2023 Vol. 40, No. 3

Research progress on preparation and properties of carbon fiber reinforced thermoplastic composites
CAO Jianfan, BAI Shulin, QIN Wenzhen, YAN Yi
2023, 40(3): 1229-1247. doi: 10.13801/j.cnki.fhclxb.20220815.001
Owing to their numerous merits, carbon fiber reinforced thermoplastic composites (CRTP) have drawn extensive attention in many fields such as aerospace, rail transportation, military industry, wind power and et al. In this paper, the research progress in recent years on the preparation technology of CRTP in the world is summarized, and is mainly described from three aspects: The preparation technology of prepreg, surface modification technology of carbon fiber (CF) and processing technology of CRTP. Furthermore, the merit and demerit of different preparation technologies of prepreg, surface modification technologies of CF and processing technologies of CRTP, as well as the influence on the properties of the prepared CRTP, are introduced in detail. In the end, the development direction of preparation technology of prepreg, surface modification technology of CF and processing technology of CRTP is prospected.
Research progress of graphene reinforced copper matrix composites
CHEN Chunjiao, BAO Hongwei, LI Yan, BAI Huizhong, YANG Shuohan, MA Fei
2023, 40(3): 1248-1262. doi: 10.13801/j.cnki.fhclxb.20221008.001
Copper (Cu) matrix composites have excellent mechanical, thermal, electrical, wear and corrosion resistance properties, and are widely used in industrial fields. Graphene (Gr) is an ideal reinforcement phase for metal matrix composites due to its two-dimensional features and excellent physical properties. Gr reinforced Cu have expanded the applications of Cu and its alloys. Appropriate preparation methods can achieve excellent electrical and thermal conductivity while maintaining the excellent mechanical properties. Gr in Cu matrix mainly exist in the form of reduced GO (r-GO), graphene nanosheets or connected with metal oxide/carbide nanoparticles to enhance the interface bonding. Therefore, the structural integrity and the form of graphene in Cu matrix directly affect its performances. In this review paper, the preparation and simulation methods of Cu/Gr composites, the evaluation on the performances and the interaction between mechanical and functional properties are summarized. The key to the development of Cu/Gr composites is suggested: (1) dispersion and interfacial bonding; (2) construction of three-dimensional graphene structures; (3) the effect of interfacial bonding on the mechanical and functional properties.
Study review on structure lithium-ion batteries of carbon fiber reinforced composites
ZHANG Juntao, WANG Yazhen, LI Hui, MA Xinqi, ZONG Wenbo, JI Tianqi, WU Haihong
2023, 40(3): 1263-1273. doi: 10.13801/j.cnki.fhclxb.20220608.001
Carbon fiber structure lithium-ion batteries (CFSLB) are combination of structural parts and energy storage system. CFSLB have excellent energy storage properties while maintaining the mechanical properties of carbon fiber reinforced polymer. Structural batteries can improve the energy efficiency and structural efficiency of the power battery pack while reducing weight and simplifying structure. Structure batteries, as a new energy storage device, have attracted great attention of home and aboard scholars in the requirement of low-carbon emission. This article reviews the research status and fundamental problems included working principle, preparing process and storing energy properties of embedded structure batteries and multifunctional composite structure batteries. The concept and design prototype on All-carbon solidity structure batteries are suggested. The representative applications of structure batteries are introduced. The future applications in aerospace, transportation and other industrial fields are discussed.
Application and development of composite materials in large-scale wind turbine blade
LI Chengliang, YANG Chao, NI Aiqing, WANG Jihui, SONG Qiuxiang
2023, 40(3): 1274-1284. doi: 10.13801/j.cnki.fhclxb.20220715.001
With the proposal of "30.60" Double Carbon Project, the wind power industry has ushered in new development opportunities. As China's wind power enters the era of parity, the cost of power per kWh is reduced with the continuous increase of the single capacity of wind turbine system, which also leads to significant increase in the wind blade length. Wind blade is now facing the contradictive requirements of "large-scale, low-cost and lightweight". Both new material and innovative processing technology are of great importance to promote wind power to the parity era. On one hand, several key raw materials, including reinforcing fiber, matrix resin, core and structural adhesive, that affect the performance and cost of wind blade are systematically examined. On the other hand, high quality blades and green environmental protection are of great concern for the wind power industry, which indicates that new processing technology such as prepreg and pultrusion are playing more and more important role in future large scale blade manufacture. Thereafter, with systematic consideration of the materials and processing technologies in the development of wind blade, some suggestions are proposed on the introduction of these materials and technologies, in order to provide some reference for future large-scale wind blade development.
Research progress in piezoelectric catalysis of barium titanate nanomaterials
ZHANG Peng, WANG Xin, LI Zhi
2023, 40(3): 1285-1299. doi: 10.13801/j.cnki.fhclxb.20220629.002
The rapid development of society has brought huge economic benefits, but also brought a series of ecological environment problems, such as water pollution, air pollution and pollutant discharge. Catalytic degradation is considered as an effective strategy to deal with various kinds of pollution. Compared with traditional photocatalysis, piezoelectric catalysis is a new catalytic method proposed in recent years. Through the piezoelectric catalytic convert mechanical energy into chemical energy is an effective means of solving the water pollution problem, large numbers of piezoelectric materials have been applied in the research of catalytic degradation of piezoelectric, including BaTiO3 nano powder as a kind of typical piezoelectric material, because of low cost, the advantages of strong piezoelectric activity, caused the wide attention of researchers. In this paper, the theory and origin of piezoelectric catalysis are summarized, some commonly used piezoelectric catalysis materials are listed and their applications are illustrated. Around BaTiO3, the basic structure, common preparation methods of nano-BaTiO3 powder, application in piezoelectric catalysis and some typical modification methods are introduced. Finally, the future development trend of BaTiO3-based nano-powders in piezoelectric catalysis field is prospected.
Research progress for preparation of composite nanofiber electromagnetic shielding and absorbing materials by electrostatic spinning technology
2023, 40(3): 1300-1310. doi: 10.13801/j.cnki.fhclxb.20220612.001
With the advent of the information age, the leakage of electromagnetic waves has brought serious harm to human health, therefore, the design of high-performance electromagnetic protection materials is imminent. The composite nanofibers prepared by electrostatic spinning technology have the advantages of lightweight, low cost, large specific surface area, easy processing, and stable physicochemical properties, which are the hot spots for the research of high-performance electromagnetic shielding and absorbing materials in recent years. This article firstly introduces the basic principles of electromagnetic shielding and absorbing, and combines the current situation of domestic and foreign research, and systematically classifies the widely used electromagnetic shielding and absorbing materials in the market into four categories: Metals and metal oxides, carbon materials, conductive polymers, and transition metal carbides. Meanwhile, the influence of filler on electromagnetic shielding and absorbing performance and the current problems being faced are overviewed.
Recent advances in thermosetting resin-based composite phase change materials and enhanced phase change energy storage
XIAO Tong, LIU Qingyi, ZHANG Jiahao, ZHAO Jiateng, LIU Changhui
2023, 40(3): 1311-1327. doi: 10.13801/j.cnki.fhclxb.20220527.001
Thermosetting resin is a kind of resin material that can be cured by cross-linking reaction under the condition of heating or radiation, and gradually hardened and molded, which has the advantages of high heat resistance and not easily deformed by pressure, and it was widely used in the fields of coating, adhesive and electronic packaging. Existing studies have shown that the problem of leakage during phase change energy storage of solid-liquid phase change materials can be effectively solved due to the curing and molding of thermosetting resin by heat. This paper presents the first review of the current research status of thermosetting resins in the field of phase change energy storage from the classification of thermosetting resins, including: (1) Research progress of stereotyped phase change materials based on phenolic resin encapsulation; (2) Research progress of stereotyped phase change materials based on epoxy resin encapsulation; (3) Possibilities of dicyclopentadiene petroleum resin for phase change energy storage applications. At the same time, the future research focus and development trend of thermoset resin-reinforced phase change energy storage materials are prospected from the perspectives of modification at preparation and disposal and recycling at disposal, aiming to provide useful references for broadening the application scope of thermoset resin in the field of phase change energy storage and to provide more research ideas for the preparation of stereotyped phase change materials with excellent performance.
Research progress of biomass derived carbon in supercapacitors
SONG Xiaoqi, LEI Xiping, FAN Kai, TIAN Tian, ZHU Hang
2023, 40(3): 1328-1339. doi: 10.13801/j.cnki.fhclxb.20220628.002
Porous carbon is widely used as an electrode material in energy storage due to its large specific surface area, high durability and unique internal structure, but the development of new energy storage systems requires renewable, low-cost and environmentally friendly electrode materials. And biomass, as one of the most widely used renewable resources on earth, has great value for exploitation. At present, in the field of energy storage, biomass carbon based supercapacitors are favored by researchers for their excellent performance. This paper classifies biomass-derived carbon according to the source of carbon precursors, highlights the latest research results on biomass-derived carbon as electrode materials for supercapacitors, and finally discusses the challenges faced by biomass-derived carbon materials in building efficient energy storage systems.
Research progress of adrenaline electrochemical sensors based on carbon nanomaterials
LIU Xueru, JIN Biao, MENG Longyue
2023, 40(3): 1340-1353. doi: 10.13801/j.cnki.fhclxb.20220623.008
Adrenaline (AD), as a neurotransmitter, plays an important role in the human body, and its level directly affects the health of the human body, so the rapid detection of AD is of great practical significance. Among the detection methods, electrochemical methods have the advantages of high sensitivity, fast detection speed, and simple operation, so the construction of electrochemical sensors for adrenaline with excellent performance has become a research hotspot. In order to improve the electrochemical performance of sensors, carbon nanomaterials have been widely adopted as novel materials to modify sensors, and have achieved great progress in low detection limit, high sensitivity and promising clinical application. Starting from carbon nanomaterials such as carbon dots, graphene, and carbon nanoparticles, the electroredox mechanism of AD on the electrode surface was analyzed. Prospects are presented for future detection in order to obtain more efficient electrochemical sensors for adrenaline.
Research progress and the prospect of humidity response actuators
ZHENG Zongmin, HE Tian, YANG Zhen, LI Zheng
2023, 40(3): 1354-1364. doi: 10.13801/j.cnki.fhclxb.20220511.001
In this review, the research progress of humidity response actuators in recent years is summarized. The responsive materials and actuator structural design are mainly discussed starting from the classification and driving principle of humidity response actuators. The current development status of humidity response materials and the existing key scientific difficulties are systematically summarized. This research attempts to provide a new design idea for intelligent micro-actuators with novel functions. Multiple stimulation response, programmable, multifunctional, and the integration of driving-sensing-control will be a breakthrough in the future research of humidity response actuators.
Research progress of non-noble metal catalysts based on electrocatalytic oxygen evolution reaction
JIANG Jinchi, JIN Biao, MENG Longyue
2023, 40(3): 1365-1380. doi: 10.13801/j.cnki.fhclxb.20220819.001
In the context of global warming and energy crisis, energy issues have become an important part of the strategic security of countries around the world. As a sustainable new renewable clean energy, hydrogen energy is of great significance to alleviate the global energy shortage. Among many hydrogen production candidate schemes, electrolysis of water to produce hydrogen is considered to be one of the most reliable and feasible ways. However, in the electrolysis process, the anodic oxygen evolution reaction (OER) with extremely slow reaction kinetics seriously restricts the overall reaction efficiency. Therefore, the development of high-efficiency OER electrocatalyst with relatively low cost, excellent catalyst performance and good durability, so as to improve the energy conversion effect of electrolytic water hydrogen production technology, has attracted widespread attention. This paper first briefly expounds the reaction mechanism of oxygen evolution reaction and the evaluation parameters of its performance, then discusses the research of non-noble metal catalysts, lists the strategies and methods to improve the catalytic performance, and finally prospects the design of new catalysts.
Research progress of self-healing coatings based on dynamic covalent crosslinking
ZHOU Weiming, DING Chunxiang, PAN Mingzhu
2023, 40(3): 1381-1394. doi: 10.13801/j.cnki.fhclxb.20220424.002
It is an important barrier for coating materials to resist external stress damage, with the development of science and technology, intelligent coating can endow the original coating with advanced functions such as fluorescence, antibacterial, detection and sensing, etc. However, it will inevitably suffer from mechanical damage (such as scratches, scratches, etc.) and macroscopic or microscopic damage caused by stress mismatch with internal components, which will lead to cracks or even cracks, and structural damage will lead to functional weakening or even disappearance. Therefore, higher requirements were put forward for the structural stability and functional continuity of the coating. The self-healing coatings, based on dynamic covalent cross-linking network, can establish a thermodynamic equilibrium between the raw materials molecules and product molecules, and obtain the self-healing capacity via the recombination of dynamic network. The activation energy value of dynamic network not only directly reflects ease of healing reaction (i.e., reaction rate), but also affects the mechanical performance of the resultant materials. In this paper, we discuss and clarify the relationship between the construction of self-healing network and activation energy of reaction according to the chemical thermodynamics, subsequently, we comment the applications of the self-healing coatings with dynamic covalent cross-linking network in the fields of traditional coatings, intelligent sensor, photochromic, biological medicine. Finally, we prospect the developed bottleneck and perspective of the dynamic covalent self-healing coatings.
Resin Polymer Composite
Epoxy resin composites with flame retardancy and thermal conductivity: Effect of graphene nanoplatelets hybridized with melamine phosphate
JIA Xi'ning, WANG Yan, SHI Hui, QU Hongqiang, HAO Jianwei
2023, 40(3): 1395-1405. doi: 10.13801/j.cnki.fhclxb.20220415.003
The development and preparation of low-cost, defect less and high-efficiency graphene nanoplatelets hybrid flame retardant is of great significance to achieve the multifunctionality of composites. A graphene nanoplatelets hybrid melamine phosphate flame retardant (GMP) with flame retardant and thermal conductivity was prepared by the reaction of powder graphite (GRA) with phosphoric acid liquid phase after mechanical ball milling with melamine as a stripping agent. The morphology, structure, composition and thermal stability of GMP were characterized. The flame retardant, thermal decomposition and thermal conductivity of GMP epoxy resin (EP) composites were studied. Thermogravimetric analysis show that the initial decomposition temperature of GMP increases 29.3℃ from melamine phosphate (MP), which matches more with EP, contributing to the improvement of flame retardant efficiency of this EP composites. The results show that when the addition of GMP reaches 30wt%, EP composites achieve the limit oxygen index of 30.4%, the vertical combustion of UL 94 reached V-0 level, the peak heat release rate (PHRR) decreases by, and the peak smoke release rate (PSPR) decreased by 69% and 74.0% respectively. The thermal conductivity increases to 2.10 W·m−1·K−1, which is increased by 708% compared with EP. This is because the interaction between graphene nanoplatelets (GNPs) and MP in GMP promote the formation of dense expanded carbon layer on EP, which effectively improves the flame retardancy of EP composites. With the increase of GMP content, the thermal conductivity of EP composite is improved by the formation of GNPs and graphite heat transfer channel. The research provides an idea for the design and preparation of graphene nanoplatelets hybrid flame retardants with both flame retardancy and thermal conductivity to solve the fire hazard caused by thermal deposition of EP composites.
Long-term mechanical properties of carbon fiber reinforced vinyl resin composites in hygrothermal environment
ZHANG Yuheng, WANG Jihui, WEI Jianhui, LIU Ming, LI Xu, DING Anxin
2023, 40(3): 1406-1416. doi: 10.13801/j.cnki.fhclxb.20220509.001
Carbon fiber reinforced polymers (CFRP) were widely used in marine environments due to their corrosion resistance, light weight and high strength, and thus were subjected to hygrothermal environment for a long time. To understand the effects of hygrothermal environment and extreme temperatures on carbon fiber reinforced vinyl resin composites, the changes of compression properties, in-plane shear properties and interlaminar shear strength of CFRP before and after hygrothermal aging and at different testing temperatures were determined. The results of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) show that the pure resin specimens undergo hydrolysis in the hygrothermal environment, which cause the microcracks and pores on the surfaces of the specimens to expand and penetrate into the interior of the specimens. The moisture absorption curve of CFRP is in high agreement with Fickian model, while the moisture absorption curve of pure resin deviated from Fickian model because the hydrolysis reaction affected the moisture absorption channels. Meanwhile, the measurement on mechanical properties reveals that the compressive strength and interlaminar shear strength decrease by 7.6% and 12.3%, respectively, after hygrothermal aging for 90 days, and the compressive strength, in-plane shear strength, and interlaminar shear strength of the specimens at elevated temperature (70℃) decrease sharply by 36.2%, 26.9% and 37.4%, respectively. Meanwhile, it can be concluded that the effect of elevated tempera-ture on the mechanical properties of the specimens is partially reversible.
Influence of nano-SiO2 dispersion on the direct current dielectric properties of SiO2/LDPE nanocomposite
ZHENG Changji, WANG Bo, YANG Jiaming, ZHAO Hong
2023, 40(3): 1417-1429. doi: 10.13801/j.cnki.fhclxb.20220428.002
The dielectric properties of SiO2/low-density polyethylene (LDPE) composites are closely related to the dispersion of nano-SiO2 in LDPE matrix. In order to study the mechanism of tensile treatment on the dispersion of nano-silica particles in the LDPE matrix at room temperature, a hydrophobic nano-SiO2 with a particle size of 7 nm was selected to be fused and blended with LDPE to prepare SiO2/LDPE nanocomposites. The prepared nanocomposites were stretched three times, and the dispersion of nanoparticles and the crystallinity of the composites were characterized by SEM and DSC, the trap energy levels and trap densities of the composites were analyzed by thermally stimulated galvanometry (TSC). The effects of stretching on the dispersion of nanoparticles and the resulting changes in direct current dielectric properties were investigated by experimentally testing the space charge, electrical conductivity, and direct current breakdown strength of the nanocomposites. The results show that stretching at room temperature helps the dispersion of nanoparticles and reduce the agglomeration size of nano-SiO2 particles from about 200 nm to about 100 nm. However, stretching will destroy the crystal structure of LDPE and deteriorate its properties; The DC dielectric properties of LDPE can be improved by introducing deep trap levels by doping nano-SiO2.The space charge accumulation of the stretched SiO2/LDPE is suppressed, and the mechanism of conducting current is changed. By fitting the conductance current data, it is found that the conductance of the stretched SiO2/LDPE is dominated by ion hopping conductance, and its hopping distance is reduced to about 1.98 nm. Compared with LDPE, the DC breakdown field strength of SiO2/LDPE is improved by about 43%, The main reason for the decrease of the breakdown strength of SiO2/LDPE after stretching at room temperature is the structural defects of the LDPE matrix caused by the stretching process.
Preparation and properties of polylactic acid composite modified by bacterial cellulose
CHEN Qian, ZENG Wei, SHI Yikang, WU Xingyu, WANG Zhaozhi
2023, 40(3): 1430-1437. doi: 10.13801/j.cnki.fhclxb.20220419.007
Polylactic acid (PLA) is a new green friendly material and has very promising applications. In this work, for effectively resolving the problems of poor toughness and low crystallization rate of PLA, a method of modifying PLA with cellulose was proposed. First, the BC-g-PLA grafting product was obtained by in situ ring opening of L-propyl cross-ester (LLA) using bacterial cellulose (BC) as the substrate, and then the grafting product was added to PLA as a toughening agent, and the composite film material was prepared by the solution casting method. The results show that the reaction efficiency of the solution grafting method is higher than that of the melt grafting method, and the grafting rate can reach 76.60%. Structural testing of the grafted products by FTIR, nuclear magnetic resonance spectrometer and XRD reveal that PLA is successfully grafted onto the BC surface. Polarizing microscopy observed that the spheres have the highest degree of homogeneous refinement when the loading of BC-g-PLA filler as a heterogeneous nucleating agent is 0.6%. It is found through mechanical property tests that the elongation at the break of PLA film can be increased by 175% and tensile strength by 22.7% after toughening and modification. The crystalline properties of the composite film material were tested by differential scanning calorimetry. The crystallinity increases from 2.53% unmodified to 13.26%, and the crystallization rate also increases.
Preparation and application of micron-sized ZnS-Qds@ polysiloxane core-shell light diffusion hybrid microspheres
LUO Peidong, ZHAO Cheng, LUO Qiuping, ZHANG Qiang, YAN Feifei
2023, 40(3): 1438-1445. doi: 10.13801/j.cnki.fhclxb.20220516.005
In liquid crystal backlight module, diffusion film is usually used to improve the scattering effect of light and improve the utilization rate of light. Light scattering particles are the main factors affecting the transmittance and haze of light scattering materials. Because of its good thermal stability and dimensional stability, particle size and refractive index can be adjusted by reaction, organosilicon microspheres have a very broad application prospect as light diffusion particles in light diffusion materials. Micron-sized ZnS-Qds@polysiloxane core-shell light-diffusion hybrid microspheres were prepared by precipitating a layer of ZnS quantum dot (ZnS-Qds) coated with mercapto polysiloxane on polysiloxane microspheres prepared by sol-gel method. Light diffusion films with different mass fractions of the hybrid microspheres added were prepared. The prepared hybrid materials were characterized by TEM, TEM mapping, fluorophotometer and other testing methods, also tested the optical properties of the light diffusion films prepared with hybrid particles. The results show that ZnS-Qds@polysiloxane light diffusion hybrid microspheres have a core-shell structure with an average particle size of 3.6 μm and an average shell thickness of 87.4 nm. Zns-Qds with an average particle size of 2 nm are uniformly dispersed in the shell layer. The particles are added to the acrylic resin and coated on the polyethylene terephthalate (PET) films to make light diffusion films. The experimental results show that when the added amount of hybrid particles increases from 0wt% to 20wt%, the haze of light diffusion films is greatly improved from 1.67% to 91.11%, but the transmittance of light diffusion films is only slightly reduced from 90.10% to 82.57%.
Functional Composite
Forming mechanism of surface nitriding of high strength and high modulus carbon fiber by electrochemical modification
QIAO Weijing, TIAN Yanhong, ZHANG Xuejun
2023, 40(3): 1446-1454. doi: 10.13801/j.cnki.fhclxb.20220406.003
CF has smooth surface and low reactivity due to high temperature graphitization, resulting in poor interfacial adhesion of CF composites. Heteroatom modification is one of the effective methods to improve the surface reactivity of CF. In the organic composite electrolyte solution, the surface oxidation and nitridation treatment of the high-strength and high-modulus carbon fiber (CF) were carried out by cyclic voltammetry (CV). The surface element composition and microscopic morphology of CF were characterized by XPS, SEM and Raman spectroscopy. A comparative analysis based on the obtained data reveals the nitriding mechanism of the CF surface and the source of the substance introducing the nitrogen-containing functional group. The results show that under the synergistic action of organic solvent, organic nitrogen source and S-containing ammonium salt, the surface nitrogen content of CF increases from 0.28at% to 4.77at%. When there is an appropriate amount of water in the solution, the number of oxygen-containing functional groups is significantly increased. The reaction between the acidic oxygen-containing functional groups formed during oxidation, the amino group of urea, and the ammonium ions in the solution is the key to forming C—N bonds on the surface of CFs. As the reaction time prolongs, the nitrogen-containing functional groups on the surface of the CF gradually transform from amide nitrogen to nitrogen oxides, then to pyridine and pyrrole, and finally to the graphitized nitrogen. The interlayer shear strength (ILSS) of CF/epoxy composites after constant current electrochemical treatment is 132% higher than that of untreated, and the tensile strength of CF increased slightly. The results show that the organic composite electrolyte is a mild and effective solution for electrochemical treatment of CF surface.
Preparation of Ag-BiOBr/WO3 composites and enhanced sulfisoxazole removal performance
GAO Shengwang, ZHAO Xingpeng, LU Jiale, CUI Juan, WANG Guoying, ZHANG Qing
2023, 40(3): 1455-1467. doi: 10.13801/j.cnki.fhclxb.20220424.003
Antibiotics have been widely used to treat human and animal diseases with good antibacterial effect. However, antibiotics are difficult to be degraded naturally in natural environment. The photocatalytic oxidation technology has bright application prospects in the degradation of persistent organic compounds. However, the spectral absorption range of conventional photocatalytic materials is not wide enough, and the recombination rate of photogenerated carriers is too high, which seriously restricts the application and promotion of catalytic materials. So, it is urgent to develop more effective and safe removal technologies. The photodeposition method was used to load Ag element on the surface of BiOBr/WO3 p-n type heterojunction material to construct a new type of Ag-BiOBr/WO3 material and apply to the photocatalytic degradation of sulfisoxazole. The samples were characterized by various techniques, such as XRD, TEM, XPS, UV-vis DRS et al. The result show that the deposition of Ag expands the photo-response range of the material, significantly accelerates the separation speed of photogenerated carriers, and thus improves the photocatalytic performance. The 15wt%Ag-BiOBr/WO3 with an Ag content of 15wt% is considered to be the most efficient composite material for the removal of sulfisoxazole. When the catalyst concentration is 0.3 g/L, the sulfisoxazole concentration is 5 mg/L, and the pH is 7, 15wt%Ag-BiOBr/WO3 demonstrates the highest photocatalytic degradation efficiency of sulfisoxazole in 60 min, which reaches up to 98.1%. The degradation rate is 28.79, 36.37 and 7.59 times higher than those of BiOBr, WO3 and BiOBr/WO3, respectively. After 5 cycles of experiments, the 15wt%Ag-BiOBr/WO3 composite material still maintains high photocatalytic activity, indicating that the material can be recycled and reuses with good stability. The quenching experiments and electron spin resonance (ESR) shows that •O2 is the most active radical group in the BiOBr/WO3 system, while 1O2 and h+ played relatively minor roles. This provides a theoretical basis for the preparation of catalytic materials and the degradation of antibiotics.
Piezoresistive effect of carbon fiber 3D angle-interlock woven composites under bending
XUE Yousong, XUE Lingming, SUN Baozhong, GU Bohong
2023, 40(3): 1468-1476. doi: 10.13801/j.cnki.fhclxb.20220516.006
Electrical resistance method has great prospects in structural health monitoring (SHM) of carbon fiber reinforced composites. The piezoresistive effect of carbon fiber 3D angle-interlock woven composites in the warp direction and weft direction under bending was investigated to find the relationship between the resistance variation and structure damage. The experimental results show that the resistance variation of the warp and weft samples under bending corresponded with the damage of the main load-bearing yarns. The resistance variation of the composite reflected the change in the load-bearing ability of the composite under the quasi-static three-point bending test. The electrical resistance did not change before the maxim load, while that increased after the main load-bearing yarns occurred breakage. The resistance variation of the composite reflected the degradation in the load-bearing ability of the composite under the bending fatigue test. In the early stage of the bending fatigue test, the negative piezoresistive effect of the composites was observed. The electrical resistance increased slowly due to the accumulation of the irreversible damage including matrix cracks and interface debonding, while that increased significantly after the main load-bearing yarns were damaged. The electrical resistance increased dramatically when the samples occurred fatigue failure.
Design, preparation and properties of honeycomb 3D integral woven structure microwave absorbing composites
LYU Lihua, WANG Rongrui, LIU Wendi, ZHOU Xinghai, GAO Yuan
2023, 40(3): 1477-1483. doi: 10.13801/j.cnki.fhclxb.20220425.001
In order to solve the problems of cracking and delamination of honeycomb sandwich structure materials, basalt fiber filament yarn and carbon fiber filament yarn were used as raw materials, the honeycomb 3D integral woven structure microwave absorbing fabric was fabricated with the top layer as the wave transmitting layer, the middle layer as the wave absorbing layer and the bottom layer as the reflecting layer on the ordinary loom through reasonable design; Secondly, honeycomb 3D integral woven structure microwave absorbing composites with different structural parameters were prepared by vacuum assisted resin transfer molding (VARTM) process with honeycomb three-dimensional integral woven structure microwave absorbing fabric as reinforcement, bisphenol A epoxy resin as matrix, carbonyl iron powder (CIP) and carbon black (CB) as microwave absorbing agent; Finally, the microwave absorbing and mechanical properties of honeycomb 3D integral woven structure microwave absorbing composites were studied by vector network analyzer and universal testing machine. The research shows that it has good overall performance, both wave absorption and bearing integration.
Preparation and performance of high-barrier transparent paper-based materials via multi-coating technology
QIU Ge, CHEN Gang, WEI Yuan, QIAN Yangyang, LEI Chunfa
2023, 40(3): 1484-1493. doi: 10.13801/j.cnki.fhclxb.20220414.002
Recently, barrier packaging products made from biodegradable materials have attracted wide attention. However, most reported methods are still difficult to achieve both high oxygen barrier and water vapor resistance in paper-based packaging. In this study, high-barrier transparent paper-based materials was prepared based on coating technology, where homemade transparent paper served as a substrate, while the natural biomass materials (starch and guar gum) and environmental-friendly waterborne resin functioned as coatings. The results show that the barrier effect between different coatings is fully utilized, which reduces the adsorption of external water vapor on the surface of paper-based materials, and increases the difficulty of diffusion of water molecules and oxygen molecules inside the paper. The oxygen transmission rate and water vapor transmission rate of our resulting transparent paper-based materials are low to 2.46 cm3/(m2·day·0.1 MPa) and 107.09 g/(m2·day), respectively, which show a significant reduction of 92% and 94% compared to the uncoated transparent paper. Meanwhile, the surface water absorption of paper and board (Cobb) values of transparent paper-based materials with waterproof layer are less than 1 g/m2, and the contact angles are greater than 90°, showing good hydrophobicity and water resisting property. In short, we provided a simple and low-cost technical route to manufacture performance-adjustable paper, suggesting a great potential to achieve industrialization and partially replace plastic packaging.
Preparation and performance of dopamine@boron nitride-carbon nanotubes/polyimide composite aerogel solar-driven evaporator
WANG Riyuan, CHEN Haoran, CHEN Fanglin, LI Tao, LU Hongdian, YANG Wei
2023, 40(3): 1494-1500. doi: 10.13801/j.cnki.fhclxb.20220410.001
It is one of the important ways to produce fresh water through solar-driven evaporator. In order to improve the solar-driven evaporation performance of polyimide (PI) aerogel, PDA@BN-CNT/PI composite aerogel was prepared by adding dopamine-modified boron nitride (PDA@BN) and hydroxylated carbon nanotubes (CNT) through four-directional freeze-drying and imidization. The influence of PDA@BN and CNT on the morphology, structure, wettability and solar-driven evaporation of the aerogel were studied. The results indicate that PDA@BN-CNT/PI aerogel has good hydrophilicity and solar photothermal conversion performance. Moreover, it exhibits unique low bending tubular structure, which is conducive to promoting the transportation of water inside the aerogel and improving the performance of solar-driven evaporator. The aerogel exhibits high evaporation rate of 1.95 kg/(m2·h) under 2 kW/m2 sun irradiation and excellent recycling performance, chemical stability and efficient wastewater purification ability.
Effect of preparation conditions of Fe2O3-graphene-carbon nanotube composites on sulfur loading properties
DONG Wei, MENG Lingqiang, ZHAO Meina, SHEN Ding, SUN Wen, YANG Shaobin, WANG Wenbo, JI Lingxiao, YANG Zongsong, LIU Yaohan
2023, 40(3): 1501-1511. doi: 10.13801/j.cnki.fhclxb.20220424.001
Lithium sulfur battery is one of the most promising alternatives to traditional lithium-ion battery. The dissolution and poor conductivity of polysulfides are two important factors restricting the application of lithium sulfur battery. In this paper, Fe2O3-reduced graphene oxide (RGO)-carbon nanotube (CNT) composite sulfur carrying materials are synthesized by hydrothermal method. By adjusting the ammonia concentration, the particle size of Fe2O3 in the composites is successfully adjusted. It is found that Fe2O3 with small particles had better adsorption and catalysis. Cathode material synthesized from it at 1 C, the first discharge capacity is 1286 mA·h/g, 718 mA·h/g remains after 500 cycles, and the capacity attenuation rate of each cycle is 0.08%. The average specific capacities at 0.2, 0.5, 1, 2 and 4 C are 983, 825, 769, 673 and 604 mA·h/g, which has good rate performance and good cycle performance at high current. 527 mA·h/g remains after 500 cycles at 5 C. Fe2O3-RGO-CNT-S cathode material is especially suitable for high-performance lithium sulfur batteries. It has excellent electrochemical performance, mainly because the three-dimensional conductive network of RGO and CNT provides strong electron transmission path, rich pore structure, and sulfur is in full contact with the three-dimensional conductive network composed of RGO and CNT.
Controllable preparation method and performance of three-dimensional reduced graphene oxide aerogel under mild conditions
ZHAO Huhu, ZHOU Yujing, HU Xiaolan, ZHU Xiangdong, REN Mingwei
2023, 40(3): 1512-1521. doi: 10.13801/j.cnki.fhclxb.20220424.005
In order to realize the large-area controllable preparation and high performance of graphene-based three-dimensional aerogels under mild environmental conditions, hydrazine hydrate is used as reducing agent in this paper. Through low-temperature pre-frozen combined with natural drying at room temperature, large-area three-dimensional reduced graphene oxide (3D-RGO) aerogels with a diameter of 30 cm can be prepared effectively and controlled. The method has mild preparation conditions and does not need any heating conditions or special freeze-drying equipment. By controlling the reduction time, pre-frozen time, pre-frozen temperature and reaction vessel during the preparation of 3D-RGO aerogel, the shape, surface wettability, volume shrinkage aerogel can be effectively adjusted to achieve controllable preparation of 3D-RGO aerogel. The 3D-RGO aerogel has no obvious volume shrinkage and structural cracks. The aerogels exhibit a stable honeycomb-like structure with a stable pore size of about 500 μm and a low density of 3.8 mg/cm3, and it can quickly undergo a compression strain of 90% and return to the initial state. The volume shrinkage rate of the aerogels is <5% in the drying process. At the same time, the graphene aerogel exhibits good and stable conductivity. When the compressive strain increases from 0% to 90%, its conductivity increases from 17.3 S/m to 115.2 S/m. This method is suitable for the cost-effective preparation of large-area graphene aerogels.
Preparation of Ti1Li3Al2-LDHs/g-C3N4 composites and its photocatalytic properties in CO2-toluene reaction system
MA Mengdan, ZHOU Anning, DUAN Feiyang, JIA Xinyu, LING Jie
2023, 40(3): 1522-1533. doi: 10.13801/j.cnki.fhclxb.20220510.001
Photocataltyic reduction of CO2 is one of the promising routes in CO2 conversion and utilization, but the very low CO2 conversion rate is the biggest hurdle for the process. Developing a new CO2 reduction reaction system and improving the visible light utilization and separation efficiency of photogenerated electrons and holes are effective ways to solve the above problems. In this work, we designed a CO2-toluene coupling reaction system to promote the CO2 reduction reaction. The Ti1Li3Al2-layered dihydroxides (LDHs)/graphite phase carbon nitride (g-C3N4) composite with heterojunction structure were synthesized by electrostatic assembly method. And the photoelectric property and photocatalytic properties of Ti1Li3Al2-LDHs/g-C3N4 composite were explored in CO2-toluene reduction reaction system. The results show that CO2 is reduced to CO, and toluene is oxidized to benzyl alcohol, benzaldehyde and benzyl benzoate in the photocataltyic coupling reaction system. Benzaldehyde and benzyl alcohol content can reach 4.80 and 4.70 mmol/gcat. This is mainly because the g-C3N4 can extend the absorption of Ti1Li3Al2-LDHs from the ultraviolet region to the visible region, and improve the dispersion of Ti1Li3Al2-LDHs which provide more active sites for photocatalytic reactions. Moreover, the S-type heterojunction is formed in the interface of Ti1Li3Al2-LDHs/g-C3N4, which is conducive to the transfer of photogenerated electrons at the interface and improves the separation efficiency of photogenerated electrons and holes. And toluene can be used as an organic substrate to accelerate the rate of hole consumption and stimulate the CO2 reduction reaction. This work provides a new idea for the synergistic reaction between CO2 reduction and small molecular organics.
Controlled construction of NaNbO3@g-C3N4 composites and their piezo-photocatalytic properties
SUN Shubo, YU Haihan, LI Qiang, GE Shenguang, JIANG Congcong, WANG Dan, ZHANG Li'na, CHENG Xin, GAO Chaomin
2023, 40(3): 1534-1540. doi: 10.13801/j.cnki.fhclxb.20220415.001
Facilitating the efficient separation of carriers in photocatalytic processes has always been a problem for researchers. Recently, the use of piezoelectric effect as an effective strategy to enhance photocatalytic process from inhibitting the recombination of electrons and holes has attracted great interest. Here, we prepared 1D NaNbO3 nanorods coated with g-C3N4 heterojunction materials as the object to investigate the performance enhancement mechanism in the piezo-photocatalytic process by applying an ultrasonic field to introduce the piezoelectric effect. The microscopic morphology and bonding of the materials were investigated through SEM and XPS characterization. The results show that after the introduction of the piezoelectric effect using ultrasonic, NaNbO3@g-C3N4 exhibites a higher H2 evolution rate in the piezo-photocatalytic process (1.02 mmol·g−1·h−1) than in the single photocatalytic process (0.49 mmol·g−1·h−1), indicating that the constructed NaNbO3@g-C3N4 heterojunction materials with the support of piezoelectric effect greatly promote the separation of carriers in the photocatalytic process, inhibite their complexation and improve the photocatalytic performance. In addition, based on the data analysis, the mechanism of piezo-photocatalytic coupling effects is proposed for the design and development of highly efficient piezoelectric photocatalysts.
Preparation of g-C3N4/Pb composites and application in anode materials for lead carbon batteries
XIE Fazhi, ZHANG Daode, YANG Shaohua, SONG Hengshuai, ZHANG Meng, FANG Liang, SHAO Yonggang
2023, 40(3): 1541-1551. doi: 10.13801/j.cnki.fhclxb.20220515.001
To improve the hydrogen precipitation defects and increase the cycle life of lead carbon batteries, layered graphite phase carbon nitride (g-C3N4) was prepared using urea as a precursor and used as an additive to prepare anode plates for lead carbon batteries. The effects of the structure and addition amount of g-C3N4 on the electrochemical performance of lead carbon batteries were investigated with activated carbon (AC) as the control. The results show that the hydrogen evolution reaction (HER) is significantly suppressed by the addition of g-C3N4, and the hydrogen precipitation current of 1wt%g-C3N4 negative plate at −1.5 V is only 6% of that of the activated carbon negative plate. The AC impedance spectra show impedances (Rs) of 0.19868 Ω and 1.749 Ω for 1wt%g-C3N4 and activated carbon anode materials. More importantly, the capacitance of 1wt%g-C3N4 negative electrode plate is 344% higher than that of 1wt%AC negative electrode plate. In the 5000 h high-rate partial-state-of-charge (HRPSoC) battery cycle life test, the addition of g-C3N4 improved the battery life by 62% compared to the addition of activated carbon. After 500 cycles, the battery capacity retention rate is still 70%. g-C3N4 can effectively inhibit the hydrogen precipitation reaction, increase the specific capacitance and thus extend the cycle life of the battery, and at low cost, can be used as a new anode additive to improve the performance of lead carbon batteries.
Partially surface exposed CoFe2O4 anchored on N-doped carbon endows its high performance for oxygen evolution reaction
LI Chuang, WANG Yu, ZHANG Yanan, HOU Liqiang, LIU Xi'en
2023, 40(3): 1552-1559. doi: 10.13801/j.cnki.fhclxb.20220510.002
The exploration of earth-abundant and high-efficiency electrocatalysts for the oxygen evolution reaction (OER) is of great significant for sustainable energy conversion applications. Although spinel-type binary transition metal oxides represent a class of promising candidates for water oxidation catalysis, their intrinsically inferior electrical conductivity could decrease their electrochemical performances to some extent. Here, we present an metal-organic frame (MOF)-assisted synthesis of partially surface exposed CoFe2O4 nanoparticles anchored on nitrogen doped carbon substrate (NC), which can act as the superior catalyst for OER. With enough exposure of active sites and high electron transfer capability and durability, CoFe2O4@NC show a low overpotential of 1.517 V at 10 mA · cm−2 with a Tafel slope of 87 mV · dec−1 in alkaline medium. Moreover, it delivers an outstanding stability with small degradation after 15 h operation. The present work would open a new avenue for the exploration of cost-effective and efficient OER electrocatalysts to substitute noble metals for various renewable energy conversion applications.
Civil Construction Composite
Mechanical properties of emulsified asphalt rubber concrete
LIN Qiang, LIU Zanqun, YU Lei, ZHOU Yunchan, CUI Yu
2023, 40(3): 1560-1568. doi: 10.13801/j.cnki.fhclxb.20220513.003
The effects of emulsified asphalt (EA) on the mechanical properties of crumb rubber concrete (CRC) were explored. The fine aggregate was replaced with 5%, 10% and 15% rubber by volume in concrete, and different EA contents corresponding to 4, 6 and 8 layers of films covering the surface of rubber particles according to theoretical calculation were studied. The results of compressive strength, flexural strength, splitting tensile strength and three-point bending experiments show that, compared with the unpretreated CRC and NaOH pretreated CRC, the compressive strength and splitting tensile strength of the CRC with different rubber contents are greatly improved by adding different amounts of EA, the peak displacement increases and the flexural elastic modulus Eb decreases significantly; when the mass ratio of emulsified asphalt to rubber is 0.15 (6 layers of EA film), compared with the unpretreated CRC, the average increase in compressive strength is 3.5%, the peak displacement is 27.6%, and Eb is 21.8% lower for CRC at three rubber contents, emulsified asphalt-rubber concrete has a more prominent composite effect of mechanical properties.
Mechanical performance of basalt fiber reinforced foam concrete subjected to quasi-static tensile and compressive tests
WANG Xiaojuan, CUI Haoru, ZHOU Hongyuan, LI Xiujie
2023, 40(3): 1569-1585. doi: 10.13801/j.cnki.fhclxb.20220422.001
To investigate the mechanical properties of basalt fiber reinforced foam concrete, the quasi-static tensile and compressive tests were carried out on the prepared 52 groups of specimens, and the effects of basalt fiber volume fraction and fiber length on the tensile and compressive properties of specimens with different densities were experimentally studied. The test results show that the basalt fiber could significantly improve the tensile peak stress (maximum improvement of 737%) and peak strain (maximum improvement of 833%) of specimens. Due to the appearance of pseudo strain hardening phenomenon, the basalt fiber could effectively improve the tensile failure mode of the medium and high density specimens, so as to improve the tensile bearing capacity and deformation ability of specimens. It is found that tensile peak stress and peak strain increase with increasing the fiber volume fraction, and increase first and then decrease with increasing the fiber length. Furthermore, basalt fiber could change the compression failure mode of specimens with the observed trend from longitudinal splitting failure to oblique shear failure and transverse crushing failure, resulting in significant improvement of the compressive bearing capacity and energy absorption ability of low and medium density specimens. In addition, it is observed that increasing the fiber volume content will lead to an increase in the energy absorption (maximum improvement of 328%) of the specimen, which increases first and then decreases with increasing the fiber length.
Dynamic compression mechanical properties of polymer modified carbon fiber reinforced concrete
WANG Zhihang, BAI Erlei, XU Jinyu, LIU Gaojie, YANG Ning
2023, 40(3): 1586-1597. doi: 10.13801/j.cnki.fhclxb.20220429.002
To explore the dynamic compression mechanical properties of polymer modified carbon fiber reinforced concrete (PMCFRC), the diameter Φ100 mm split Hopkinson pressure bar (SHPB) test device was used to carry out impact compression tests under five sets of different air pressures on carbon fiber reinforced concrete and PMCFRC with polymer content of 4vol%, 8vol%, and 12vol% respectively. The dynamic stress-strain curve and failure morphology of concrete under different strain rates were obtained, and the influence of strain rate and polymer content on the dynamic compressive strength, deformation and toughness of PMCFRC was analyzed. The results show that the dynamic compression strength, deformation and toughness of PMCFRC have obvious strain rate strengthening effects, and the polymer has both strengthening and degrading effects on the dynamic compression mechanical properties of PMCFRC. As the strain rate increases, the dynamic compressive strength, dynamic strength increase factor (DIF), dynamic peak strain and impact toughness of PMCFRC gradually increase. With the increase of the polymer content, the dynamic compressive strength, DIF and impact toughness of PMCFRC first increase and then decrease, and the dynamic peak strain continues to increase. Under the same strain rate level, 4%PMCFRC has the largest dynamic compressive strength, impact toughness, and the least damage; 8%PMCFRC has the best strain rate sensitivity, the maximum DIF is 1.94, and the greatest increase in concrete strength. On the one hand, the polymer plays the role of filling, crack resistance and toughening in the concrete matrix, and on the other hand, it improves the bonding performance of the carbon fiber-concrete matrix interface; when the polymer content is large, it will form a “soft interlayer” in the concrete matrix.
Effect of graphene oxide on the impermeability of cementitious capillary crystalline waterproofing
QI Meng, PU Yundong, YANG Sen, SHENG Kuang, YUAN Xiaoya
2023, 40(3): 1598-1610. doi: 10.13801/j.cnki.fhclxb.20220509.003
The effect of sodium lignosulfonate (MN) on the dispersion ability of graphene oxide (GO) in simulated cement hydration pore solution was studied, and the effect of MN-dispersed GO on the impermeability of cementitious capillary crystalline waterproofing (CCCW) was studied. The results of absorbance test, Zeta potential and atomic force microscope (AFM) show that GO has the best dispersion in saturated calcium hydroxide solution when the mass ratio of MN and GO is 3:1. The mechanical strength test of mortar shows that when the GO content is 0.03% of the cement mass, the flexural and compressive strength of 3 days and 28 days are increased by 39.13% and 39.37%, 33.84% and 33.48%, respectively, compared with the GO mortar without MN. The impermeability pressure and chloride ion diffusion coefficient of mortar are 160.0% and 50.6% higher than those of standard mortar specimens, respectively. The impermeability test shows that when the GO content is 0.03% of the cement mass, the impermeability pressure of the GO modified CCCW coating is 116.7% higher than that of the CCCW coating. Micro-test shows that GO promotes the hydration reaction, plays a filling role and template role in the mortar matrix, enhances the density of hydration products, and increases the impermeability of mortar and CCCW. This study provides a GO modified CCCW to improve the impermeability of cement mortar, and its application value in coating waterproof effect and reducing CCCW material cost is improved.
Effect law and mechanism of ceramic tile powder on compressive strength of ultra high performance concrete
ZHANG Liqing, PAN Yannian, HU Wenbing, XU Kaicheng, FU Shucheng, CHEN Mengcheng, HAN Baoguo
2023, 40(3): 1611-1623. doi: 10.13801/j.cnki.fhclxb.20220630.002
Ultra high performance concrete (UHPC) is faced with the problems of high cost and high self-shrinkage of cement matrix due to its extremely low water-binder ratio and high cement content in its wide application. One of the effective solutions is to replace part of cement with industrial by-products or wastes. As the waste ceramic tile has become a large amount of industrial waste, the application of ceramic tile powder in UHPC can effectively solve the problems of high consumption of cement and accumulation of waste ceramic tile. Therefore, ceramic tile powder was used to replace 10wt%, 15wt%, 20wt% and 25wt% by mass of cement to prepare a new type of green low-carbon UHPC. The effect law of ceramic tile powder on the compressive strength of UHPC was studied, and the modified Andreasen accumulation model, XRD analyses, TG/DTG, SEM observation were used to investigate the modification mechanisms, and the environmental footprint and the cost of ceramic tile powder on UHPC were also analyzed. The results show that the effect of the addition of ceramic tile powder on the compressive strength of UHPC is within ±10% at all age. Interestingly, ceramic tile powder has a significant influence on the development of compressive strength at 7-28 days and 28-60 days, and the increase rates of compressive strength of UHPC with 25wt% ceramic tile powder can reach 104.6% and 51.8%, respectively. This is mainly because that the addition of ceramic tile powder improves the packing compactness of UHPC, produces secondary hydration reaction and calcium silicate hydrate gel with low calcium-silicon ratio, improves the hydration degree of cement, and reduces the width of interface transition zone. According to environmental impact and cost calculation, ceramic tile powder can effectively reduce energy consumption, CO2 emission and cost of UHPC.
Experimental on the shear behavior of pre-damaged RC beams strengthened by textile reinforced highly ductile concrete
ZHANG Min, DENG Mingke, ZHI Aolong, MA Xiangkun
2023, 40(3): 1624-1636. doi: 10.13801/j.cnki.fhclxb.20220428.003
Static load tests were conducted on eight reinforced concrete (RC) beams strengthened by textile reinforced high ductile concrete (TRHDC) and one control beam to study the effect of secondary loading on the shear behavior of TRHDC-strengthened beams. The influence of the number of the textile layer, damage degree of beams, and different sustained loads on the failure mode, load-deflection curves, load-strain curves of stirrups, and load-strain curves of textile were analyzed. The results indicate that all beams fail in shear compression mode, and the debonding phenomenon is only observed in one beam. TRHDC can effectively restrain the development of shear cracks, delay the yielding of stirrups and the stiffness degradation. This strengthening method can significantly improve the shear strength and deformation capacity of RC beams by up to 67% and 54%, respectively. The strengthening effectiveness does not completely increase with the number of the textile layer increase, which is related to the utilization rate of the TRHDC layer. When the stirrup of the original beam does not reach its yielding strength, the damage degree has no obvious influence on the shear behavior of strengthened beams. On the contrary, the shear strength of strengthened beams decreases with the increase of the damage degree. The strengthening effectiveness decreases with the sustained load increasing. The completely damaged RC beams can be restored by the TRHDC with two numbers of the textile layer. A calculation formula for the shear strength of TRHDC-strengthened beams considering the secondary loading was proposed. The calculation values are in good agreement with the test results.
Effect of graphene surface properties on mechanical properties and microstructure of cement mortar composites
KONG Xiangqing, WANG Rongzheng, GAO Wei, ZHANG Tingting, FU Ying, SUN Ruoxi
2023, 40(3): 1637-1648. doi: 10.13801/j.cnki.fhclxb.20220420.001
In recent years, the use of graphene and its derivatives to improve the properties of cementitious composites have received much attention. However, there are few reports on the effect of graphene surface properties on the performance of cement-based materials. Graphene oxide (GO) was converted to reduced graphene oxide (rGO) using different concentrations of L-ascorbic acid (10wt%, 20wt%, 30wt%, 50wt% and 70wt%) and reduction time (15 min, 30 min, 45 min and 60 min) which was then added to the cement mortar composites at the same dosing level 0.05% (by weight cement). The effects of different degrees of reduced rGO on the mechanical properties of cement mortar were investigated. The test results show that the incorporation of rGO prepared by 50wt% L-ascorbic acid reduction 30 min increases the 28 days compressive strength and flexural strength of cement mortar by 36.84% and 43.24%, respectively, compared to the normal specimens. SEM and other analyses show that both GO and rGO with different degrees of reduction could promote the crystallization of Ca(OH)2 and the formation of silica tetrahedra in hydrated calcium silicate gels (C-S-H) to form dense microstructures. However, an optimal threshold exists (i.e., 30 min reduction by 50wt% L-ascorbic acid). At this threshold, the binding of rGO surface functional groups to hydration products is favored.
Biological and Nano-composite
Preparation and properties of cryogels composed of agarose and nanoparticles of tannic acid and amino-capped poly(propylene glycol)
WANG Liwei, YU Xueying, HAN Jianmei, HE Wei
2023, 40(3): 1649-1654. doi: 10.13801/j.cnki.fhclxb.20220512.003
Here a new type of agarose-based composite cryogel has been developed using a facile and green method. By introducing nanoparticles derived of polyphenol tannic acid (TA) and amine-terminated poly(propylene glycol) (D400) to agarose, the TA-D400 nanoparticles/agarose composite cryogel (ATD) was successfully prepared and the effect of TA-D400 complexation time on the properties of the resulting cryogels was studied. The ATD cryogels prepared by the freezing method have an interconnected macroporous structure, and the nanoparticles are embedded in the agarose matrix. The storage modulus of the composite cryogels ATD-0 and ATD-24 with complexation times of 0 h and 24 h is 1.8 kPa and 0.8 kPa respectively. The introduction of nanoparticles increases the mechanical properties of agarose cryogel. The ATD gels are antioxidative, shown by their excellent 1, 1-diphenyl-2-picrohydrazine (DPPH) free radical scavenging ability and total antioxidant capacity based on the ferric ion reducing/antioxidant power (FRAP) assay result. In vitro cytoprotection experiments show that the ATD gels can protect fibroblasts from H2O2-induced oxidative damage. Furthermore, the ATD gels support the adhesion of fibroblasts, pre-osteoblasts, and primary cortical neurons. In summary, by rationally introducing TA-D400 nanoparticles, we have developed a multifunctional cryogel with innate ability for cell adhesion and antioxidation, providing a new option of macroporous materials as potential scaffolds for tissue engineering.
Injectable nanomotors-hydrogel system with high cellular uptake for targeted cancer gene therapy
REN Jiaoyu, WANG Hong
2023, 40(3): 1655-1662. doi: 10.13801/j.cnki.fhclxb.20220524.001
Small interfering RNA (siRNA) often acts as an important therapeutic agent in gene therapy due to its ability of reducing gene expression. However, the low cell uptake rate of siRNA limits its efficacy in cancer treatment. Here, we report a biocompatible nanomotors-hydrogel system to obtain high cell uptake rate for targeted cancer therapy. Nanomotors (NM) loaded with siRNA were prepared employing polyethyleneimine (PEI) and sodium polystyrene sulfonate (PSS) via layer-by-layer self-assembly technology. For the sake of intratumoral administration and slow release, the nanomotors were loaded in Schiff-base hydrogel to build NM-hydrogel system. Taking advantage of the tumor microenvironment featured with an acidic pH and a high content of hydrogen peroxide, the hydrogel releases nanomotors in response to slightly acidic tumor matrix, and the released nanomotors can autonomously move through catalytic decomposition of hydrogen peroxide, the speed of which can be maintained at 1.78 µm/s at 1wt%H2O2 (22.25 body lengths per second). The autonomous motion of nanomotors and specific endocytosis which is mediated by folic acid (FA) modified on the nanomotors gives the NM-hydrogel system a high cell uptake rate of 63.8%. The proton sponge effect caused by PEI and autonomous motion promote the deep penetration and long-time retention of namomotors in tumor cells, which facilitates the anticancer effect of the NM-hydrogel system. The results show that the anticancer activity of the system is 74.8% at 72 h. Meanwhile, the NM-hydrogel system has good biocompatibility and biodegradability, which lays the foundation for its future application in gene therapy in vivo.
Preparation of catalytic composite copper oxide nanoparticles (CuO NPs)@cellulose nanofiber (CNF)-Si-N(OH)2 and its catalytic reduction of 4-nitrophenol
JI Dexian, LIN Zhaoyun, CHEN Jiachuan, LI Xincai, QIU Chenglong, YANG Guihua
2023, 40(3): 1663-1675. doi: 10.13801/j.cnki.fhclxb.20220406.002
In view of the low efficiency and poor catalytic activity of 4-nitrophenol (4-NP) catalysts for degradation of industrial wastewater, eucalyptus wood bleaching chemical pulp was used as the raw material and treated with ultrafine grinder and high pressure homogenizer to produce cellulose nanofiber (CNF) with the diameter of 50-100 nm and the length of 1500-2000 nm. Then, copper oxide nanoparticles (CuO NPs) were in-situ loaded onto CNF, 3-chloropropyltrimethoxysilane (CPTES) and diethanolamine (DEA) were added for grafting reaction to obtain the catalytic composite of CuO NPs@CNF-Si-N(OH)2. The catalytic composite was characterized with Zeta potential, FTIR, XRD, XPS, thermal gravimetric analysis and morphology analysis. The results show that CuO NPs are in-situ loaded on CNF, and the grafting of amine groups can make the loading of CuO NPs more uniform and stable. In addition, it is also found that CuO NPs@CNF-Si-N(OH)2 show the optimal catalytic performance with 20wt% DEA. Furthermore, 98.39% of 4-NP is catalytically reduced after 180 s, and the reaction fit the pseudo-first order kinetics equation, in which the reacting constant reaches 5.50×10−3 s−1 and the turnover frequency achieves 1723.24 h−1. The composite catalysts of CuO NPs@CNF-Si-N(OH)2 exhibite excellent recycling performance, and 94.42% of 4-NP can be catalytically reduced after a recycling time of 8. The results can provide a new idea and approach for the preparation of high-performance catalytic composite.
Preparation and photo-thermal controlled release properties of nanodiamond/yeast-chitosan composite microspheres
WANG Jin, BAI Bo, LUO Yu, GE Guangning, DENG Xiangyun, WANG Qizhao, CAO Fangli
2023, 40(3): 1676-1685. doi: 10.13801/j.cnki.fhclxb.20220616.001
It is important to develop high-performance functional photo-thermal materials and establish controlled drug release models for the development of intelligent transportation materials for pesticides. Herein, nanodiamond (DND) was employed to prepare novel nanodiamond/yeast-chitosan (DND/YS-CS) composite hydrogel microspheres which had a cross-linked network structure through alkali gelation method. The microstructure, mechanical resistance and photo-thermal conversion performance of the composites were investigated. Moreover, indole-3-butyric acid (IBA) was used as a model to discuss the loading and controlled drug release and reveal the photo-thermal controlled release mechanism of IBA by DND/YS-CS. The results show that the composite microspheres has good mechanical properties, and the water retention capacity of the composite microspheres with DND content of 2.0 mg/mL reached 70.5% and 74% after ultrasonication and centrifugation for 1 h, respec-tively. The maximum temperature of the composites can reach to 37.6℃ under one sunlight intensity, proving that the composites possess excellent photothermal conversion ability. The maximum adsorption of IBA is 41.73 μg/mg when the composites have a DND concentration of 1.2 mg/mL. Finally, the controled drug release pattern of the composites is in accordance with the Korsmeyer-Peppas model, which exhibits an obvious stimulus response behavior and an "on-off" pattern of drug release under light.
Microwave in-situ synthesis of 2D Ni-Fe MOF/diatomite composite and oil-water separation performance of modified polyvinyl alcohol hydrogel stainless steel screen
GAO Deyu, CHENG Zhilin
2023, 40(3): 1686-1695. doi: 10.13801/j.cnki.fhclxb.20220429.003
How to efficiently treat oil-polluted water has been a common concern of researchers all over the world. Polyvinyl alcohol (PVA) hydrogel as a soft material with high water content and three-dimensional hydrophilic network had attracted wide attention in the field of oil-water separation. However, like most hydrogel with super wettability, PVA hydrogel oil-water separation materials have poor mechanical properties and poor chemical stability. Based on this, 2D Ni-Fe metal-organic frame material (MOF)-diatomite (Dia) nanomaterials and their PVA compo-site hydrogels were prepared by microwave method. After immersion in 2D Ni-Fe MOF-Dia/PVA solution, the 2D Ni-Fe MOF-Dia/PVA stainless steel mesh was obtained, showing super hydrophilic and super hydrophobic properties. The chemical composition and surface morphology of 2D Ni-Fe MOF-Dia and its composite hydrogels were analyzed by SEM and XPS. The mechanical properties of 2D Ni-Fe MOF-Dia/PVA composite hydrogel and the separation efficiency and water flux of 2D Ni-Fe MOF-Dia/PVA composite hydrogel stainless steel screen were studied. The salt resistance, acid and alkali resistance of oil-water separation were tested. The results show that 2D Ni-Fe MOF-Dia/PVA composite hydrogel has excellent mechanical properties, tensile strength and compressive strength reached 1.49 MPa and 0.58 MPa respectively, and exhibited super hydrophilic underwater super thinning oil. The efficiency and flux of 2D Ni-Fe MOF-Dia/PVA stainless steel screen are 99.2% and 742.7 L·m−2·h−1 respectively. It maintains excellent separation efficiency and flux in acidic, alkaline and salt environments, and still maintains stable separation efficiency and flux after 5 cycles.
Metal and Ceramic Matrix Composite
Design, fabrication and testing of ceramic-matrix composite turbine blisk
LIU Xiaochong, XU Youliang, LI Jian, LUO Xiao, GUO Xiaojun, HU Xiaoan, CAO Xueqiang, LI Longbiao, LIU Chidong, DONG Ning, LIU Yongsheng
2023, 40(3): 1696-1706. doi: 10.13801/j.cnki.fhclxb.20220407.001
Turbine rotor is the key component of gas turbine engines. Design, fabrication, and experimental verification of SiC/SiC turbine blisk were investigated. The Spider Web Structure (SWS) SiC preform was used as the reinforcement in turbine blisk. The BN interphase and SiC matrix were deposited on the surface of the SWS SiC fiber preform, respectively. The SiC/SiC turbine blisk was machined by "on-line processing" to form a turbine bisk that meets the design requirements. The environmental barrier coatings (EBCs) were prepared on the surface of SiC/SiC turbine blisk using the atmospheric plasma spraying (APS) method. The CT scan was conducted to characterize the internal defects in SiC/SiC turbine blisk. The mechanical performance evaluation, over rotation test and engine bench test were performed, respectively. The maximum failure strength approached 300 MPa. During the over rotation test, when the rotating speed reached n=104166 r/min, the blade in the turbine blisk broke; and when the rotating speed reached n=108072 r/min, the disk in the turbine blisk broke. During the engine bench test, low cyclic fatigue of N=994 cyclic with maximum speed nmax=60000 r/min and N=100 cyclic with maximum speed nmax=70000 r/min were completed. On January 1, 2022, the SiC/SiC turbine blisk successfully completed the first flight test in Zhuzhou, which is also the first flight test of the domestic SiC/SiC rotor assembly platform and verified the feasibility of SiC/SiC turbine rotor application in gas turbine engines.
Composite Micro-mechanics
Shear stability test and strength prediction of composite laminates
YANG Junchao, CHEN Xiangming, ZOU Peng, WANG Zhe
2023, 40(3): 1707-1717. doi: 10.13801/j.cnki.fhclxb.20220530.002
The shear stability tests of composite laminates without damage and with impact damage were carried out. The post buckling behavior of composite laminates was measured in real time based on digital image correlation (DIC). The test results show that after the introduction of impact damage, the shear buckling waveform and buckling load of composite laminates do not change significantly, and the failure mode changes, the bearing capacity decreased by 9.69%. Then, based on the fracture surface failure theory, a progressive damage failure model of composite materials considering shear nonlinear effect was established, and the shear failure process of composite laminates was simulated. The softened inclusion method was used to simplify the impact damage, and the geometric boundary information of the damage area was directly written into the material model. There was no need to cut the impact damage area, so as to ensure the overall grid quality. Compared with the experimental results, it is found that the model considering shear nonlinearity has no obvious influence on the prediction of buckling load, and has a great influence on the prediction accuracy of post buckling capacity. The error without considering shear nonlinearity can reach more than 20%; The softened inclusion method can effectively simulate the impact damage. The predicted buckling load and failure load errors of composite laminates with impact damage are −3.17% and −1.27% respectively.
Effects of the adhesive layer and prestress on the flexural behavior of damaged steel beams strengthened with CFRP plates
WANG Haitao, BIAN Zhining, XIONG Hao, CHEN Minsheng, WU Qiong
2023, 40(3): 1718-1728. doi: 10.13801/j.cnki.fhclxb.20220409.001
In order to investigate the effects of the adhesive layer and prestress on the flexural behavior of damaged steel beams strengthened with carbon fiber reinforced polymer (CFRP) plates, five damaged H-steel beams were tested under flexure. The characteristic load, load-deflection curve, CFRP plate strain and its strength utilization were analyzed. Test results show that the unbonded CFRP plate has a similar strengthening efficiency to the bonded CFRP plate, with a difference of less than 2% in the characteristic loads. The non-prestressed CFRP plate provides only a very small strengthening efficiency under the normal service state. However, the characteristic loads of steel beams strengthened with the prestressed CFRP plate can be significantly increased by about 30% compared with the non-prestressed CFRP plate. The plane section assumption is satisfied in the bonded CFRP plate-steel beam composite section while it is not satisfied in the unbonded CFRP plate-steel beam composite section. Compared with the non-prestressed CFRP plate, the strength utilization of the CFRP plate can be obviously increased when a prestress is applied in the CFRP plate. The developed finite element model can predict the flexural behavior of the specimens with good accuracy. The increase in the prestress, thickness and elastic modulus of the CFRP plate can increase the flexural strengthening efficiency of damaged steel beams.
Study on the optimization strategy of variable stiffness laminate considering out-of-plane fiber waviness
JU Xiangwen, XIAO Jun, WANG Dongli, ZHAO Cong, WANG Xianfeng
2023, 40(3): 1729-1739. doi: 10.13801/j.cnki.fhclxb.20220429.001
Aiming at the problem of a large number of out-of-plane fiber waviness defects due to gap/overlap defects formed in the automated fiber placement process of variable stiffness laminate, two optimization strategies of ply offset and cut strategy were proposed to design variable stiffness laminate, and the modeling method considering gap/overlap defects was introduced. According to the characteristics of variable stiffness laminate, the influence of out-of-plane fiber waviness was reflected through the analysis of defect-repeating elements, and the out-of-plane fiber coefficient was proposed to characterize the scale of waviness in variable stiffness laminate. Finally, the bending performance of variable stiffness laminate with different optimization strategies was analyzed. The coefficients of out-of-plane waviness corresponding to the benchmark scheme, the optimization strategy of ply offset method and the cut strategy are 0.83, 0.95 and 0.93. The proposed optimization strategy has an obvious inhibitory effect on the scale of out-of-plane waviness of variable stiffness laminate. The maximum thickness deviation of [±<50/65>]6s variable stiffness laminate optimized by ply offset method is 33%, the corresponding buckling load is 9117.1 N, increasing by 17.6%; The maximum thickness deviation of [±<50/65>]6s variable stiffness laminate optimized by the cut strategy is 50%, the corresponding buckling load is 9716.3N, increasing by 25.3%.
Damage and repair study of in-situ polymerized carbon fiber reinforced PMMA composites
GONG Ming, ZHANG Daijun, ZHANG Jiayang, FU Shanlong, LI Jun, CHEN Xiangbao
2023, 40(3): 1740-1750. doi: 10.13801/j.cnki.fhclxb.20220516.002
According to the repairability of thermoplastic composites, the repair process of carbon fiber reinforced PMMA composites was studied. The effects of temperature, pressure, and time on the mechanical properties of the composites were compared. Results show that the optimal repaired properties of composites could be obtained at 200℃ and 0.75 MPa pressure for 10 minutes. By introducing low-speed impact damage, the damaged parts of the composites were repaired by a hot pressing process. The composite's damage behaviors and repair effect were investigated by nondestructive testing and cross-section photography. Experimental results show that the impact damage of carbon fiber reinforced PMMA composites can be divided into two types: Lengthways cracking and delamination in small deformation areas and the mixed-mode of fiber fracture and resin failure in big deformation areas. After repairing, the damaged shape and the internal delamination damages of the damaged samples are recovered well, the volume of the damaged area is significantly reduced, and the compressive strength of the composite is recovered from 140 MPa to 263 MPa, which is 85.7% of the undamaged composite (307 MPa).
Meso-structure analysis and permeability prediction of satin fabric based on Micro-CT
CAO Pengjun, ZHAO Wenbin, YANG Bin, NI Aiqing, WANG Jihui
2023, 40(3): 1751-1763. doi: 10.13801/j.cnki.fhclxb.20220420.002
The optimal resolution determination method of micro-computed tomography (Micro-CT) scanning was presented here based on two-dimensional slices at different resolutions for ideal unit cell model, and the meso-structure and permeability of 3K 5-harness satin woven fabric were characterized based on the CT image at the optimal resolution. Firstly, the ideal unit cell model of the fabric was converted into 2D slices at different resolutions and the effects of resolution on the characterization of cell structure and permeability were investigated. Thereafter, the optimal resolution was determined for fabric CT scanning. Then, the CT image of the fabric with the optimal resolution was used for the meso-structure and through-thickness permeability characterizations of the fabric. The results show that the optimal resolution for the CT scanning of 5-harness satin woven fabric is 15 μm. The path and cross-sectional variation of the yarns in the fabric can be obtained by Micro-CT accurately. The inter-tow voids of the multilayer fabric are arranged periodically along the three main directions with an average inter-tow porosity of 16.6%. The through-thickness permeabilities obtained based on Micro-CT are in good agreement with experimental results.
Fracture mechanism of low-density fiber reinforced nanoporous resin composites
ZHANG Hongyu, QIAN Zhen, CAI Hongxiang, NIU Bo, ZHANG Yayun, LONG Donghui
2023, 40(3): 1764-1772. doi: 10.13801/j.cnki.fhclxb.20220518.002
Fiber reinforced nanoporous resin composites are a kind of lightweight, good insulation and excellent anti-ablation material, which have a typical heterogeneous structure. Under applied load, the internal nanopores will spawn microcracks. Initiation, aggregation and propagation of these microcracks should play a significant role on the strength, deformation and failure properties of the materials. Herein, nanoporous resin composites with different fiber reinforcements have been prepared using needled quartz fiber mesh (NQF) and needled quartz fiber mesh/fiber cloth (NQCF) respectively. Focusing on the mechanical behavior, the present work studied the tensile strength, tensile modulus, elongation at break, crushing strength, bending strength and the tensile fatigue resistance of composites, and the microstructure evolution of composites have been characterized by CT in situ tensile device. The results show that the mechanical properties of composites are greatly improved by introducing the fiber cloth, and the microcracks firstly initiate in the resin matrix around the edge of the needling areas, while the damage of the resin matrix could be effectively hindered by the fiber structure. Finally, finite element models of nano-porous phenolic resin (NPR) and fiber cloth have been established to analyze the fracture mechanism of materials at different scales.
Bearing capacity of reinforced concrete columns strengthened by engineered cementitious composite under small eccentric compression load
WANG Xinling, LI Shiwei, LUO Pengcheng, FAN Jiajun
2023, 40(3): 1773-1784. doi: 10.13801/j.cnki.fhclxb.20220513.002
Small eccentric compression tests on engineered cementitious composite (ECC)-strengthened reinforced concrete (RC) columns and the unstrengthened column as reference were carried out to investigate the influence of the thickness of the ECC reinforcement layer on the compressive performance of strengthened RC columns. The test results show that the ECC reinforcement layer effectively restrains the core concrete, and strengthened columns exhibit obvious ductile failure pattern. Compared with the unstrengthened RC column, the cracks of the reinforced column are thin and dense. When the peak load is reached, the compression zone is not crushed, and the failure process is relatively gentle, with better integrity, exhibiting certain ductility characteristics; The cracking load, peak load and ductility are increased by 107%-236%, 45%-159% and 37.4%-41.3%. The mid-span load-deflection curves are drawn based on the test results, which could be divided into four stages: The elastic stage, the stable crack propagation stage, the maximum load stage and the descending stage. With the increase of reinforcement layer thickness, the strains of ECC and reinforcing bars are smaller under the same load; With the increase of relative eccentricity, the strains of ECC and reinforcing bars are larger under the same load. Based on the theory of concrete structure and mechanical principle, the action mechanism of ECC reinforced layer on the core column was analyzed and the expressions of compressive strength and peak strain of the ECC-strengthened RC columns were proposed. The calculation formula of the bearing capacity of the strengthened column was established and the relative error between the theoretical results and the experimental values is less than 10%, which is in good agreement with the test results. Hence, the established calculation method could provide theoretical support for the application of ECC strengthened concrete column in practical engineering.
Intelligent detection of delamination defect in curved structural quartz fiber reinforced polymer composites using terahertz technology
WANG Qiang, ZHAO Boyan, LIU Qiuhan, LIU Wenquan, GAO Jianguo, ZHANG Pengtao
2023, 40(3): 1785-1796. doi: 10.13801/j.cnki.fhclxb.20220516.001
In order to explore an intelligent means of detecting delamination defects in airborne warning and control system radomes made of quartz fiber reinforced polymers (QFRP), a reflective terahertz time-domain spectroscopy system based on fiber coupling was built by combining a cooperative robot. The signal noise ratio dynamic range is about 60 dB after testing. Terahertz nondestructive testing of curved structural QFRP sample with pre-buried simulated delamination defects was performed using the build system. The internal pre-buried defects were visually identified in the reflected terahertz images obtained from different scanning areas. An improved YOLOv4 algorithm was used to obtain 90.18% accuracy and 91.26% recall in automatic defect identification, which were 3.37% and 4.01% higher than the original YOLOv4 algorithm, respectively. The small target defects can also be recognized well. This experiment enriches the design and detection of airborne warning and control system radome sample, explores the detection of curved structural QFRP sample using terahertz imaging method and provides a new intelligent nondestructive testing method of airborne warning and control system radomes detection, which has the value of engineering application.
Interface connection mechanism and fracture behavior of nickel-based composites fabricated by selective laser melting
GAO Yongkang, CHEN Hongsheng, NIE Huihui, XUE Bolin, LIU Run'ai, ZHENG Liuwei, WANG Wenxian, CHEN Xiaochun
2023, 40(3): 1797-1806. doi: 10.13801/j.cnki.fhclxb.20220419.006
Based on the excellent structural/functional properties of particle-reinforced nickel-based composites, they have a wide application prospects in aerospace, nuclear power, military industry and electronics. The internal heterogeneous interface connection mechanism, reinforcement mechanism and fracture behavior of the tungsten carbide (WC) particle-reinforced IN718 composites (WC/IN718) prepared by using the mechanical ball grinding powder+selective laser melting (SLM) was analyzed. The results show that with the increase of WC particles content (0wt%-20wt%), the specimen is well-formed, WC particles are evenly distributed inside the matrix and no defects at the heterogeneous interface, carbon-poor W2C layer and carbide layer are produced at the interface, and the matrix alloy mainly grows at the form of columnar crystals. Due to the different energy density distribution within the melting pool, the fracture mode of WC particles at the low temperature position is that firstly the interface reaction layer form at the periphery of WC particle and then WC are fractured by thermal stress. However, WC particles at the high temperature position preferentially break into small particles in size, and then the interface reaction layer is formed with the molten matrix alloy, which is distributed within the matrix. As the content of WC particles increases, the strength of composites tends to increase, while the fracture toughness is reduced, and the tensile strength can be up to 1280 MPa. The reinforcement mechanism is mainly the load transfer effect, the fracture mechanism is the brittle fracture of WC particles and the toughness fracture of matrix alloy.
Simulation of curing process of epoxy resin with embedded FBGs considering interfacial strain transfer mechanism
LEI Weihua, HU Haixiao, CAO Dongfeng, XIAO Lei, TIAN Yizhou, LI Shuxin, WANG Jingnan
2023, 40(3): 1807-1817. doi: 10.13801/j.cnki.fhclxb.20220419.002
The strain transfer mechanism between fiber Bragg grating sensor (FBGs) and matrix, which is the basic problem of cure monitoring, was explored by combining of experimental and numerical analysis. Firstly, curing kinetics, thermal expansion, chemical shrinkage and glass transition behavior of the resin were characterized. Then, the developments of temperature and strain were monitored by thermocouple and FBGs during the curing process of epoxy resin. Finally, the thermal-chemical-mechanical multi-field coupling numerical analysis was used to simulate the curing process. The interface transfer mechanism was discussed by comparing the results of pure resin model, FBGs model with binding constraint and FBSs model with cohesive behavior. The results indicate that the strain monitored by FBGs is significantly smaller than that of the resin due to the shear lag effect and interface slip behavior at the early curing stage, and the shear lag effect plays a dominant role. The interfacial strain transfer mechanism during curing process can be described properly by cohesive behavior, and the error between numerical prediction and experimental value is small.