2022 Vol. 39, No. 3
2022, 39(3): 863-883.
doi: 10.13801/j.cnki.fhclxb.20211027.004
Abstract:
Carbon nanotubes (CNTs) has excellent mechanical, thermal and electromagnetic properties. One of its important applications is to modify continuous fiber reinforced resin matrix composites to afford them better mecha-nical and multifunctional properties. For continuous fiber reinforced resin matrix composites, several methods of introducing CNTs are summarized. The interlaminar properties of CNTs-continuous fiber reinforced resin matrix composites are revealed. The latest progress on CNT assemblies-continuous fiber reinforced resin matrix compo-sites is introduced in detail and their future development is also discussed.
Carbon nanotubes (CNTs) has excellent mechanical, thermal and electromagnetic properties. One of its important applications is to modify continuous fiber reinforced resin matrix composites to afford them better mecha-nical and multifunctional properties. For continuous fiber reinforced resin matrix composites, several methods of introducing CNTs are summarized. The interlaminar properties of CNTs-continuous fiber reinforced resin matrix composites are revealed. The latest progress on CNT assemblies-continuous fiber reinforced resin matrix compo-sites is introduced in detail and their future development is also discussed.
2022, 39(3): 884-895.
doi: 10.13801/j.cnki.fhclxb.20210816.001
Abstract:
Carbon dots (CDs) have attracted extensive attention in biological imaging, fluorescent probe and so on owing to their simple synthesis methods, wide range of raw materials, excellent photoluminescence properties and good biocompatibility. However, CDs still undergo some limitations such as low quantum yield, aggregation induced fluorescence quenching and so on, which will limit their application on photoelectric devices. Organosilane functionalized CDs (SiCDs) exhibit bright emission in solution, and their fluorescence properties could be maintained in solid state, which is an effective strategy to exploit the application field of CDs. The preparation methods of SiCDs are reported, including direct synthesis method and post-processing method, and the fluorescence properties of SiCDs prepared by different methods were compared. We also reviewed the applications of SiCDs in different fields, and further summarized the problems of SiCDs in the preparations and applications, which need to be solved in future. Finally, the preparation method, performance regulation and application of SiCDs are prospected.
Carbon dots (CDs) have attracted extensive attention in biological imaging, fluorescent probe and so on owing to their simple synthesis methods, wide range of raw materials, excellent photoluminescence properties and good biocompatibility. However, CDs still undergo some limitations such as low quantum yield, aggregation induced fluorescence quenching and so on, which will limit their application on photoelectric devices. Organosilane functionalized CDs (SiCDs) exhibit bright emission in solution, and their fluorescence properties could be maintained in solid state, which is an effective strategy to exploit the application field of CDs. The preparation methods of SiCDs are reported, including direct synthesis method and post-processing method, and the fluorescence properties of SiCDs prepared by different methods were compared. We also reviewed the applications of SiCDs in different fields, and further summarized the problems of SiCDs in the preparations and applications, which need to be solved in future. Finally, the preparation method, performance regulation and application of SiCDs are prospected.
2022, 39(3): 896-906.
doi: 10.13801/j.cnki.fhclxb.20210820.005
Abstract:
Graphene is considered to be a promising gas barrier filler, complete monolayer graphene blocks the vast majority of small gaseous molecules through its surface, so graphene is widely used as a filler to improve the gas density of the polymer. The research progress of graphene and its derivatives enhancing polymer airtightness in recent years is reviewed. The characteristics of graphene and its barrier mechanism in polymer matrix are introduced, the main factors affecting the barrier of layered graphene/polymer nanocomposite are discussed. The methods of enhancement of graphene and the derivatives of different polymer gas density are analyzed. Finally, the research of graphene and its derivatives enhancing polymer airtightness is summarized and the future development direction is prospected.
Graphene is considered to be a promising gas barrier filler, complete monolayer graphene blocks the vast majority of small gaseous molecules through its surface, so graphene is widely used as a filler to improve the gas density of the polymer. The research progress of graphene and its derivatives enhancing polymer airtightness in recent years is reviewed. The characteristics of graphene and its barrier mechanism in polymer matrix are introduced, the main factors affecting the barrier of layered graphene/polymer nanocomposite are discussed. The methods of enhancement of graphene and the derivatives of different polymer gas density are analyzed. Finally, the research of graphene and its derivatives enhancing polymer airtightness is summarized and the future development direction is prospected.
2022, 39(3): 907-925.
doi: 10.13801/j.cnki.fhclxb.20210830.001
Abstract:
Curing tooling is one of the key factors to induce the deformation of thermosetting resin matrix compo-site components. The development trend of integrated, mass, high precision and high performance of composite components for large aerospace composite material components has put forward higher requirements on the precision and life of curing tooling, and promoted the new development of tooling materials, design and manufacturing processing. However, there is still a lack of systematic review of relevant research. Therefore, contraposing the widespread demanding of high precision tooling for large aerospace composite material components, this paper summarizes the research status including interfacial functional mechanism between tooling and components, the pro-perties of tooling materials, the structural characteristics and manufacturing processing. The development from tooling material to manufacturing processing is emphasized in detail under the comprehensive consideration of manufacturing precision, efficiency and cost. Finally, the current development status of high precision tooling is summarized in aspect of materials, design and manufacturing technology for large composite components and the main research directions in the future are proposed.
Curing tooling is one of the key factors to induce the deformation of thermosetting resin matrix compo-site components. The development trend of integrated, mass, high precision and high performance of composite components for large aerospace composite material components has put forward higher requirements on the precision and life of curing tooling, and promoted the new development of tooling materials, design and manufacturing processing. However, there is still a lack of systematic review of relevant research. Therefore, contraposing the widespread demanding of high precision tooling for large aerospace composite material components, this paper summarizes the research status including interfacial functional mechanism between tooling and components, the pro-perties of tooling materials, the structural characteristics and manufacturing processing. The development from tooling material to manufacturing processing is emphasized in detail under the comprehensive consideration of manufacturing precision, efficiency and cost. Finally, the current development status of high precision tooling is summarized in aspect of materials, design and manufacturing technology for large composite components and the main research directions in the future are proposed.
2022, 39(3): 926-941.
doi: 10.13801/j.cnki.fhclxb.20210902.004
Abstract:
In order to solve the problems of steel bar corrosion and resource shortage, fiber reinforced polymer (FRP) bars with light weight, high strength and corrosion resistance and coral aggregate with similar mechanical properties as common aggregate have become new materials studied by researchers in recent years. In this paper, from the following three aspects: the material characteristics of FRP and coral aggregate as well as mechanical properties of coral aggregate made concrete, the bonding performance and durability between FRP bars and coral aggregate concrete, and the mechanical properties of FRP bars reinforced coral aggregate concrete beams and columns, the relevant research results are summarized. It is considered that FRP bars and coral aggregate concrete have better compatibility and can effectively enhance the performance of coral aggregate concrete structures. In addition, the limitations of FRP bars, coral aggregate and other materials, as well as the shortcomings of the research on the service performance, durability and design method of FRP reinforced coral aggregate concrete members are summarized, which can provide reference for the further research on this new structure.
In order to solve the problems of steel bar corrosion and resource shortage, fiber reinforced polymer (FRP) bars with light weight, high strength and corrosion resistance and coral aggregate with similar mechanical properties as common aggregate have become new materials studied by researchers in recent years. In this paper, from the following three aspects: the material characteristics of FRP and coral aggregate as well as mechanical properties of coral aggregate made concrete, the bonding performance and durability between FRP bars and coral aggregate concrete, and the mechanical properties of FRP bars reinforced coral aggregate concrete beams and columns, the relevant research results are summarized. It is considered that FRP bars and coral aggregate concrete have better compatibility and can effectively enhance the performance of coral aggregate concrete structures. In addition, the limitations of FRP bars, coral aggregate and other materials, as well as the shortcomings of the research on the service performance, durability and design method of FRP reinforced coral aggregate concrete members are summarized, which can provide reference for the further research on this new structure.
2022, 39(3): 942-955.
doi: 10.13801/j.cnki.fhclxb.20211018.001
Abstract:
The problem of electromagnetic pollution is becoming more and more serious with the rapid development of the information age. The development of advanced microwave absorbing materials can not only reduce electromagnetic pollution, but also have important implications for military security. MXene is a new type of two-dimensional material. The unique two-dimensional structure, abundant and controllable surface functional groups, high specific surface area, high conductivity and low density make it an ideal high-performance microwave absorbing material. This paper first discussed the preparation methods of MXene and its composite absorbing composites, then introduced the electromagnetic performance of MXene, which is closely related to the absorbing performance. In addition, MXene and its composite microwave absorbing materials are summarized and analyzed according to the loss mechanism. Finally, the development direction of MXene and its composite absorbing materials is prospected from the aspects of type, structure and application.
The problem of electromagnetic pollution is becoming more and more serious with the rapid development of the information age. The development of advanced microwave absorbing materials can not only reduce electromagnetic pollution, but also have important implications for military security. MXene is a new type of two-dimensional material. The unique two-dimensional structure, abundant and controllable surface functional groups, high specific surface area, high conductivity and low density make it an ideal high-performance microwave absorbing material. This paper first discussed the preparation methods of MXene and its composite absorbing composites, then introduced the electromagnetic performance of MXene, which is closely related to the absorbing performance. In addition, MXene and its composite microwave absorbing materials are summarized and analyzed according to the loss mechanism. Finally, the development direction of MXene and its composite absorbing materials is prospected from the aspects of type, structure and application.
2022, 39(3): 956-968.
doi: 10.13801/j.cnki.fhclxb.20211015.001
Abstract:
With the significantly increasing demand for new thermal interface materials with high thermal conduc-tivity and high insulation, epoxy resin (EP) with various excellent properties has been widely used as the matrix of thermal conducting composites. However, its practical application is limited by its inherent low thermal conduc-tivity. The incorporation of two-dimensional boron nitride nanosheets (BNNS) with high thermal conductivity and high insulation into epoxy resin can effectively overcome the shortcomings of EP and thereby significantly improve the comprehensive performance. Based on the domestic and foreign research progresses, various preparation methods of BNNS are discussed in this article, and their advantages and disadvantages are summarized. Various strategies for improving the thermal conductivity of BNNS/EP composites is reviewed, including surface modification of BNNS, hybridization between BNNS and multi-dimensional fillers, and construction of 3D-BNNS thermal conductivity network. The key problems in the preparation of BNNS/EP composites with high thermal conductivity are proposed. Finally, the development trend of BNNS/EP composites is prospected.
With the significantly increasing demand for new thermal interface materials with high thermal conduc-tivity and high insulation, epoxy resin (EP) with various excellent properties has been widely used as the matrix of thermal conducting composites. However, its practical application is limited by its inherent low thermal conduc-tivity. The incorporation of two-dimensional boron nitride nanosheets (BNNS) with high thermal conductivity and high insulation into epoxy resin can effectively overcome the shortcomings of EP and thereby significantly improve the comprehensive performance. Based on the domestic and foreign research progresses, various preparation methods of BNNS are discussed in this article, and their advantages and disadvantages are summarized. Various strategies for improving the thermal conductivity of BNNS/EP composites is reviewed, including surface modification of BNNS, hybridization between BNNS and multi-dimensional fillers, and construction of 3D-BNNS thermal conductivity network. The key problems in the preparation of BNNS/EP composites with high thermal conductivity are proposed. Finally, the development trend of BNNS/EP composites is prospected.
2022, 39(3): 969-980.
doi: 10.13801/j.cnki.fhclxb.20211115.003
Abstract:
Renewable nanocellulose has attracted much attention in recent years. The advantages of nanocellulose include wide sources, diverse preparation methods, biodegradability, safe and non-toxic, high specific surface area, high strength, low density and good thermal stability. The preparation methods of nanocellulose, and the application research progress of 2D membrane material sensors and 3D gel material sensors based on nanocellulosic materials are mainly introduced. The applications of nanocellulose-based sensors in proximity sensing, pH sensing, electrochemical sensing, glucose sensing and ion sensing detection are highlighted. The results show that the sensitivity, mechanical properties, stability, specificity and environmental friendliness of nanocellulose based sensors are better than those prepared by some traditional materials. Nanocellulose based sensors have broad potential applications.
Renewable nanocellulose has attracted much attention in recent years. The advantages of nanocellulose include wide sources, diverse preparation methods, biodegradability, safe and non-toxic, high specific surface area, high strength, low density and good thermal stability. The preparation methods of nanocellulose, and the application research progress of 2D membrane material sensors and 3D gel material sensors based on nanocellulosic materials are mainly introduced. The applications of nanocellulose-based sensors in proximity sensing, pH sensing, electrochemical sensing, glucose sensing and ion sensing detection are highlighted. The results show that the sensitivity, mechanical properties, stability, specificity and environmental friendliness of nanocellulose based sensors are better than those prepared by some traditional materials. Nanocellulose based sensors have broad potential applications.
2022, 39(3): 981-992.
doi: 10.13801/j.cnki.fhclxb.20211117.001
Abstract:
Textile-based energy storage is an important energy supply element of the microelectronic signal collection system for flexible wearable textiles. The recent research progress of flexible supercapacitors from multiple perspectives of fibers, yarns and fabrics, and states the preparation methods, advantages and disadvantages of supercapacitors of different matrix types are summarized. Focusing on the technological characteristics of textile supercapacitors, analysis the method that should be adopted to improve the performance of materials. Finally, an explanation for the presence of textile-based supercapacitor development and the key work of future which need to overcome is given an analysis and outlook.
Textile-based energy storage is an important energy supply element of the microelectronic signal collection system for flexible wearable textiles. The recent research progress of flexible supercapacitors from multiple perspectives of fibers, yarns and fabrics, and states the preparation methods, advantages and disadvantages of supercapacitors of different matrix types are summarized. Focusing on the technological characteristics of textile supercapacitors, analysis the method that should be adopted to improve the performance of materials. Finally, an explanation for the presence of textile-based supercapacitor development and the key work of future which need to overcome is given an analysis and outlook.
2022, 39(3): 993-1004.
doi: 10.13801/j.cnki.fhclxb.20210909.003
Abstract:
Cellulose is the most abundant organic polymer in nature, with many advantages like broad resource of raw material, large specific surface area, abundant hydroxyl groups and environmentally friendly. Besides, cellulose can form three-dimensional network structure in aqueous suspension, which provides loading sites for metal nanoparticles to make them disperse well and binds well with cellulose and prepares the composite catalysts with improved catalytic performance. Herein, the preparation and application of cellulose-based composite catalysts with metal nanoparticles were summarized, the methods and merits of the composite catalysts with various cellulosic materials were highlighted. Furthermore, the loading methods and principles of metal nanoparticles were generalized, and the main functions of cellulosic materials in composite catalysts were elaborated. Finally, the researches of cellulose-based composite catalysts with metal nanoparticle were summarized. This work can be a reference for the preparing and applying of cellulosic composite catalysts.
Cellulose is the most abundant organic polymer in nature, with many advantages like broad resource of raw material, large specific surface area, abundant hydroxyl groups and environmentally friendly. Besides, cellulose can form three-dimensional network structure in aqueous suspension, which provides loading sites for metal nanoparticles to make them disperse well and binds well with cellulose and prepares the composite catalysts with improved catalytic performance. Herein, the preparation and application of cellulose-based composite catalysts with metal nanoparticles were summarized, the methods and merits of the composite catalysts with various cellulosic materials were highlighted. Furthermore, the loading methods and principles of metal nanoparticles were generalized, and the main functions of cellulosic materials in composite catalysts were elaborated. Finally, the researches of cellulose-based composite catalysts with metal nanoparticle were summarized. This work can be a reference for the preparing and applying of cellulosic composite catalysts.
2022, 39(3): 1005-1016.
doi: 10.13801/j.cnki.fhclxb.20210701.001
Abstract:
Compared with individual two-dimensional MoS2 and MXene, MoS2/MXene nanocomposites show excellent and stable physical and chemical properties, attracting widespread attention among domestic and foreign researchers. This paper reviews recent research progress in MoS2/MXene nanocomposites. First, the preparation methods of MoS2/MXene nanocomposites as well as their advantages and disadvantages are elaborated, including hydrothermal methods, intercalation methods and thermal annealing. Then, the applications of MoS2/MXene composites in various fields are introduced, such as energy storage, catalysis and sensors. In the end, the prospects of future development and application of MoS2/MXene nanocomposites are proposed.
Compared with individual two-dimensional MoS2 and MXene, MoS2/MXene nanocomposites show excellent and stable physical and chemical properties, attracting widespread attention among domestic and foreign researchers. This paper reviews recent research progress in MoS2/MXene nanocomposites. First, the preparation methods of MoS2/MXene nanocomposites as well as their advantages and disadvantages are elaborated, including hydrothermal methods, intercalation methods and thermal annealing. Then, the applications of MoS2/MXene composites in various fields are introduced, such as energy storage, catalysis and sensors. In the end, the prospects of future development and application of MoS2/MXene nanocomposites are proposed.
2022, 39(3): 1017-1025.
doi: 10.13801/j.cnki.fhclxb.20210830.003
Abstract:
The modified chitosan magnetic nanomaterials, which was prepared by the composite of modified chitosan and magnetic materials, retains the strong chelating ability of chitosan with metal ions, and have good regeneration performance. These two properties greatly expand the application prospect of chitosan. This article focuses on the preparation methods of modified chitosan nanomaterials, and the latest research and application progress in wastewater treatment, immobilization of active substances, medicine and medical treatment, etc, which is to provide some theoretical support for the development and utilization of chitosan resources.
The modified chitosan magnetic nanomaterials, which was prepared by the composite of modified chitosan and magnetic materials, retains the strong chelating ability of chitosan with metal ions, and have good regeneration performance. These two properties greatly expand the application prospect of chitosan. This article focuses on the preparation methods of modified chitosan nanomaterials, and the latest research and application progress in wastewater treatment, immobilization of active substances, medicine and medical treatment, etc, which is to provide some theoretical support for the development and utilization of chitosan resources.
2022, 39(3): 1026-1035.
doi: 10.13801/j.cnki.fhclxb.20210608.003
Abstract:
Nano-SiO2 layer was obtained on the jute fibers by sol-gel method, and nano-SiO2 deposited jute fiber/polypropylene composites (n-SiO2@jute fiber/PP composites) were prepared by molding process. The molecular model of the multi-phase interfaces for n-SiO2@jute fiber/PP composites was established by molecular dynamic (MD) simulation. Combined with the analyses of the impact performance and fracture morphologies for n-SiO2@jute fiber/PP composites, the multi-phase interface structure and toughening mechanism of the compo-sites were revealed. The impact toughness of n-SiO2@jute fiber/PP composites is increased by 54.87% than that of the control ones. n-SiO2 layer forms an interphase between jute fiber and PP by C—O—Si chemical bond and the mechanical interlocking of molecular chains, which enhances the interface binding energy of jute fiber/PP compo-sites by 27.22%. When the impact fracture of the composites occurs, n-SiO2 interphase causes the crack deflection at the interface, which will absorb more fracture energy by increasing the crack propagation path and decreasing the crack propagation velocity. Additionally, the multi-phase interfaces with good bonding performance make the PP surrounding n-SiO2 interphase undergo plastic deformation during the impact failure process, absorbing massive impact energy. Moreover, the multi-phase interfaces transfer the part of impact energy from PP to jute fibers effec-tively, causing the internal debonding of the jute fibers and thus consuming more impact energy. This is because the interface bonding strength between the fibrils in the jute fibers is stronger than that between the jute fibers and PP.
Nano-SiO2 layer was obtained on the jute fibers by sol-gel method, and nano-SiO2 deposited jute fiber/polypropylene composites (n-SiO2@jute fiber/PP composites) were prepared by molding process. The molecular model of the multi-phase interfaces for n-SiO2@jute fiber/PP composites was established by molecular dynamic (MD) simulation. Combined with the analyses of the impact performance and fracture morphologies for n-SiO2@jute fiber/PP composites, the multi-phase interface structure and toughening mechanism of the compo-sites were revealed. The impact toughness of n-SiO2@jute fiber/PP composites is increased by 54.87% than that of the control ones. n-SiO2 layer forms an interphase between jute fiber and PP by C—O—Si chemical bond and the mechanical interlocking of molecular chains, which enhances the interface binding energy of jute fiber/PP compo-sites by 27.22%. When the impact fracture of the composites occurs, n-SiO2 interphase causes the crack deflection at the interface, which will absorb more fracture energy by increasing the crack propagation path and decreasing the crack propagation velocity. Additionally, the multi-phase interfaces with good bonding performance make the PP surrounding n-SiO2 interphase undergo plastic deformation during the impact failure process, absorbing massive impact energy. Moreover, the multi-phase interfaces transfer the part of impact energy from PP to jute fibers effec-tively, causing the internal debonding of the jute fibers and thus consuming more impact energy. This is because the interface bonding strength between the fibrils in the jute fibers is stronger than that between the jute fibers and PP.
2022, 39(3): 1036-1043.
doi: 10.13801/j.cnki.fhclxb.20210528.001
Abstract:
With the advent of 5G era, the heating power of various electronic components has increased significantly. Therefore, the problem of heat dissipation of electronic components and equipment needs to be solved urgently, which makes the demand for high thermal conductivity materials increasingly urgent. The two-dimensional MXene material (Ti3C2Tx) was prepared by chemical etching method, and the MXene/silicone rubber composites were obtained by using standard solution blending method. The effect of the addition amount of MXene on the thermal conductivity of the MXene/silicone rubber composites were studied. SEM and XRD were used to characterize the structure of MXene, and the mechanical properties, thermal conductivity and thermal stability of pure silicone rubber and the composites were tested. The results show that the classic accordion layered MXene is successfully prepared by chemical etch method. When the added MXene is 2.00wt%, the thermal conductivity of the composites is up to 1.32 W/(m·K), which is 4.55 times that of pure silicone rubber. At this time, the volume resistivity of the composites is reduced by 4 orders of magnitude. The mechanical properties and thermal stability of silicone rubber are also improved remarkably.
With the advent of 5G era, the heating power of various electronic components has increased significantly. Therefore, the problem of heat dissipation of electronic components and equipment needs to be solved urgently, which makes the demand for high thermal conductivity materials increasingly urgent. The two-dimensional MXene material (Ti3C2Tx) was prepared by chemical etching method, and the MXene/silicone rubber composites were obtained by using standard solution blending method. The effect of the addition amount of MXene on the thermal conductivity of the MXene/silicone rubber composites were studied. SEM and XRD were used to characterize the structure of MXene, and the mechanical properties, thermal conductivity and thermal stability of pure silicone rubber and the composites were tested. The results show that the classic accordion layered MXene is successfully prepared by chemical etch method. When the added MXene is 2.00wt%, the thermal conductivity of the composites is up to 1.32 W/(m·K), which is 4.55 times that of pure silicone rubber. At this time, the volume resistivity of the composites is reduced by 4 orders of magnitude. The mechanical properties and thermal stability of silicone rubber are also improved remarkably.
2022, 39(3): 1044-1054.
doi: 10.13801/j.cnki.fhclxb.20210514.001
Abstract:
A method of ultrasonic vibration + cryogenic liquid nitrogen + frozen support layer (UCF) is proposed to assist carbon fiber reinforced polymer (CFRP) drilling and effectively reduce machining defects. The basic principle of this method is as follows: the high frequency vibration of the drill bit under ultrasonic action is used to weaken the axial drilling force; the cryogenic temperature liquid nitrogen and the formation of frozen support layer are used to realize the constraint and support of the material at the drilling exit side, and effectively reduce the whole process of drilling heat effect. Based on the basic principle of UCF, corresponding experiment of UCF assisted drilling were carried out, and the hole quality of CFRP under traditional drilling mode (TD) and cryogenic liquid nitrogen + freezing support mode (CF) was compared and analyzed by means of microscopic inspection and characterization and defect factor calculation. The results show that both UCF and CF can increase the axial force, but the maximum axial force increased little. Compared with TD mode, UCF can reduce burr factor by 75%, tear factor by 8.9%, delamination factor by 34.6% and surface roughness Ra by 53.6%.
A method of ultrasonic vibration + cryogenic liquid nitrogen + frozen support layer (UCF) is proposed to assist carbon fiber reinforced polymer (CFRP) drilling and effectively reduce machining defects. The basic principle of this method is as follows: the high frequency vibration of the drill bit under ultrasonic action is used to weaken the axial drilling force; the cryogenic temperature liquid nitrogen and the formation of frozen support layer are used to realize the constraint and support of the material at the drilling exit side, and effectively reduce the whole process of drilling heat effect. Based on the basic principle of UCF, corresponding experiment of UCF assisted drilling were carried out, and the hole quality of CFRP under traditional drilling mode (TD) and cryogenic liquid nitrogen + freezing support mode (CF) was compared and analyzed by means of microscopic inspection and characterization and defect factor calculation. The results show that both UCF and CF can increase the axial force, but the maximum axial force increased little. Compared with TD mode, UCF can reduce burr factor by 75%, tear factor by 8.9%, delamination factor by 34.6% and surface roughness Ra by 53.6%.
2022, 39(3): 1055-1067.
doi: 10.13801/j.cnki.fhclxb.20210601.006
Abstract:
An integrated manufacturing of continuous functionally graded materials-structures based on multi-material 3D printing and constrained sacrificial layer was proposed to solve the limitations of the existing functionally graded material preparation methods, such as difficult to control the shape of low-viscosity liquids accurately, poor interlayer bonding strength, and simple forming structure. This technology is capable of realizing the brand-new preparation of polymer-based continuous functionally graded materials. Through theoretical analysis and experimental investigation, the influence law of main process parameters including extrusion speed, printing speed and line spacing, on the forming quality and performance of printing continuous functionally graded materials are revealed. Graphene/UV curable resin dielectric functionally graded material (d-FGM) were prepared by using lab self-developed device, and realizing the integrated manufacturing of polymer-based continuous functionally graded insulators. Compared with the homogeneous UV curable resin, the dielectric constant has doubled, the resistivity has been reduced by 93.3%, and the amplitude of the creeping electric field strength has increased by more than 14%. Besides, the rigidity of the Al2O3 side with 40% content has doubled than a single polydimethylsiloxane (PDMS) material. With the features of realizing the continuous gradient distribution of the Al2O3. The 3D printing process provides a low-cost and high-efficiency solution for the preparation of polymer-based continuous functionally graded materials.
An integrated manufacturing of continuous functionally graded materials-structures based on multi-material 3D printing and constrained sacrificial layer was proposed to solve the limitations of the existing functionally graded material preparation methods, such as difficult to control the shape of low-viscosity liquids accurately, poor interlayer bonding strength, and simple forming structure. This technology is capable of realizing the brand-new preparation of polymer-based continuous functionally graded materials. Through theoretical analysis and experimental investigation, the influence law of main process parameters including extrusion speed, printing speed and line spacing, on the forming quality and performance of printing continuous functionally graded materials are revealed. Graphene/UV curable resin dielectric functionally graded material (d-FGM) were prepared by using lab self-developed device, and realizing the integrated manufacturing of polymer-based continuous functionally graded insulators. Compared with the homogeneous UV curable resin, the dielectric constant has doubled, the resistivity has been reduced by 93.3%, and the amplitude of the creeping electric field strength has increased by more than 14%. Besides, the rigidity of the Al2O3 side with 40% content has doubled than a single polydimethylsiloxane (PDMS) material. With the features of realizing the continuous gradient distribution of the Al2O3. The 3D printing process provides a low-cost and high-efficiency solution for the preparation of polymer-based continuous functionally graded materials.
2022, 39(3): 1068-1078.
doi: 10.13801/j.cnki.fhclxb.20210603.001
Abstract:
Despite carbon fiber/epoxy (CF/EP) composites have the characteristics of excellent mechanical properties, light weight and corrosion resistance, problems such as high cost and severe environmental impact of waste restrict their further applications. Most of the recycled carbon fibers (RCF) recovered by the existing methods are fluffy, short and entangled with each other, which limit its mechanical properties. To address this issue, a wet fiber orientation technology was proposed to reorient and arrange RCF with different lengths. An oriented fiber felt was obtained via this method and RCF/EP fabricate specimens were prepared by compression moulding. The orientation tensor in the 2D plane was applied to evaluate the preferential alignment degree (DPA) of the fiber. The microstructure and properties of the composites were analyzed by SEM and mechanical tests, respectively. The results show that the increasing of RCF length leads to poor fiber orientation. The mechanical properties of the composites are improved with the increase of RCF length and DPA. Compared with 2 mm RCF, the DPA of 6 mm RCF decreases by about 11%, whereas the tensile strength and modulus, flexural strength and modulus of the reinforced resin matrix composites increase by 63.6%, 91.5%, 48.8% and 43.0%, respectively.
Despite carbon fiber/epoxy (CF/EP) composites have the characteristics of excellent mechanical properties, light weight and corrosion resistance, problems such as high cost and severe environmental impact of waste restrict their further applications. Most of the recycled carbon fibers (RCF) recovered by the existing methods are fluffy, short and entangled with each other, which limit its mechanical properties. To address this issue, a wet fiber orientation technology was proposed to reorient and arrange RCF with different lengths. An oriented fiber felt was obtained via this method and RCF/EP fabricate specimens were prepared by compression moulding. The orientation tensor in the 2D plane was applied to evaluate the preferential alignment degree (DPA) of the fiber. The microstructure and properties of the composites were analyzed by SEM and mechanical tests, respectively. The results show that the increasing of RCF length leads to poor fiber orientation. The mechanical properties of the composites are improved with the increase of RCF length and DPA. Compared with 2 mm RCF, the DPA of 6 mm RCF decreases by about 11%, whereas the tensile strength and modulus, flexural strength and modulus of the reinforced resin matrix composites increase by 63.6%, 91.5%, 48.8% and 43.0%, respectively.
2022, 39(3): 1079-1090.
doi: 10.13801/j.cnki.fhclxb.20210513.005
Abstract:
Polydopamine (PDA) and octadecyl isocyanate were selected to functionalize barium titanate nanowires (BTW) and boron nitride nanosheets (BNNSs) respectively, and construct D@BTW-fBNNSs particles. The influences of D@BTW-fBNNSs on dielectric property, breakdown strength and thermal conductivity of poly (m-phenyleneisophthalamide) (PMIA) dielectric were investigated. The results show that, with increasing content of D@BTW-fBNNSs, the dielectric constant of PMIA dielectric significantly increases. The dielectric constant of PMIA composite with 15wt%D@BTW-fBNNSs displays 75% improvement at 103 Hz compared with PMIA matrix, and the dielectric loss of corresponding PMIA composite maintains at relatively low value. Furthermore, the dielectric properties of D@BTW-fBNNSs/PMIA dielectric are stable under high temperature (>150℃), which can meet the requirement in high temperature environment. Additionally, the thermal conductivity of PMIA dielectric is obviously improved with increased content of D@BTW-fBNNSs. The thermal conductivity of PMIA dielectric with 15wt% D@BTW-fBNNSs is 1.5 times higher than that of PMIA matrix. This research will provide new method and idea for the design of high-temperature polymer dielectric with enhanced dielectric constant and low thermal effect.
Polydopamine (PDA) and octadecyl isocyanate were selected to functionalize barium titanate nanowires (BTW) and boron nitride nanosheets (BNNSs) respectively, and construct D@BTW-fBNNSs particles. The influences of D@BTW-fBNNSs on dielectric property, breakdown strength and thermal conductivity of poly (m-phenyleneisophthalamide) (PMIA) dielectric were investigated. The results show that, with increasing content of D@BTW-fBNNSs, the dielectric constant of PMIA dielectric significantly increases. The dielectric constant of PMIA composite with 15wt%D@BTW-fBNNSs displays 75% improvement at 103 Hz compared with PMIA matrix, and the dielectric loss of corresponding PMIA composite maintains at relatively low value. Furthermore, the dielectric properties of D@BTW-fBNNSs/PMIA dielectric are stable under high temperature (>150℃), which can meet the requirement in high temperature environment. Additionally, the thermal conductivity of PMIA dielectric is obviously improved with increased content of D@BTW-fBNNSs. The thermal conductivity of PMIA dielectric with 15wt% D@BTW-fBNNSs is 1.5 times higher than that of PMIA matrix. This research will provide new method and idea for the design of high-temperature polymer dielectric with enhanced dielectric constant and low thermal effect.
2022, 39(3): 1091-1101.
doi: 10.13801/j.cnki.fhclxb.20210609.003
Abstract:
The development of science and technology has put forward higher and higher requirements for material properties. It is an effective way to achieve the best performance in a specific direction by ordering the internal structure of materials. However, the traditional one-way freezing technology cannot achieve the preparation of two-dimensional ordered structure. B4C layered scaffolds with single orientation were prepared by bidirectional freezing method. The layered scaffolds were filled with polydimethylsiloxane (PDMS) to prepare the two-dimensional layered boron carbide and organosilicate composites with anisotropy. There is an alternate arrangement structure of PDMS and B4C skeleton at the growth plane of A in the composite material. It is a stacked structure like ocean waves at the growth plane of B. The layered scaffold maintains an obvious two-dimensional ordered layered structure in the composite material. The maximum in-plane anisotropy ratio of dynamic modulus of the composite can reach 12.9, and the dynamic modulus shows obvious Payne effect. It provides some new methods and ideas for the preparation of anisotropic composite material systems.
The development of science and technology has put forward higher and higher requirements for material properties. It is an effective way to achieve the best performance in a specific direction by ordering the internal structure of materials. However, the traditional one-way freezing technology cannot achieve the preparation of two-dimensional ordered structure. B4C layered scaffolds with single orientation were prepared by bidirectional freezing method. The layered scaffolds were filled with polydimethylsiloxane (PDMS) to prepare the two-dimensional layered boron carbide and organosilicate composites with anisotropy. There is an alternate arrangement structure of PDMS and B4C skeleton at the growth plane of A in the composite material. It is a stacked structure like ocean waves at the growth plane of B. The layered scaffold maintains an obvious two-dimensional ordered layered structure in the composite material. The maximum in-plane anisotropy ratio of dynamic modulus of the composite can reach 12.9, and the dynamic modulus shows obvious Payne effect. It provides some new methods and ideas for the preparation of anisotropic composite material systems.
2022, 39(3): 1102-1109.
doi: 10.13801/j.cnki.fhclxb.20210513.004
Abstract:
Anti-icing has now become an urgent problem to be solved in the fields of aircraft structure, power transmission lines, and refrigeration equipment. This paper conducted a comprehensive comparative study on the anti-icing characteristics of three independently developed hydrophobic/superhydrophobic composite coatings, focusing on the analysis of the advantages of each coating in mechanical durability and deicing under ultra-low temperature conditions. The results show that the primer-finish composite superhydrophobic coating has excellent mechanical durability, and the ice adhesion strength is less than 30 kPa after 40 abrasion under a 250 g load of the abrasion meter and after 100 freezing/melting cycles; the hydrophobic nanoparticle-lubricating grease composite coating has excellent deicing performance at ultra-low temperature −150℃, and its initial ice adhesion strength is only 11.5 kPa. The research results of this thesis will provide useful theoretical and practical guidance for the application of hydrophobic/superhydrophobic coatings in the field of anti-icing.
Anti-icing has now become an urgent problem to be solved in the fields of aircraft structure, power transmission lines, and refrigeration equipment. This paper conducted a comprehensive comparative study on the anti-icing characteristics of three independently developed hydrophobic/superhydrophobic composite coatings, focusing on the analysis of the advantages of each coating in mechanical durability and deicing under ultra-low temperature conditions. The results show that the primer-finish composite superhydrophobic coating has excellent mechanical durability, and the ice adhesion strength is less than 30 kPa after 40 abrasion under a 250 g load of the abrasion meter and after 100 freezing/melting cycles; the hydrophobic nanoparticle-lubricating grease composite coating has excellent deicing performance at ultra-low temperature −150℃, and its initial ice adhesion strength is only 11.5 kPa. The research results of this thesis will provide useful theoretical and practical guidance for the application of hydrophobic/superhydrophobic coatings in the field of anti-icing.
2022, 39(3): 1110-1119.
doi: 10.13801/j.cnki.fhclxb.20210506.001
Abstract:
Preparation of electrocatalyst composites with high activity and stability is of great significance for the development of fuel cells and metal-air cells. In this study, nitrogen doped nanosheets loaded with Fe-Co alloy(Fe1-Co1-N/C)were firstly obtained by simple pyrolysis of the mixture composed of dicyandiamide as carbon and nitrogen sources, cobalt phthalocyanine and ferrocene as metal nanoparticles sources. Finally, a small amount of platinum was introduced into Fe1-Co1-N/C by a facile deposition method to obtain Pt-Fe-Co loaded nitrogen-doped carbon nanosheet composites (Fe1-Co1-Pt-N/C). Electroactivity of the prepared samples towards oxygen reduction reaction (ORR) in acidic medium was investigated. Results show that the Fe1-Co1-N/C itself displays a strong electroactivity for ORR. Further, the Fe1-Co1-Pt-N/C catalysts with Pt mass-loadings of 2.36%−3.58% present a significant improvement on ORR electrocatalytic performance. Their ORR onset potential, half-wave potential and limiting diffusion current are comparable to commercial Pt/C (40%). Also, they exhibit excellent electroactivity stability for ORR. The prepared catalyst in this work can be used as a good candidate material applied to fuel cells.
Preparation of electrocatalyst composites with high activity and stability is of great significance for the development of fuel cells and metal-air cells. In this study, nitrogen doped nanosheets loaded with Fe-Co alloy(Fe1-Co1-N/C)were firstly obtained by simple pyrolysis of the mixture composed of dicyandiamide as carbon and nitrogen sources, cobalt phthalocyanine and ferrocene as metal nanoparticles sources. Finally, a small amount of platinum was introduced into Fe1-Co1-N/C by a facile deposition method to obtain Pt-Fe-Co loaded nitrogen-doped carbon nanosheet composites (Fe1-Co1-Pt-N/C). Electroactivity of the prepared samples towards oxygen reduction reaction (ORR) in acidic medium was investigated. Results show that the Fe1-Co1-N/C itself displays a strong electroactivity for ORR. Further, the Fe1-Co1-Pt-N/C catalysts with Pt mass-loadings of 2.36%−3.58% present a significant improvement on ORR electrocatalytic performance. Their ORR onset potential, half-wave potential and limiting diffusion current are comparable to commercial Pt/C (40%). Also, they exhibit excellent electroactivity stability for ORR. The prepared catalyst in this work can be used as a good candidate material applied to fuel cells.
2022, 39(3): 1120-1130.
doi: 10.13801/j.cnki.fhclxb.20210623.001
Abstract:
In recent years, flexible piezoresistive sensors have shown great application potential in human health monitoring, smart robots, wearable electronic devices, and human-computer interaction, while it is challenging to efficiently fabricate highly sensitive and low-cost flexible piezoresistive sensor for detecting micro strains. In this work, reduced graphene oxide (rGO) was prepared by Hummer's method, then carbon nanotubes (CNTs) were immobilized on the surface of rGO by electrostatic assembly. Subsequently, the hybrid nanofillers were introduced into thermoplastic polyurethane (TPU) matrix to prepare conductive polymer composite. The further dispersion and parallel orientation of nanofillers in the matrix were achieved by the sequential biaxial stretching process. It is shown that the sensor prepared by biaxially stretched conductive polymer composite exhibits higher sensing performance compared to the sensor without experiencing biaxial stretching. The rGO-CNT/TPU4×4 sensor (with a stretching ratio of 4×4) shows high sensitivity (GF=46.7 at 1.5% strain), high linearity (R2=0.98), responsive capability to different strains and frequencies, excellent stability and repeatability in cyclic loading tests. The flexible piezoresistive sensor can be used to identify subtle human physiological activities, including pulse and exhalation. In addition, a compressible sensor array was fabricated to achieve accurate identification of weight distribution. This study provides an important scientific guidance for the rapid large-scale fabrication and structure and property tuning of high-performance flexible piezoresistive strain sensors.
In recent years, flexible piezoresistive sensors have shown great application potential in human health monitoring, smart robots, wearable electronic devices, and human-computer interaction, while it is challenging to efficiently fabricate highly sensitive and low-cost flexible piezoresistive sensor for detecting micro strains. In this work, reduced graphene oxide (rGO) was prepared by Hummer's method, then carbon nanotubes (CNTs) were immobilized on the surface of rGO by electrostatic assembly. Subsequently, the hybrid nanofillers were introduced into thermoplastic polyurethane (TPU) matrix to prepare conductive polymer composite. The further dispersion and parallel orientation of nanofillers in the matrix were achieved by the sequential biaxial stretching process. It is shown that the sensor prepared by biaxially stretched conductive polymer composite exhibits higher sensing performance compared to the sensor without experiencing biaxial stretching. The rGO-CNT/TPU4×4 sensor (with a stretching ratio of 4×4) shows high sensitivity (GF=46.7 at 1.5% strain), high linearity (R2=0.98), responsive capability to different strains and frequencies, excellent stability and repeatability in cyclic loading tests. The flexible piezoresistive sensor can be used to identify subtle human physiological activities, including pulse and exhalation. In addition, a compressible sensor array was fabricated to achieve accurate identification of weight distribution. This study provides an important scientific guidance for the rapid large-scale fabrication and structure and property tuning of high-performance flexible piezoresistive strain sensors.
2022, 39(3): 1131-1140.
doi: 10.13801/j.cnki.fhclxb.20210517.003
Abstract:
In this work, in-situ free-radical solution polymerization method was used to fabricate poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/poly(acrylamide-co-methacrylic acid) (P(AAM-MAA)) conductive hydrogels. The composition and morphology were characterized by FTIR, Raman, TGA, and SEM, respectively. The visible-light transmittance, electrical conductivity, tensile properties, and strain sensitivity were also tested. The results show that PEDOT:PSS is well dispersed in the P(AAM-MAA) hydrogel network, and the hydrogel shows good conductivity and transparency (>50%). The introduction of MAA not only improves the electrical conductivity but also enhances the tensile properties and strain sensitivity of the hydrogel. When the amount of MAA increases from 0wt% to 2.52wt%, the conductivity of PEDOT:PSS/P(AAM-MAA) rises from 0.043 S·m−1 to 0.060 S·m−1, and the tensile strength, elongation at break increases from 46 kPa, 76% to 68 kPa, 129%, respectively. PEDOT:PSS/P(AAM-MAA) also has demonstrated excellent linear sensitivity (R2>0.983) (strain: 0%-70%). The resistance variation curve shows that the prepared hydrogels can be used as sensors to monitor various small movements of human body through the resistance signal change.
In this work, in-situ free-radical solution polymerization method was used to fabricate poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/poly(acrylamide-co-methacrylic acid) (P(AAM-MAA)) conductive hydrogels. The composition and morphology were characterized by FTIR, Raman, TGA, and SEM, respectively. The visible-light transmittance, electrical conductivity, tensile properties, and strain sensitivity were also tested. The results show that PEDOT:PSS is well dispersed in the P(AAM-MAA) hydrogel network, and the hydrogel shows good conductivity and transparency (>50%). The introduction of MAA not only improves the electrical conductivity but also enhances the tensile properties and strain sensitivity of the hydrogel. When the amount of MAA increases from 0wt% to 2.52wt%, the conductivity of PEDOT:PSS/P(AAM-MAA) rises from 0.043 S·m−1 to 0.060 S·m−1, and the tensile strength, elongation at break increases from 46 kPa, 76% to 68 kPa, 129%, respectively. PEDOT:PSS/P(AAM-MAA) also has demonstrated excellent linear sensitivity (R2>0.983) (strain: 0%-70%). The resistance variation curve shows that the prepared hydrogels can be used as sensors to monitor various small movements of human body through the resistance signal change.
2022, 39(3): 1141-1151.
doi: 10.13801/j.cnki.fhclxb.20210518.002
Abstract:
Given the low conductivity, poor catalytic activity, and high cost of traditional noble metal-oxygen evolution reaction (OER) electrocatalysts, it is urgent to develop electrocatalysts with high efficiency, durability, low cost, high exposed active surface, and excellent electrical conductivity. The Silver nanowire@Polypyrrole (AgNWs@PPy) aerogels were synthesized by freeze-drying method, and then nano-CoNi alloy was grown on the surface of AgNWs@PPy aerogels framework by solvothermal method, and AgNWs@PPy@CoNi aerogels with good OER electrocatalytic performance was obtained. The results show that the catalytic performance of AgNWs@PPy@CoNi aerogels first increase and then weaken with the increase of Co2+ and Ni2+ concentrations. When the Co2+ and Ni2+ concentrations are 0.0175 mol/L, the AgNWs@PPy@CoNi aerogels exhibite high current density. At 10 mA·cm−2, the overpotential is 346 mV, and the Tafel slope is 86.25 mV·dec−1. After a 10-hour stability test under a constant voltage, the current retention rate reaches 93.9%, which has good stability. The three-dimensional independent AgNWs@PPy aerogels provide excellent electrical conductivity, and the CoNi alloy provides abundant active sites. The combined effect of them shows excellent OER catalytic performance, which is expected to replace precious metal catalysts and become a new type of OER catalytic material.
Given the low conductivity, poor catalytic activity, and high cost of traditional noble metal-oxygen evolution reaction (OER) electrocatalysts, it is urgent to develop electrocatalysts with high efficiency, durability, low cost, high exposed active surface, and excellent electrical conductivity. The Silver nanowire@Polypyrrole (AgNWs@PPy) aerogels were synthesized by freeze-drying method, and then nano-CoNi alloy was grown on the surface of AgNWs@PPy aerogels framework by solvothermal method, and AgNWs@PPy@CoNi aerogels with good OER electrocatalytic performance was obtained. The results show that the catalytic performance of AgNWs@PPy@CoNi aerogels first increase and then weaken with the increase of Co2+ and Ni2+ concentrations. When the Co2+ and Ni2+ concentrations are 0.0175 mol/L, the AgNWs@PPy@CoNi aerogels exhibite high current density. At 10 mA·cm−2, the overpotential is 346 mV, and the Tafel slope is 86.25 mV·dec−1. After a 10-hour stability test under a constant voltage, the current retention rate reaches 93.9%, which has good stability. The three-dimensional independent AgNWs@PPy aerogels provide excellent electrical conductivity, and the CoNi alloy provides abundant active sites. The combined effect of them shows excellent OER catalytic performance, which is expected to replace precious metal catalysts and become a new type of OER catalytic material.
2022, 39(3): 1152-1162.
doi: 10.13801/j.cnki.fhclxb.20210616.002
Abstract:
With the rapid development of wireless information technology, electromagnetic interference has become a prominent problem, which has attracted worldwide attention. Exposure to electromagnetic radiation for a long time will damage the central nervous system, cardiovascular system and visual system to varying degrees. The key to solving this problem is to develop materials that can absorb electromagnetic waves. In order to improve the microwave absorption properties of reduced graphene oxide (RGO), the tetrahedral needle-like ZnO was successfully obtained by induction heating, and ZnO@RGO composites with different proportions were prepared by simple hydrothermal method. The morphology, size, and phase structure of ZnO@RGO composites were analyzed by SEM, XRD and Raman. And the effects of the mass ratio of ZnO and the paraffin filling amount on the electromagnetic parameters and absorbing properties of ZnO@RGO composites were also discussed. The ZnO@RGO composite with ZnO∶GO mass ratio of 3∶1 has the best wave absorption performance (−44.5 dB; 3 mm). Electromagnetic parame-ters show that the attenuation mechanism of ZnO@RGO composites can be attributed to the conductance loss and polarization effect. ZnO@RGO composites have a low reflection loss value and thin thickness, which has great potential for military stealth.
With the rapid development of wireless information technology, electromagnetic interference has become a prominent problem, which has attracted worldwide attention. Exposure to electromagnetic radiation for a long time will damage the central nervous system, cardiovascular system and visual system to varying degrees. The key to solving this problem is to develop materials that can absorb electromagnetic waves. In order to improve the microwave absorption properties of reduced graphene oxide (RGO), the tetrahedral needle-like ZnO was successfully obtained by induction heating, and ZnO@RGO composites with different proportions were prepared by simple hydrothermal method. The morphology, size, and phase structure of ZnO@RGO composites were analyzed by SEM, XRD and Raman. And the effects of the mass ratio of ZnO and the paraffin filling amount on the electromagnetic parameters and absorbing properties of ZnO@RGO composites were also discussed. The ZnO@RGO composite with ZnO∶GO mass ratio of 3∶1 has the best wave absorption performance (−44.5 dB; 3 mm). Electromagnetic parame-ters show that the attenuation mechanism of ZnO@RGO composites can be attributed to the conductance loss and polarization effect. ZnO@RGO composites have a low reflection loss value and thin thickness, which has great potential for military stealth.
2022, 39(3): 1163-1172.
doi: 10.13801/j.cnki.fhclxb.20210616.001
Abstract:
Chromium is a common heavy metal pollutant and extensively used in variety of industrial processes. CuS-Bi2WO6/CNFs (carbon nanofibers) composite photocatalysts with different CNFs content were prepared by solvothermal method to remove Cr(VI) from the aqueous solution. The crystal form, morphology, structure, elemental composition, surface functional groups and optical properties of the samples were characterized by XRD, SEM, TEM, FTIR, XPS, UV-Vis and PL. The photocatalytic degradation of Cr(VI) by CuS-Bi2WO6/CNFs composite materials was evaluated. The results show that the photocatalytic activity of the CuS-Bi2WO6/CNFs composite is obviously higher than that of the CuS、Bi2WO6 and CuS/Bi2WO6. Under visible light irradiation, 1%CuS-Bi2WO6/CNFs composites show higher photocatalytic degradation performance, and the reduction rate of Cr(VI) is 98% within 3 h. And 1%CuS-Bi2WO6/CNFs composites also show strong stability and recoverability after four cycles. In addition, the experimental results of active group capture show that hydroxyl radical (•OH), photogenerated hole (h+) and superoxide radical (•O2−) are involved in the reduction of Cr(VI) on CuS-Bi2WO6/CNFs, and •O2− is the main active components of the system. The photocatalytic reaction mechanism was discussed. The research results show that the preparation of CuS-Bi2WO6/CNFs can be achieved by a simple and controllable solvothermal method, and it has confirmed the good prospects of CuS-Bi2WO6/CNFs composites in the treatment of hexavalent chromium.
Chromium is a common heavy metal pollutant and extensively used in variety of industrial processes. CuS-Bi2WO6/CNFs (carbon nanofibers) composite photocatalysts with different CNFs content were prepared by solvothermal method to remove Cr(VI) from the aqueous solution. The crystal form, morphology, structure, elemental composition, surface functional groups and optical properties of the samples were characterized by XRD, SEM, TEM, FTIR, XPS, UV-Vis and PL. The photocatalytic degradation of Cr(VI) by CuS-Bi2WO6/CNFs composite materials was evaluated. The results show that the photocatalytic activity of the CuS-Bi2WO6/CNFs composite is obviously higher than that of the CuS、Bi2WO6 and CuS/Bi2WO6. Under visible light irradiation, 1%CuS-Bi2WO6/CNFs composites show higher photocatalytic degradation performance, and the reduction rate of Cr(VI) is 98% within 3 h. And 1%CuS-Bi2WO6/CNFs composites also show strong stability and recoverability after four cycles. In addition, the experimental results of active group capture show that hydroxyl radical (•OH), photogenerated hole (h+) and superoxide radical (•O2−) are involved in the reduction of Cr(VI) on CuS-Bi2WO6/CNFs, and •O2− is the main active components of the system. The photocatalytic reaction mechanism was discussed. The research results show that the preparation of CuS-Bi2WO6/CNFs can be achieved by a simple and controllable solvothermal method, and it has confirmed the good prospects of CuS-Bi2WO6/CNFs composites in the treatment of hexavalent chromium.
2022, 39(3): 1173-1179.
doi: 10.13801/j.cnki.fhclxb.20210414.002
Abstract:
In order to improve the photocatalytic performance of TiO2 under visible light, a highly ordered β-FeOOH/TiO2 composite film material was prepared on FTO conductive glass through a secondary hydrothermal reaction, using scanning electron microscopy (SEM) and X-ray diffraction (XRD), Raman (Raman) and infrared spectroscopy (FTIR) analyzed its surface morphology, crystal structure and phase composition. UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS) was used to test its light absorption performance. Finally, using methyl orange (MO) as a simulated pollutant, the photocatalytic activity of the composite film material under visible light was investigated. The results show that: TiO2 and β-FeOOH are connected by Fe—O—Ti bond, and the β-FeOOH/TiO2 composite film material successfully prepared has good structural stability. The β-FeOOH/TiO2 composite film material, due to its structural heterojunction and suitable energy band structure, effectively improves the migration efficiency of photogenerated carriers, and successfully expands its photoresponse range to about 540 nm. The composite film material exhibits excellent photocatalytic performance under visible light. The photocatalytic efficiency of β-FeOOH/TiO2 is 60.6% higher than that of the unmodified TiO2 sample. After six photocatalytic degradation cycles, the composite film is still in good condition. The continuity of the photocatalytic degradation of MO is still maintained at about 94%.
In order to improve the photocatalytic performance of TiO2 under visible light, a highly ordered β-FeOOH/TiO2 composite film material was prepared on FTO conductive glass through a secondary hydrothermal reaction, using scanning electron microscopy (SEM) and X-ray diffraction (XRD), Raman (Raman) and infrared spectroscopy (FTIR) analyzed its surface morphology, crystal structure and phase composition. UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS) was used to test its light absorption performance. Finally, using methyl orange (MO) as a simulated pollutant, the photocatalytic activity of the composite film material under visible light was investigated. The results show that: TiO2 and β-FeOOH are connected by Fe—O—Ti bond, and the β-FeOOH/TiO2 composite film material successfully prepared has good structural stability. The β-FeOOH/TiO2 composite film material, due to its structural heterojunction and suitable energy band structure, effectively improves the migration efficiency of photogenerated carriers, and successfully expands its photoresponse range to about 540 nm. The composite film material exhibits excellent photocatalytic performance under visible light. The photocatalytic efficiency of β-FeOOH/TiO2 is 60.6% higher than that of the unmodified TiO2 sample. After six photocatalytic degradation cycles, the composite film is still in good condition. The continuity of the photocatalytic degradation of MO is still maintained at about 94%.
2022, 39(3): 1180-1185.
doi: 10.13801/j.cnki.fhclxb.20210414.003
Abstract:
In order to solve the problem of wave absorption performance degradation in the 26.5-40 GHz frequency band caused by the introduction of skin material, the design of the skin structure was improved, the influence mecha-nism and law of A-type skin structure on the wave absorption performance of multi-layer honeycomb were studied, and the optimal structure parameters of A-type skin were obtained. The research results show that the A-type skin can improve the high frequency wave-transmitting property effectively. With the thickness of the honeycomb increasing, the reflectivity in the 2-18 GHz frequency band remains at the same level and the reflectivity in the 26.5-40 GHz frequency band increases at first and then decreases. The optimal thickness of the honeycomb is 2 mm. Based on five kinds of absorbing honeycomb sheets, the composite honeycomb was designed and prepared with the structure of quartz cloth (0.3 mm)/wave-transmitting honeycomb (2 mm)/quartz cloth (0.3 mm). The optimized absorbing honeycomb has excellent absorbing property in the wide frequency band of 2-18 GHz and 26.5-40 GHz, which is corresponding to the simulation result.
In order to solve the problem of wave absorption performance degradation in the 26.5-40 GHz frequency band caused by the introduction of skin material, the design of the skin structure was improved, the influence mecha-nism and law of A-type skin structure on the wave absorption performance of multi-layer honeycomb were studied, and the optimal structure parameters of A-type skin were obtained. The research results show that the A-type skin can improve the high frequency wave-transmitting property effectively. With the thickness of the honeycomb increasing, the reflectivity in the 2-18 GHz frequency band remains at the same level and the reflectivity in the 26.5-40 GHz frequency band increases at first and then decreases. The optimal thickness of the honeycomb is 2 mm. Based on five kinds of absorbing honeycomb sheets, the composite honeycomb was designed and prepared with the structure of quartz cloth (0.3 mm)/wave-transmitting honeycomb (2 mm)/quartz cloth (0.3 mm). The optimized absorbing honeycomb has excellent absorbing property in the wide frequency band of 2-18 GHz and 26.5-40 GHz, which is corresponding to the simulation result.
2022, 39(3): 1186-1193.
doi: 10.13801/j.cnki.fhclxb.20210517.004
Abstract:
Using Poly (ethylene-vinyl alcohol) (EVOH) and Lithium montmorillonite (Li-OMMT), an ionic resin is synthesized first, and then compounded with the lithium montmorillonite to prepare a new organic-inorganic hybrid material EVOLi-OMMT. Electrospinning is used to make it into a non-woven fabric separator for lithium-ion batteries. The bonding structure of the hybrid material was first characterized by infrared, and the microstructure of the diaphragm was characterized by SEM. Then the two composite diaphragms synthesized were compared with the Celgard diaphragm for liquid absorption, porosity, thermal performance and electrical performance. The results show that a new chemical bond is formed between EVOLi and OMMT to form an intercalation cross-linked structure. The mechanical strength of the diaphragm is 68.12% higher than that of EVOLi. The pore diameter of the diaphragm is uniform. The modified diaphragm has a porosity and liquid absorption rate of 457% and 73% respectively, the initial temperature is higher, up to 270℃, and can withstand 175℃ without shrinkage; the electrochemical test results show that the modified membrane has a small ion interface migration resistance, which can be as low as 96.59 Ω; 100 times 0.1 C After the cycle, the capacity retention rate can reach 93.4%, and it shows excellent rate performance in the cycle test.
Using Poly (ethylene-vinyl alcohol) (EVOH) and Lithium montmorillonite (Li-OMMT), an ionic resin is synthesized first, and then compounded with the lithium montmorillonite to prepare a new organic-inorganic hybrid material EVOLi-OMMT. Electrospinning is used to make it into a non-woven fabric separator for lithium-ion batteries. The bonding structure of the hybrid material was first characterized by infrared, and the microstructure of the diaphragm was characterized by SEM. Then the two composite diaphragms synthesized were compared with the Celgard diaphragm for liquid absorption, porosity, thermal performance and electrical performance. The results show that a new chemical bond is formed between EVOLi and OMMT to form an intercalation cross-linked structure. The mechanical strength of the diaphragm is 68.12% higher than that of EVOLi. The pore diameter of the diaphragm is uniform. The modified diaphragm has a porosity and liquid absorption rate of 457% and 73% respectively, the initial temperature is higher, up to 270℃, and can withstand 175℃ without shrinkage; the electrochemical test results show that the modified membrane has a small ion interface migration resistance, which can be as low as 96.59 Ω; 100 times 0.1 C After the cycle, the capacity retention rate can reach 93.4%, and it shows excellent rate performance in the cycle test.
2022, 39(3): 1194-1204.
doi: 10.13801/j.cnki.fhclxb.20210512.001
Abstract:
In order to study the bond performance between carbon fibre reinforced polymer (CFRP) bars and seawater sea sand concrete, the pull-out test of CFRP and seawater sea sand concrete was carried out in different conditions and the bond-slip curve was obtained. During the test, different failure modes were observed and concluded to analyze the failure mechanism between CFRP bars and seawater sea sand concrete. The influence of different factors on the bond performance was analyzed based on orthogonal experiment. The results show that the strength of concrete is the most important factor affecting the bond strength, and the friction plays a large part in the bond stress. Besides the pull-out damage and concrete splitting damage, CFRP damage exists in the test due to the production process and mechanical performance of CFRP itself. Based on the results above, three types of bond-slip constitutive relation expression of CFRP/seawater sea sand concrete were finally concluded by curve fitting and comparing.
In order to study the bond performance between carbon fibre reinforced polymer (CFRP) bars and seawater sea sand concrete, the pull-out test of CFRP and seawater sea sand concrete was carried out in different conditions and the bond-slip curve was obtained. During the test, different failure modes were observed and concluded to analyze the failure mechanism between CFRP bars and seawater sea sand concrete. The influence of different factors on the bond performance was analyzed based on orthogonal experiment. The results show that the strength of concrete is the most important factor affecting the bond strength, and the friction plays a large part in the bond stress. Besides the pull-out damage and concrete splitting damage, CFRP damage exists in the test due to the production process and mechanical performance of CFRP itself. Based on the results above, three types of bond-slip constitutive relation expression of CFRP/seawater sea sand concrete were finally concluded by curve fitting and comparing.
2022, 39(3): 1205-1214.
doi: 10.13801/j.cnki.fhclxb.20210520.005
Abstract:
In order to study the basic mechanical properties and dynamic mechanical properties of recycled aggregate concrete mixed with polyvinyl alcohol (PVA) fiber after modified recycled coarse aggregate with nano-SiO2 solution and cement paste, recycled aggregate pre-soaking tests were carried out on different concentrations of nano-SiO2 solutions and cement pastes with different water-cement ratios. The nano-SiO2 solutions with a concentration of 2wt% and the cement paste with a water-cement ratio of 0.5 were selected. The mechanical properties of recycled aggregate concrete were tested for comparison. The replacement percentage of recycled coarse aggregate, the content of PVA fiber and the strain rate were variable. The static mechanical properties were tested by a universal press, and the dynamic mechanical properties were tested by using a split Hopkinson pressure bar (SHPB). The 28 days cube compressive strength, axial compressive strength and flexural strength of the specimen were tested, the stress-strain curves of the specimen under different strain rate conditions were obtained, and the static performance, dynamic compressive strength, dynamic increase factor (DIF), dynamic peak strain and specific energy absorption of the specimen changes with variables were analyzed. The results show that with the increase of the replacement percentage, the basic mechanical properties of the specimen decrease, and the content of PVA fiber increases, the compressive strength of the specimen decreases while the flexural strength increases; with the increase of the replacement percentage and PVA fiber content, the dynamic peak stress of the specimen decreases, while the dynamic peak strain shows an increasing trend; the increase of the replacement percentage increases the DIF value of the specimen, while the PVA fiber has no obvious effect on the DIF value; the increase in strain rate enhances the dynamic strength and strain of the specimen, and the cement paste modified recycled aggregate concrete has a higher specific energy absorption than the nano-SiO2 modified recycled aggregate concrete.
In order to study the basic mechanical properties and dynamic mechanical properties of recycled aggregate concrete mixed with polyvinyl alcohol (PVA) fiber after modified recycled coarse aggregate with nano-SiO2 solution and cement paste, recycled aggregate pre-soaking tests were carried out on different concentrations of nano-SiO2 solutions and cement pastes with different water-cement ratios. The nano-SiO2 solutions with a concentration of 2wt% and the cement paste with a water-cement ratio of 0.5 were selected. The mechanical properties of recycled aggregate concrete were tested for comparison. The replacement percentage of recycled coarse aggregate, the content of PVA fiber and the strain rate were variable. The static mechanical properties were tested by a universal press, and the dynamic mechanical properties were tested by using a split Hopkinson pressure bar (SHPB). The 28 days cube compressive strength, axial compressive strength and flexural strength of the specimen were tested, the stress-strain curves of the specimen under different strain rate conditions were obtained, and the static performance, dynamic compressive strength, dynamic increase factor (DIF), dynamic peak strain and specific energy absorption of the specimen changes with variables were analyzed. The results show that with the increase of the replacement percentage, the basic mechanical properties of the specimen decrease, and the content of PVA fiber increases, the compressive strength of the specimen decreases while the flexural strength increases; with the increase of the replacement percentage and PVA fiber content, the dynamic peak stress of the specimen decreases, while the dynamic peak strain shows an increasing trend; the increase of the replacement percentage increases the DIF value of the specimen, while the PVA fiber has no obvious effect on the DIF value; the increase in strain rate enhances the dynamic strength and strain of the specimen, and the cement paste modified recycled aggregate concrete has a higher specific energy absorption than the nano-SiO2 modified recycled aggregate concrete.
2022, 39(3): 1215-1227.
doi: 10.13801/j.cnki.fhclxb.20210426.005
Abstract:
In order to popularize the use of marine resources, sea sand was used to prepare engineering cementitious composite (ECC) instead of silica sand. By combining sea sand ECC with basalt fiber reinforced polymer (BFRP) bars, the advantages of the two kinds of materials can be fully exploited to obtain higher corrosion resistance and better tensile properties. Through uniaxial tensile and four-point bending tests, the effects of different erosion systems and reinforcement ratio on the tensile and bending properties of BFRP reinforced sea sand ECC were studied, and compared with the sea sand ECC without BFRP reinforcement. The results show that the ultimate tensile stress of BFRP reinforced sea sand ECC is increased by 2.46-4.92 times and the ultimate tensile strain is increased by 1.40-2.94 times compared with the sea sand ECC. The ultimate load of BFRP reinforced sea sand ECC is 3.14-4.29 times of the sea sand ECC without BFRP reinforcement under the effect of dry-wetting cycling. Under different erosion systems, the optimal reinforcement ratio of BFRP reinforced sea sand ECC is 0.67%. The BFRP reinforced sea sand ECC can provide reference for the design of seamless bridge deck.
In order to popularize the use of marine resources, sea sand was used to prepare engineering cementitious composite (ECC) instead of silica sand. By combining sea sand ECC with basalt fiber reinforced polymer (BFRP) bars, the advantages of the two kinds of materials can be fully exploited to obtain higher corrosion resistance and better tensile properties. Through uniaxial tensile and four-point bending tests, the effects of different erosion systems and reinforcement ratio on the tensile and bending properties of BFRP reinforced sea sand ECC were studied, and compared with the sea sand ECC without BFRP reinforcement. The results show that the ultimate tensile stress of BFRP reinforced sea sand ECC is increased by 2.46-4.92 times and the ultimate tensile strain is increased by 1.40-2.94 times compared with the sea sand ECC. The ultimate load of BFRP reinforced sea sand ECC is 3.14-4.29 times of the sea sand ECC without BFRP reinforcement under the effect of dry-wetting cycling. Under different erosion systems, the optimal reinforcement ratio of BFRP reinforced sea sand ECC is 0.67%. The BFRP reinforced sea sand ECC can provide reference for the design of seamless bridge deck.
2022, 39(3): 1228-1238.
doi: 10.13801/j.cnki.fhclxb.20210520.002
Abstract:
The rapid carbonization method was used to study the influence of basalt fiber (BF) content and recycled coarse aggregate (RCA) replacement ratio on the anti-carbonization performance of recycled aggregate concrete (RAC). The carbonization depth of 3 days, 7 days, 14 days and 28 days was measured, and the relationship between carbonization depth with BF content and replacement ratio of RCA was analyzed with the increase of carbonization days. The results show that the carbonization of RAC is similar to that of natural aggregate concrete (NAC). The depth of carbonization increases with the increase of carbonization days. As the replacement ratio of RCA increases, the carbonization depth of RAC first decreases and then increases, when the RCA mass replacement ratio is 50%, the carbonization resistance of RAC is the best. Incorporating BF can effectively improve the anti-carbonization performance of RAC. With the increase of BF content, the anti-carbonization performance of RAC increases first and then decreases. In this experiment, the optimal content of RAC is 2 kg/m3. In addition, using scanning electron microscope to observe the microstructure of BF/RAC, combined with diffusion theory, the carbonization damage mechanism was revealed. Using test data for fitting, a carbonization depth model of BF/RAC was established. The research results have reference value for future research and engineering applications.
The rapid carbonization method was used to study the influence of basalt fiber (BF) content and recycled coarse aggregate (RCA) replacement ratio on the anti-carbonization performance of recycled aggregate concrete (RAC). The carbonization depth of 3 days, 7 days, 14 days and 28 days was measured, and the relationship between carbonization depth with BF content and replacement ratio of RCA was analyzed with the increase of carbonization days. The results show that the carbonization of RAC is similar to that of natural aggregate concrete (NAC). The depth of carbonization increases with the increase of carbonization days. As the replacement ratio of RCA increases, the carbonization depth of RAC first decreases and then increases, when the RCA mass replacement ratio is 50%, the carbonization resistance of RAC is the best. Incorporating BF can effectively improve the anti-carbonization performance of RAC. With the increase of BF content, the anti-carbonization performance of RAC increases first and then decreases. In this experiment, the optimal content of RAC is 2 kg/m3. In addition, using scanning electron microscope to observe the microstructure of BF/RAC, combined with diffusion theory, the carbonization damage mechanism was revealed. Using test data for fitting, a carbonization depth model of BF/RAC was established. The research results have reference value for future research and engineering applications.
2022, 39(3): 1239-1248.
doi: 10.13801/j.cnki.fhclxb.20210609.006
Abstract:
Due to the current state of ozone layer depletion and plastic pollution, researches on cellulose-based films with ultraviolet (UV) blocking properties has attracted widespread attention. In order to realize the uniform dispersion of UV absorbent (lignin) and cellulose, a method of using high pressure homogenization to achieve mixing of lignin particles and carboxymethylated fibers was proposed. Then lignin-cellulose nanofiber(Lignin-CNF, L-CNF) composite film was fabricated through vacuum filtration and hot pressing process. Moreover, the micro-morphology of the L-CNF composite film was observed and the forming process was determined. At the same time, the influence of different lignin additions on the light transmittance, UV light blocking performance, and surface color value (L*a*b* value) of the composite films was investigated. The results reveal that, with the increase of lignin additions, the light transmittance of the composite films at 600 nm decreases, while the UV-blocking efficiency at the bands of UVA (320-400 nm) and UVB (280-320 nm) increase significantly. Besides, when the amount of lignin reaches 12wt%, the L-CNF composite film still maintains a light transmittance of 40%, and the UV-blocking efficiency in the UVA and UVB bands reaches 98% and 100% respectively, exhibiting an excellent UV shielding performance. Overall, the L-CNF composite film with different performances can be obtained by adjusting the ratio of lignin, which shows high potentials in photosensitive material coating and food packaging materials.
Due to the current state of ozone layer depletion and plastic pollution, researches on cellulose-based films with ultraviolet (UV) blocking properties has attracted widespread attention. In order to realize the uniform dispersion of UV absorbent (lignin) and cellulose, a method of using high pressure homogenization to achieve mixing of lignin particles and carboxymethylated fibers was proposed. Then lignin-cellulose nanofiber(Lignin-CNF, L-CNF) composite film was fabricated through vacuum filtration and hot pressing process. Moreover, the micro-morphology of the L-CNF composite film was observed and the forming process was determined. At the same time, the influence of different lignin additions on the light transmittance, UV light blocking performance, and surface color value (L*a*b* value) of the composite films was investigated. The results reveal that, with the increase of lignin additions, the light transmittance of the composite films at 600 nm decreases, while the UV-blocking efficiency at the bands of UVA (320-400 nm) and UVB (280-320 nm) increase significantly. Besides, when the amount of lignin reaches 12wt%, the L-CNF composite film still maintains a light transmittance of 40%, and the UV-blocking efficiency in the UVA and UVB bands reaches 98% and 100% respectively, exhibiting an excellent UV shielding performance. Overall, the L-CNF composite film with different performances can be obtained by adjusting the ratio of lignin, which shows high potentials in photosensitive material coating and food packaging materials.
2022, 39(3): 1249-1258.
doi: 10.13801/j.cnki.fhclxb.20210518.006
Abstract:
Fiber mass fraction was one of the key factors that affect the preparation of high-performance fiber composites by vacuum assisted resin transfer molding (VARTM). This research studied the influence of bamboo fiber (BF) mass fraction on the epoxy resin (EP) impregnated fiber effect and the performance of BF/EP composites made by VARTM, which provided theoretical support for the practical application of bamboo fiber composites. The bamboo fiber bundles were made into bamboo fiber mat by wet layering, using the VARTM process to prepare the fiber mass fraction of 0wt%, 15wt%, 25wt%, 35wt% and 45wt% BF/EP composites. The resin-impregnated fiber effect, water absorption, mechanical properties, and heat resistance of BF/EP composites were characterized by ESEM, ultra-depth-of-field microscope, mechanical testing machine, TG and DMA. It is observed that the difficulty of EP injection and the water absorption rate of BF/EP composites gradually increases with increasing fiber mass fraction. The water absorption rate of the BF/EP composites increases significantly when the fiber mass fraction is 35wt% or more. The mechanical interlocking between BF is stronger in BF/EP composites with higher fiber mass fraction, which can effectively disperse the failure stress, leading to higher mechanical performance, compared with 15wt%, the flexural strength, flexural modulus, shear strength and impact toughness of 45wt% BF/EP composites are significantly improved by 84%, 64%, 103% and 101%, respectively. The pyrolysis rate of BF/EP composites with increasing fiber mass fraction increases when the temperature is lower than 380℃ and decreases when higher than 380℃, when the fiber mass fraction is more than 35wt%, the amorphous carbon obtained from the thermal decomposition of the BF can be used as a protective layer to reduce the penetration of volatile degradation products into the BF/EP composites and delay the pyrolysis reaction. When the fiber mass fraction is 45wt%, the dense bamboo fiber mat can limit the movement of the resin molecular segments, thereby improving the heat resistance of the BF/EP composites. The BF/EP composites prepared with fiber mass fraction at 45wt% can be used in the fields where the characteristics of high performance, low cost are required, such as indoor decoration.
Fiber mass fraction was one of the key factors that affect the preparation of high-performance fiber composites by vacuum assisted resin transfer molding (VARTM). This research studied the influence of bamboo fiber (BF) mass fraction on the epoxy resin (EP) impregnated fiber effect and the performance of BF/EP composites made by VARTM, which provided theoretical support for the practical application of bamboo fiber composites. The bamboo fiber bundles were made into bamboo fiber mat by wet layering, using the VARTM process to prepare the fiber mass fraction of 0wt%, 15wt%, 25wt%, 35wt% and 45wt% BF/EP composites. The resin-impregnated fiber effect, water absorption, mechanical properties, and heat resistance of BF/EP composites were characterized by ESEM, ultra-depth-of-field microscope, mechanical testing machine, TG and DMA. It is observed that the difficulty of EP injection and the water absorption rate of BF/EP composites gradually increases with increasing fiber mass fraction. The water absorption rate of the BF/EP composites increases significantly when the fiber mass fraction is 35wt% or more. The mechanical interlocking between BF is stronger in BF/EP composites with higher fiber mass fraction, which can effectively disperse the failure stress, leading to higher mechanical performance, compared with 15wt%, the flexural strength, flexural modulus, shear strength and impact toughness of 45wt% BF/EP composites are significantly improved by 84%, 64%, 103% and 101%, respectively. The pyrolysis rate of BF/EP composites with increasing fiber mass fraction increases when the temperature is lower than 380℃ and decreases when higher than 380℃, when the fiber mass fraction is more than 35wt%, the amorphous carbon obtained from the thermal decomposition of the BF can be used as a protective layer to reduce the penetration of volatile degradation products into the BF/EP composites and delay the pyrolysis reaction. When the fiber mass fraction is 45wt%, the dense bamboo fiber mat can limit the movement of the resin molecular segments, thereby improving the heat resistance of the BF/EP composites. The BF/EP composites prepared with fiber mass fraction at 45wt% can be used in the fields where the characteristics of high performance, low cost are required, such as indoor decoration.
2022, 39(3): 1259-1267.
doi: 10.13801/j.cnki.fhclxb.20210521.001
Abstract:
In order to efficiently remove organic dyes from waste water, ZIF-67/waste cotton cellulose composite aerogels (ZIF-67/WCCA) were prepared by freeze drying technology using waste cotton fabrics as cellulose raw materials, alkali/urea as dissolution system, N, N’-Methylenediacrylamide (MBA) as cross-linking agent, and cobalt-based zeolite imidazolate metal-organic framework (ZIF-67) nanoparticles were grown in situ on the surface of WCCA. ZIF-67/WCCA were prepared and used to adsorb malachite green (MG) and degrade methylene blue (MB) with peroxymonosulfate (PMS) activation. The structure and composition of the ZIF-67/WCCA were characterized by scanning electron microscopy and X-ray diffraction. The conditions affecting the adsorption and degradation properties of the dyes were also discussed. The results show that ZIF-67 nanoparticles of dodecahedron are loaded on the network framework of cellulose aerogels from waste cotton. The adsorption capacity of MG can reach 1474.01 mg·g−1 at room temperature, and the degradation rate of MB at 100 s can reach 100% by using ZIF-67/WCCA. ZIF-67/WCCA can be applied in fields of dye adsorption and catalytic degradation in sewage.
In order to efficiently remove organic dyes from waste water, ZIF-67/waste cotton cellulose composite aerogels (ZIF-67/WCCA) were prepared by freeze drying technology using waste cotton fabrics as cellulose raw materials, alkali/urea as dissolution system, N, N’-Methylenediacrylamide (MBA) as cross-linking agent, and cobalt-based zeolite imidazolate metal-organic framework (ZIF-67) nanoparticles were grown in situ on the surface of WCCA. ZIF-67/WCCA were prepared and used to adsorb malachite green (MG) and degrade methylene blue (MB) with peroxymonosulfate (PMS) activation. The structure and composition of the ZIF-67/WCCA were characterized by scanning electron microscopy and X-ray diffraction. The conditions affecting the adsorption and degradation properties of the dyes were also discussed. The results show that ZIF-67 nanoparticles of dodecahedron are loaded on the network framework of cellulose aerogels from waste cotton. The adsorption capacity of MG can reach 1474.01 mg·g−1 at room temperature, and the degradation rate of MB at 100 s can reach 100% by using ZIF-67/WCCA. ZIF-67/WCCA can be applied in fields of dye adsorption and catalytic degradation in sewage.
Preparation of MnO2-rGO/bamboo cellulose based carbon aerogel and its application in supercapacitors
2022, 39(3): 1268-1279.
doi: 10.13801/j.cnki.fhclxb.20210520.001
Abstract:
Reduced graphene oxide (rGO)/bamboo cellulose based carbon aerogel was prepared after gel and pyrolysis by adding GO in sodium hydroxide and urea solution system. Then, the δ-MnO2 nanosheets were deposited on this conductive substrate by hydrothermal method. The effect of MnO2 deposition content on the electrochemical properties of the composites and the energy storage mechanism of the composites were studied. The results show that the electrochemical properties of the composites are firstly improved and then decreased with increasing MnO2 deposition amount. When 0.005 mol KMnO4 is added, the specific capacitance of the composite material is 330 F/g. In addition, the asymmetric supercapacitor exhibits a high specific capacitance of 68.8 F/g at 0.5 A/g, and reveals a high energy density of 16.2 W•h/kg at a power density of 163 W/kg. It retains 94% of the initial specific capacitance after 8000 cycles at 2 A/g.
Reduced graphene oxide (rGO)/bamboo cellulose based carbon aerogel was prepared after gel and pyrolysis by adding GO in sodium hydroxide and urea solution system. Then, the δ-MnO2 nanosheets were deposited on this conductive substrate by hydrothermal method. The effect of MnO2 deposition content on the electrochemical properties of the composites and the energy storage mechanism of the composites were studied. The results show that the electrochemical properties of the composites are firstly improved and then decreased with increasing MnO2 deposition amount. When 0.005 mol KMnO4 is added, the specific capacitance of the composite material is 330 F/g. In addition, the asymmetric supercapacitor exhibits a high specific capacitance of 68.8 F/g at 0.5 A/g, and reveals a high energy density of 16.2 W•h/kg at a power density of 163 W/kg. It retains 94% of the initial specific capacitance after 8000 cycles at 2 A/g.
2022, 39(3): 1280-1290.
doi: 10.13801/j.cnki.fhclxb.20210607.004
Abstract:
In order to improve the adsorption capacity of cellulose to metal ion pollutants, this study prepared C6 carboxylic microcrystalline cellulose (CMCC) by selective oxidation system. The oxidation process and oxidation mechanism of CMCC were analyzed by using modern test and characterization techniques, and the adsorption capacity of CMCC for Cu2+ was studied. The results show that the HNO3/H3PO4-NaNO2 system selectively oxidized the C6 primary hydroxyl group on the pyranose ring in microcrystalline cellulose (MCC) macromolecule to carboxyl group by NMR and FTIR testing. The oxidation reaction etches the MCC surface to a certain extent, which improves the hygroscopicity of the CMCC, decreases the crystallinity, and reduces the thermal stability of the CMCC. Cu2+ adsorption experiments show that the adsorption behavior of CMCC follows the quasi-second-order kinetic model and Langmuir isotherm, and the saturated adsorption capacity of Cu2+ is as high as 165.5 mg/g. The adsorption thermodynamic analysis show that the adsorption of Cu2+ by CMCC is mainly through the chemical reaction between the carboxyl group and metal ions. The results indicate that the functional cellulose containing carboxyl active group can be used as a highly efficient adsorbent and will be widely used in the field of metal ion pollutant treatment.
In order to improve the adsorption capacity of cellulose to metal ion pollutants, this study prepared C6 carboxylic microcrystalline cellulose (CMCC) by selective oxidation system. The oxidation process and oxidation mechanism of CMCC were analyzed by using modern test and characterization techniques, and the adsorption capacity of CMCC for Cu2+ was studied. The results show that the HNO3/H3PO4-NaNO2 system selectively oxidized the C6 primary hydroxyl group on the pyranose ring in microcrystalline cellulose (MCC) macromolecule to carboxyl group by NMR and FTIR testing. The oxidation reaction etches the MCC surface to a certain extent, which improves the hygroscopicity of the CMCC, decreases the crystallinity, and reduces the thermal stability of the CMCC. Cu2+ adsorption experiments show that the adsorption behavior of CMCC follows the quasi-second-order kinetic model and Langmuir isotherm, and the saturated adsorption capacity of Cu2+ is as high as 165.5 mg/g. The adsorption thermodynamic analysis show that the adsorption of Cu2+ by CMCC is mainly through the chemical reaction between the carboxyl group and metal ions. The results indicate that the functional cellulose containing carboxyl active group can be used as a highly efficient adsorbent and will be widely used in the field of metal ion pollutant treatment.
2022, 39(3): 1291-1299.
doi: 10.13801/j.cnki.fhclxb.20210819.001
Abstract:
In order to study the effect of reduced graphene oxide (RGO) on the properties of chitosan (CS) films, graphite oxide and CS were used as raw materials to prepare reduced graphene oxide-chitosan film (RGO-CS) by ultrasonic dispersion and vacuum induced self-assembly and various properties of the film was characterized in this paper. In addition, CS and RGO were used as surface sizing agents to study the effects on the water resistance of corrugated paper. The results show that: the RGO-CS film was successfully prepared. SEM images reveal the surface of the RGO-CS film is flat and smooth. Besides, GO-CS composite film has the highest resistivity (17310 mΩ·cm), while resistivity of the RGO-CS film is only about 52.7 mΩ·cm. Using RGO-CS and RGO as additives to coat corrugated paper, compared with the blank sample, it is found that the water resistance is significantly improved. The sizing degree reached 78 s and 74 s, and the maximum contact angle reached 112° and 110°, respectively.
In order to study the effect of reduced graphene oxide (RGO) on the properties of chitosan (CS) films, graphite oxide and CS were used as raw materials to prepare reduced graphene oxide-chitosan film (RGO-CS) by ultrasonic dispersion and vacuum induced self-assembly and various properties of the film was characterized in this paper. In addition, CS and RGO were used as surface sizing agents to study the effects on the water resistance of corrugated paper. The results show that: the RGO-CS film was successfully prepared. SEM images reveal the surface of the RGO-CS film is flat and smooth. Besides, GO-CS composite film has the highest resistivity (17310 mΩ·cm), while resistivity of the RGO-CS film is only about 52.7 mΩ·cm. Using RGO-CS and RGO as additives to coat corrugated paper, compared with the blank sample, it is found that the water resistance is significantly improved. The sizing degree reached 78 s and 74 s, and the maximum contact angle reached 112° and 110°, respectively.
2022, 39(3): 1300-1307.
doi: 10.13801/j.cnki.fhclxb.20210520.003
Abstract:
In view of the frequent occurrence of harmful algal blooms in rivers, lakes and reservoirs, high-efficiency flocculants and natural clay minerals are commonly used to remove algae, but there are some problems, such as large amounts of clay minerals, silt and thickening of sediments. The sunken algae will still wait for an opportunity to erupt and other shortcomings, unable to achieve a satisfactory algae removal effect. In this paper, a lightweight floating mineral pumice was used as a carrier to prepare a chitosan-pumice floating composite algae-removing material that does not produce sediment. With microcrystal aeruginosa as the test object, the material ratio, dosage, the effect of pH and reaction time of the algae suspension on its flocculation and algae removal performance, the surface morphology and composition of the composite algae removal material were characterized by SEM and XRF, and the algae removal mechanism of the material was discussed by Zeta potential measurement. The results show that the optimal preparation and use conditions are: chitosan-pumice ratio is 10∶1, the pH of the algae suspension is 7, 100 mL of the algae suspension is added 6 g of the composite algae-removing material, and the reaction time is 180 minutes, the maximum removal rate of the composite material for turbidity (NTU) is 94%, and the removal rate for Chlorophyll a (Chl-a) can reach 98%; the reason for its excellent performance is that the surface of the material is uneven, large surface area, and its Zeta potential is positive. It is easy to adsorb and flocculate and neutralize the charge with negatively charged algae, causing the algae cells to continuously aggregate to form large flocs, showing a good floating algae removal effect.
In view of the frequent occurrence of harmful algal blooms in rivers, lakes and reservoirs, high-efficiency flocculants and natural clay minerals are commonly used to remove algae, but there are some problems, such as large amounts of clay minerals, silt and thickening of sediments. The sunken algae will still wait for an opportunity to erupt and other shortcomings, unable to achieve a satisfactory algae removal effect. In this paper, a lightweight floating mineral pumice was used as a carrier to prepare a chitosan-pumice floating composite algae-removing material that does not produce sediment. With microcrystal aeruginosa as the test object, the material ratio, dosage, the effect of pH and reaction time of the algae suspension on its flocculation and algae removal performance, the surface morphology and composition of the composite algae removal material were characterized by SEM and XRF, and the algae removal mechanism of the material was discussed by Zeta potential measurement. The results show that the optimal preparation and use conditions are: chitosan-pumice ratio is 10∶1, the pH of the algae suspension is 7, 100 mL of the algae suspension is added 6 g of the composite algae-removing material, and the reaction time is 180 minutes, the maximum removal rate of the composite material for turbidity (NTU) is 94%, and the removal rate for Chlorophyll a (Chl-a) can reach 98%; the reason for its excellent performance is that the surface of the material is uneven, large surface area, and its Zeta potential is positive. It is easy to adsorb and flocculate and neutralize the charge with negatively charged algae, causing the algae cells to continuously aggregate to form large flocs, showing a good floating algae removal effect.
2022, 39(3): 1308-1321.
doi: 10.13801/j.cnki.fhclxb.20210423.002
Abstract:
Aiming at the problem of unclear interface connection performance of the sandwich structure with the core of elastic damping spiral wire mesh, two typical connection processes of vacuum brazing and cementing were adopted. The physical interface bonding mechanism and mechanical properties of the sandwich structure have been studied in-depth through compression and shear tests and microscopic characterizations such as SEM and EDS. The results show that the interface characteristics by brazing process are uniform and continuous rather than that by cementing process. The brazing interface of the sandwich panel has formed a good metallurgical bond, i.e., the Ni and Si elements in the brazing filler metal diffuse obviously with the Fe and Cr elements in the panel and core material. The highest loss factors of the brazed sandwich panel and the cemented sandwich panel under the static compression load can reach 0.194 and 0.128, respectively. This means that the sandwich panel with metal spiral mesh has a large energy dissipation capacity. The peak loads of tensile shear test for the brazed cemented sandwich panels are up to 2 589 N and 1 302 N, respectively. The peak load of the former increases with the increase of the core material density, while the latter is the opposite. The failure mode of the brazed sandwich panel in the tensile shear experiment is peeling of the panel and the core material, while the cemented sandwich panel mainly occurs crack propagation and fracture of core material. This research provides a theoretical and application guideline for the connection and mechanical performance analysis of porous metallic sandwich structures.
Aiming at the problem of unclear interface connection performance of the sandwich structure with the core of elastic damping spiral wire mesh, two typical connection processes of vacuum brazing and cementing were adopted. The physical interface bonding mechanism and mechanical properties of the sandwich structure have been studied in-depth through compression and shear tests and microscopic characterizations such as SEM and EDS. The results show that the interface characteristics by brazing process are uniform and continuous rather than that by cementing process. The brazing interface of the sandwich panel has formed a good metallurgical bond, i.e., the Ni and Si elements in the brazing filler metal diffuse obviously with the Fe and Cr elements in the panel and core material. The highest loss factors of the brazed sandwich panel and the cemented sandwich panel under the static compression load can reach 0.194 and 0.128, respectively. This means that the sandwich panel with metal spiral mesh has a large energy dissipation capacity. The peak loads of tensile shear test for the brazed cemented sandwich panels are up to 2 589 N and 1 302 N, respectively. The peak load of the former increases with the increase of the core material density, while the latter is the opposite. The failure mode of the brazed sandwich panel in the tensile shear experiment is peeling of the panel and the core material, while the cemented sandwich panel mainly occurs crack propagation and fracture of core material. This research provides a theoretical and application guideline for the connection and mechanical performance analysis of porous metallic sandwich structures.
2022, 39(3): 1322-1331.
doi: 10.13801/j.cnki.fhclxb.20210415.001
Abstract:
The AgCuOIn2O3SnO2 electrical contact materials with different SnO2 content were prepared by the reaction synthesis method combined with the plastic deformation process. Electrical contact experiments were carried out on electrical contact materials with different SnO2 content on the JF04C contact material testing machine, and the contact resistance, welding resistance, and material transfer characteristics of the material were studied. The microscopic morphology under erosion was analyzed. The results show that the contact resistance of AgCuOIn2O3SnO2 contact material is small. When the test voltage does not exceed 12 V, the contact resistance decreases slowly with the increase of the number of tests and finally tends to stabilize. When the voltage increases to 18 V, the contact resistance of each sample is equal increase, and the degree of increase varies. For samples with constant SnO2 content, the welding force first increases and then decreases with the increase of the number of tests. The arcing energy of the material increases with the increase of the voltage, as the number of tests increases, it fluctuates in a zigzag shape. The material in the electrical contact process is mainly cathode transfer, and the loss of the material first increases and then decreases with the increase in the amount of SnO2. The surface of the cathode/anode contacts is convex and concave, and there are molten metal solidification patterns on the surface. The material transfer is mainly carried out by melting bridge, and the electrical contact performance is best when the SnO2 content is 0.5wt%-1.0wt%.
The AgCuOIn2O3SnO2 electrical contact materials with different SnO2 content were prepared by the reaction synthesis method combined with the plastic deformation process. Electrical contact experiments were carried out on electrical contact materials with different SnO2 content on the JF04C contact material testing machine, and the contact resistance, welding resistance, and material transfer characteristics of the material were studied. The microscopic morphology under erosion was analyzed. The results show that the contact resistance of AgCuOIn2O3SnO2 contact material is small. When the test voltage does not exceed 12 V, the contact resistance decreases slowly with the increase of the number of tests and finally tends to stabilize. When the voltage increases to 18 V, the contact resistance of each sample is equal increase, and the degree of increase varies. For samples with constant SnO2 content, the welding force first increases and then decreases with the increase of the number of tests. The arcing energy of the material increases with the increase of the voltage, as the number of tests increases, it fluctuates in a zigzag shape. The material in the electrical contact process is mainly cathode transfer, and the loss of the material first increases and then decreases with the increase in the amount of SnO2. The surface of the cathode/anode contacts is convex and concave, and there are molten metal solidification patterns on the surface. The material transfer is mainly carried out by melting bridge, and the electrical contact performance is best when the SnO2 content is 0.5wt%-1.0wt%.
2022, 39(3): 1332-1342.
doi: 10.13801/j.cnki.fhclxb.20210518.007
Abstract:
The physical morphology of wrinkles and their spatial distribution in fiber-reinforced resin composites show inhomogeneity. It’s no use to improve the performance consistency of composite structures if just tracking the evolution and effect of a specific wrinkle. This paper proposed a novel model which considered the normal distribution of wrinkle’s geometrical size and the spatial random distribution, and the implementation algorithm of the model implanted in a self-developed finite element procedure is achieved. The computation combining hetero-geneous wrinkles can be considered as a virtual test since it allows every computation to produce a different result, thus the upper and lower limits of structural response can be obtained by multiple computations. The influence of wrinkle heterogeneity on macro-mechanical response can be predicted in design stage, and a quantitative relationship between the statistical parameters of defects and mechanical properties can be established. The virtual test method is the key to the innovative design method of composites, which can effectively reduce the dependence of mass testing of composite material in engineering practice.
The physical morphology of wrinkles and their spatial distribution in fiber-reinforced resin composites show inhomogeneity. It’s no use to improve the performance consistency of composite structures if just tracking the evolution and effect of a specific wrinkle. This paper proposed a novel model which considered the normal distribution of wrinkle’s geometrical size and the spatial random distribution, and the implementation algorithm of the model implanted in a self-developed finite element procedure is achieved. The computation combining hetero-geneous wrinkles can be considered as a virtual test since it allows every computation to produce a different result, thus the upper and lower limits of structural response can be obtained by multiple computations. The influence of wrinkle heterogeneity on macro-mechanical response can be predicted in design stage, and a quantitative relationship between the statistical parameters of defects and mechanical properties can be established. The virtual test method is the key to the innovative design method of composites, which can effectively reduce the dependence of mass testing of composite material in engineering practice.
2022, 39(3): 1343-1352.
doi: 10.13801/j.cnki.fhclxb.20210518.004
Abstract:
A method for buckling analysis of liner of composite pressure vessel with depression was proposed. Based on the assumption of plane strain, the shrinkage buckling analysis model of the semicircular ring with depress-ion was established, and the depression was introduced into the finite element analysis model by modifying the coordinates of nodes. The nonlinear iterative method was used to gradually increase the in-plane load, and the shrinkage buckling analysis of the semicircular ring with depression was analyzed. On this basis, a three-dimensional finite element analysis model of composite pressure vessel containing a liner with depression was established, the hoop and axial components of the residual stress of the liner after autofrettage was considered to analysis the buckling of the liner with depression after autofrettage of composite pressure vessel. Taking a 130 L spherical head and thin-walled aluminum alloy liner full-wound composite pressure vessel as an example, the critical buckling load of the liner and the stress and deformation of the liner when buckling occurred were analyzed. The results show that the buckling mode of the liner with initial depression after autofrettage is local buckling; the greater the initial depression depth, the lower the critical buckling load; the area where the distance from the middle of the straight section is 1/2 of the axial width of the depression and near the head of the straight section is prone to buckling, which is the weakness zone of the metal liner.
A method for buckling analysis of liner of composite pressure vessel with depression was proposed. Based on the assumption of plane strain, the shrinkage buckling analysis model of the semicircular ring with depress-ion was established, and the depression was introduced into the finite element analysis model by modifying the coordinates of nodes. The nonlinear iterative method was used to gradually increase the in-plane load, and the shrinkage buckling analysis of the semicircular ring with depression was analyzed. On this basis, a three-dimensional finite element analysis model of composite pressure vessel containing a liner with depression was established, the hoop and axial components of the residual stress of the liner after autofrettage was considered to analysis the buckling of the liner with depression after autofrettage of composite pressure vessel. Taking a 130 L spherical head and thin-walled aluminum alloy liner full-wound composite pressure vessel as an example, the critical buckling load of the liner and the stress and deformation of the liner when buckling occurred were analyzed. The results show that the buckling mode of the liner with initial depression after autofrettage is local buckling; the greater the initial depression depth, the lower the critical buckling load; the area where the distance from the middle of the straight section is 1/2 of the axial width of the depression and near the head of the straight section is prone to buckling, which is the weakness zone of the metal liner.
2022, 39(3): 1353-1362.
doi: 10.13801/j.cnki.fhclxb.20210512.002
Abstract:
Carbon fiber reinforced phenolic resin composite (CF/S-157) and carbon fiber reinforced epoxy composite (CF/TDE-85), which are widely used at present, were selected to carry out the salt spray aging, hydrothermal aging and salt water immersion environmental test in laboratory. Based on various mechanical properties (tensile strength, flexural strength, compressive strength and interlaminar shear strength), the corrosion behaviors of the composite materials were studied. The changes of molecular segments and functional groups of resin matrix in various aging environments were analyzed by attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR), and the failure modes of various matrix resins were obtained. The failure mode of resin/fiber interface was identified based on the characterization of SEM and ultrasonic C-scanning testing and imaging system. The effects of various aging methods on glass transition temperature Tg and thermal mass loss of composites were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results show that the deterioration severity order of the three aging methods is hydrothermal aging, salt spray and salt water immersion. The corrosion characterization, failure mechanism and failure mode of the composites in simulated marine environment are obtained, which lays a foundation for environmental adaptability evaluation and service life prediction of high-performance resin matrix composites.
Carbon fiber reinforced phenolic resin composite (CF/S-157) and carbon fiber reinforced epoxy composite (CF/TDE-85), which are widely used at present, were selected to carry out the salt spray aging, hydrothermal aging and salt water immersion environmental test in laboratory. Based on various mechanical properties (tensile strength, flexural strength, compressive strength and interlaminar shear strength), the corrosion behaviors of the composite materials were studied. The changes of molecular segments and functional groups of resin matrix in various aging environments were analyzed by attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR), and the failure modes of various matrix resins were obtained. The failure mode of resin/fiber interface was identified based on the characterization of SEM and ultrasonic C-scanning testing and imaging system. The effects of various aging methods on glass transition temperature Tg and thermal mass loss of composites were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results show that the deterioration severity order of the three aging methods is hydrothermal aging, salt spray and salt water immersion. The corrosion characterization, failure mechanism and failure mode of the composites in simulated marine environment are obtained, which lays a foundation for environmental adaptability evaluation and service life prediction of high-performance resin matrix composites.
