concrete composite specimens with different interfacial agents were produced. Moreover, mechanical tests (splitting tensile, shear and bending tests) and SEM tests were performed to investigate the effect of interfacial agents on the mechanical properties of the interface between full lightweight ceramsite concrete and ordinary concrete. The mechanical test results show that firstly, the applying interfacial agent can effectively improve the structure of the interfacial zone and substantially enhance the mechanical properties of the interface. For interfacial splitting tensile strength and flexural strength, epoxy resin is the optimal interfacial agent and the strength values will be increased by 56.5% and 38.3%, respectively. The polymer mortar has the most significant effect on the improvement of interfacial shear strength, which can be improved by 71.2%. The mechanical properties of the interface coated with cement paste can also meet the requirements of industry standards. As an interfacial agent, cement paste containing silica fume is superior to cement mortar. Secondly, the influence degree of interface agent on mechanical indexes from strong to weak is splitting tensile strength, flexural strength and shear strength. Thirdly, based on the mechanical indexes of full lightweight ceramsite concrete, a formula for calculating the mechanical strength of the interface between old and new concrete considering the influence of interfacial agents was established. Finally, SEM testing provides a good explanation of the conclusions of mechanical performance testing at the micro level. The use of interfacial agent can reduce the microcrack width between new and old concrete. Among them, the effect of epoxy resin interfacial agent and polymer mortar is more obvious. Besides, it can effectively reduce the porosity of the interfacial transition zone, with a decrease of 46.44%-60.81%. The research conclusions have reference value for the interface treatment of concrete structure reinforcement.
Biological and Nano-composite
Effect of various nucleating agents on mechanical properties and crystallizationbehavior of poly(lactic acid)
LYU Chao, LUO Shupin, GUO Wenjing
2024, 41(6): 3168-3181. doi: 10.13801/j.cnki.fhclxb.20231008.002
The aim of this study was to investigate the effect of poplar wood fiber as a bio-nucleating agent on the mechanical properties and crystallization behaviors of poly(lactic acid) (PLA), and compare with common nucleating agents talc powder and hydrazide compounds. Poplar wood fiber (WF) (0.5wt%, 1wt%, 2wt%, 4wt%), talc powder (Talc) (1wt%, 2wt%, 4wt%, 8wt%) and hydrazide compounds (TMC-300) (0.3wt%, 0.5wt%, 1wt%, 2wt%) were blended with PLA to prepare composite at various contents by extrusion and molding process, respectively. The optimal content of each nucleating agent was determined based on mechanical properties of composites. The effect of WF, Talc and TMC-300 under optimal content on the crystallization properties including crystallization behaviors, crystal morphology and structure of PLA-based composites was compared. All the three types of nucleating agents can improve the notched impact strength of PLA. Compared with Talc and TMC-300, the addition of WF results in more significant improvement in tensile and flexural properties of PLA-based composite. Under the optimal addition content (1wt%) of WF, the elongation at break, tensile and flexural strength increase by 27%, 17% and 18% in comparison with neat PLA, respectively. The effect of WF, Talc and TMC-300 on the crystallization behaviors of PLA was studied through differential scanning calorimetry. Results show that adding 1wt% WF can improve the crystallinity of PLA in the non-isothermal crystallization, but it is much lower than that of composite with 1wt% Talc and 0.5wt% TMC-300. According to the isothermal crystallization kinetic analysis, WF can also reduce the half-crystallization time of PLA matrix, and improve the crystallization rate. The half-crystallization time under isothermal crystallization at 110℃ is reduced from 23.6 min (neat PLA) to 7.2, 2.7 and 1.4 min when adding 1wt% WF, 1wt% Talc and 0.5wt% TMC-300, respectively. Hot-stage polarized light microscope observation shows that the crystal morphology of PLA induced by various nucleating agents is different during 110℃ isothermal crystallization. WF and Talc provide a large number of nucleation sites for PLA crystallization, which promotes the grain refinement of PLA. TMC-300 induces PLA to form fibrous bundle-like crystals accompanied with higher crystallization rate, which is consistent with isothermal crystallization kinetic analysis results. The SEM observation of impact facture morphology after etching treatment indicates that the accumulation of crystals with different morphologies is one reason for the difference of mechanical properties. Wide angle X-diffraction analysis shows that all the three types of nucleating agents can promote the generation of orderly α-crystal. The diffraction peak intensity of α(110)/(200) crystals is highest when adding WF. Besides, WF can significantly decrease the crystal size of PLA. This study demonstrates that poplar wood fiber can be used as a bio-nucleating agent for PLA, which plays dual effect of reinforcement and nucleation. This study provides a basis for optimizing the nucleation ability of WF for PLA, and also provides references for further promoting the green development of wood-plastic composite.
Design and performance of hollow mesoporous SiO2-based nanodrug carrier materials with controllable particle size
YIN Chengwu, CHEN Yuxin, WANG Yujie, ZHU Dehui, YIN Fulin, CHENG Lin, ZHAO Yu, ZHOU Guoyong
2024, 41(6): 3182-3192. doi: 10.13801/j.cnki.fhclxb.20230926.003
In this paper, hollow mesoporous SiO2 nanocarriers (HMSNs-69-FITC) with fluorescence labeling were prepared by self-template method using polyacrylic acid (PAA), tetraethyl orthosilicate (TEOS) and silane coupling agent Si-69 as the main raw materials and fluorescein isothiocyanate (FITC) as the fluorescent agent. The structure and particle size of nanocarriers were determined by FTIR, DLS, BET, Raman and TEM, their reduction-sensitive properties were characterized by ultraviolet spectrophotometer and TEM, and sorafenib (SOR) was loaded with solvent volatilization, and calculate its load efficiency. The results show that the amount of regulating PAA can achieve controllable particle size of HMSNs in the range of 28-380 nm, among which, HMSNs with 0.024 g/mL PAA and an average particle size of 100 nm have excellent stability performance, HMSNs-69-FITC has a loading efficiency of 280.0 μg/mg for SOR, and in phosphate buffered saline (PBS) solution containing 0.0083 g/mL dithiothreitol (DTT), the cumulative release rate of 48 h is about 82.4%. In the absence of DTT, the cumulative release rate at 48 h is about 25.1%, which has significant disulfide bond reduction sensitivity. This work helps advance research in the field of particle size controllable and reduction-sensitive SiO2 nanocarriers.
Preparation and properties of lignocellulose network ionic thermoelectric gels
GUAN Jilun, LI Wenjing, FANG Huayang, CHENG Fangchao
2024, 41(6): 3193-3201. doi: 10.13801/j.cnki.fhclxb.20231201.001
Thermoelectric materials enable the direct conversion of thermal energy into electrical energy and are increasingly used in domestic and industrial waste heat reuse. However, traditional inorganic thermoelectric materials suffer from low thermal power (or Seebeck coefficient) and high thermal conductivity, and do not offer advantages in low-grade waste heat (<130℃) collection. Using the ionic thermal diffusion effect (Soret effect), cellulose network ionic thermoelectric gels were prepared by a simple syringe injection method using cellulose as the network and poly(vinyl alcohol) (PVA) as the electrolyte matrix, and the differences in the thermoelectric properties of different contents of NaOH and LiOH as the ion donor were investigated. FTIR was used to characterize the internal groups of the material, while a homemade thermoelectric test setup proved its higher thermopower. The results showed that the incorporation of cellulose results in an ionic conductivity of 3.31 mS·cm−1, which is enhanced by 98.2% compared to the pure PVA ionogel. At the same time, the addition of cellulose reduces the thermal conductivity to keep the upper and lower temperature difference constant for a longer period of time under the temperature difference between human body temperature and 26℃ room temperature. The ionic Seebeck coefficient reaches +12 mV·K−1 at 2℃ temperature difference. This research proposes a cost-effective and environmentally friendly solution for the reuse of low-grade waste heat, which is of greater significance for the sustainable development of human society.
Ecofriendly and antibacterial poly(lactic acid) nanofibrous membranes forhigh-efficiency and low-resistance filtration of airborne particulate matters
LI Feng, JIANG Liang, LI Xiaopeng, TANG Mengke, HUANG Rongting, ZHU Jintuo, HE Xinjian, LI Heguo, XU Huan
2024, 41(6): 3202-3214. doi: 10.13801/j.cnki.fhclxb.20231031.002
Fine particulate matters (PMs) generated during industrial production pose a serious threat to human health and are one of the main hazards causing occupational diseases at work. The contemporary traditional masks have poor filtration effect, high breathing resistance, low dust holding capacity, not easy to degrade as well as insignificant antibacterial effect, for this reason, a high-efficiency and low-resistance poly(lactic acid) (PLA) antibacterial biodegradable nanofibrous filtration membrane has been developed. Structurally ordered nanohybrid structure CNT@ZIF-8 with large specific surface area were successfully synthesized by inducing the growth of zeolitic imidazolium ester framework-8 (ZIF-8) on carbon nanotubes (CNT) by microwave-assisted synthesis method. Based on the electrospinning-electrospray technology, CNT@ZIF-8 was successfully embedded onto PLA fiber, and PLA composite fibrous membranes (CNT@ZIF/PLA) with different fiber diameters were prepared by regulating the mass fraction of CNT@ZIF-8. The filtration performance and air resistance of CNT@ZIF/PLA nanofibrous membranes at different flow rates were investigated, and the effects of different mass ratio of CNT@ZIF-8 on the mechanical properties and antibacterial properties were investigated. The results show that the tensile strength of CNT@ZIF/PLA nanofibrous membrane increases up to 47% (18.5 MPa) and the fracture toughness increases 100% (2.9 MJ/m3) compared with that of pure PLA membrane. As the mass fraction of CNT@ZIF-8 increases, the air resistance gradually decreases, and at the test flow rate of 32 L/min, the air resistance of 12%CNT@ZIF/PLA nanofibrous membrane is only 82.6 Pa, which is 45.1% less than that of Pure PLA fiber membrane, and after the 180 min long filtration test, there is no significant change observed in the filtration efficiency of PMs. At the test flow rate of 85 L/min, the filtration efficiency of CNT@ZIF/PLA nanofibrous membrane for PM0.3 is more than 89%, and after 5 min of irradiation by the sunlight simulator, the antibacterial efficiency against both E. coli and S. aureus reach 100%.
Metal and Ceramic Matrix Composite
Durability of CFRP-steel interface modified by liquid rubber under chlorine salt erosion
PANG Yuyang, LYU Yuanchen, WANG Qiang
2024, 41(6): 3219-3231. doi: 10.13801/j.cnki.fhclxb.20231110.001
Fifty-four carbon fiber reinforced resin composite (CFRP)-steel double lap specimens were designed to study the effects of liquid rubber modifier content and corrosion age on the mechanical properties of CFRP-steel modified interface under the erosion of two kinds of chlorine salts: High temperature water bath and dry-wet cycles at normal temperature. The results show that under the action of high temperature water bath and dry-wet cycles at normal temperature, the unmodified specimens show CFRP interlayer stripping failure and steel/binder interface stripping failure, respectively, while the liquid rubber modified specimens could transform the failure mode into adhesive cohesion failure, among which 10wt% liquid rubber has the best effect on improving interface durability. After 180 days of high temperature water bath and dry-wet cycles chloride salt erosion at normal temperature, the ultimate load retention rates of the specimens increase by 28.11% and 29.94%, respectively, compared with that of the unmodified specimens. Based on the experimental results, modified interface bond-slip models are established which are suitable for two kinds of chlorine salt erosion environments, and the predicted results are in good agreement with the experimental results.
Damage accumulation simulation and residual performance evaluation of ceramic ballistic plate under the multi-hit strikes
HE Chenglong, HUO Ziyi, LIU Yaqing, YANG Kexu, MAO Xiang
2024, 41(6): 3228-3238. doi: 10.13801/j.cnki.fhclxb.20231121.002
The ceramic/fibre composite ballistic panels are widely used in personal protection equipment, and the performance of the ballistic plate under multiple impact loadings are important to keep soldiers safe. The numerical simulation was used to analyze the failure distribution and residual ballistic performance of ballistic panels subjected to multiple impacting, and specifically focusing on the operating condition of 53-type 7.62 mm armor-piercing bullet impacting SiC/ultra-high molecular weight polyethylene (UHMWPE) ballistic panels. The damage of the ballistic plate was characterized by the ceramic failure, fiber deformation and bond surface stripping, and the residual properties of the bulletproof plate with different damage were established. The results show that the damage radius (R) of ballistic panels is 30 mm under the first impact, and the damage (D) is greater than 0.6 when R<15 mm, and the target can't resist the second bullet impacting. Under two impacts, the damage in the middle zone becomes seriously when the distance between two bullets (ΔL) is less than 50 mm, and the cumulative effect of damage is not significant when ΔL>50 mm. Ballistic panels are discretized with 5 mm×5 mm grid, and the proportions of different damage areas are obtained. The penetration probability of the integral ballistic plate is 0.94% under the two impacts' loadings. The penetration probability of the integral ballistic plate under the third impacting is decided by the striking distance of the first two impacts, and the penetration probability by the third impacting is 1.94% when ΔL=20 mm.
Microstructure and properties investigation of B4C/Al composite materialsfabricated by selective laser melting
DENG Yunqi, HU Qiyao
2024, 41(6): 3239-3247. doi: 10.13801/j.cnki.fhclxb.20231007.001
In order to solve the problems of uneven distribution of B4C particles, agglomeration and violent reaction with Al matrix during the preparation of B4C/Al composites. In this paper, B4C/Al composites were prepared by selective laser melting method. The effects of laser power and Ti elements on microstructure and mechanical properties of B4C/Al composites were studied. The results show that the density of B4C/Al composites increases first and then decreases with the increase of laser power, and reaches the maximum density of 94.1% at 240 W. During the preparation process, B4C particles are prone to interfacial reaction with Al matrix and increase with the increase of laser power, resulting in brittle phases and micro-cracks of Al3BC and Al3B48C2, resulting in decreased interfacial bonding properties. The density of B4C/Al composite with Ti increases to 95.2%, the resulting interface products TiC and TiB2 can effectively inhibit the interface reaction, and the interface is clear and complete with high bonding properties. The tensile strength and elongation of the composite are increased by 41% and 49.3%, respectively, and the tensile fracture mode changes from brittle fracture to ductile fracture.
Co材料细观力学 mposite Micro-mechanics
Effect of temperature on mechanical properties of metal-compositehybrid multi-bolt joint
WANG Dong, DONG Chuanrui, ZHU Hongmin, DING Guoyuan, HUANG Heyuan, ZHAO Meiying
2024, 41(6): 3248-3257. doi: 10.13801/j.cnki.fhclxb.20231017.003
Taking the aluminum alloy-carbon fiber/bismaleimide (BMI) resin composite multi-bolt double-lap structure as the research object, combined with digital image correlation (DIC) technology, quasi-static tensile tests under different temperature environments (−100℃, 25℃, 150℃) were carried out. The elastic-plastic model of metal and the progressive damage model of composite were used for numerical simulation. A UMAT subroutine considering the influence of temperature was developed to predict the damage of composite materials. The influence of temperature on load-bearing capacity, failure mode, damage evolution and bolt-load distribution of metal-composite hybrid multi-bolt joint structure was studied. The results show that the maximum load of the structure in the environment of 150℃ and −100℃ is reduced by 4.46% and 2.06% compared with the room temperature environment of 25℃, respectively. The failure modes of three temperature environments are all tensile fracture of the hole edge of the composite. The delamination and extrusion phenomenon of the hole edge are more serious at the high temperature, but the fiber and the matrix are tightly bonded and the extrusion and delamination of the hole edge are weaker in the cryogenic temperature environment. The unevenness of the multi-bolt hole edge damage is weakened at 150℃ and enhanced at −100℃, compared with at the room temperature. Due to the difference in thermal expansion between metal and composite, the bolt load distribution of the three bolts at high and cryogenic temperatures is different.
Composite Micro-mechanics
Numerical simulation of progressive damage of single-lap CFRP/Al connected by blind rivet under interference condition
WANG Bingbing, ZHOU Zhaoyuan, JIN Wanjun, HE Chao, TANG Zhengqiang
2024, 41(6): 3258-3270. doi: 10.13801/j.cnki.fhclxb.20231025.001
Interference fit has advantages in improving the mechanical performance of blind rivet in connections for composite materials. However, the installation of blind rivets under interference fit leads to the damage of carbon fiber reinforced plastic (CFRP) laminates, weakening the mechanical performance of the joints. In this paper, based on continuous damage mechanics, extended three-dimensional failure criteria and strain rate effect, a complete blind rivet model, which combining finite element method and secondary development of Abaqus was developed to study the effect of interference and installation speed on the damage of composite materials. From the simulation results, the installation resistance force exhibits two typical stages, which are generated by the friction between the aluminum alloy and the CFRP laminate with the blind rivet, respectively. Under interference fit conditions, a higher installation speed is highly advantageous in reducing installation resistance. However, excessive installation speed can lead to increased damage to the hole walls, which is especially noticeable in cases of high interference fit. The failure mode of the joint is mainly caused by CFRP damage and is significantly influenced by the interference size.
Response and damage characteristics of composite laminates under high-energywide-area blunt impact
ZOU Jun, LIU Jiaxin, WANG Jizhen, GUO Yazhou, LI Lingling, FENG Zhenyu
2024, 41(6): 3271-3278. doi: 10.13801/j.cnki.fhclxb.20231016.001
High-energy wide-area blunt impact (HEWABI) can lead to severe internal damage to the composite aircraft, which is barely visible from the outside of fuselage and cause a significant threat to flight safety. High energy quasi-static loading tests were carried out on the laminates with different shapes of rigid impactors and rubber impactors, then the finite element simulation models based on continuum damage mechanics (CDM) were developed. The results show that the established simulation analysis models can effectively predict the response and damage of the laminated panels under rigid or rubber impactors. When the load reaches 40 kN, severe delamination damages will occur in the laminated panel for the rigid impactors. On the other hand, no damage can be observed at 90 kN for the rubber impactors, which can be attributed to the significant deformation of rubber impactors and the reduced local contact loads. The shape of rigid impactors has great effect on the damage to laminated panels, while the shape of the rubber impactors has almost no impact on the damages.
Buckling of metallic cylindrical shells stiffened with helical carbon fiber reinforced polymer stripes
ZUO Xinlong, TANG Wenxian
2024, 41(6): 3279-3289. doi: 10.13801/j.cnki.fhclxb.20230920.002
Buckling of metallic cylindrical shells stiffened with helical composite stripes was investigated in the current study. A mathematical relationship between area ratio and thickness ratio of composite layer for externally pressurized metallic cylinder stiffened with helical composite stripes was proposed. An analytical formula for collapse load of such hybrid structure was derived. Numerical analysis and experimental verification were conducted. Furthermore, depth chart for full-scale hybrid cylinder was designed using analytical formulae. The results indicate that the maximum and minimum difference between numerical and theoretical results obtained using interpolation method are 5.2% and 0.9%, respectively. The theoretical, numerical and experimental data for samples agree favorably. The difference between theoretical and numerical results is 3.20%. The difference between theoretical and experimental results is 3.46%. Metallic cylindrical shells stiffened with multiple helical composite stripes is satisfy for a wide range of depths. Composite stripe stiffeners have vast potential for application in installed and reusable tubes.
Low-frequency broadband sound absorption performance of butterfly-like arc resonant cavity acoustic metamaterials
KONG Weifan, FU Tao
2024, 41(6): 3290-3299. doi: 10.13801/j.cnki.fhclxb.20240325.001
A novel acoustic metamaterial structure, inspired by the shape of butterfly arc, is proposed to address the issue of low-frequency absorption performance in Helmholtz resonators. In this paper, a butterfly-like arc resonance cavity acoustic metamaterial structure is proposed, and a stepped round hole is introduced into the neck tube of the Helmholtz resonator, and the traditional negative Poisson's ratio concave sandwich structure is changed, so that the structure can effectively provide the acoustic impedance required for low-frequency sound absorption for the sound absorber without changing the overall size, so as to reduce the resonance frequency. The structure was numerically simulated using COMSOL 6.1 finite element software and validated through a standing wave tube absorption test experiment, showing a high level of consistency between the experimental and simulated results. The results demonstrate that butterfly-like arc resonance cavity acoustic metamaterial structure can effectively reduce the absorption peak frequency of Helmholtz resonators, achieving excellent sound absorption performance in the frequency range of 650-1050 Hz, with an average sound absorption coefficient greater than 0.9. The structure achieves near-perfect absorption of sound waves. At the resonance absorption peak of 740 Hz, the structure thickness is only 1/15 of the corresponding wavelength, highlighting its deep subwavelength characteristics. Even at a height of 30 mm, the structure still exhibits a wide absorption bandwidth with a bandwidth ratio of 62% (Sound absorption coefficient > 0.5). The sound absorption performance is also influenced by different parameters of the butterfly arc-shaped negative Poisson's ratio unit cell. When the circular arc radius (r) of the arc-shaped cell is 11.8 mm, the number of steps (n) in the step-like circular hole is 4, and the diameter (da) and length (la) of the step-like circular hole correspond to the specimen size, the Helmholtz resonator exhibits excellent sound absorption performance over a wide low-frequency band.
2024, 41(6): 3300-3300.