2024 Vol. 41, No. 1
2024, 41(1): 1-15.
doi: 10.13801/j.cnki.fhclxb.20230921.002
Abstract:
Compared to traditional liquid-state lithium batteries, solid-state lithium batteries have distinct advantages such as high safety and high specific energy, and have attracted widespread attention in both academia and industry. Exploring organic-inorganic composite solid electrolytes that combine excellent mechanical properties, high ion conductivity, and large electrochemical windows is a feasible solution to developing high-performance solid-state lithium batteries. In recent years, composite solid-state electrolytes based on polymer electrolytes and inorganic materials have become a hot topic. In this tutorial review, we focus on recent advances in various classes of organic-inorganic composite electrolytes and summarize the state-of-the-art strategies for improving the performance (Especially the ionic conductivity) of solid-state electrolytes. This is followed by detailed discussions on the implementation of composite solid-electrolytes in various energy storage systems, including solid-state lithium-metal batteries, solid-state lithium-sulfur batteries and solid-state lithium-air batteries, and the current challenges and future opportunities of organic-inorganic composite solid-state electrolytes for lithium batteries are also provided.
Compared to traditional liquid-state lithium batteries, solid-state lithium batteries have distinct advantages such as high safety and high specific energy, and have attracted widespread attention in both academia and industry. Exploring organic-inorganic composite solid electrolytes that combine excellent mechanical properties, high ion conductivity, and large electrochemical windows is a feasible solution to developing high-performance solid-state lithium batteries. In recent years, composite solid-state electrolytes based on polymer electrolytes and inorganic materials have become a hot topic. In this tutorial review, we focus on recent advances in various classes of organic-inorganic composite electrolytes and summarize the state-of-the-art strategies for improving the performance (Especially the ionic conductivity) of solid-state electrolytes. This is followed by detailed discussions on the implementation of composite solid-electrolytes in various energy storage systems, including solid-state lithium-metal batteries, solid-state lithium-sulfur batteries and solid-state lithium-air batteries, and the current challenges and future opportunities of organic-inorganic composite solid-state electrolytes for lithium batteries are also provided.
2024, 41(1): 16-37.
doi: 10.13801/j.cnki.fhclxb.20230814.002
Abstract:
Thermal conductive composites have a wide range of applications in the fields of electronic packaging, motor materials, batteries and heat exchange equipment. Polyvinylidene fluoride (PVDF) has excellent electrical properties, good mechanical strength and high temperature resistance. It is one of the ideal materials for applications in electronics, aerospace and other industries. However, the low thermal conductivity restricts its further development. It is urgent to develop PVDF-based high thermal conductivity composites. The key to its preparation is how to select high thermal conductivity fillers, design thermal conduction pathways, and regulate interface thermal resistance. Based on the theoretical knowledge of the mechanism, model, equation and numerical simulation of polymer-based thermal conductive composites, combined with the crystal structure of PVDF, this paper introduces the current development level of thermal conductivity of PVDF-based thermal conductive composites, and the different effects of various fillers and preparation processes on their thermal conductivity. The latest research progress of high thermal conductivity PVDF composites is reviewed from the perspectives of composite strategy, network structure and interface bonding. In addition, its future development is also prospected.
Thermal conductive composites have a wide range of applications in the fields of electronic packaging, motor materials, batteries and heat exchange equipment. Polyvinylidene fluoride (PVDF) has excellent electrical properties, good mechanical strength and high temperature resistance. It is one of the ideal materials for applications in electronics, aerospace and other industries. However, the low thermal conductivity restricts its further development. It is urgent to develop PVDF-based high thermal conductivity composites. The key to its preparation is how to select high thermal conductivity fillers, design thermal conduction pathways, and regulate interface thermal resistance. Based on the theoretical knowledge of the mechanism, model, equation and numerical simulation of polymer-based thermal conductive composites, combined with the crystal structure of PVDF, this paper introduces the current development level of thermal conductivity of PVDF-based thermal conductive composites, and the different effects of various fillers and preparation processes on their thermal conductivity. The latest research progress of high thermal conductivity PVDF composites is reviewed from the perspectives of composite strategy, network structure and interface bonding. In addition, its future development is also prospected.
2024, 41(1): 38-49.
doi: 10.13801/j.cnki.fhclxb.20230423.001
Abstract:
Bone defects caused by bone diseases are a very challenging issue in modern medicine. Both pathological changes in normal bone tissue and physical damage caused by external factors can lead to difficult-to-heal bone defects. The complex microenvironment of the bone defect site makes treatment conditions more demanding. Constructing scaffolds for bone defects is an important direction in bone tissue engineering technology and a crucial means to solve the problem of bone defect diseases. This article briefly introduces the preparation principles and methods of hydroxyapatite/graphene oxide (HA/GO) composite materials. HA/GO has no apparent toxicity to bone cells, and its rough surface structure is more conducive to the proliferation and differentiation of bone cells. Based on this, the construction methods and performance of HA/GO composite scaffolds for treating bone defect diseases are described in detail. Finally, the development prospects and challenges of HA/GO composite scaffolds in the treatment of bone diseases are discussed.
Bone defects caused by bone diseases are a very challenging issue in modern medicine. Both pathological changes in normal bone tissue and physical damage caused by external factors can lead to difficult-to-heal bone defects. The complex microenvironment of the bone defect site makes treatment conditions more demanding. Constructing scaffolds for bone defects is an important direction in bone tissue engineering technology and a crucial means to solve the problem of bone defect diseases. This article briefly introduces the preparation principles and methods of hydroxyapatite/graphene oxide (HA/GO) composite materials. HA/GO has no apparent toxicity to bone cells, and its rough surface structure is more conducive to the proliferation and differentiation of bone cells. Based on this, the construction methods and performance of HA/GO composite scaffolds for treating bone defect diseases are described in detail. Finally, the development prospects and challenges of HA/GO composite scaffolds in the treatment of bone diseases are discussed.
2024, 41(1): 50-59.
doi: 10.13801/j.cnki.fhclxb.20230731.004
Abstract:
Nanostructured catalytic materials are considered to be a favorable design concept for various energy conversion and storage systems. Nanosized metal catalysts supported on oxide scaffolds have been adopted in numerous fields, including fuel cells, gas sensors, and chemical reforming devices. Nevertheless, nanometal catalysts often suffer from durability issues. Although surface-decorated nanometal catalysts can deliver sufficient catalytic activity, some of them still exhibit durability issues in severe operating environments. Recently, nanocatalysts produced by in situ exsolution have been demonstrated to overcome the practical limitations of conventional nanometal catalysts. The exsolution is defined as a process in which a catalytically active dopant in perovskite oxide is exsolved on its surface as highly dispersed nanometal catalysts. In particular, exsolution nanocatalysts embedded on perovskite oxides exhibit higher nanoparticle densities and greater resistance to particle agglomeration than conventional nanometal catalysts. This perspective presents an overview of recent advances in exsolution materials for energy applications including fundamental mechanisms, design strategies for host oxides, and practical applications. The future prospects of these materials and the scope for further optimization are also discussed.
Nanostructured catalytic materials are considered to be a favorable design concept for various energy conversion and storage systems. Nanosized metal catalysts supported on oxide scaffolds have been adopted in numerous fields, including fuel cells, gas sensors, and chemical reforming devices. Nevertheless, nanometal catalysts often suffer from durability issues. Although surface-decorated nanometal catalysts can deliver sufficient catalytic activity, some of them still exhibit durability issues in severe operating environments. Recently, nanocatalysts produced by in situ exsolution have been demonstrated to overcome the practical limitations of conventional nanometal catalysts. The exsolution is defined as a process in which a catalytically active dopant in perovskite oxide is exsolved on its surface as highly dispersed nanometal catalysts. In particular, exsolution nanocatalysts embedded on perovskite oxides exhibit higher nanoparticle densities and greater resistance to particle agglomeration than conventional nanometal catalysts. This perspective presents an overview of recent advances in exsolution materials for energy applications including fundamental mechanisms, design strategies for host oxides, and practical applications. The future prospects of these materials and the scope for further optimization are also discussed.
2024, 41(1): 60-77.
doi: 10.13801/j.cnki.fhclxb.20230802.001
Abstract:
Textiles are widely used for drug loading because of their large specific surface area, good flexibility, wide applicability, good loading of drugs and slow release and controlled release ability. The preparation methods of drug-loaded textiles mainly include spinning method, finishing method and composite method. The preparation methods of drug-loaded textiles were used as the starting point to classify the drug-loaded textiles, the preparation methods, drug release characteristics, applicability and current research status of each type of drug-loaded textiles were described, the preparation characteristics, advantages and disadvantages of preparation methods of each type of drug-loaded textiles were summarized, and finally the future research directions of drug-loaded textiles were proposed, to provide reference for further research on drug-loaded textiles and their preparation methods.
Textiles are widely used for drug loading because of their large specific surface area, good flexibility, wide applicability, good loading of drugs and slow release and controlled release ability. The preparation methods of drug-loaded textiles mainly include spinning method, finishing method and composite method. The preparation methods of drug-loaded textiles were used as the starting point to classify the drug-loaded textiles, the preparation methods, drug release characteristics, applicability and current research status of each type of drug-loaded textiles were described, the preparation characteristics, advantages and disadvantages of preparation methods of each type of drug-loaded textiles were summarized, and finally the future research directions of drug-loaded textiles were proposed, to provide reference for further research on drug-loaded textiles and their preparation methods.
2024, 41(1): 78-91.
doi: 10.13801/j.cnki.fhclxb.20230731.003
Abstract:
MXene materials have been widely used in many fields, such as electromagnetic shielding, sensing, and wastewater treatment. The excellent electrochemical properties of MXene makes it demonstrate broad application prospects in the field of energy storage as well. However, the self-stacking and easy oxidation characteristics of MXene limit its further development. The assembly of MXene into three-dimensional (3D) structural composites is one of the effective way to solve the above problems. The 3D porous structure can provide more channels and active sites for ion transport or storage, which can effectively improve the electrochemical performance. This article reviews the recent researches of MXene composite aerogels. The preparation methods and applications of MXene composite aerogels in energy storage, such as batteries and supercapacitors, are discussed in detail. Finally, the prospects for its future development direction were also presented.
MXene materials have been widely used in many fields, such as electromagnetic shielding, sensing, and wastewater treatment. The excellent electrochemical properties of MXene makes it demonstrate broad application prospects in the field of energy storage as well. However, the self-stacking and easy oxidation characteristics of MXene limit its further development. The assembly of MXene into three-dimensional (3D) structural composites is one of the effective way to solve the above problems. The 3D porous structure can provide more channels and active sites for ion transport or storage, which can effectively improve the electrochemical performance. This article reviews the recent researches of MXene composite aerogels. The preparation methods and applications of MXene composite aerogels in energy storage, such as batteries and supercapacitors, are discussed in detail. Finally, the prospects for its future development direction were also presented.
2024, 41(1): 92-107.
doi: 10.13801/j.cnki.fhclxb.20230728.002
Abstract:
Carbon dots (CDs) have advantages such as low toxicity, water tolerance, good biocompatibility, easy modification, excellent electrochemical activity, and optical properties. CDs can be used for the modification of polymer materials, endowing them with good optical properties and various other functionalities. Adding CDs to polyvinyl alcohol (PVA) not only effectively improves the mechanical properties and thermal stability of PVA, but also endows PVA with new properties, such as improved conductivity, dielectric properties, thermoelectric properties, and other electrical parameters, optical properties such as fluorescence, phosphorescence, and UV resistance, antibacterial, antioxidant, and water resistance, which make PVA stand out in the fields of electromagnetic shielding, storage devices, capacitors, sensors, optical devices and functional packaging bags. This article focuses on the latest research progress in the properties of PVA modified with CDs (CDs/PVA), and prospects the future application of CDs/PVA, which is of great significance for expanding its application fields.
Carbon dots (CDs) have advantages such as low toxicity, water tolerance, good biocompatibility, easy modification, excellent electrochemical activity, and optical properties. CDs can be used for the modification of polymer materials, endowing them with good optical properties and various other functionalities. Adding CDs to polyvinyl alcohol (PVA) not only effectively improves the mechanical properties and thermal stability of PVA, but also endows PVA with new properties, such as improved conductivity, dielectric properties, thermoelectric properties, and other electrical parameters, optical properties such as fluorescence, phosphorescence, and UV resistance, antibacterial, antioxidant, and water resistance, which make PVA stand out in the fields of electromagnetic shielding, storage devices, capacitors, sensors, optical devices and functional packaging bags. This article focuses on the latest research progress in the properties of PVA modified with CDs (CDs/PVA), and prospects the future application of CDs/PVA, which is of great significance for expanding its application fields.
2024, 41(1): 108-120.
doi: 10.13801/j.cnki.fhclxb.20230802.003
Abstract:
Thermal insulation of buildings plays an important role to reduce energy consumption for maintaining an optimal atmosphere inside the building. Hence, it is crucial to improve the thermal insulation performance of the building materials, especially to achieve energy savings through the reduction of energy losses for heating-cooling purposes. Therefore, the research on building materials with excellent thermal insulation properties has become one of the focuses of current thermal insulation research. Compared with traditional thermal insulation building materials, biomass-based cellulose thermal insulation aerogel has superior physical and chemical properties, such as low thermal conductivity, high specific surface area, renewable, cost-effective and environment-friendly. It is an ideal new building material for future building energy saving technology. In this paper, the preparation technology, research status, existing problems and application of biomass-based cellulose thermal insulation aerogel in building materials (roof, interior and exterior walls and glass, etc.) in recent years are reviewed. Finally, the challenges faced by biomass-based cellulose aerogel in the application of thermal insulation materials are briefly discussed, and its future development direction is prospected.
Thermal insulation of buildings plays an important role to reduce energy consumption for maintaining an optimal atmosphere inside the building. Hence, it is crucial to improve the thermal insulation performance of the building materials, especially to achieve energy savings through the reduction of energy losses for heating-cooling purposes. Therefore, the research on building materials with excellent thermal insulation properties has become one of the focuses of current thermal insulation research. Compared with traditional thermal insulation building materials, biomass-based cellulose thermal insulation aerogel has superior physical and chemical properties, such as low thermal conductivity, high specific surface area, renewable, cost-effective and environment-friendly. It is an ideal new building material for future building energy saving technology. In this paper, the preparation technology, research status, existing problems and application of biomass-based cellulose thermal insulation aerogel in building materials (roof, interior and exterior walls and glass, etc.) in recent years are reviewed. Finally, the challenges faced by biomass-based cellulose aerogel in the application of thermal insulation materials are briefly discussed, and its future development direction is prospected.
2024, 41(1): 121-133.
doi: 10.13801/j.cnki.fhclxb.20230724.003
Abstract:
Under the background of the "dual carbon" strategy, the research progress of bio-based fluorescent intelligent materials and their multifunctional applications have attracted much attention. Cellulose is the most abundant natural polymer material in nature. Cellulose-based solid-state fluorescence sensors not only have the advantages of green, low cost, biodegradability, good hydrophilicity, good biocompatibility, and non-toxicity, but also have advantages such as portability, efficiency, long lifespan, high stability, and wide applicability compared to traditional fluorescent molecular probes. The research progress of cellulose-based solid-state fluorescent sensors prepared by chemical modification in recent years was reviewed. The mechanism of the combination of cellulose with different fluorescent molecules was clarified. Fluorescent molecules were introduced to the surface of cellulose by covalent crosslinking or introduction of functional groups. Various types of cellulose-based solid-state fluorescence sensors, including cationic, anionic, pH-type, nitroaromatic, gas-type and double (multi) re-responsive types, were introduced. The advantages of cellulose-based solid-state fluorescence sensors in environmental detection, bioimaging, food safety, fluorescence printing and anti-counterfeiting applications were also introduced. Finally, the relevant research on cellulose-based fluorescent smart sensors is discussed in detail, and their development opportunities and future challenges are prospected.
Under the background of the "dual carbon" strategy, the research progress of bio-based fluorescent intelligent materials and their multifunctional applications have attracted much attention. Cellulose is the most abundant natural polymer material in nature. Cellulose-based solid-state fluorescence sensors not only have the advantages of green, low cost, biodegradability, good hydrophilicity, good biocompatibility, and non-toxicity, but also have advantages such as portability, efficiency, long lifespan, high stability, and wide applicability compared to traditional fluorescent molecular probes. The research progress of cellulose-based solid-state fluorescent sensors prepared by chemical modification in recent years was reviewed. The mechanism of the combination of cellulose with different fluorescent molecules was clarified. Fluorescent molecules were introduced to the surface of cellulose by covalent crosslinking or introduction of functional groups. Various types of cellulose-based solid-state fluorescence sensors, including cationic, anionic, pH-type, nitroaromatic, gas-type and double (multi) re-responsive types, were introduced. The advantages of cellulose-based solid-state fluorescence sensors in environmental detection, bioimaging, food safety, fluorescence printing and anti-counterfeiting applications were also introduced. Finally, the relevant research on cellulose-based fluorescent smart sensors is discussed in detail, and their development opportunities and future challenges are prospected.
2024, 41(1): 134-143.
doi: 10.13801/j.cnki.fhclxb.20230404.002
Abstract:
With the increasing integration density and power density of electronic products. It is particularly important to optimize the research of thermal interface materials. In this paper, one-dimensional silicon carbide whisker (SiCw) was used as filler and silicone rubber was used as matrix to prepare thermal conductive silicone rubber composites. The microstructure, phase structure, thermal conductivity and insulation of the composites were comprehensively analyzed. Firstly, the modified material of SiCw coated by Fe3O4 was prepared by coprecipitation method. Secondly, SiCw coated with Fe3O4 was evenly dispersed in the liquid silicone rubber matrix. Finally, it is placed in a constant magnetic field to complete whisker orientation and matrix curing. The results show that the surface of SiCw whiskers is coated with Fe3O4 nanoparticles, and they are oriented in the silicone rubber matrix. Silicone rubber composites with SiCw oriented structure were prepared. When the oriented SiCw reaches 10wt%, the thermal conductivity can be increased by 72% compared with pure silicone rubber, and it is 40% higher than that filled with non-oriented 10wt%SiCw. Compared with pure silicone rubber, the volume resistivity decreases by two orders of magnitude. But it still has good insulation. The silicone rubber composites with randomly dispersed and oriented SiCw were simulated by COMSOL. The simulation results show that the thermal conductivity of silicone rubber can be improved by 60% with 10wt%SiCw. The volume resistivity is above 1015 Ω∙cm. However, 10wt% oriented SiCw can improve the thermal conductivity of silicone rubber by 170% and the volume resistivity is above 1014 Ω∙cm. It is consistent with the trend of experimental results.
With the increasing integration density and power density of electronic products. It is particularly important to optimize the research of thermal interface materials. In this paper, one-dimensional silicon carbide whisker (SiCw) was used as filler and silicone rubber was used as matrix to prepare thermal conductive silicone rubber composites. The microstructure, phase structure, thermal conductivity and insulation of the composites were comprehensively analyzed. Firstly, the modified material of SiCw coated by Fe3O4 was prepared by coprecipitation method. Secondly, SiCw coated with Fe3O4 was evenly dispersed in the liquid silicone rubber matrix. Finally, it is placed in a constant magnetic field to complete whisker orientation and matrix curing. The results show that the surface of SiCw whiskers is coated with Fe3O4 nanoparticles, and they are oriented in the silicone rubber matrix. Silicone rubber composites with SiCw oriented structure were prepared. When the oriented SiCw reaches 10wt%, the thermal conductivity can be increased by 72% compared with pure silicone rubber, and it is 40% higher than that filled with non-oriented 10wt%SiCw. Compared with pure silicone rubber, the volume resistivity decreases by two orders of magnitude. But it still has good insulation. The silicone rubber composites with randomly dispersed and oriented SiCw were simulated by COMSOL. The simulation results show that the thermal conductivity of silicone rubber can be improved by 60% with 10wt%SiCw. The volume resistivity is above 1015 Ω∙cm. However, 10wt% oriented SiCw can improve the thermal conductivity of silicone rubber by 170% and the volume resistivity is above 1014 Ω∙cm. It is consistent with the trend of experimental results.
2024, 41(1): 144-154.
doi: 10.13801/j.cnki.fhclxb.20230616.006
Abstract:
2.5D woven carbon fiber-glass fiber/bismaleimide resin composite was prepared by three-dimensional textile technology and resin transfer molding (RTM), and the mechanical properties of three-point bending and interlaminar shear were tested at room temperature (25℃) and high temperature (150℃, 240℃, 300℃), respectively, and the influence of temperature on the mechanical behavior and damage mechanism of the composites was explored. The results show that temperature has a significant effect on the mechanical properties and damage mode of 2.5D woven carbon fiber-glass fiber/bismaleimide resin composites. Temperature rise leads to weakening of fiber/matrix interface adhesion. Compared with the room temperature environment, the flexural strength, flexural modulus and interlaminar shear strength of the composite at 300℃ decrease by 23.06%, 70.01% and 18.93%. Under bending load, the failure mode of 2.5D woven hybrid composites at room temperature is mainly dominated by local fiber fracture and matrix cracking, while high temperature damage is dominated by fiber/matrix interface debonding. Under shear load, the failure mode of 2.5D woven hybrid composites at room temperature is mainly stratified failure. With the increase of temperature, the composites appear plastic deformation due to the softening of matrix, matrix cracking, interface debonding and stratified failure determine the final failure of the material.
2.5D woven carbon fiber-glass fiber/bismaleimide resin composite was prepared by three-dimensional textile technology and resin transfer molding (RTM), and the mechanical properties of three-point bending and interlaminar shear were tested at room temperature (25℃) and high temperature (150℃, 240℃, 300℃), respectively, and the influence of temperature on the mechanical behavior and damage mechanism of the composites was explored. The results show that temperature has a significant effect on the mechanical properties and damage mode of 2.5D woven carbon fiber-glass fiber/bismaleimide resin composites. Temperature rise leads to weakening of fiber/matrix interface adhesion. Compared with the room temperature environment, the flexural strength, flexural modulus and interlaminar shear strength of the composite at 300℃ decrease by 23.06%, 70.01% and 18.93%. Under bending load, the failure mode of 2.5D woven hybrid composites at room temperature is mainly dominated by local fiber fracture and matrix cracking, while high temperature damage is dominated by fiber/matrix interface debonding. Under shear load, the failure mode of 2.5D woven hybrid composites at room temperature is mainly stratified failure. With the increase of temperature, the composites appear plastic deformation due to the softening of matrix, matrix cracking, interface debonding and stratified failure determine the final failure of the material.
2024, 41(1): 155-169.
doi: 10.13801/j.cnki.fhclxb.20230529.006
Abstract:
Polydicyclopentadiene (PDCPD) as a thermosetting resin with excellent comprehensive performance, can be composited with continuous carbon fibers (CF), for the application of various engineering field to meet the requirements of lightweight, energy conservation and environmental protection. In this paper, firstly, the viscosity of the DCPD prepolymer could meet the demands of vacuum assisted resin infusion (VARI) molding process by adjusting the content of Grubbs 2 catalyst. Subsequently, the carbon fiber was subjected desizing treatment, and then compounded with the prepolymer added with sufficient catalyst. The tensile, flexural, V-notch shear, interlaminar fracture toughness, impact, and thermodynamic properties of PDCPD/CF composites were compared with thegeneral epoxy resin (EP)/CF composites, The failure mechanisms of PDCPD/CF composites under different loading modes were detected, and the key points and directions for their application in the engineering field were explored. The results show that the interface between the carbon fibers after desizing and PDCPD is well bonded, and the strength of PDCPD/CF composite is comparable to that of EP/CF composite. Although PDCPD/CF composite had weaker deformation resistance, they still had a certain degree of bearing capacity after being subjected to the ultimate loads. From the perspective of interlaminar fracture toughness, PDCPD/CF composites have excellent delamination resistance, with mode I and mode II fracture toughness equivalent to 406% and 250% of CF/EP composites, respectively. A barely visible impact damage (BVID) has formed on the top surface of a 3.2 mm-thickness PDCPD laminate after being subjected to a 40 J impact, while there is no significant fiber breakage on the bottom surface. The residual compression strength of PDCPD/CF composites is 34.7% higher than the EP/CF composite.
Polydicyclopentadiene (PDCPD) as a thermosetting resin with excellent comprehensive performance, can be composited with continuous carbon fibers (CF), for the application of various engineering field to meet the requirements of lightweight, energy conservation and environmental protection. In this paper, firstly, the viscosity of the DCPD prepolymer could meet the demands of vacuum assisted resin infusion (VARI) molding process by adjusting the content of Grubbs 2 catalyst. Subsequently, the carbon fiber was subjected desizing treatment, and then compounded with the prepolymer added with sufficient catalyst. The tensile, flexural, V-notch shear, interlaminar fracture toughness, impact, and thermodynamic properties of PDCPD/CF composites were compared with thegeneral epoxy resin (EP)/CF composites, The failure mechanisms of PDCPD/CF composites under different loading modes were detected, and the key points and directions for their application in the engineering field were explored. The results show that the interface between the carbon fibers after desizing and PDCPD is well bonded, and the strength of PDCPD/CF composite is comparable to that of EP/CF composite. Although PDCPD/CF composite had weaker deformation resistance, they still had a certain degree of bearing capacity after being subjected to the ultimate loads. From the perspective of interlaminar fracture toughness, PDCPD/CF composites have excellent delamination resistance, with mode I and mode II fracture toughness equivalent to 406% and 250% of CF/EP composites, respectively. A barely visible impact damage (BVID) has formed on the top surface of a 3.2 mm-thickness PDCPD laminate after being subjected to a 40 J impact, while there is no significant fiber breakage on the bottom surface. The residual compression strength of PDCPD/CF composites is 34.7% higher than the EP/CF composite.
2024, 41(1): 170-179.
doi: 10.13801/j.cnki.fhclxb.20230515.003
Abstract:
The liquid oxygen tanks that made of carbon fiber/epoxy resin composites are vital for weight reduction in new generation spacecraft such as heavy rockets and space shuttles. However, the incompatibility of epoxy resin with liquid oxygen limits their application. Thermogravimetric analyser, the Kissinger method, the Coasts-Redfern method and thermogravimetric-infrared-gas chromatography/mass spectrometry were used to investigate the thermal degradation behaviors and mechanism of 10-(2, 5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphafi-10-oxide (ODOPB)-modified liquid oxygen-compatible epoxy resin (ODOPB-EP). The results show that the thermal degradation mechanism of ODOPB-EP is a phase boundary reaction, corresponding to the degradation mechanism function g(α)=1−(1−α)1/3, α is conversion rate. During the thermal degradation process, the resin breaks from the weak bonds of C—N and C—O. With the increase of temperature, aromatic substances such as phenol and its derivatives are released. Besides, ODOPB part in resin produces biphenyl and other substances, accompanied by the release of phosphorus-containing radicals. The phosphorus-containing radicals could exert quenching effects, which is conducive to improving the compatibility of the resin with liquid oxygen. This study provides a theoretic basis for verifying the compatible mechanism of polymers with liquid oxygen.
The liquid oxygen tanks that made of carbon fiber/epoxy resin composites are vital for weight reduction in new generation spacecraft such as heavy rockets and space shuttles. However, the incompatibility of epoxy resin with liquid oxygen limits their application. Thermogravimetric analyser, the Kissinger method, the Coasts-Redfern method and thermogravimetric-infrared-gas chromatography/mass spectrometry were used to investigate the thermal degradation behaviors and mechanism of 10-(2, 5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphafi-10-oxide (ODOPB)-modified liquid oxygen-compatible epoxy resin (ODOPB-EP). The results show that the thermal degradation mechanism of ODOPB-EP is a phase boundary reaction, corresponding to the degradation mechanism function g(α)=1−(1−α)1/3, α is conversion rate. During the thermal degradation process, the resin breaks from the weak bonds of C—N and C—O. With the increase of temperature, aromatic substances such as phenol and its derivatives are released. Besides, ODOPB part in resin produces biphenyl and other substances, accompanied by the release of phosphorus-containing radicals. The phosphorus-containing radicals could exert quenching effects, which is conducive to improving the compatibility of the resin with liquid oxygen. This study provides a theoretic basis for verifying the compatible mechanism of polymers with liquid oxygen.
2024, 41(1): 180-187.
doi: 10.13801/j.cnki.fhclxb.20230525.001
Abstract:
Carbon soot particles (CSPS) widely exists and is easy to collect in the production and living, with the size of the nanoscale and good photothermal properties, is one of the important candidate materials for photothermal materials. CSPS are obtained by collecting the incomplete combustion by-products of fuels such as candles and edible oils. The composite coating CSPS/MPVDF-ER was constructed with carbon soot particles, alkali modified polyvinylidene fluoride (MPVDF) and epoxy resin (ER) as the main raw materials, and various factors affecting the photothermal properties, hydrophobicity of the composite coating were studied. The results show that the water repellency of CSPS/MPVDF-ER is significantly improved with the addition of CSPS (Water contact angle (WCA)>163°, water sliding angle (WSA)<1°). With the addition of CSPS, the photothermal efficiency of CSPS/MPVDF-ER coating is gradually increased, and the contact angle and water impact resistance of CSPS/MPVDF-ER coating are gradually enhanced. The maximum photothermal efficiency (temperature difference with the environment ΔT=88℃) of the coating is reached when the mass ratio of CSPS and MPVDF-ER is 0.05, CSPS/MPVDF-ER coating has good resistance to acid, alkali and UV. The CSPS/MPVDF-ER coating prepared by a simple method from a wide range of CSPS nanoparticles has excellent photothermal conversion efficiency and superhydrophobic properties, which provides a feasible method for the preparation of low-cost and high-strength superhydrophobic antifouling photothermal coatings.
Carbon soot particles (CSPS) widely exists and is easy to collect in the production and living, with the size of the nanoscale and good photothermal properties, is one of the important candidate materials for photothermal materials. CSPS are obtained by collecting the incomplete combustion by-products of fuels such as candles and edible oils. The composite coating CSPS/MPVDF-ER was constructed with carbon soot particles, alkali modified polyvinylidene fluoride (MPVDF) and epoxy resin (ER) as the main raw materials, and various factors affecting the photothermal properties, hydrophobicity of the composite coating were studied. The results show that the water repellency of CSPS/MPVDF-ER is significantly improved with the addition of CSPS (Water contact angle (WCA)>163°, water sliding angle (WSA)<1°). With the addition of CSPS, the photothermal efficiency of CSPS/MPVDF-ER coating is gradually increased, and the contact angle and water impact resistance of CSPS/MPVDF-ER coating are gradually enhanced. The maximum photothermal efficiency (temperature difference with the environment ΔT=88℃) of the coating is reached when the mass ratio of CSPS and MPVDF-ER is 0.05, CSPS/MPVDF-ER coating has good resistance to acid, alkali and UV. The CSPS/MPVDF-ER coating prepared by a simple method from a wide range of CSPS nanoparticles has excellent photothermal conversion efficiency and superhydrophobic properties, which provides a feasible method for the preparation of low-cost and high-strength superhydrophobic antifouling photothermal coatings.
2024, 41(1): 188-195.
doi: 10.13801/j.cnki.fhclxb.20230512.002
Abstract:
The low frequency radar-stealth performance of the dielectric metamaterial for broadband wave-absorbing honeycomb sandwich composites was studied. The electromagnetic response characteristics of the carbon fiber dielectric metamaterial units and their effects on the electrical and mechanical properties of wave-absorbing honeycomb sandwich composites were analyzed. The results show that the electromagnetic response of the carbon fiber metamaterial units can be comparable to that of the metal metamaterial units. When the height of the wave-absorbing honeycomb is 50 mm and the thickness of the wave-transmitting skin is 1 mm, the introduction of the carbon fiber metamaterial units can significantly improve the low-frequency wave-absorbing performance of the honeycomb sandwich composites. The weakest reflectivity and the averaged reflectivity in the L-band are increased by more than 2 dB and 4 dB, respectively. The mechanical properties of the wave-transmitting skin with carbon fiber dielectric metamaterial are close to that without metamaterial units. The introduction of carbon fiber dielectric metamaterial units shows no negative effects on the mechanical properties of the wave-transmitting skin.
The low frequency radar-stealth performance of the dielectric metamaterial for broadband wave-absorbing honeycomb sandwich composites was studied. The electromagnetic response characteristics of the carbon fiber dielectric metamaterial units and their effects on the electrical and mechanical properties of wave-absorbing honeycomb sandwich composites were analyzed. The results show that the electromagnetic response of the carbon fiber metamaterial units can be comparable to that of the metal metamaterial units. When the height of the wave-absorbing honeycomb is 50 mm and the thickness of the wave-transmitting skin is 1 mm, the introduction of the carbon fiber metamaterial units can significantly improve the low-frequency wave-absorbing performance of the honeycomb sandwich composites. The weakest reflectivity and the averaged reflectivity in the L-band are increased by more than 2 dB and 4 dB, respectively. The mechanical properties of the wave-transmitting skin with carbon fiber dielectric metamaterial are close to that without metamaterial units. The introduction of carbon fiber dielectric metamaterial units shows no negative effects on the mechanical properties of the wave-transmitting skin.
2024, 41(1): 196-206.
doi: 10.13801/j.cnki.fhclxb.20230427.002
Abstract:
Due to the poor conductivity, carbon fiber reinforced resin matrix composites (CFRP) cannot meet the lightning strike protection requirement of aircrafts. The metallization of carbon nanotube (CNT) films are lightweight, and possess high conductivity and high current-carrying capacity, making them promising for lightning strike protection of composite materials. CNT/Cu composite films were successfully prepared by electrochemical deposition process, and its microstructure, electrical properties and current-carrying failure behavior were characterized and analyzed. The results show that CNT/Cu composite films are flexible and have gradient microstructures, where the content of Cu gradually decreases from one side to another. The electrical conductivity of the composite films is 2.16×107 S/m, and their specific conductivity is 2 times of pure Cu, and the current carrying capacity and specific current carrying capacity are 1.4 times and 7 times of copper mesh, respectively. CNTs in the composite film can inhibit the electromigration of Cu, thus prolonging its current-carrying failure time. CFRPs for lightning strike protection testing were prepared by using CNT/Cu composite films, and the lightning strike protection performance was evaluated by artificial simulation lightning test and damage analysis. Compared with copper mesh, CNT/Cu composite films are 61% lighter and showed more excellent lightning protection performance.
Due to the poor conductivity, carbon fiber reinforced resin matrix composites (CFRP) cannot meet the lightning strike protection requirement of aircrafts. The metallization of carbon nanotube (CNT) films are lightweight, and possess high conductivity and high current-carrying capacity, making them promising for lightning strike protection of composite materials. CNT/Cu composite films were successfully prepared by electrochemical deposition process, and its microstructure, electrical properties and current-carrying failure behavior were characterized and analyzed. The results show that CNT/Cu composite films are flexible and have gradient microstructures, where the content of Cu gradually decreases from one side to another. The electrical conductivity of the composite films is 2.16×107 S/m, and their specific conductivity is 2 times of pure Cu, and the current carrying capacity and specific current carrying capacity are 1.4 times and 7 times of copper mesh, respectively. CNTs in the composite film can inhibit the electromigration of Cu, thus prolonging its current-carrying failure time. CFRPs for lightning strike protection testing were prepared by using CNT/Cu composite films, and the lightning strike protection performance was evaluated by artificial simulation lightning test and damage analysis. Compared with copper mesh, CNT/Cu composite films are 61% lighter and showed more excellent lightning protection performance.
2024, 41(1): 207-218.
doi: 10.13801/j.cnki.fhclxb.20230531.003
Abstract:
Microstructuring is one of the important techniques to improve the performance of flexible pressure sensors. In this paper, a method for designing and fabricating hierarchical microstructures based on micro/nano fibers was proposed. First, a sacrificial mold with hierarchical microstructures was prepared by integrating near-field direct writing and fused deposition modeling. Carbon nanotubes (CNTs) were doped into polydimethylsiloxane (PDMS) as the dielectric layer material for the flexible sensor. The CNTs/PDMS flexible dielectric layer with hierarchical microstructures was then prepared by sacrificial template method. Furthermore, the effect of design parameters of hierarchical microstructures on the sensing performance was studied. The experimental results show that the designed microstructures can significantly enhance the output electrical performance of the flexible sensor. Among them, the hierarchical microstructure with a height of 1.3 mm and a spacing of 1.5 mm exhibits the best output electrical performance under a pressure load of 14 N at a frequency of 3 Hz. In addition, the fabricated sensor exhibits good stability and durability after 20000 cycles of testing. Finally, a flexible pressure sensing insole was designed for observing the distribution of foot pressure and gait detection, which demonstrates good sensitivity and stability. This study provides a new approach for low-cost and rapid fabrication of hierarchical microstructures and serves as a reference for the development of high-performance flexible pressure sensors.
Microstructuring is one of the important techniques to improve the performance of flexible pressure sensors. In this paper, a method for designing and fabricating hierarchical microstructures based on micro/nano fibers was proposed. First, a sacrificial mold with hierarchical microstructures was prepared by integrating near-field direct writing and fused deposition modeling. Carbon nanotubes (CNTs) were doped into polydimethylsiloxane (PDMS) as the dielectric layer material for the flexible sensor. The CNTs/PDMS flexible dielectric layer with hierarchical microstructures was then prepared by sacrificial template method. Furthermore, the effect of design parameters of hierarchical microstructures on the sensing performance was studied. The experimental results show that the designed microstructures can significantly enhance the output electrical performance of the flexible sensor. Among them, the hierarchical microstructure with a height of 1.3 mm and a spacing of 1.5 mm exhibits the best output electrical performance under a pressure load of 14 N at a frequency of 3 Hz. In addition, the fabricated sensor exhibits good stability and durability after 20000 cycles of testing. Finally, a flexible pressure sensing insole was designed for observing the distribution of foot pressure and gait detection, which demonstrates good sensitivity and stability. This study provides a new approach for low-cost and rapid fabrication of hierarchical microstructures and serves as a reference for the development of high-performance flexible pressure sensors.
2024, 41(1): 219-226.
doi: 10.13801/j.cnki.fhclxb.20230614.001
Abstract:
Noble-metal, as co-catalysts, can improve the photocatalytic hydrogen production performance of graphitic carbon nitride (g-C3N4). It has been paid extensive attention, however, due to the non-renewability and high expense of noble-metal, "less noble-metal, better performance" is always the goal. To achieve this goal, composite CN with different Pt loadings (Pt/CN) was successfully prepared by photoreduction deposition and used for photocatalytic hydrogen production. The results show that Pt/CN with different Pt loadings can improved photocatalytic hydrogen production performance than CN. It is found that Pt/CN loaded with 0.5wt%Pt have the best photocatalytic hydrogen production activity, with a hydrogen production rate of 409.2 μmol/g, which is 23 times higher than that of CN (17.8 μmol/g). At the same time, it is confirmed that a Schottky barrier is formed between Pt and CN, which makes the electrons of the conduction band migrate rapidly to Pt, which reduces the electron-hole recombination rate of CN. Moreover, Pt is used as the active site of photocatalytic water splitting, which promotes the rapid adsorption of most of the hydrogen protons in the water to the Pt site, and the electrons are reduced to hydrogen, realizing efficient photocatalytic hydrogen production.
Noble-metal, as co-catalysts, can improve the photocatalytic hydrogen production performance of graphitic carbon nitride (g-C3N4). It has been paid extensive attention, however, due to the non-renewability and high expense of noble-metal, "less noble-metal, better performance" is always the goal. To achieve this goal, composite CN with different Pt loadings (Pt/CN) was successfully prepared by photoreduction deposition and used for photocatalytic hydrogen production. The results show that Pt/CN with different Pt loadings can improved photocatalytic hydrogen production performance than CN. It is found that Pt/CN loaded with 0.5wt%Pt have the best photocatalytic hydrogen production activity, with a hydrogen production rate of 409.2 μmol/g, which is 23 times higher than that of CN (17.8 μmol/g). At the same time, it is confirmed that a Schottky barrier is formed between Pt and CN, which makes the electrons of the conduction band migrate rapidly to Pt, which reduces the electron-hole recombination rate of CN. Moreover, Pt is used as the active site of photocatalytic water splitting, which promotes the rapid adsorption of most of the hydrogen protons in the water to the Pt site, and the electrons are reduced to hydrogen, realizing efficient photocatalytic hydrogen production.
2024, 41(1): 227-239.
doi: 10.13801/j.cnki.fhclxb.20230511.001
Abstract:
In order to improve the durability of superhydrophobic coatings, in this work, we designed a bottom-up coating system of “substrate-viscous self-healing polymer-hydrophobic particle”, thereby the superhydrophobic surface with self-healing function was successfully fabricated: Hyperbranched polydimethylsiloxane (HB-PDMS) with abundant hydrogen bonds as viscous self-healing polymer; Nano-SiO2 was hydrophobic modified by myristic acid (MA) as hydrophobic particles to construct rough surface structure. When the mass ratio of MA to SiO2 is 1∶1 and the modification time is 3 h, the superhydrophobic coating prepared has a contact angle of 152.61° and a sliding angle of 1.9°, which has excellent antifouling performance. The coating can be healed by simple heat treatment after being scratched by the blade, and has excellent self-healing performance. Compared with pure aluminum, the composite coating has better anti-corrosion performance and the corrosion inhibition efficiency can reach 87.53%. In addition, After 5 tape peel tests, linear wear tests with a wear length of 30 cm, ultrasonic shock tests of 50 min, 10 temperature differential cycles and 24 h ultraviolet irradiation, the contact angle remained above 150°, indicating that the coating has good mechanical stability and weather resistance. This study provides a new effective strategy for the preparation of self-healing superhydrophobic coatings, which is expected to be applied in the field of building antifouling.
In order to improve the durability of superhydrophobic coatings, in this work, we designed a bottom-up coating system of “substrate-viscous self-healing polymer-hydrophobic particle”, thereby the superhydrophobic surface with self-healing function was successfully fabricated: Hyperbranched polydimethylsiloxane (HB-PDMS) with abundant hydrogen bonds as viscous self-healing polymer; Nano-SiO2 was hydrophobic modified by myristic acid (MA) as hydrophobic particles to construct rough surface structure. When the mass ratio of MA to SiO2 is 1∶1 and the modification time is 3 h, the superhydrophobic coating prepared has a contact angle of 152.61° and a sliding angle of 1.9°, which has excellent antifouling performance. The coating can be healed by simple heat treatment after being scratched by the blade, and has excellent self-healing performance. Compared with pure aluminum, the composite coating has better anti-corrosion performance and the corrosion inhibition efficiency can reach 87.53%. In addition, After 5 tape peel tests, linear wear tests with a wear length of 30 cm, ultrasonic shock tests of 50 min, 10 temperature differential cycles and 24 h ultraviolet irradiation, the contact angle remained above 150°, indicating that the coating has good mechanical stability and weather resistance. This study provides a new effective strategy for the preparation of self-healing superhydrophobic coatings, which is expected to be applied in the field of building antifouling.
2024, 41(1): 240-249.
doi: 10.13801/j.cnki.fhclxb.20230417.002
Abstract:
In order to improve the utilization rate of active substances, chitosan-polyvinylpyrrolidone hydrogel film loaded with tea polyphenols with pH response was prepared by selecting chitosan, polyvinylpyrrolidone as the substrate, glycerin as plasticizer, glutaraldehyde as crosslinker and tea polyphenol as antioxidant. The microstructure of the film was characterized by SEM and FTIR, and the water vapor transmittance, mechanical properties, swelling, gel content and oxidation resistance of the film were tested, and then the release rate of tea polyphenols in hydrogel films under different pH values was determined, the pH responsiveness was explored, and the release law of tea polyphenols was determined by constructing a kinetic model. The results show that the interaction between the crosslinker and chitosan forms a stable hydrogel structure, while the addition of tea polyphenols further improves the crosslinking strength and more stable structure between the components. The addition of crosslinking agent and tea polyphenols improves the physical and chemical properties of the film as a whole, the water vapor transmittance of the hydrogel film is (0.159±0.010) g·mm/(m2·h·kPa), the tensile strength was (40.58±2.11) MPa, the elongation at break is 62.32%±3.50%, the swelling ratio at swelling equilibrium is 346.27%±3.16%, and the gel content is 87.94%±0.50%. Compared with traditional films, the antioxidant activity is nearly 5 times higher. The hydrogel film loaded with tea polyphenols can effectively respond to pH changes, when the pH value is smaller, the cumulative release rate of tea polyphenols is larger, compared with the Higuchi and Ritger-Peppas model, the release law of tea polyphenols is consistent with the first-order kinetic model. Chitosan-polyvinylpyrrolidone hydrogel film loaded with tea polyphenols can effectively realize the pH response release of tea polyphenols and other active substances, and has the potential to be used in the field of food packaging.
In order to improve the utilization rate of active substances, chitosan-polyvinylpyrrolidone hydrogel film loaded with tea polyphenols with pH response was prepared by selecting chitosan, polyvinylpyrrolidone as the substrate, glycerin as plasticizer, glutaraldehyde as crosslinker and tea polyphenol as antioxidant. The microstructure of the film was characterized by SEM and FTIR, and the water vapor transmittance, mechanical properties, swelling, gel content and oxidation resistance of the film were tested, and then the release rate of tea polyphenols in hydrogel films under different pH values was determined, the pH responsiveness was explored, and the release law of tea polyphenols was determined by constructing a kinetic model. The results show that the interaction between the crosslinker and chitosan forms a stable hydrogel structure, while the addition of tea polyphenols further improves the crosslinking strength and more stable structure between the components. The addition of crosslinking agent and tea polyphenols improves the physical and chemical properties of the film as a whole, the water vapor transmittance of the hydrogel film is (0.159±0.010) g·mm/(m2·h·kPa), the tensile strength was (40.58±2.11) MPa, the elongation at break is 62.32%±3.50%, the swelling ratio at swelling equilibrium is 346.27%±3.16%, and the gel content is 87.94%±0.50%. Compared with traditional films, the antioxidant activity is nearly 5 times higher. The hydrogel film loaded with tea polyphenols can effectively respond to pH changes, when the pH value is smaller, the cumulative release rate of tea polyphenols is larger, compared with the Higuchi and Ritger-Peppas model, the release law of tea polyphenols is consistent with the first-order kinetic model. Chitosan-polyvinylpyrrolidone hydrogel film loaded with tea polyphenols can effectively realize the pH response release of tea polyphenols and other active substances, and has the potential to be used in the field of food packaging.
2024, 41(1): 250-260.
doi: 10.13801/j.cnki.fhclxb.20230504.003
Abstract:
In this study, a graphene-carbon nanotube-poly(lactic acid)/polyethylene glycol (Gr-CNT-PLA/PEG) phase change energy storage composite material was prepared using a solution-melt blending method. The effects of conductive particles and PEG on the crystallization behavior, electrical conductivity, and temperature-sensitive response of the PLA phase change energy storage composite material were investigated in detail. During the solution-melt blending process, the two-dimensional graphene and one-dimensional carbon nanotubes can physically hybridize into three-dimensional Gr-CNT hybrid particles under the influence of thermodynamic and kinetic factors, improving the dispersion of conductive particles in the composite material and reducing the percolation threshold to about 0.51wt%. Furthermore, the electrical conductivity and crystallization behavior of the Gr-CNT-PLA/PEG composite material are further improved by the interaction between PEG phase change energy storage material and conductive particles, and the crystallization temperature is increased from 100℃ (PLA) to about 130℃ ((Gr-CNT50)0.6-PLA/PEG10). In the constant temperature-resistance test, the conductivity of the Gr-CNT-PLA/PEG composite material decreases and then increases with the increase of isothermal heat treatment temperature. In the cyclic temperature-resistance test, the Gr-CNT-PLA composite material exhibites low-temperature PTC and high-temperature NTC effects in the cyclic temperature range of 37℃ to 140℃. Through the synergistic regulation of phase change energy storage material PEG and cyclic temperature value, the Gr-CNT-PLA/PEG composite material exhibites a good phase transition energy storage platform during cooling, successfully achieving a monotonic PTC effect and high-temperature sensitivity, with a sensitivity (ΔR/R0) up to 3000%. Moreover, with the increase of PEG mass content, the energy storage platform of the composite material can be effectively widened, up to 16.28 min, providing a basis for the preparation of high-sensitivity temperature sensors.
In this study, a graphene-carbon nanotube-poly(lactic acid)/polyethylene glycol (Gr-CNT-PLA/PEG) phase change energy storage composite material was prepared using a solution-melt blending method. The effects of conductive particles and PEG on the crystallization behavior, electrical conductivity, and temperature-sensitive response of the PLA phase change energy storage composite material were investigated in detail. During the solution-melt blending process, the two-dimensional graphene and one-dimensional carbon nanotubes can physically hybridize into three-dimensional Gr-CNT hybrid particles under the influence of thermodynamic and kinetic factors, improving the dispersion of conductive particles in the composite material and reducing the percolation threshold to about 0.51wt%. Furthermore, the electrical conductivity and crystallization behavior of the Gr-CNT-PLA/PEG composite material are further improved by the interaction between PEG phase change energy storage material and conductive particles, and the crystallization temperature is increased from 100℃ (PLA) to about 130℃ ((Gr-CNT50)0.6-PLA/PEG10). In the constant temperature-resistance test, the conductivity of the Gr-CNT-PLA/PEG composite material decreases and then increases with the increase of isothermal heat treatment temperature. In the cyclic temperature-resistance test, the Gr-CNT-PLA composite material exhibites low-temperature PTC and high-temperature NTC effects in the cyclic temperature range of 37℃ to 140℃. Through the synergistic regulation of phase change energy storage material PEG and cyclic temperature value, the Gr-CNT-PLA/PEG composite material exhibites a good phase transition energy storage platform during cooling, successfully achieving a monotonic PTC effect and high-temperature sensitivity, with a sensitivity (ΔR/R0) up to 3000%. Moreover, with the increase of PEG mass content, the energy storage platform of the composite material can be effectively widened, up to 16.28 min, providing a basis for the preparation of high-sensitivity temperature sensors.
2024, 41(1): 261-270.
doi: 10.13801/j.cnki.fhclxb.20230504.001
Abstract:
The styrene-acrylic emulsion used to prepare waterborne damping coatings needs to further increase the damping factor and broaden the effective damping temperature range. In order to improve the damping performance of styrene-acrylic emulsion, oleic acid (OA) modified nano-Fe3O4 (OA-Fe3O4) was used as the coated filler to prepare Fe3O4/poly(styrene acrylate) (Fe3O4/P(St-2-EHA)) composite damping emulsion via miniemulsion polymerization. The composite emulsion and its latex film were characterized by FTIR, XRD, TEM, SEM, DLS, TG and DMA. The effects of copolymer composition, surface properties and content of nano-Fe3O4 on the structure and performance of the emulsion and latex film were studied. The results show that the direct agglomeration of OA-Fe3O4 nanoparticles is weakened, and its dispersion in the composite emulsion is significantly improved. When the mass ratio of monomer St to 2-EHA is 5∶5, the obtained P(St-2-EHA) latex film has the highest loss factor (tanδ) peak (1.926). When the mass ratio of OA-Fe3O4 to the total mass of St and 2-EHA is 10wt%, the obtained Fe3O4/P(St-2-EHA) composite latex film has the best performance. Its tanδ peak value and effective damping temperature range width are 2.066 and 59.2℃, which are better than pure P(St-2-EHA) latex film and composite latex film prepared by blending method. Its water absorption rate is 3.4% and 10.4% lower than the latter two respectively. And the initial thermal decomposition temperature is higher, with the thermal stability improved.
The styrene-acrylic emulsion used to prepare waterborne damping coatings needs to further increase the damping factor and broaden the effective damping temperature range. In order to improve the damping performance of styrene-acrylic emulsion, oleic acid (OA) modified nano-Fe3O4 (OA-Fe3O4) was used as the coated filler to prepare Fe3O4/poly(styrene acrylate) (Fe3O4/P(St-2-EHA)) composite damping emulsion via miniemulsion polymerization. The composite emulsion and its latex film were characterized by FTIR, XRD, TEM, SEM, DLS, TG and DMA. The effects of copolymer composition, surface properties and content of nano-Fe3O4 on the structure and performance of the emulsion and latex film were studied. The results show that the direct agglomeration of OA-Fe3O4 nanoparticles is weakened, and its dispersion in the composite emulsion is significantly improved. When the mass ratio of monomer St to 2-EHA is 5∶5, the obtained P(St-2-EHA) latex film has the highest loss factor (tanδ) peak (1.926). When the mass ratio of OA-Fe3O4 to the total mass of St and 2-EHA is 10wt%, the obtained Fe3O4/P(St-2-EHA) composite latex film has the best performance. Its tanδ peak value and effective damping temperature range width are 2.066 and 59.2℃, which are better than pure P(St-2-EHA) latex film and composite latex film prepared by blending method. Its water absorption rate is 3.4% and 10.4% lower than the latter two respectively. And the initial thermal decomposition temperature is higher, with the thermal stability improved.
2024, 41(1): 271-280.
doi: 10.13801/j.cnki.fhclxb.20230524.001
Abstract:
In this paper, two kinds of multi-functional composites integrated with heat-shielding and radar-absorbing were prepared by high pressure resin transfer molding (HP-RTM), employing traditional phenolic and silicone resin as matrix, needle stitched quartz fiber fabric as reinforcing material, and metamaterials as radar absorbing layers. The effects of microstructure, mechanical properties, and ablation on the microwave absorbing properties of the multi-functional composites were systematically investigated. The results show that the two multi-functional composites prepared have uniform microstructure and excellent mechanical properties. The average reflectivity of the composites in 2-18 GHz are lower than −10 dB, especially in S, C, and X bands, and the effective bandwidth is wider than 9 GHz, which is ascribed to the good transmissivity of the medium layer and the resonant absorption effect of metamaterial layers. However, a continuous carbon layer with high conductivity are formed on the surface of phenolic matrix composite after ablation, which seriously degraded its wave absorbing property. In contrast, the wave absorbing property of silicone matrix composite remains the same due to discontinuity of the carbon layer with band shifting to high frequency, which shows its great application potential in high temperature ablation/stealth field.
In this paper, two kinds of multi-functional composites integrated with heat-shielding and radar-absorbing were prepared by high pressure resin transfer molding (HP-RTM), employing traditional phenolic and silicone resin as matrix, needle stitched quartz fiber fabric as reinforcing material, and metamaterials as radar absorbing layers. The effects of microstructure, mechanical properties, and ablation on the microwave absorbing properties of the multi-functional composites were systematically investigated. The results show that the two multi-functional composites prepared have uniform microstructure and excellent mechanical properties. The average reflectivity of the composites in 2-18 GHz are lower than −10 dB, especially in S, C, and X bands, and the effective bandwidth is wider than 9 GHz, which is ascribed to the good transmissivity of the medium layer and the resonant absorption effect of metamaterial layers. However, a continuous carbon layer with high conductivity are formed on the surface of phenolic matrix composite after ablation, which seriously degraded its wave absorbing property. In contrast, the wave absorbing property of silicone matrix composite remains the same due to discontinuity of the carbon layer with band shifting to high frequency, which shows its great application potential in high temperature ablation/stealth field.
2024, 41(1): 281-292.
doi: 10.13801/j.cnki.fhclxb.20230511.005
Abstract:
The control of the morphology and structure has an important influence on the electrochemical properties of materials. In this work, NiCo2O4 samples with different morphologies and structures were synthesized by solvothermal method combined with calcination at different solvent ratios and temperatures. The phase composition and morphology of the samples were characterized by XRD, SEM and TEM et al, and the electrochemical performance was further studied. The results show that the sample is hollow sea urchin-like NiCo2O4, when the volume ratio of water to ethanol is 1∶1. With the increase of the content of water, the morphology gradually changes to regular central radial needle-like morphology, and there is a second phase substance. Under the condition of the volume ratio of water to ethanol is 1∶1, with the increase of temperature, the morphology mainly changes from fluffy ball to a flower-like, sea urchin-like, and center-radiating needle, while the phases of samples are pure NiCo2O4. The sample synthesized at 90℃ exhibits better electrochemical performance. The specific capacitance is up to 1287.5 F·g−1 at a current density of 1 A·g−1. The specific capacitance retention rate reaches 59.4% with the scan rate changes from 20-100 mV·s−1, and the specific capacitance retention rate is up to 80.1% after 1500 cycles. In addition, the whole electrochemical reaction is dominated by the diffusion-controlled process.
The control of the morphology and structure has an important influence on the electrochemical properties of materials. In this work, NiCo2O4 samples with different morphologies and structures were synthesized by solvothermal method combined with calcination at different solvent ratios and temperatures. The phase composition and morphology of the samples were characterized by XRD, SEM and TEM et al, and the electrochemical performance was further studied. The results show that the sample is hollow sea urchin-like NiCo2O4, when the volume ratio of water to ethanol is 1∶1. With the increase of the content of water, the morphology gradually changes to regular central radial needle-like morphology, and there is a second phase substance. Under the condition of the volume ratio of water to ethanol is 1∶1, with the increase of temperature, the morphology mainly changes from fluffy ball to a flower-like, sea urchin-like, and center-radiating needle, while the phases of samples are pure NiCo2O4. The sample synthesized at 90℃ exhibits better electrochemical performance. The specific capacitance is up to 1287.5 F·g−1 at a current density of 1 A·g−1. The specific capacitance retention rate reaches 59.4% with the scan rate changes from 20-100 mV·s−1, and the specific capacitance retention rate is up to 80.1% after 1500 cycles. In addition, the whole electrochemical reaction is dominated by the diffusion-controlled process.
2024, 41(1): 293-306.
doi: 10.13801/j.cnki.fhclxb.20230425.004
Abstract:
With the deepening standards and requirements of zero wastewater discharge, efficient and sustainable membrane separation water treatment technology has become a research hotspot, but faces problems such as low water flux and easy pollution. In this work, photocatalytic self-cleaning composite membranes were prepared by the organic combination of graphitic carbon nitride (g-C3N4), bacterial cellulose (BC) and bismuth sulfide (Bi2S3) by vacuum-assisted filtration. The effects of different additions of g-C3N4 and Bi2S3 on the dye separation performance of the composite membranes were investigated through a series of characterization methods to analyze the physical structure and elemental energy states of the powders and membrane materials, and the degradation mechanism of the dyes under photocatalysis were explored. The results show that 60wt%g-C3N4, 10wt%BC, 30wt%Bi2S3 and the composite membrane have the best overall performance, with the water flux and rejection rate of 23.48 L·m−2·h−1 and 100%, respectively. The water flux of 16.65 L·m−2·h−1 and dye rejection rate of about 90% are still maintained in the long term filtration. The flux recovery rate reach 96.5% after soaking for 3 h under light, indicating that the membrane has good photocatalytic self-cleaning performance. This paper provides new ideas and basic exploration for the design of high-throughput and sustainable separation membranes.
With the deepening standards and requirements of zero wastewater discharge, efficient and sustainable membrane separation water treatment technology has become a research hotspot, but faces problems such as low water flux and easy pollution. In this work, photocatalytic self-cleaning composite membranes were prepared by the organic combination of graphitic carbon nitride (g-C3N4), bacterial cellulose (BC) and bismuth sulfide (Bi2S3) by vacuum-assisted filtration. The effects of different additions of g-C3N4 and Bi2S3 on the dye separation performance of the composite membranes were investigated through a series of characterization methods to analyze the physical structure and elemental energy states of the powders and membrane materials, and the degradation mechanism of the dyes under photocatalysis were explored. The results show that 60wt%g-C3N4, 10wt%BC, 30wt%Bi2S3 and the composite membrane have the best overall performance, with the water flux and rejection rate of 23.48 L·m−2·h−1 and 100%, respectively. The water flux of 16.65 L·m−2·h−1 and dye rejection rate of about 90% are still maintained in the long term filtration. The flux recovery rate reach 96.5% after soaking for 3 h under light, indicating that the membrane has good photocatalytic self-cleaning performance. This paper provides new ideas and basic exploration for the design of high-throughput and sustainable separation membranes.
2024, 41(1): 307-314.
doi: 10.13801/j.cnki.fhclxb.20230523.004
Abstract:
The unique asymmetry of chemistry or composition of external and internal surface for Janus cage allows it to be used as a special microcontainer for separation, enrichment, transport and restricted reactions. To some extent, large aperture of cage can enhance the material transport efficiency between microcontainer and the environment. A two-step method to prepare magnetic organic/inorganic composite Janus cages with large aperture and pH responsiveness was introduced in this paper. Firstly, a magnetic inorganic Janus cage with a well-supported shell and adjustable aperture was prepared by the sol-gel of silane coupling agents and microphase separation of two surfactants at the interface. Then pH-responsive polymer poly diethylaminoethyl methacrylate (PDEAEMA) was grafted on the interior surface of inorganic Janus cage by Cu-mediated controlled radical polymerization to obtain functional Janus composite cages. SEM, TEM, FTIR and TGA were performed on composite cages. The size of cages is about 1-3 μm, with tunable pore size from 40 nm to 1 μm. The proportion of polymer in the composite cages is 41.7wt%. Controlled absorption and release of oil and oriented transport of substance can be achieved by changing pH and magnetic manipulation respectively with these composite Janus cages, which means it is promising for drug loading and targeted release in vivo.
The unique asymmetry of chemistry or composition of external and internal surface for Janus cage allows it to be used as a special microcontainer for separation, enrichment, transport and restricted reactions. To some extent, large aperture of cage can enhance the material transport efficiency between microcontainer and the environment. A two-step method to prepare magnetic organic/inorganic composite Janus cages with large aperture and pH responsiveness was introduced in this paper. Firstly, a magnetic inorganic Janus cage with a well-supported shell and adjustable aperture was prepared by the sol-gel of silane coupling agents and microphase separation of two surfactants at the interface. Then pH-responsive polymer poly diethylaminoethyl methacrylate (PDEAEMA) was grafted on the interior surface of inorganic Janus cage by Cu-mediated controlled radical polymerization to obtain functional Janus composite cages. SEM, TEM, FTIR and TGA were performed on composite cages. The size of cages is about 1-3 μm, with tunable pore size from 40 nm to 1 μm. The proportion of polymer in the composite cages is 41.7wt%. Controlled absorption and release of oil and oriented transport of substance can be achieved by changing pH and magnetic manipulation respectively with these composite Janus cages, which means it is promising for drug loading and targeted release in vivo.
2024, 41(1): 315-322.
doi: 10.13801/j.cnki.fhclxb.20230509.003
Abstract:
With the rapid development of mobile communication, intelligent manufacturing, automotive electronics, electronic new energy and other emerging fields, reducing the magnetic loss and improving other properties of SMCs are required. The silicone resin mixed with epoxy resin was used to coat the phosphatized carbonyl iron powder (CIP). And the coated powders were fabricated into iron based soft magnetic composites (SMCs) through compression and curing. The effects of different mixed resins on the microstructure and electromagnetic properties of iron-based SMCs were studied. The results show that the mixed resin has been formed a reasonable coating layer on the surface of powders, which leads to reduce the strain of the powders introduced during compression and isolate the powders to cut off the eddy current. As a result, the density of SMCs can reach 6.82 g/cm3, the resistivity is as high as 1.1×106 Ω·cm. Meanwhile, its quality factor is improved and the magnetic loss at high frequency is reduced. When the mixed resin is composed of 33.3wt% epoxy resin and 66.7wt% silicone resin, the SMCs are provided with optimal comprehensive performance with 1182.7 kW/m3 loss only at 200 kHz. The magnetic properties of iron-based SMCs are further optimized through selecting the blending resin coating agent with suitable composition, which has a broad application prospect in the field of medium and high frequency.
With the rapid development of mobile communication, intelligent manufacturing, automotive electronics, electronic new energy and other emerging fields, reducing the magnetic loss and improving other properties of SMCs are required. The silicone resin mixed with epoxy resin was used to coat the phosphatized carbonyl iron powder (CIP). And the coated powders were fabricated into iron based soft magnetic composites (SMCs) through compression and curing. The effects of different mixed resins on the microstructure and electromagnetic properties of iron-based SMCs were studied. The results show that the mixed resin has been formed a reasonable coating layer on the surface of powders, which leads to reduce the strain of the powders introduced during compression and isolate the powders to cut off the eddy current. As a result, the density of SMCs can reach 6.82 g/cm3, the resistivity is as high as 1.1×106 Ω·cm. Meanwhile, its quality factor is improved and the magnetic loss at high frequency is reduced. When the mixed resin is composed of 33.3wt% epoxy resin and 66.7wt% silicone resin, the SMCs are provided with optimal comprehensive performance with 1182.7 kW/m3 loss only at 200 kHz. The magnetic properties of iron-based SMCs are further optimized through selecting the blending resin coating agent with suitable composition, which has a broad application prospect in the field of medium and high frequency.
2024, 41(1): 323-334.
doi: 10.13801/j.cnki.fhclxb.20230522.001
Abstract:
To investigate the stress-strain behavior of geopolymer concrete (GPC) under multi-axial stress states, axial compression tests were conducted on GPC columns with and without carbon fiber reinforced polymer (CFRP) confinement. The characteristics of stress-strain curves for GPC under various confinement conditions were examined, and models for axial stress-strain, compressive strength, and ultimate axial compressive strain were established. Specifically, novel expressions for model parameters were proposed for CFRP-confined normal strength GPC, and the model was validated using experimental results from other studies. The results demonstrate that the compressive strength model has good predictive capability, with an average absolute error of 3.55%. Additionally, the ultimate axial compressive strain model accurately predicts experimental results from other studies, with an average absolute error of 17.03%. The newly proposed parameter expressions for the axial stress-strain model are applicable not only to CFRP-confined high-strength GPC but also to CFRP-confined normal strength GPC.
To investigate the stress-strain behavior of geopolymer concrete (GPC) under multi-axial stress states, axial compression tests were conducted on GPC columns with and without carbon fiber reinforced polymer (CFRP) confinement. The characteristics of stress-strain curves for GPC under various confinement conditions were examined, and models for axial stress-strain, compressive strength, and ultimate axial compressive strain were established. Specifically, novel expressions for model parameters were proposed for CFRP-confined normal strength GPC, and the model was validated using experimental results from other studies. The results demonstrate that the compressive strength model has good predictive capability, with an average absolute error of 3.55%. Additionally, the ultimate axial compressive strain model accurately predicts experimental results from other studies, with an average absolute error of 17.03%. The newly proposed parameter expressions for the axial stress-strain model are applicable not only to CFRP-confined high-strength GPC but also to CFRP-confined normal strength GPC.
2024, 41(1): 323-332.
doi: 10.13801/j.cnki.fhclxb.20230516.003
Abstract:
Glass-fibre reinforced polypropylene (GFRPP) composite rod integrate the advantages of thermoplastic resin multi-molding, environmental friendliness, recyclability, and high strain and low cost of glass fiber. In the field of concrete structures, GFRPP rods are expected to replace steel bars and thermoset fibre reinforced polyer (FRP) bars as a new composite material. In this paper, accelerated experiments were used to study the long-term evolution of water absorption, interlaminar shear properties and degenerative mechanism of GFRPP rod under simulated seawater and sea sand concrete environment. The results show that the water absorption behavior of GFRPP rod conforms to Fick's law, and the saturation water absorption rates of GFRPP rods at immersion temperatures of 21°C, 40°C and 60°C are 0.63%, 0.78% and 0.81%, respectively. After 120 days of immersion in 21°C, 40°C and 60°C simulated seawater sea sand concrete pore solutions, the shear strength retention rates between GFRPP rods are 80.5%, 72.8% and 66.5%. Finally, the performance degradation mechanism of GFRPP rods under simulated seawater-sea sand concrete pore solution immersion was revealed by combining SEM and FTIR characterization techniques.
Glass-fibre reinforced polypropylene (GFRPP) composite rod integrate the advantages of thermoplastic resin multi-molding, environmental friendliness, recyclability, and high strain and low cost of glass fiber. In the field of concrete structures, GFRPP rods are expected to replace steel bars and thermoset fibre reinforced polyer (FRP) bars as a new composite material. In this paper, accelerated experiments were used to study the long-term evolution of water absorption, interlaminar shear properties and degenerative mechanism of GFRPP rod under simulated seawater and sea sand concrete environment. The results show that the water absorption behavior of GFRPP rod conforms to Fick's law, and the saturation water absorption rates of GFRPP rods at immersion temperatures of 21°C, 40°C and 60°C are 0.63%, 0.78% and 0.81%, respectively. After 120 days of immersion in 21°C, 40°C and 60°C simulated seawater sea sand concrete pore solutions, the shear strength retention rates between GFRPP rods are 80.5%, 72.8% and 66.5%. Finally, the performance degradation mechanism of GFRPP rods under simulated seawater-sea sand concrete pore solution immersion was revealed by combining SEM and FTIR characterization techniques.
2024, 41(1): 333-347.
doi: 10.13801/j.cnki.fhclxb.20230612.003
Abstract:
To solve the initial damage, poor durability, and other problems of concrete caused by steam curing, the nano-hydrated calcium silicate polycarboxylate ether composite (n-C-S-H-PCE) was used to prepare high-strength non-steam-cured concrete. The effects of n-C-S-H-PCE on the compressive strength, hydration rate, pore size distribution, autogenous shrinkage and durability of concrete were studied using hydration heat, low-field nuclear magnetic resonance and other methods. Results show that the crystal nucleus of nano-C-S-H provides nucleation sites for the hydration products of cement, reducing the critical ion concentration Ksp of nucleation. And the induction and acceleration periods are advanced significantly. Also, the early compressive strength of concrete is improved considerably. The compressive strength of concrete increases by 64% after 1 day of curing, and the strength of concrete has no regression after 28 days of curing. The addition of the n-C-S-H-PCE refines the pore size of concrete matrix and increases the proportion of gel pores and capillary pores. As a result, the negative capillary pressure increases during the auto-drying process of concrete. Thus, the autogenous shrinkage of concrete increases. However, the most probable pore size of the concrete matrix and the cumulative volume of pores with a diameter of 50-100 nm decrease. This improves the resistance to chloride migration into concrete. The content of pores with a pore diameter larger than 14 nm (the critical pore diameter) decreases (from 0.0287 mL/g to 0.0156 mL/g). As a result, the freeze-thaw resistance of concrete is improved. The addition of n-C-S-H-PCE can reduce the porosity of concrete. In addition, with the increase of slag content, the concentration of calcium aluminate phase and Ca2+ decreases. In this way, the resistance to sulfate attack of concrete increases. The results provide a theoretical basis for the preparation of non-steam-cured, low shrinkage, high durability and high-strength concrete.
To solve the initial damage, poor durability, and other problems of concrete caused by steam curing, the nano-hydrated calcium silicate polycarboxylate ether composite (n-C-S-H-PCE) was used to prepare high-strength non-steam-cured concrete. The effects of n-C-S-H-PCE on the compressive strength, hydration rate, pore size distribution, autogenous shrinkage and durability of concrete were studied using hydration heat, low-field nuclear magnetic resonance and other methods. Results show that the crystal nucleus of nano-C-S-H provides nucleation sites for the hydration products of cement, reducing the critical ion concentration Ksp of nucleation. And the induction and acceleration periods are advanced significantly. Also, the early compressive strength of concrete is improved considerably. The compressive strength of concrete increases by 64% after 1 day of curing, and the strength of concrete has no regression after 28 days of curing. The addition of the n-C-S-H-PCE refines the pore size of concrete matrix and increases the proportion of gel pores and capillary pores. As a result, the negative capillary pressure increases during the auto-drying process of concrete. Thus, the autogenous shrinkage of concrete increases. However, the most probable pore size of the concrete matrix and the cumulative volume of pores with a diameter of 50-100 nm decrease. This improves the resistance to chloride migration into concrete. The content of pores with a pore diameter larger than 14 nm (the critical pore diameter) decreases (from 0.0287 mL/g to 0.0156 mL/g). As a result, the freeze-thaw resistance of concrete is improved. The addition of n-C-S-H-PCE can reduce the porosity of concrete. In addition, with the increase of slag content, the concentration of calcium aluminate phase and Ca2+ decreases. In this way, the resistance to sulfate attack of concrete increases. The results provide a theoretical basis for the preparation of non-steam-cured, low shrinkage, high durability and high-strength concrete.
2024, 41(1): 348-360.
doi: 10.13801/j.cnki.fhclxb.20230529.004
Abstract:
A new ceramsite concrete, fly ash cenosphere-desert sand ceramsite concrete (FDCC), was prepared using desert sand (DS) and fly ash cenosphere (FAC) as a partial replacement for river sand and mixed with polymer (PL). The effects of the DS replacement rate, FAC replacement rate and PL admixture on the workability and mechanical properties of the FDCC were investigated by means of univariate variables, and prediction models for compressive strength and splitting tensile strength of the FDCC were established. The results show that the DS and FAC can partly replace river sand to prepare the lightweight aggregate concrete. The apparent density of the FDCC is linearly related to the compressive strength, the slump decreases with the DS replacement rate increasing and increases with the FAC replacement rate and the PL admixture increasing. The compressive strength of the FDCC increases and then decreases with the DS replacement rate increasing, and decreases then increases with the FAC replacement rate increasing. The optimal DS and FAC replacement rates and the optimal PL admixture are 20vol%, 30vol% and 1wt%, respectively. The splitting tensile strength of the FDCC decreases with the DS and FAC replacement rates and PL admixture increasing. The incorporation of the DS and FAC promotes the formation of hydration products and is beneficial to the microstructure of FDCC concrete.
A new ceramsite concrete, fly ash cenosphere-desert sand ceramsite concrete (FDCC), was prepared using desert sand (DS) and fly ash cenosphere (FAC) as a partial replacement for river sand and mixed with polymer (PL). The effects of the DS replacement rate, FAC replacement rate and PL admixture on the workability and mechanical properties of the FDCC were investigated by means of univariate variables, and prediction models for compressive strength and splitting tensile strength of the FDCC were established. The results show that the DS and FAC can partly replace river sand to prepare the lightweight aggregate concrete. The apparent density of the FDCC is linearly related to the compressive strength, the slump decreases with the DS replacement rate increasing and increases with the FAC replacement rate and the PL admixture increasing. The compressive strength of the FDCC increases and then decreases with the DS replacement rate increasing, and decreases then increases with the FAC replacement rate increasing. The optimal DS and FAC replacement rates and the optimal PL admixture are 20vol%, 30vol% and 1wt%, respectively. The splitting tensile strength of the FDCC decreases with the DS and FAC replacement rates and PL admixture increasing. The incorporation of the DS and FAC promotes the formation of hydration products and is beneficial to the microstructure of FDCC concrete.
2024, 41(1): 350-361.
doi: 10.13801/j.cnki.fhclxb.20230529.003
Abstract:
To further enhance the shear strength characteristics of sandy soils cured by enzyme-induced carbonate precipitation (EICP) technology, and to improve the brittle damage characteristics of the cured sandy soils, the abandoned disposable masks were blended into the sandy soils for improvement. Based on the triaxial compression test, the influence of different contents of the mask on the shear strength of EICP solidified sand was studied. However, the change of the shear strength characteristics of improved sand and the benefit of mask reinforcement were analyzed after changing the EICP drip rounds and the initial relative compactness of sand. The results show that the best content of the mask is 0.2%. At this time, the peak partial stress of improved sandy soil increases by 59.9%-34% under different confining pressures, the cohesive force increases by 188%, and the internal friction angle increases by 14.5%. The post-peak strength loss is effectively reduced and the brittle damage of cured sand is improved. However, increasing the number of drip rounds and relative compactness could increase the peak partial stress, cohesive force and internal friction angle, but the effect of mask reinforcement is slightly weakened. Finally, mask reinforcement can improve the calcium carbonate generation rate, and the calcium carbonate generation rate increases with the increase of drip rounds, but decreases with the increase of relative compactness.
To further enhance the shear strength characteristics of sandy soils cured by enzyme-induced carbonate precipitation (EICP) technology, and to improve the brittle damage characteristics of the cured sandy soils, the abandoned disposable masks were blended into the sandy soils for improvement. Based on the triaxial compression test, the influence of different contents of the mask on the shear strength of EICP solidified sand was studied. However, the change of the shear strength characteristics of improved sand and the benefit of mask reinforcement were analyzed after changing the EICP drip rounds and the initial relative compactness of sand. The results show that the best content of the mask is 0.2%. At this time, the peak partial stress of improved sandy soil increases by 59.9%-34% under different confining pressures, the cohesive force increases by 188%, and the internal friction angle increases by 14.5%. The post-peak strength loss is effectively reduced and the brittle damage of cured sand is improved. However, increasing the number of drip rounds and relative compactness could increase the peak partial stress, cohesive force and internal friction angle, but the effect of mask reinforcement is slightly weakened. Finally, mask reinforcement can improve the calcium carbonate generation rate, and the calcium carbonate generation rate increases with the increase of drip rounds, but decreases with the increase of relative compactness.
2024, 41(1): 361-372.
doi: 10.13801/j.cnki.fhclxb.20230529.005
Abstract:
Thermoelectric cement-based composite materials can convert thermal energy in building environments into electrical energy, and as a new energy conversion approach, have received widespread attention and research in recent years. There is a problem of mismatch between the optimal working temperature and environmental temperature in the application of thermoelectric cement-based composite materials, and the low thermoelectric conversion efficiency restricts the application of thermoelectric cement. This study incorporated expanded graphite (EG)/paraffin wax (PW) phase change composite materials prepared by melt blending into cement-based materials to prepare phase change expanded graphite/cement composite materials. The effect of the addition amount of phase change composites on the thermoelectric properties of cement-based materials was studied. The increase in the content of phase change composites regulates the temperature range for the optimal thermoelectric performance of cement-based composite materials. The test results show that the temperature point corresponding to the maximum thermoelectric performance is adjusted from 55℃ to 60℃ and 65℃. The corresponding Seebeck coefficient is −24.65, −30.97 and −30.90 μV/K. The power factor is 1.39, 1.57 and 1.67 μW·m−1·K−2. Thermoelectric merit (ZT) value is 5.53×10−5, 6.50×10−5 and 7.07×10−5. Phase change composites absorb heat during the phase change process, reducing the heating rate of cement-based materials, weakening the decrease in Seebeck coefficient caused by an increase in carrier concentration due to temperature rise, adjusting the temperature range corresponding to the peak power factor of cement-based materials, and regulating the temperature range of use of thermoelectric cement-based composite materials. This study provides a new approach and method for improving the performance of thermoelectric cement-based composite materials.
Thermoelectric cement-based composite materials can convert thermal energy in building environments into electrical energy, and as a new energy conversion approach, have received widespread attention and research in recent years. There is a problem of mismatch between the optimal working temperature and environmental temperature in the application of thermoelectric cement-based composite materials, and the low thermoelectric conversion efficiency restricts the application of thermoelectric cement. This study incorporated expanded graphite (EG)/paraffin wax (PW) phase change composite materials prepared by melt blending into cement-based materials to prepare phase change expanded graphite/cement composite materials. The effect of the addition amount of phase change composites on the thermoelectric properties of cement-based materials was studied. The increase in the content of phase change composites regulates the temperature range for the optimal thermoelectric performance of cement-based composite materials. The test results show that the temperature point corresponding to the maximum thermoelectric performance is adjusted from 55℃ to 60℃ and 65℃. The corresponding Seebeck coefficient is −24.65, −30.97 and −30.90 μV/K. The power factor is 1.39, 1.57 and 1.67 μW·m−1·K−2. Thermoelectric merit (ZT) value is 5.53×10−5, 6.50×10−5 and 7.07×10−5. Phase change composites absorb heat during the phase change process, reducing the heating rate of cement-based materials, weakening the decrease in Seebeck coefficient caused by an increase in carrier concentration due to temperature rise, adjusting the temperature range corresponding to the peak power factor of cement-based materials, and regulating the temperature range of use of thermoelectric cement-based composite materials. This study provides a new approach and method for improving the performance of thermoelectric cement-based composite materials.
2024, 41(1): 373-382.
doi: 10.13801/j.cnki.fhclxb.20230524.003
Abstract:
In order to investigate the flexural performance of ultra-high performance fiber reinforced cementitious composite material (UHPFRC) doped with copolymer formaldehyde fiber, five groups of bending specimens were designed and tested, including three groups of single mixed specimens and two groups of fiber hybrid specimens. The results show that among the copolymer formaldehyde fiber UHPFRC specimens, 2vol% copolymer formaldehyde fiber UHPFRC specimens have better flexural strength, with an average strength of 13.4 MPa. An appropriate amount of co-formaldehyde fiber can delay the cracking of UHPFRC matrix and enhance its ability to deformation before cracking. Among the five groups of test pieces, the cracking deflection of 2vol% copolymer formaldehyde fiber UHPFRC test piece is the largest, which can reach 0.65 mm. Hybrid fiber can better enhance the flexural strength and toughness of UHPFRC. When 1.5vol% copolymer formaldehyde fiber and 1.5vol% steel fiber are mixed, the flexural strength of UHPFRC specimens can reach 13.9 MPa, and the toughness of this group of specimens is the best. The research reveals the effect of copolymer formaldehyde fiber on the flexural mechanical properties of UHPFRC, which has important reference value for its application in UHPFRC and the promotion of UHPFRC.
In order to investigate the flexural performance of ultra-high performance fiber reinforced cementitious composite material (UHPFRC) doped with copolymer formaldehyde fiber, five groups of bending specimens were designed and tested, including three groups of single mixed specimens and two groups of fiber hybrid specimens. The results show that among the copolymer formaldehyde fiber UHPFRC specimens, 2vol% copolymer formaldehyde fiber UHPFRC specimens have better flexural strength, with an average strength of 13.4 MPa. An appropriate amount of co-formaldehyde fiber can delay the cracking of UHPFRC matrix and enhance its ability to deformation before cracking. Among the five groups of test pieces, the cracking deflection of 2vol% copolymer formaldehyde fiber UHPFRC test piece is the largest, which can reach 0.65 mm. Hybrid fiber can better enhance the flexural strength and toughness of UHPFRC. When 1.5vol% copolymer formaldehyde fiber and 1.5vol% steel fiber are mixed, the flexural strength of UHPFRC specimens can reach 13.9 MPa, and the toughness of this group of specimens is the best. The research reveals the effect of copolymer formaldehyde fiber on the flexural mechanical properties of UHPFRC, which has important reference value for its application in UHPFRC and the promotion of UHPFRC.
2024, 41(1): 383-394.
doi: 10.13801/j.cnki.fhclxb.20230529.002
Abstract:
The axial tensile mechanical properties of ultra-high performance concrete (UHPC) mixed with straight (short straight, long straight) and end-hooked steel fibers were studied through the uniaxial tensile test. Based on the test results, the effects of steel fiber content and mixed ratio on tensile strength, strain capacity and toughness of UHPC were analyzed. The results show that the multi-crack ductile failure occurs in UHPC specimens under axial tensile, and the inclination and bending degree of macro main cracks become more and more obvious with the mixing of end-hooked fibers. The axial tensile properties of UHPC with hybrid short straight and end-hooked steel fibers increase significantly with the increase of end-hooked fiber content, while the axial tensile properties of UHPC with hybrid long straight and end-hooked steel fibers show an opposite trend. Hybrid steel fibers exhibit the characteristics of staged, layered and interactive crack resistance and toughening during the UHPC tensile process. The UHPC with 1.0vol% short straight and 1.0vol% end-hooked steel fibers has the best axial tensile mechanical properties, and its tensile strength, strain capacity and toughness are improved by 28.2%, 147% and 31.1% respectively compared with the specimens with single short straight fibers. A uniaxial tensile constitutive model of UHPC with hybrid steel fibers considering fiber interaction and fiber reinforcement factor is proposed by analyzing the measured axial tensile stress-strain curves. The proposed model is in good agreement with the relevant test curves and can be used to predict the tensile stress-strain relationship of UHPC.
The axial tensile mechanical properties of ultra-high performance concrete (UHPC) mixed with straight (short straight, long straight) and end-hooked steel fibers were studied through the uniaxial tensile test. Based on the test results, the effects of steel fiber content and mixed ratio on tensile strength, strain capacity and toughness of UHPC were analyzed. The results show that the multi-crack ductile failure occurs in UHPC specimens under axial tensile, and the inclination and bending degree of macro main cracks become more and more obvious with the mixing of end-hooked fibers. The axial tensile properties of UHPC with hybrid short straight and end-hooked steel fibers increase significantly with the increase of end-hooked fiber content, while the axial tensile properties of UHPC with hybrid long straight and end-hooked steel fibers show an opposite trend. Hybrid steel fibers exhibit the characteristics of staged, layered and interactive crack resistance and toughening during the UHPC tensile process. The UHPC with 1.0vol% short straight and 1.0vol% end-hooked steel fibers has the best axial tensile mechanical properties, and its tensile strength, strain capacity and toughness are improved by 28.2%, 147% and 31.1% respectively compared with the specimens with single short straight fibers. A uniaxial tensile constitutive model of UHPC with hybrid steel fibers considering fiber interaction and fiber reinforcement factor is proposed by analyzing the measured axial tensile stress-strain curves. The proposed model is in good agreement with the relevant test curves and can be used to predict the tensile stress-strain relationship of UHPC.
2024, 41(1): 395-403.
doi: 10.13801/j.cnki.fhclxb.20230511.004
Abstract:
To enhance the mechanical properties of magnesium oxysulfade (MOS) cement, wollastonite powder (WS) was utilized as an additive before and after calcination to study its effect on the mechanical properties of MOS. The WS and WS/MOS composite system before and after calcination (1000℃) were analyzed by DSC-TG, XRD, FTIR, NMR, SEM, and mercury intrusion porosimetry (MIP). The results show that calcination stimulates the hydration activity of 29Si in WS, and the calcined WS stimulates its hydration activity in magnesium alkali environment, resulting in better performance of WS/MOS composite materials. WS enhances the mechanical properties of MOS, and the strength of WS/MOS composite system with the calcined WS increases more significantly. The bending strength and compressive strength of MOS on the 28 days reach their maximum values when the after calcination WS content is 20wt%, which are 11.4 MPa and 63.4 MPa, respectively, with increments of 71.4% and 21.2%. WS optimizes the pore structure and reduces the proportion of pores larger than 100 nm in MOS. The calcined WS has good interface compatibility with MOS, which is more conducive to improving the mechanical properties of MOS.
To enhance the mechanical properties of magnesium oxysulfade (MOS) cement, wollastonite powder (WS) was utilized as an additive before and after calcination to study its effect on the mechanical properties of MOS. The WS and WS/MOS composite system before and after calcination (1000℃) were analyzed by DSC-TG, XRD, FTIR, NMR, SEM, and mercury intrusion porosimetry (MIP). The results show that calcination stimulates the hydration activity of 29Si in WS, and the calcined WS stimulates its hydration activity in magnesium alkali environment, resulting in better performance of WS/MOS composite materials. WS enhances the mechanical properties of MOS, and the strength of WS/MOS composite system with the calcined WS increases more significantly. The bending strength and compressive strength of MOS on the 28 days reach their maximum values when the after calcination WS content is 20wt%, which are 11.4 MPa and 63.4 MPa, respectively, with increments of 71.4% and 21.2%. WS optimizes the pore structure and reduces the proportion of pores larger than 100 nm in MOS. The calcined WS has good interface compatibility with MOS, which is more conducive to improving the mechanical properties of MOS.
2024, 41(1): 404-413.
doi: 10.13801/j.cnki.fhclxb.20230506.001
Abstract:
Application of coral waste in concrete is an effective strategy to produce building materials suitable for offshore island construction, but excessive application of coral waste can lead to drastic degradation of concrete properties. In order to improve the replacement ratio of coral waste while ensuring the performance of mortar, this study combined coral sand (CS) and coral powder (CP) to replace part of the aggregate and binder to produce mortar, and the effect of CS substitution ratio on the mechanical properties, autogenous shrinkage and drying shrinkage of mortar was investigated, and its influencing mechanism was analyzed in combination with microstructure and pore structure. The results demonstrate that the mortar produced by combined application of 10wt%-40wt%CS and 10wt%CP has higher strength than the mortar without CS. When the replacement ratio of CS is 30wt%, the strength of the mortar is the highest, and its 28 days compressive strength is increased by 29.50% compared with the reference group. Meanwhile, with the increase of CS content, the autogenous shrinkage of mortar decreases. When the CS content is 40wt%, the 28 days autogenous shrinkage value of the mortar is decreased by 33.74%, compared with the reference group. In addition, the addition of CS is also beneficial to reduce the drying shrinkage of mortar, and the drying shrinkage of mortar reaches the lowest when the substitution ratio of CS is 30wt%. The porous structure of CS makes it tightly occluded with the cement matrix, and its internal curing effect also promotes the improvement of interface performance. The results of the specific surface area (BET) also show that adding 30wt%CS reduces the porosity of the sample, but further increasing the CS content is not conducive to the development of the pore structure of the sample.
Application of coral waste in concrete is an effective strategy to produce building materials suitable for offshore island construction, but excessive application of coral waste can lead to drastic degradation of concrete properties. In order to improve the replacement ratio of coral waste while ensuring the performance of mortar, this study combined coral sand (CS) and coral powder (CP) to replace part of the aggregate and binder to produce mortar, and the effect of CS substitution ratio on the mechanical properties, autogenous shrinkage and drying shrinkage of mortar was investigated, and its influencing mechanism was analyzed in combination with microstructure and pore structure. The results demonstrate that the mortar produced by combined application of 10wt%-40wt%CS and 10wt%CP has higher strength than the mortar without CS. When the replacement ratio of CS is 30wt%, the strength of the mortar is the highest, and its 28 days compressive strength is increased by 29.50% compared with the reference group. Meanwhile, with the increase of CS content, the autogenous shrinkage of mortar decreases. When the CS content is 40wt%, the 28 days autogenous shrinkage value of the mortar is decreased by 33.74%, compared with the reference group. In addition, the addition of CS is also beneficial to reduce the drying shrinkage of mortar, and the drying shrinkage of mortar reaches the lowest when the substitution ratio of CS is 30wt%. The porous structure of CS makes it tightly occluded with the cement matrix, and its internal curing effect also promotes the improvement of interface performance. The results of the specific surface area (BET) also show that adding 30wt%CS reduces the porosity of the sample, but further increasing the CS content is not conducive to the development of the pore structure of the sample.
2024, 41(1): 427-445.
doi: 10.13801/j.cnki.fhclxb.20230511.003
Abstract:
With the rapid consumption of fossil fuels, the issues of energy security and climate change are becoming increasingly prominent. The research of clean and sustainable energy development technology and energy storage technology has become a hot topic. By combining molecular dynamics simulation and experimental research, the influence of interface effects on the heat transport characteristics of mixed nitrate composite phase change materials (CPCM) was studied. Firstly, the thermal conductivity and specific heat capacity of CPCM were measured by laser thermal conductivity meter and differential scanning calorimeter respectively. Then Materials Studio software was used to establish the models of composite phase change materials with different NaNO3 and KNO3 ratios in eutectic states and different skeletons and the molecular dynamics simulation calculation of its thermal conductivity and specific heat at constant pressure was carried out. The internal mechanism of the experimental results was analyzed through the changes in radial distribution function, interface binding energy, and bulk thermal expansion coefficient, and then the competitive relationship between the interface effect and the mixed nitrate ratio on the thermal properties was further analyzed. The results show that when the mass ratio of NaNO3 and KNO3 is 4∶6, the interaction between ions is weaker than other ratios, and the interface binding energy and thermal conductivity are the largest. An increase in interfacial binding energy enhances the thermal conductivity more strongly than a decrease in the interaction between ions weakens the thermal conductivity, the interfacial effect plays a dominant role in the change in the thermal conductivity of CPCM. The specific heat of CPCM at constant pressure is affected by the change of ratio and skeleton material, interfacial binding energy and ionic interaction have no obvious effect on specific heat at constant pressure.
With the rapid consumption of fossil fuels, the issues of energy security and climate change are becoming increasingly prominent. The research of clean and sustainable energy development technology and energy storage technology has become a hot topic. By combining molecular dynamics simulation and experimental research, the influence of interface effects on the heat transport characteristics of mixed nitrate composite phase change materials (CPCM) was studied. Firstly, the thermal conductivity and specific heat capacity of CPCM were measured by laser thermal conductivity meter and differential scanning calorimeter respectively. Then Materials Studio software was used to establish the models of composite phase change materials with different NaNO3 and KNO3 ratios in eutectic states and different skeletons and the molecular dynamics simulation calculation of its thermal conductivity and specific heat at constant pressure was carried out. The internal mechanism of the experimental results was analyzed through the changes in radial distribution function, interface binding energy, and bulk thermal expansion coefficient, and then the competitive relationship between the interface effect and the mixed nitrate ratio on the thermal properties was further analyzed. The results show that when the mass ratio of NaNO3 and KNO3 is 4∶6, the interaction between ions is weaker than other ratios, and the interface binding energy and thermal conductivity are the largest. An increase in interfacial binding energy enhances the thermal conductivity more strongly than a decrease in the interaction between ions weakens the thermal conductivity, the interfacial effect plays a dominant role in the change in the thermal conductivity of CPCM. The specific heat of CPCM at constant pressure is affected by the change of ratio and skeleton material, interfacial binding energy and ionic interaction have no obvious effect on specific heat at constant pressure.
2024, 41(1): 438-447.
doi: 10.13801/j.cnki.fhclxb.20230511.002
Abstract:
CuAlNi shape memory alloy is chosen as damping reinforced phase, then novel jujube-cake shaped CuAlNi/Al composites were designed and prepared. The whole preparation process can be summarized as two steps, i.e. initial production of parent CuAlNi foam by powder metallurgy process basing on space occupation and dissolution of pore-forming agent and subsequent fabrication of CuAlNi/Al composites by negative pressure infiltration. The microstructure, damping and compressive mechanical properties of the composites were investigated in details. Internal friction measurements indicate that the CuAlNi/Al composites can obtain ultrahigh damping capacity, and the value of damping near the room temperature is even 6 times relative to pure Al. The excellent damping capacity of the composite is rationalized not only to relate to high intrinsic damping of CuAlNi reinforcement, but also to associate with the weak-bonding interface damping introduced between CuAlNi and pure Al and the additional damping arising from the residual micro-pores in the composites. Moreover, the composites exhibit similar compressive stress-strain curves and deformation mechanism as pure Al when the Al volume percent in the composite is more than 59.5vol%, but higher compressive mechanical strength and energy absorption capacity.
CuAlNi shape memory alloy is chosen as damping reinforced phase, then novel jujube-cake shaped CuAlNi/Al composites were designed and prepared. The whole preparation process can be summarized as two steps, i.e. initial production of parent CuAlNi foam by powder metallurgy process basing on space occupation and dissolution of pore-forming agent and subsequent fabrication of CuAlNi/Al composites by negative pressure infiltration. The microstructure, damping and compressive mechanical properties of the composites were investigated in details. Internal friction measurements indicate that the CuAlNi/Al composites can obtain ultrahigh damping capacity, and the value of damping near the room temperature is even 6 times relative to pure Al. The excellent damping capacity of the composite is rationalized not only to relate to high intrinsic damping of CuAlNi reinforcement, but also to associate with the weak-bonding interface damping introduced between CuAlNi and pure Al and the additional damping arising from the residual micro-pores in the composites. Moreover, the composites exhibit similar compressive stress-strain curves and deformation mechanism as pure Al when the Al volume percent in the composite is more than 59.5vol%, but higher compressive mechanical strength and energy absorption capacity.
2024, 41(1): 467-480.
doi: 10.13801/j.cnki.fhclxb.20230623.002
Abstract:
Composite structures play an important role in the fields of aerospace, ocean engineering and rail transit. Due to their defects in impact resistance, real-time on-line impact monitoring technology has attracted more and more attention. In this paper, an impact localization method for stiffened composite plates based on adaptive time reversal focusing imaging was proposed. Firstly, the impact response signal was received by piezoelectric sensor network arranged on the surface of the structure. Then, the narrowband Lamb wave signal of impact response signal was extracted by continuous wavelet transform. And a virtual time-reversal imaging function with impact position coordinates and narrowband Lamb wave group velocity as variables was constructed according to the time-reversal focusing principle. Finally, the virtual time reversal imaging results corresponding to different group velocities were iteratively calculated, and the adaptive time reversal focusing image was obtained according to the maximum pixel curve corresponding to different group velocities to realize impact localization. Drop ball impact experiments were carried out on a stiffened braided composite plate of 800 mm×400 mm (length×width) to verify the effectiveness of the method. The results show that this method can accurately identify the impact location and has a good accuracy in the cases of noise, reducing the number of sensors, and changing temperature.
Composite structures play an important role in the fields of aerospace, ocean engineering and rail transit. Due to their defects in impact resistance, real-time on-line impact monitoring technology has attracted more and more attention. In this paper, an impact localization method for stiffened composite plates based on adaptive time reversal focusing imaging was proposed. Firstly, the impact response signal was received by piezoelectric sensor network arranged on the surface of the structure. Then, the narrowband Lamb wave signal of impact response signal was extracted by continuous wavelet transform. And a virtual time-reversal imaging function with impact position coordinates and narrowband Lamb wave group velocity as variables was constructed according to the time-reversal focusing principle. Finally, the virtual time reversal imaging results corresponding to different group velocities were iteratively calculated, and the adaptive time reversal focusing image was obtained according to the maximum pixel curve corresponding to different group velocities to realize impact localization. Drop ball impact experiments were carried out on a stiffened braided composite plate of 800 mm×400 mm (length×width) to verify the effectiveness of the method. The results show that this method can accurately identify the impact location and has a good accuracy in the cases of noise, reducing the number of sensors, and changing temperature.
2024, 41(1): 467-476.
doi: 10.13801/j.cnki.fhclxb.20230516.001
Abstract:
As a new type of metamaterials, negative Poisson's ratio materials have great potential application prospects in aerospace, aviation, industry, medical science and other fields due to its excellent mechanical properties. In order to obtain metamaterials with actively adjustable performance and structure, a unit model of metamaterial structure was first designed based on the negative Poisson's ratio structure. Then, through the calculation of basic beam theory, the critical parameters between the positive and negative transition of the Poisson's ratio of the macrostructure and the rigid body structure were obtained. In addition, through finite element simulation, the relationship between positive and negative adjustment of Poisson's ratio of materials and the proportion and arrangement of filling elements was determined. Finally, the vibration characteristics and mechanical properties of this two-dimensional structural material were analyzed in detail. The results show that this material shows excellent performance in regulating the structure and reducing vibration. Adjusting the filling form and arrangement of the internal unit, we can obtain different mechanical properties and energy absorption effects. At the same time, by introducing shape memory materials and microstructures, the materials show excellent macrostructure and intelligent adjustment of stiffness.
As a new type of metamaterials, negative Poisson's ratio materials have great potential application prospects in aerospace, aviation, industry, medical science and other fields due to its excellent mechanical properties. In order to obtain metamaterials with actively adjustable performance and structure, a unit model of metamaterial structure was first designed based on the negative Poisson's ratio structure. Then, through the calculation of basic beam theory, the critical parameters between the positive and negative transition of the Poisson's ratio of the macrostructure and the rigid body structure were obtained. In addition, through finite element simulation, the relationship between positive and negative adjustment of Poisson's ratio of materials and the proportion and arrangement of filling elements was determined. Finally, the vibration characteristics and mechanical properties of this two-dimensional structural material were analyzed in detail. The results show that this material shows excellent performance in regulating the structure and reducing vibration. Adjusting the filling form and arrangement of the internal unit, we can obtain different mechanical properties and energy absorption effects. At the same time, by introducing shape memory materials and microstructures, the materials show excellent macrostructure and intelligent adjustment of stiffness.
2024, 41(1): 477-484.
doi: 10.13801/j.cnki.fhclxb.20230609.001
Abstract:
As a typical metamaterial, negative Poisson's ratio structures have been widely used in aerospace, automotive, and other fields due to their unique deformation mechanism and energy absorption characteristics. However, there is relatively little research on its vibration damping characteristics. Research on the development of multifunctional negative Poisson's ratio structures with simultaneous excellent load-bearing, energy-absorbing and vibration-damping properties is even more scarce. Inspired by the star-shaped and inner-concave negative Poisson's ratio structure, a novel chiral negative Poisson's ratio structure is proposed. Four configurations with different geometric parameters are designed and prepared by 3D printing technology. In the previous study, it has been found that the novel structure exhibits excellent static properties and energy absorption characteristics. Based on this, the damping performances of novel structures are demonstrated by combination of experiments and numerical simulations, which are compared with that of the conventional non-chiral negative Poisson's ratio structure. The results show that the stronger the negative Poisson's ratio effect of novel chiral negative Poisson's ratio structure, the better the vibration damping performance. The results and laws can provide theoretical guidance for the design of the novel chiral negative Poisson's ratio vibration damping structure.
As a typical metamaterial, negative Poisson's ratio structures have been widely used in aerospace, automotive, and other fields due to their unique deformation mechanism and energy absorption characteristics. However, there is relatively little research on its vibration damping characteristics. Research on the development of multifunctional negative Poisson's ratio structures with simultaneous excellent load-bearing, energy-absorbing and vibration-damping properties is even more scarce. Inspired by the star-shaped and inner-concave negative Poisson's ratio structure, a novel chiral negative Poisson's ratio structure is proposed. Four configurations with different geometric parameters are designed and prepared by 3D printing technology. In the previous study, it has been found that the novel structure exhibits excellent static properties and energy absorption characteristics. Based on this, the damping performances of novel structures are demonstrated by combination of experiments and numerical simulations, which are compared with that of the conventional non-chiral negative Poisson's ratio structure. The results show that the stronger the negative Poisson's ratio effect of novel chiral negative Poisson's ratio structure, the better the vibration damping performance. The results and laws can provide theoretical guidance for the design of the novel chiral negative Poisson's ratio vibration damping structure.
2024, 41(1): 495-506.
doi: 10.13801/j.cnki.fhclxb.20230411.001
Abstract:
The tensile damage failure mode and high-temperature thermal damage morphology of S2/430LV under the combined action of heat and force were studied from macro and micro perspectives, and the thermal properties of the materials were analyzed by DMA and TG. The failure mechanism of S2/430LV tensile specimens at 20-180℃ and the variation rule of tensile strength/modulus with temperature were revealed, and the prediction was made. The results show that with the increase of ambient temperature, the softening degree and fluidity of 430LV resin increase, and the adhesive ability between resin and fiber tow decreases. Under the combined action of heat and force, the tensile strength and modulus decrease with the increase of temperature, and both decrease most rapidly around 100℃. The failure mode of the sample also changes with the increase of temperature. Before 100℃, the failure mode shows complete fracture of the fiber, and the stress-strain curve shows significant linear elastic characteristics. But after 100℃, the failure mode changes to interlaminar delamination failure. The change of the failure mode also has a certain impact on the tensile bearing mode of the material, resulting in the tensile modulus retention rate higher than the strength retention rate, and the stress-strain curve also shows concave curve characteristics. Based on Gibson prediction model and Bisby prediction model, Origin software was used to quickly and accurately obtain the optimal values of unknown parameters of the prediction model. It is found that the fitting results of the two models are highly consistent with the experimental results.
The tensile damage failure mode and high-temperature thermal damage morphology of S2/430LV under the combined action of heat and force were studied from macro and micro perspectives, and the thermal properties of the materials were analyzed by DMA and TG. The failure mechanism of S2/430LV tensile specimens at 20-180℃ and the variation rule of tensile strength/modulus with temperature were revealed, and the prediction was made. The results show that with the increase of ambient temperature, the softening degree and fluidity of 430LV resin increase, and the adhesive ability between resin and fiber tow decreases. Under the combined action of heat and force, the tensile strength and modulus decrease with the increase of temperature, and both decrease most rapidly around 100℃. The failure mode of the sample also changes with the increase of temperature. Before 100℃, the failure mode shows complete fracture of the fiber, and the stress-strain curve shows significant linear elastic characteristics. But after 100℃, the failure mode changes to interlaminar delamination failure. The change of the failure mode also has a certain impact on the tensile bearing mode of the material, resulting in the tensile modulus retention rate higher than the strength retention rate, and the stress-strain curve also shows concave curve characteristics. Based on Gibson prediction model and Bisby prediction model, Origin software was used to quickly and accurately obtain the optimal values of unknown parameters of the prediction model. It is found that the fitting results of the two models are highly consistent with the experimental results.
2024, 41(1): 521-532.
doi: 10.13801/j.cnki.fhclxb.20230526.001
Abstract:
The compressive performance test of S2/430LV under the combined effect of heat and force was carried out, with a focus on revealing the compression damage failure mechanism and the variation law of strength/modulus of S2/430LV from 20 to 180℃. A segmented curve fitting method based on the Ha-Springer model was proposed, and the variation law of strength/modulus with temperature was predicted. The study shows that under the combined effect of heat and force, the compressive strength and modulus decrease with the increasing temperature, but the modulus retention rate is higher than that of strength. With the increase of temperature, the final failure mode of the sample changes. Before 100℃, the sample shows an overall shear failure mode, with fiber bundles twisting and accompanied by fiber fracture and damage path fracture. However, after 100℃, the final failure mode is manifested as the shear damage of resin matrix, while the fiber fabric morphology remains basically unchanged. The strength and modulus exhibit an "S"-shaped trend with temperature, where the strength-temperature curve is a convex curve in the range of 20-80℃ and a concave curve in the range of 80-180℃; The modulus-temperature curve is a convex curve in the range of 20-100℃ and a concave curve in the range of 100-180℃. A segmented curve fitting method based on the Ha-Springer model was proposed, and Origin software was used to predict the variation of strength/modulus with temperature. The prediction results are highly consistent with the experimental results and the degree of agreement is better than that of the Mahieux model.
The compressive performance test of S2/430LV under the combined effect of heat and force was carried out, with a focus on revealing the compression damage failure mechanism and the variation law of strength/modulus of S2/430LV from 20 to 180℃. A segmented curve fitting method based on the Ha-Springer model was proposed, and the variation law of strength/modulus with temperature was predicted. The study shows that under the combined effect of heat and force, the compressive strength and modulus decrease with the increasing temperature, but the modulus retention rate is higher than that of strength. With the increase of temperature, the final failure mode of the sample changes. Before 100℃, the sample shows an overall shear failure mode, with fiber bundles twisting and accompanied by fiber fracture and damage path fracture. However, after 100℃, the final failure mode is manifested as the shear damage of resin matrix, while the fiber fabric morphology remains basically unchanged. The strength and modulus exhibit an "S"-shaped trend with temperature, where the strength-temperature curve is a convex curve in the range of 20-80℃ and a concave curve in the range of 80-180℃; The modulus-temperature curve is a convex curve in the range of 20-100℃ and a concave curve in the range of 100-180℃. A segmented curve fitting method based on the Ha-Springer model was proposed, and Origin software was used to predict the variation of strength/modulus with temperature. The prediction results are highly consistent with the experimental results and the degree of agreement is better than that of the Mahieux model.
2024, 41(1): 525-534.
doi: 10.13801/j.cnki.fhclxb.20230516.002
Abstract:
Polypropylene (PP), as an environment-friendly thermoplastic material, has great potential in the application of ultra high voltage cable lines. However, in practical applications, the thermal and mechanical properties are difficult to improve in coordination, and the humid environment accelerates the initiation of water branches, which seriously hampers the rapid development of PP. To this end, based on molecular dynamics simulation technology, pure PP, composite model of ZnO/PP with sphericalnanoparticles with radius of 0.4 nm and 0.6 nm and water-containing molecular models were built, and the effects of spherical nano-ZnO on the properties of PP were studied from the molecular level by using the changes of thermal and mechanical properties and other parameters. The results show that nano-ZnO can improve the thermal stability of PP and its mechanical properties, and the lifting effect of ZnO particles with different radii is different. Among them, the glass transition temperature of PP increases by 56 K with nano-ZnO with a radius of 0.6 nm, which can significantly reduce its Young's modulus and shear modulus, and has a good inhibition effect on the movement of PP molecular chain and water molecules. Water molecules significantly increase the average azimuthal shift, reduce the glass transition temperature and mechanical parameters, and enhance the diffusion ability with the increase of temperature. Due to the hydrogen bonding between nano ZnO and water molecules, the movement of water molecules in the composite system is limited, thus maintaining good thermal stability. The research results provide micro-level reference for inhibiting the growth and aging of PP water tree and developing practical and environment-friendly cable materials.
Polypropylene (PP), as an environment-friendly thermoplastic material, has great potential in the application of ultra high voltage cable lines. However, in practical applications, the thermal and mechanical properties are difficult to improve in coordination, and the humid environment accelerates the initiation of water branches, which seriously hampers the rapid development of PP. To this end, based on molecular dynamics simulation technology, pure PP, composite model of ZnO/PP with sphericalnanoparticles with radius of 0.4 nm and 0.6 nm and water-containing molecular models were built, and the effects of spherical nano-ZnO on the properties of PP were studied from the molecular level by using the changes of thermal and mechanical properties and other parameters. The results show that nano-ZnO can improve the thermal stability of PP and its mechanical properties, and the lifting effect of ZnO particles with different radii is different. Among them, the glass transition temperature of PP increases by 56 K with nano-ZnO with a radius of 0.6 nm, which can significantly reduce its Young's modulus and shear modulus, and has a good inhibition effect on the movement of PP molecular chain and water molecules. Water molecules significantly increase the average azimuthal shift, reduce the glass transition temperature and mechanical parameters, and enhance the diffusion ability with the increase of temperature. Due to the hydrogen bonding between nano ZnO and water molecules, the movement of water molecules in the composite system is limited, thus maintaining good thermal stability. The research results provide micro-level reference for inhibiting the growth and aging of PP water tree and developing practical and environment-friendly cable materials.
