2023 Vol. 40, No. 10
2023, 40(10): 5447-5465.
doi: 10.13801/j.cnki.fhclxb.20230607.001
Abstract:
In recent years, all-inorganic perovskite solar cells have become a hot topic in the photovoltaic field due to their excellent optoelectronic properties and outstanding thermal stability. This type of cell has achieved a photovoltaic conversion efficiency (PCE) of 21.15%, and further improvements are expected. However, the effective area of currently efficient all-inorganic perovskite cells is relatively small, mostly around 0.1 cm2, and the PCE of large-area all-inorganic perovskite solar cells will decrease significantly with an increase in effective area. The preparation of large-area cells is crucial for the commercial application of all-inorganic perovskite solar cells. In order to make all-inorganic perovskite materials better apply in the photovoltaic field, it is the simplest and most effective method to construct a multi-component composite structure and adjust the preparation process of all-inorganic perovskite. This article provides a systematic review of the progress in large-area all-inorganic perovskite solar cells, summarizing the achievements of all-inorganic perovskite solar cells with larger area. An analysis of the current status of large-area all-inorganic perovskite solar cells is also presented, and systematic summaries are given for the process of preparing large-area perovskite solar cells and strategies for optimizing cell performance. Finally, the future development trends in this field are discussed.
In recent years, all-inorganic perovskite solar cells have become a hot topic in the photovoltaic field due to their excellent optoelectronic properties and outstanding thermal stability. This type of cell has achieved a photovoltaic conversion efficiency (PCE) of 21.15%, and further improvements are expected. However, the effective area of currently efficient all-inorganic perovskite cells is relatively small, mostly around 0.1 cm2, and the PCE of large-area all-inorganic perovskite solar cells will decrease significantly with an increase in effective area. The preparation of large-area cells is crucial for the commercial application of all-inorganic perovskite solar cells. In order to make all-inorganic perovskite materials better apply in the photovoltaic field, it is the simplest and most effective method to construct a multi-component composite structure and adjust the preparation process of all-inorganic perovskite. This article provides a systematic review of the progress in large-area all-inorganic perovskite solar cells, summarizing the achievements of all-inorganic perovskite solar cells with larger area. An analysis of the current status of large-area all-inorganic perovskite solar cells is also presented, and systematic summaries are given for the process of preparing large-area perovskite solar cells and strategies for optimizing cell performance. Finally, the future development trends in this field are discussed.
2023, 40(10): 5466-5485.
doi: 10.13801/j.cnki.fhclxb.20230427.001
Abstract:
Reliable numerical simulation results depend on the use of accurate numerical models. Micro-computed tomography (Micro-CT) technology is capable of non-destructively imaging the internal structure of composite materials, hence, numerical models reconstructed from it are more representative than the idealized ones. Here, a review is presented for constructing mesoscopic models of composite materials based on Micro-CT images and its application in virtual testing. A novel concept, Micro-CT aided numerical simulation, is proposed. First, the principle of Micro-CT imaging, the characteristics of equipment, and the difficulties with scanning fabric-reinforced composites are discussed. Second, the characteristics of existing Micro-CT aided modeling techniques are analyzed and compared. The models are divided into three types including indirect, voxel, and digital material twin ones. The theoretical basis and technical approaches for constructing each type of model are highlighted, and the advantages and limitations of each are analyzed. Then recent applications of Micro-CT aided numerical simulation in composite molding process and mechanical property prediction of fabric reinforced composites are summarized, showing the potential and importance of the technology. Finally, the future of Micro-CT aided numerical simulation technology is anticipated.
Reliable numerical simulation results depend on the use of accurate numerical models. Micro-computed tomography (Micro-CT) technology is capable of non-destructively imaging the internal structure of composite materials, hence, numerical models reconstructed from it are more representative than the idealized ones. Here, a review is presented for constructing mesoscopic models of composite materials based on Micro-CT images and its application in virtual testing. A novel concept, Micro-CT aided numerical simulation, is proposed. First, the principle of Micro-CT imaging, the characteristics of equipment, and the difficulties with scanning fabric-reinforced composites are discussed. Second, the characteristics of existing Micro-CT aided modeling techniques are analyzed and compared. The models are divided into three types including indirect, voxel, and digital material twin ones. The theoretical basis and technical approaches for constructing each type of model are highlighted, and the advantages and limitations of each are analyzed. Then recent applications of Micro-CT aided numerical simulation in composite molding process and mechanical property prediction of fabric reinforced composites are summarized, showing the potential and importance of the technology. Finally, the future of Micro-CT aided numerical simulation technology is anticipated.
2023, 40(10): 5486-5501.
doi: 10.13801/j.cnki.fhclxb.20230423.002
Abstract:
Photonic crystal (PC) is a structure formed by the periodic arrangement of dielectric materials. Due to its distinct photoregulatory features, it has drawn significant attention in the realm of optics and photonics. From the structure, mechanism, material, and functional application, people have carried out in-depth research and continuous development. Because of their large specific surface area and customizable three-dimensional structure, photonic crystal fibers (PCFs) in particular provide new opportunities for the development of detecting sensing, smart wearables, photoelectric transmission, and other sectors. In this paper, the structure and color mechanism of PC, basic materials, preparation methods, and applications of PCFs are reviewed. The contribution of electrostatic spinning technology in the field of PCFs is highlighted, as are the functional applications of PCFs in textile printing and dyeing, intelligent response, sensing detection, and hydrophobic regulation are discussed. Finally, the problems in macro preparation and practical production application of PCFs are pointed out, and the possible research focus and direction in the future have prospected.
Photonic crystal (PC) is a structure formed by the periodic arrangement of dielectric materials. Due to its distinct photoregulatory features, it has drawn significant attention in the realm of optics and photonics. From the structure, mechanism, material, and functional application, people have carried out in-depth research and continuous development. Because of their large specific surface area and customizable three-dimensional structure, photonic crystal fibers (PCFs) in particular provide new opportunities for the development of detecting sensing, smart wearables, photoelectric transmission, and other sectors. In this paper, the structure and color mechanism of PC, basic materials, preparation methods, and applications of PCFs are reviewed. The contribution of electrostatic spinning technology in the field of PCFs is highlighted, as are the functional applications of PCFs in textile printing and dyeing, intelligent response, sensing detection, and hydrophobic regulation are discussed. Finally, the problems in macro preparation and practical production application of PCFs are pointed out, and the possible research focus and direction in the future have prospected.
2023, 40(10): 5502-5517.
doi: 10.13801/j.cnki.fhclxb.20230607.003
Abstract:
Biomimetic superhydrophobic surfaces have been widely used in critical areas such as healthcare, environment, and energy. First, this work briefly reviewed bioinspired design and preparation technology, which combined with theoretical basis on superhydrophobicity. Second, due to the significant biological effects for high water/blood-repellency, biological/blood compatibility, anticoagulation/thrombosis, anti-bacteria, low bio-adhesion, etc., superhydrophobic surfaces have attracted much attention in biomedical applications. The present work mainly focused on summarizing representative applications of bioinspired superhydrophobic surfaces in wound healing (hemostatic dressings), anti-coagulation/anti-thrombotic (blood-contact medical devices), antibacterial surfaces, drug release, motion monitoring, biochips, anticorrosion of magnesium alloy, biomedical detection and so on in recent years. Finally, combining with our own research experience, we deeply analyzed the existing issues and challenges of bioinspired superhydrophobic surfaces in practical biomedical applications, mainly involving mechanical durability, chemical corrosion, biofouling, interfacial construction, and biomedical applications. Therefore, focusing on practical functions and high performance, conceptual design of superhydrophobic surfaces will be moved toward industrial applications.
Biomimetic superhydrophobic surfaces have been widely used in critical areas such as healthcare, environment, and energy. First, this work briefly reviewed bioinspired design and preparation technology, which combined with theoretical basis on superhydrophobicity. Second, due to the significant biological effects for high water/blood-repellency, biological/blood compatibility, anticoagulation/thrombosis, anti-bacteria, low bio-adhesion, etc., superhydrophobic surfaces have attracted much attention in biomedical applications. The present work mainly focused on summarizing representative applications of bioinspired superhydrophobic surfaces in wound healing (hemostatic dressings), anti-coagulation/anti-thrombotic (blood-contact medical devices), antibacterial surfaces, drug release, motion monitoring, biochips, anticorrosion of magnesium alloy, biomedical detection and so on in recent years. Finally, combining with our own research experience, we deeply analyzed the existing issues and challenges of bioinspired superhydrophobic surfaces in practical biomedical applications, mainly involving mechanical durability, chemical corrosion, biofouling, interfacial construction, and biomedical applications. Therefore, focusing on practical functions and high performance, conceptual design of superhydrophobic surfaces will be moved toward industrial applications.
2023, 40(10): 5518-5528.
doi: 10.13801/j.cnki.fhclxb.20230310.002
Abstract:
Secondary particle assembed with radial oriented primary grains can inhibit the formation of microcracks and provide a good Li+ diffusion path, and it is an ideal morphology for high-end polycrystalline Ni-rich cathode materials. In recent years, some researchers have obtained nickel-rich cathode materials assembed with grains with large length-width ratio by regulating precursor precipitation crystallization and high temperature lithium crystallization. However, the regulation method and formation mechanism of the radially oriented structure of Ni-rich cathode, especially the regulation method of the radially oriented hydroxide precursor and the influence of the key parameters on the radially oriented structure, have not been elaborated. In this paper, the necessity of regulating the radially oriented structure of polycrystalline Ni-rich cathode and the mechanism on enhancing electrochemical performance are introduced. Secondly, the regulation method and formation mechanism of the radially oriented polycrystalline Ni-rich cathode are introduced, including the influence of the key parameters of precipitation crystallization process (pH, ammonia concentration and solid content) on the radially oriented precursor, and the influence of temperature and doping elements induced in calcination process on the maintenance of the oriented structure of precursor. Finally, the challenges facing for the regulation of radially oriented Ni-rich cathode are discussed.
Secondary particle assembed with radial oriented primary grains can inhibit the formation of microcracks and provide a good Li+ diffusion path, and it is an ideal morphology for high-end polycrystalline Ni-rich cathode materials. In recent years, some researchers have obtained nickel-rich cathode materials assembed with grains with large length-width ratio by regulating precursor precipitation crystallization and high temperature lithium crystallization. However, the regulation method and formation mechanism of the radially oriented structure of Ni-rich cathode, especially the regulation method of the radially oriented hydroxide precursor and the influence of the key parameters on the radially oriented structure, have not been elaborated. In this paper, the necessity of regulating the radially oriented structure of polycrystalline Ni-rich cathode and the mechanism on enhancing electrochemical performance are introduced. Secondly, the regulation method and formation mechanism of the radially oriented polycrystalline Ni-rich cathode are introduced, including the influence of the key parameters of precipitation crystallization process (pH, ammonia concentration and solid content) on the radially oriented precursor, and the influence of temperature and doping elements induced in calcination process on the maintenance of the oriented structure of precursor. Finally, the challenges facing for the regulation of radially oriented Ni-rich cathode are discussed.
2023, 40(10): 5529-5541.
doi: 10.13801/j.cnki.fhclxb.20230413.001
Abstract:
Polyphenols are compounds with abundant phenolic hydroxyl groups which can be widely found in natural plants. Polyphenols can interact with the various materials to form hydrogen bonds, metal coordination and π-π interactions. Over the past few years, polyphenols have been widely applied in material functional modifications. In this paper, the structures and properties of polyphenols, including dopamine, catechol, gallic acid and tannic acid were reviewed. Meanwhile, the modification methods of fiber surface and the applications of fiber reinforced polymer composites were introduced. Finally, a prospective analysis on the future research direction and focus of polyphenol modification studies were provided.
Polyphenols are compounds with abundant phenolic hydroxyl groups which can be widely found in natural plants. Polyphenols can interact with the various materials to form hydrogen bonds, metal coordination and π-π interactions. Over the past few years, polyphenols have been widely applied in material functional modifications. In this paper, the structures and properties of polyphenols, including dopamine, catechol, gallic acid and tannic acid were reviewed. Meanwhile, the modification methods of fiber surface and the applications of fiber reinforced polymer composites were introduced. Finally, a prospective analysis on the future research direction and focus of polyphenol modification studies were provided.
2023, 40(10): 5542-5553.
doi: 10.13801/j.cnki.fhclxb.20230523.003
Abstract:
Copper and copper alloys are widely used in electrical contact materials, electronic packaging materials, heat exchange materials and other fields because of their high electrical conductivity, thermal conductivity, easy machinability and corrosion resistance. However, the contradiction between strength, electrical conductivity and thermal conductivity in copper alloys limits its development. Copper matrix composites can improve the strength of materials by strengthening phase, avoid serious lattice distortion to copper matrix, and maximize the conductivity of materials, thus obtaining materials with excellent strength-resistance ratio. Therefore, copper matrix composites are an important development direction of high performance copper materials. In this paper, the main preparation methods of high performance copper matrix composites are summarized, and the reinforcing phase of composites, its characteristics and development direction are summarized. The main research progress and its application status in rail transit, electrics and electronics, military industry are described, and the future development direction of this material is prospected, which provides reference for the research and application of high performance copper matrix composites.
Copper and copper alloys are widely used in electrical contact materials, electronic packaging materials, heat exchange materials and other fields because of their high electrical conductivity, thermal conductivity, easy machinability and corrosion resistance. However, the contradiction between strength, electrical conductivity and thermal conductivity in copper alloys limits its development. Copper matrix composites can improve the strength of materials by strengthening phase, avoid serious lattice distortion to copper matrix, and maximize the conductivity of materials, thus obtaining materials with excellent strength-resistance ratio. Therefore, copper matrix composites are an important development direction of high performance copper materials. In this paper, the main preparation methods of high performance copper matrix composites are summarized, and the reinforcing phase of composites, its characteristics and development direction are summarized. The main research progress and its application status in rail transit, electrics and electronics, military industry are described, and the future development direction of this material is prospected, which provides reference for the research and application of high performance copper matrix composites.
2023, 40(10): 5554-5566.
doi: 10.13801/j.cnki.fhclxb.20230302.001
Abstract:
To clarity the preparation of anti-overburden/de-icing coating and improve its properties on composite materials, the anti-overburden/de-icing mechanisms were systematically introduced in this article, including the structure, properties and influencing factors of superhydrophobic, super lubricating and composite coating finishing process. From the technical characteristics of textile composite coating finishing, the latest research anti-icing/de-icing functional finishing of textile composites was summarized. Finally, considering the weak weather resistance, poor shape plasticity and hard disassemble of present materials, the views that couple the advantages of different coating finishing technology to develop flexible type, composite synergy proof anti-overburden/de-icing functional textile materials were put forward. The review article may promote the development and research of anti-icing/deicing function textile composite materials.
To clarity the preparation of anti-overburden/de-icing coating and improve its properties on composite materials, the anti-overburden/de-icing mechanisms were systematically introduced in this article, including the structure, properties and influencing factors of superhydrophobic, super lubricating and composite coating finishing process. From the technical characteristics of textile composite coating finishing, the latest research anti-icing/de-icing functional finishing of textile composites was summarized. Finally, considering the weak weather resistance, poor shape plasticity and hard disassemble of present materials, the views that couple the advantages of different coating finishing technology to develop flexible type, composite synergy proof anti-overburden/de-icing functional textile materials were put forward. The review article may promote the development and research of anti-icing/deicing function textile composite materials.
2023, 40(10): 5567-5576.
doi: 10.13801/j.cnki.fhclxb.20230512.001
Abstract:
In recent years, environmentally friendly green solvents have become an important research direction in green chemistry. As a new type of green solvent with certain degradability, good biocompatibility and relatively environmental protection, the deep eutectic solvent has preliminarily shown its strong development potential in the preparation and functional modification of nanocellulose. This paper mainly reviews the basic properties and formation mechanism of the deep eutectic solvent, and introduces the application of different deep eutectic solvent in the preparation and functional modification of nanocellulose, so as to achieve efficient preparation and modification of nanocellulose. In the future, the designability of the deep eutectic solvent can be brought into full play through the combination of experiment and computational simulation technology and reveal the law of its dissolution, degradation and functionalization in the preparation of nanocellulose, so as to provide references for the preparation and modification of the pretreatment of the deep eutectic solvent and promote its large-scale application in biomass pretreatment.
In recent years, environmentally friendly green solvents have become an important research direction in green chemistry. As a new type of green solvent with certain degradability, good biocompatibility and relatively environmental protection, the deep eutectic solvent has preliminarily shown its strong development potential in the preparation and functional modification of nanocellulose. This paper mainly reviews the basic properties and formation mechanism of the deep eutectic solvent, and introduces the application of different deep eutectic solvent in the preparation and functional modification of nanocellulose, so as to achieve efficient preparation and modification of nanocellulose. In the future, the designability of the deep eutectic solvent can be brought into full play through the combination of experiment and computational simulation technology and reveal the law of its dissolution, degradation and functionalization in the preparation of nanocellulose, so as to provide references for the preparation and modification of the pretreatment of the deep eutectic solvent and promote its large-scale application in biomass pretreatment.
2023, 40(10): 5577-5587.
doi: 10.13801/j.cnki.fhclxb.20230221.001
Abstract:
Magnesium (Mg) alloy is the lightest metal material in practical application, and its structural parts are expected to be widely used in aerospace, rail transit, automobile, electronics and other lightweight fields. However, Mg alloy has the disadvantage of corrosion resistance, which seriously limits its wide application in the field of lightweight. Coating Mg alloy with good corrosion resistance aluminum (Al) alloy to form Mg-Al laminate can not only protect Mg alloy, but also play the advantages of high specific strength and specific stiffness of Mg alloy, good shock absorption and electromagnetic shielding performance. In this paper, the preparation methods and characteristics of Mg-Al laminates are reviewed, the microstructure evolution of component plates and layer interfaces in Mg-Al laminates and their influence on mechanical properties of the laminates are analyzed, and the innovative research results of our research group on stamping forming and deformation microscopic mechanism of Mg-Al laminates are introduced. How to prepare wider and thinner Mg-Al laminates with intermetallic compounds controllable at the interface is the focus of future research.
Magnesium (Mg) alloy is the lightest metal material in practical application, and its structural parts are expected to be widely used in aerospace, rail transit, automobile, electronics and other lightweight fields. However, Mg alloy has the disadvantage of corrosion resistance, which seriously limits its wide application in the field of lightweight. Coating Mg alloy with good corrosion resistance aluminum (Al) alloy to form Mg-Al laminate can not only protect Mg alloy, but also play the advantages of high specific strength and specific stiffness of Mg alloy, good shock absorption and electromagnetic shielding performance. In this paper, the preparation methods and characteristics of Mg-Al laminates are reviewed, the microstructure evolution of component plates and layer interfaces in Mg-Al laminates and their influence on mechanical properties of the laminates are analyzed, and the innovative research results of our research group on stamping forming and deformation microscopic mechanism of Mg-Al laminates are introduced. How to prepare wider and thinner Mg-Al laminates with intermetallic compounds controllable at the interface is the focus of future research.
2023, 40(10): 5588-5600.
doi: 10.13801/j.cnki.fhclxb.20230105.002
Abstract:
Three-dimensional (3D) braided glass fiber/epoxy resin composite thin-walled tubes with three braiding angles of 15°, 25°, and 35° were prepared by 3D braiding molding technology and resin transfer molding process (RTM). The quasi-static compression performance test of 3D braided composite thin-walled tubes was carried out at low temperature (−100℃, −50℃), normal temperature (20℃) and high temperature field (80°C, 110°C, 140°C and 170°C). The effects of temperature and braiding angle on compression properties and compression failure pattern of 3D braided composite thin-walled tubes were studied based on X-ray micro-computer tomography (Micro-CT). The results show that the quasi-static compression behavior of 3D braided composite thin-walled tubes has a significant temperature effect. As the temperature increases, the failure mode of the braided composite thin-walled tubes changes from local shear failure to large-area debonding of the fiber tows-matrix interface. The braiding angle has different effects on the compressive strength, compressive modulus and specific energy absorption of 3D braided composite thin-walled tubes. The braided composite thin-walled tubes with small braiding angle have a higher orientation along the braided yarn direction which can withstand greater axial compounding, so the compression performance is better.
Three-dimensional (3D) braided glass fiber/epoxy resin composite thin-walled tubes with three braiding angles of 15°, 25°, and 35° were prepared by 3D braiding molding technology and resin transfer molding process (RTM). The quasi-static compression performance test of 3D braided composite thin-walled tubes was carried out at low temperature (−100℃, −50℃), normal temperature (20℃) and high temperature field (80°C, 110°C, 140°C and 170°C). The effects of temperature and braiding angle on compression properties and compression failure pattern of 3D braided composite thin-walled tubes were studied based on X-ray micro-computer tomography (Micro-CT). The results show that the quasi-static compression behavior of 3D braided composite thin-walled tubes has a significant temperature effect. As the temperature increases, the failure mode of the braided composite thin-walled tubes changes from local shear failure to large-area debonding of the fiber tows-matrix interface. The braiding angle has different effects on the compressive strength, compressive modulus and specific energy absorption of 3D braided composite thin-walled tubes. The braided composite thin-walled tubes with small braiding angle have a higher orientation along the braided yarn direction which can withstand greater axial compounding, so the compression performance is better.
2023, 40(10): 5601-5610.
doi: 10.13801/j.cnki.fhclxb.20221221.001
Abstract:
With the rapid development of China's domestic space engineering, the harsher requirements are put forward for lightweight, dimensional stability, thermal protection efficiency and long service capability of the thermal protection system. Rigid nanoporous phenolic resin-based RMI/PR composites are prepared via a sol-gel polymerization and ambient-pressure gradient drying using rigid mullite ceramic tile (RMI) as the reinforcement and hybrid phenolic resin (PR) as matrix. The effects of resin concentration on the microstructure, mechanical properties, thermal insulation properties and ablative properties of the composites are systematically studied. The results show that RMI has obvious transverse isotropy, and the room-temperature thermal conductivity in the Z direction is 0.036 W/(m∙K). With the increase of the resin concentration from 15wt% to 45wt%, the density of RMI/PR increases from 0.52 g/cm3 to 0.85 g/cm3, and the most probable pore size of the resin matrix decreases sharply from 2081 nm to 32 nm. With the increase of resin concentration, the room-temperature thermal conductivity of RMI/PR increases slowly and all of them are less than 0.07 W/(m∙K), but its mechanical properties are significantly enhanced and the maximum compressive strength in the Z direction of composites is up to 20.8 MPa. After static heat insulation test at 1000℃ for 300 s, the backside temperature of composites decreases from 277℃ to 240℃. Under the oxy-acetylene ablation at 2000℃ for 30 s, the linear ablation rate of the composites is reduced from 0.200 mm/s to 0.081 mm/s, indicating that the increase of resin concentration can significantly improve the high-temperature thermal insulation properties and ablation resistance of the composites.
With the rapid development of China's domestic space engineering, the harsher requirements are put forward for lightweight, dimensional stability, thermal protection efficiency and long service capability of the thermal protection system. Rigid nanoporous phenolic resin-based RMI/PR composites are prepared via a sol-gel polymerization and ambient-pressure gradient drying using rigid mullite ceramic tile (RMI) as the reinforcement and hybrid phenolic resin (PR) as matrix. The effects of resin concentration on the microstructure, mechanical properties, thermal insulation properties and ablative properties of the composites are systematically studied. The results show that RMI has obvious transverse isotropy, and the room-temperature thermal conductivity in the Z direction is 0.036 W/(m∙K). With the increase of the resin concentration from 15wt% to 45wt%, the density of RMI/PR increases from 0.52 g/cm3 to 0.85 g/cm3, and the most probable pore size of the resin matrix decreases sharply from 2081 nm to 32 nm. With the increase of resin concentration, the room-temperature thermal conductivity of RMI/PR increases slowly and all of them are less than 0.07 W/(m∙K), but its mechanical properties are significantly enhanced and the maximum compressive strength in the Z direction of composites is up to 20.8 MPa. After static heat insulation test at 1000℃ for 300 s, the backside temperature of composites decreases from 277℃ to 240℃. Under the oxy-acetylene ablation at 2000℃ for 30 s, the linear ablation rate of the composites is reduced from 0.200 mm/s to 0.081 mm/s, indicating that the increase of resin concentration can significantly improve the high-temperature thermal insulation properties and ablation resistance of the composites.
2023, 40(10): 5611-5620.
doi: 10.13801/j.cnki.fhclxb.20221228.002
Abstract:
Carbon fiber reinforced polymer (CFRP) composites are widely used because of their excellent properties such as high specific strength and high specific modulus, but their mechanical properties along the thickness are poor due to the laminar structure characteristics and the intrinsic brittleness of epoxy resin, and they are prone to delamination under out-of-plane impact and in-plane compression loads, which in turn reduce the strength of the composites. Therefore it is especially important to improve the interlaminar fracture toughness of the composites. In this paper, we attempt to improve the interlaminar fracture toughness of the composite by introducing highly oriented carbon nanotube (CNT) fiber veils in the interlaminar region. To ensure that the fiber veils are well infiltrated by the resin, they are first immersed in an epoxy resin solution diluted with acetone. After the acetone evaporated, it is inserted into the interlayer region of the homemade carbon fiber prepreg and subsequently cured by a hot pressing process. The mode I and mode II interlaminar fracture toughness of the toughened samples are evaluated via ASTM testing standards. Combined with the optical microscopic observation of the cross-section and scanning electron microscopy analysis of the fracture surface, the crack propagation paths are clearly shown and the interlaminar toughening mechanisms of CNT fiber veils are revealed. The results show that the mode I and mode II interlaminar fracture toughness of CNT veil toughened samples are improved by 37.4% and 41.8%, respectively. The toughening mechanisms mainly include matrix toughening, strengthening carbon fiber bridging and crack deflection.
Carbon fiber reinforced polymer (CFRP) composites are widely used because of their excellent properties such as high specific strength and high specific modulus, but their mechanical properties along the thickness are poor due to the laminar structure characteristics and the intrinsic brittleness of epoxy resin, and they are prone to delamination under out-of-plane impact and in-plane compression loads, which in turn reduce the strength of the composites. Therefore it is especially important to improve the interlaminar fracture toughness of the composites. In this paper, we attempt to improve the interlaminar fracture toughness of the composite by introducing highly oriented carbon nanotube (CNT) fiber veils in the interlaminar region. To ensure that the fiber veils are well infiltrated by the resin, they are first immersed in an epoxy resin solution diluted with acetone. After the acetone evaporated, it is inserted into the interlayer region of the homemade carbon fiber prepreg and subsequently cured by a hot pressing process. The mode I and mode II interlaminar fracture toughness of the toughened samples are evaluated via ASTM testing standards. Combined with the optical microscopic observation of the cross-section and scanning electron microscopy analysis of the fracture surface, the crack propagation paths are clearly shown and the interlaminar toughening mechanisms of CNT fiber veils are revealed. The results show that the mode I and mode II interlaminar fracture toughness of CNT veil toughened samples are improved by 37.4% and 41.8%, respectively. The toughening mechanisms mainly include matrix toughening, strengthening carbon fiber bridging and crack deflection.
2023, 40(10): 5621-5629.
doi: 10.13801/j.cnki.fhclxb.20230104.002
Abstract:
Due to the high strength and lightweight, epoxy-based composites have high application value in the fields of aerospace and automotive. However, the brittle nature of epoxy resins significantly hinder theirapplication in real engineering, and it is still a great challenge to improve the strength and toughness of the epoxy-based composites. Herein, we develop an epoxy-based composite lattice composing of strengthening zones and toughening zones, which are rationally assembled into a layered structure through direct ink writing technique. The physical and chemical properties of the epoxy-based composite inks and printed filaments were characterized by rotational rheometer and optical microscope, and a universal testing machine was used to evaluate the mechanical properties of the epoxy-based composite lattice with various structural parameters. It is found that the specific strength, toughness and fracture toughness of the epoxy-based composite lattice increase by 95%, 630% and 19.1% compared to the solid composite, respectively. Based on the fracture surfaces and finite element analysis, it can be concluded that the strengthening zones ensure the structural strength, while the toughening zones are capable of effectively sharing the external deformation and preventing the crack propagation. The current research provides new ideas and theoretical basis for the design, manufacturing, and applications of structural nanocomposites with high strength and toughness.
Due to the high strength and lightweight, epoxy-based composites have high application value in the fields of aerospace and automotive. However, the brittle nature of epoxy resins significantly hinder theirapplication in real engineering, and it is still a great challenge to improve the strength and toughness of the epoxy-based composites. Herein, we develop an epoxy-based composite lattice composing of strengthening zones and toughening zones, which are rationally assembled into a layered structure through direct ink writing technique. The physical and chemical properties of the epoxy-based composite inks and printed filaments were characterized by rotational rheometer and optical microscope, and a universal testing machine was used to evaluate the mechanical properties of the epoxy-based composite lattice with various structural parameters. It is found that the specific strength, toughness and fracture toughness of the epoxy-based composite lattice increase by 95%, 630% and 19.1% compared to the solid composite, respectively. Based on the fracture surfaces and finite element analysis, it can be concluded that the strengthening zones ensure the structural strength, while the toughening zones are capable of effectively sharing the external deformation and preventing the crack propagation. The current research provides new ideas and theoretical basis for the design, manufacturing, and applications of structural nanocomposites with high strength and toughness.
2023, 40(10): 5630-5640.
doi: 10.13801/j.cnki.fhclxb.20230110.001
Abstract:
By compounding rice straw with phenolic resin (PF) foam, to improve the shortcomings of PF foam itself, such as high brittleness and poor mechanical strength, and to investigate the effects of length (8 cm, 12 cm and 16 cm) and form (cross-cutting straw, slope-cutting straw and grinding straw fiber) of rice straw on the physical properties, mechanical and combustion properties of the composite material. The results show that the inner and outer surfaces of rice straw have an obvious mechanical engagement with PF foam. The bending strength, compressive strength and tensile strength perpendicular to the board surface of rice straw/PF foam composites are better than PF foam. The bending strength of 16 cm long slope-cutting rice straw/PF foam composite reaches 1.18 MPa, which is 195% higher than PF foam. The compressive stress at 10% strain and tensile strength perpendicular to the plate surface of 16 cm long grinding rice straw/PF foam composite are 251.30 kPa and 121.26 kPa, respectively, which are 112.1% and 20.7% higher than PF foam. The vertical combustion and limited oxygen index (LOI) results show that PF foam has better wrapping effect on straw, the thermal stability of the composite is almost the same as that of PF foam, with almost no change in LOI value. The flammability test results of both rice straw/PF foam composites and PF foam meet the requirements of B1 class building materials, which show an excellent fire resistance. To sum up, 8 cm slope-cutting rice straw reinforced PF foam composite has an optimal integrated mechanical property.
By compounding rice straw with phenolic resin (PF) foam, to improve the shortcomings of PF foam itself, such as high brittleness and poor mechanical strength, and to investigate the effects of length (8 cm, 12 cm and 16 cm) and form (cross-cutting straw, slope-cutting straw and grinding straw fiber) of rice straw on the physical properties, mechanical and combustion properties of the composite material. The results show that the inner and outer surfaces of rice straw have an obvious mechanical engagement with PF foam. The bending strength, compressive strength and tensile strength perpendicular to the board surface of rice straw/PF foam composites are better than PF foam. The bending strength of 16 cm long slope-cutting rice straw/PF foam composite reaches 1.18 MPa, which is 195% higher than PF foam. The compressive stress at 10% strain and tensile strength perpendicular to the plate surface of 16 cm long grinding rice straw/PF foam composite are 251.30 kPa and 121.26 kPa, respectively, which are 112.1% and 20.7% higher than PF foam. The vertical combustion and limited oxygen index (LOI) results show that PF foam has better wrapping effect on straw, the thermal stability of the composite is almost the same as that of PF foam, with almost no change in LOI value. The flammability test results of both rice straw/PF foam composites and PF foam meet the requirements of B1 class building materials, which show an excellent fire resistance. To sum up, 8 cm slope-cutting rice straw reinforced PF foam composite has an optimal integrated mechanical property.
2023, 40(10): 5641-5653.
doi: 10.13801/j.cnki.fhclxb.20221228.003
Abstract:
Carbon fiber reinforced poly aryl ether ketone (SCF35/PAEK) thermoplastic composites were prepared using two different melt viscosities of domestic high performance poly aryl ether ketone resins (PAEK-L and PAEK-H) and domestic T300 grade carbon fibers (SCF35), and the effects of resin matrix viscosity and impact energy and impact energy on the impact properties of the composites were investigated. In addition, the internal morphology of quasi-static indentation specimens was characterized by Micro-CT to study the impact damage mechanism of the composites. The results show that PAEK-L resin matrix composite with lower fluidity has higher impact resistance than PAEK-H resin matrix composite with higher fluidity. The impact energy loss of the SCF35/PAEK-L composite system is ~7% lower than that of the SCF35/PAEK-H composite system, its damage area is ~90% smaller, and its compression strength after impact reaches ~307 MPa at an impact energy of 6.67 J/mm, which is ~50% higher than that of SCF35/PAEK-H composite system (205 MPa). The depth of surface dent in SCF35/PAEK-L composites tends to increase with the increase of impact energy, and the compression strength after impact tends to decrease with the increase of impact energy, and the compression strength after impact is ~268 MPa when the depth of surface dent of the composites reaches about 1.0 mm, i.e., when the threshold value of barely visible impact damage (BVID) is reached. In addition, the results of quasi-static indentation tests show that the surface dent of SCF35/PAEK-L composite after impact is mainly caused by plastic deformation of the resin matrix and fiber flexure, the cracks around the surface dent are caused by compressive stress, the fiber on the back side of the specimen is fractured under the action of tensile stress during the impact process, the fiber on the bottom layer of the specimen sprouts interlayer cracks under the action of shear force, with the increase of flexural deformation of the specimen, the degree of fiber fracture increases and the interlayer cracks gradually expand.
Carbon fiber reinforced poly aryl ether ketone (SCF35/PAEK) thermoplastic composites were prepared using two different melt viscosities of domestic high performance poly aryl ether ketone resins (PAEK-L and PAEK-H) and domestic T300 grade carbon fibers (SCF35), and the effects of resin matrix viscosity and impact energy and impact energy on the impact properties of the composites were investigated. In addition, the internal morphology of quasi-static indentation specimens was characterized by Micro-CT to study the impact damage mechanism of the composites. The results show that PAEK-L resin matrix composite with lower fluidity has higher impact resistance than PAEK-H resin matrix composite with higher fluidity. The impact energy loss of the SCF35/PAEK-L composite system is ~7% lower than that of the SCF35/PAEK-H composite system, its damage area is ~90% smaller, and its compression strength after impact reaches ~307 MPa at an impact energy of 6.67 J/mm, which is ~50% higher than that of SCF35/PAEK-H composite system (205 MPa). The depth of surface dent in SCF35/PAEK-L composites tends to increase with the increase of impact energy, and the compression strength after impact tends to decrease with the increase of impact energy, and the compression strength after impact is ~268 MPa when the depth of surface dent of the composites reaches about 1.0 mm, i.e., when the threshold value of barely visible impact damage (BVID) is reached. In addition, the results of quasi-static indentation tests show that the surface dent of SCF35/PAEK-L composite after impact is mainly caused by plastic deformation of the resin matrix and fiber flexure, the cracks around the surface dent are caused by compressive stress, the fiber on the back side of the specimen is fractured under the action of tensile stress during the impact process, the fiber on the bottom layer of the specimen sprouts interlayer cracks under the action of shear force, with the increase of flexural deformation of the specimen, the degree of fiber fracture increases and the interlayer cracks gradually expand.
2023, 40(10): 5654-5665.
doi: 10.13801/j.cnki.fhclxb.20230213.003
Abstract:
To reduce the porosity of 3D printing continuous fiber reinforced polymer (CFRP) composites and improve the degree of resin impregnation on fibers, it is of great necessity to conduct research on the preparation and 3D printing performance of melt-impregnated continuous fiber prepreg filaments, as well as develop integrated fiber prepreg equipment. With glass fiber (GF) and carbon fiber (CF) as reinforcement, and polycarbonate (PC) as matrix, this study aims to develop a melt-impregnated prepreg wire preparation process and study the influence of the impregnation process on prepreg wire properties. Besides, using prepreg yarn as the raw material, this study is aimed at studying the effect of 3D printing forming process parameters on the fiber content, porosity and mechanical properties as well. The results indicate that when the tensile strength of continuous glass fiber reinforced polycarbonate (CGF/PC) prepreg filament is 627.8 MPa, the printing temperature is 260℃, the layering thickness is 0.10 mm, the scan spacing is 1.0 mm, the fiber content of continuous carbon fiber reinforced polycarbonate (CCF/PC) composite is 28.66vol%, the tensile strength and modulus are respectively 644.8 MPa and 85.6 GPa, and the optimized porosity is 3.87%. When the printing temperature is 280℃, the layering thickness is 0.14 mm, and the scan spacing is 1.2 mm, the fiber content of continuous glass fiber reinforced polycarbonate (CGF/PC) composite turn out to be 51.35vol%, the tensile strength and modulus are respectively 381.4 MPa and 23.6 GPa, and the optimized porosity is 4.41%.
To reduce the porosity of 3D printing continuous fiber reinforced polymer (CFRP) composites and improve the degree of resin impregnation on fibers, it is of great necessity to conduct research on the preparation and 3D printing performance of melt-impregnated continuous fiber prepreg filaments, as well as develop integrated fiber prepreg equipment. With glass fiber (GF) and carbon fiber (CF) as reinforcement, and polycarbonate (PC) as matrix, this study aims to develop a melt-impregnated prepreg wire preparation process and study the influence of the impregnation process on prepreg wire properties. Besides, using prepreg yarn as the raw material, this study is aimed at studying the effect of 3D printing forming process parameters on the fiber content, porosity and mechanical properties as well. The results indicate that when the tensile strength of continuous glass fiber reinforced polycarbonate (CGF/PC) prepreg filament is 627.8 MPa, the printing temperature is 260℃, the layering thickness is 0.10 mm, the scan spacing is 1.0 mm, the fiber content of continuous carbon fiber reinforced polycarbonate (CCF/PC) composite is 28.66vol%, the tensile strength and modulus are respectively 644.8 MPa and 85.6 GPa, and the optimized porosity is 3.87%. When the printing temperature is 280℃, the layering thickness is 0.14 mm, and the scan spacing is 1.2 mm, the fiber content of continuous glass fiber reinforced polycarbonate (CGF/PC) composite turn out to be 51.35vol%, the tensile strength and modulus are respectively 381.4 MPa and 23.6 GPa, and the optimized porosity is 4.41%.
2023, 40(10): 5666-5677.
doi: 10.13801/j.cnki.fhclxb.20221227.001
Abstract:
The preparation of polymeric materials with good mechanical properties and efficient self-healing properties at room temperature has been a difficult challenge. Herein, a lignin-reinforced self-healing polyurea elastomer (T-L-PUA) was prepared by a two-step process (polyurea reaction and Schiff base reaction) using natural aromatic-based lignin as the reinforcing phase. The effects of lignin addition on the thermal, UV-blocking and mechanical properties of T-L-PUA were investigated and the self-healing property and recyclability based on dynamic reversible imine bonding (C=N) of T-L-PUA were analyzed. The results show that the thermal stability of T-L-PUA is significantly enhanced with the increase of lignin ratio, where the maximum increase of residual carbon is 16.6% compared with the sample without lignin. The low transmittance of T-L-PUA in the UV region (280-400 nm) helps to realize the UV-blocking function. Compared with the average transmittance of self-healing polyurea composite elastomer (T-PUA) (41.6%), the average transmittance of all T-L-PUAs is around 0.2%. The best mechanical property appears at 20% of lignin addition, and the corresponding tensile strength of T-L-PUA is 12.44 MPa, which is 937% higher than that of pure polyurea elastomer. T-L-PUA exhibits good self-healing properties. When T-L-PUA is repaired at room temperature for 48 h, the recovery efficiencies of tensile strength and elongation at break is above 91% and 92%, respectively. In addition, the T-L-PUA can also be recovered by the hot-pressing and solvent dissolution processes, and the mechanical properties remain largely unchanged after remolding.
The preparation of polymeric materials with good mechanical properties and efficient self-healing properties at room temperature has been a difficult challenge. Herein, a lignin-reinforced self-healing polyurea elastomer (T-L-PUA) was prepared by a two-step process (polyurea reaction and Schiff base reaction) using natural aromatic-based lignin as the reinforcing phase. The effects of lignin addition on the thermal, UV-blocking and mechanical properties of T-L-PUA were investigated and the self-healing property and recyclability based on dynamic reversible imine bonding (C=N) of T-L-PUA were analyzed. The results show that the thermal stability of T-L-PUA is significantly enhanced with the increase of lignin ratio, where the maximum increase of residual carbon is 16.6% compared with the sample without lignin. The low transmittance of T-L-PUA in the UV region (280-400 nm) helps to realize the UV-blocking function. Compared with the average transmittance of self-healing polyurea composite elastomer (T-PUA) (41.6%), the average transmittance of all T-L-PUAs is around 0.2%. The best mechanical property appears at 20% of lignin addition, and the corresponding tensile strength of T-L-PUA is 12.44 MPa, which is 937% higher than that of pure polyurea elastomer. T-L-PUA exhibits good self-healing properties. When T-L-PUA is repaired at room temperature for 48 h, the recovery efficiencies of tensile strength and elongation at break is above 91% and 92%, respectively. In addition, the T-L-PUA can also be recovered by the hot-pressing and solvent dissolution processes, and the mechanical properties remain largely unchanged after remolding.
2023, 40(10): 5678-5691.
doi: 10.13801/j.cnki.fhclxb.20221222.001
Abstract:
Ti3CNTx/TMAOH was prepared when tetramethylammonium hydroxide (TMAOH) was selected as the intercalating agent. Adsorption performance of Ti3CNTx/TMAOH on Sr2+ in simulated radioactive wastewater was evaluated. The synthesized Ti3CNTx/TMAOH was characterized by SEM-EDS, XRD, BET and FTIR. In the batch experiment, the effects of the dosage of adsorbent Ti3CNTx/TMAOH, time, pH and competitive ions on Sr2+ removal were investigated. The results show that the removal rate of Sr2+ is 99.28% when the dosage is 1.0 g·L−1, pH is 6, and the time is 10 min. The inhibition order of competitive ions is Ca2+\begin{document}$ \text{ > > } $\end{document} \begin{document}$ \text{ > } $\end{document} \begin{document}$ \text{ > } $\end{document} \begin{document}$ \text{ > } $\end{document}
Ti3CNTx/TMAOH was prepared when tetramethylammonium hydroxide (TMAOH) was selected as the intercalating agent. Adsorption performance of Ti3CNTx/TMAOH on Sr2+ in simulated radioactive wastewater was evaluated. The synthesized Ti3CNTx/TMAOH was characterized by SEM-EDS, XRD, BET and FTIR. In the batch experiment, the effects of the dosage of adsorbent Ti3CNTx/TMAOH, time, pH and competitive ions on Sr2+ removal were investigated. The results show that the removal rate of Sr2+ is 99.28% when the dosage is 1.0 g·L−1, pH is 6, and the time is 10 min. The inhibition order of competitive ions is Ca2+
2023, 40(10): 5692-5705.
doi: 10.13801/j.cnki.fhclxb.20221223.004
Abstract:
To explore a simple method to prepare a epoxy resin (EP)-silicone sealant-SiO2 superhydrophobic composite coating with self-repairing property and capable of being applied to the surface of a structure like concrete, which can be self-repairing in the case of chemical and mechanical damage, The EP-silicone sealant-SiO2 superhydrophobic composite coating with self-repairing property was prepared on the surface of concrete by one-step method. The specific steps were to dissolve the EP, silicone adhesive and nano-SiO2 in anhydrous ethanol solution, and the compound solution would be obtained after 8 h magnetic stirring and 20 min ultrasonic dispersion. Then the superhydrophobic coating with self-repairing performance would be successfully prepared on the surface of concrete by spraying compound solution. When the content of epoxy resin is 2wt%, the content of silicone adhesive is 3wt% and the content of nano-SiO2 is 3wt%, the coating could exhibit optimal superhydrophobic performance. The average contact angle (CA) of the coating is 156°±1.2° and the average slid angle (SA) is 6°±0.8°. After 8 m of abrasion length at a pressure of 2.66 kPa (Sandpaper: 1.7 µm) or 8 h of immerse time in saline (2 mol/L NaCl solution) or acidic environments (pH=3, acetic acid), the coating still maintain superhydrophobicity. The contact angle of the coating remains above 150° after 8 cycles of alkaline damage and self-repair (pH=12, NaOH solution) or 4 cycles of mechanical damage and self-repair. Moreover, the coating also displays excellent self-cleaning and waterproof performance according to the self-cleaning test and waterproof test. The experiments of mechanical and environmental corrosion damage show that the similar structure of the coating can ensure that the micro-nano rough structure of the lower layer maintain superhydrophobicity after the upper layer being damaged. The damage and self-repair experiments show that the coating can be repaired when the coating is heated. This is because the flow of silicone adhesive can promote the migration of low surface energy molecules and nano-SiO2 particles in the coating during the heating process. The simple preparation method, good mechanical wear resistance and excellent self-healing properties of this coating offer the possibility of practical application of superhydrophobic coatings.
To explore a simple method to prepare a epoxy resin (EP)-silicone sealant-SiO2 superhydrophobic composite coating with self-repairing property and capable of being applied to the surface of a structure like concrete, which can be self-repairing in the case of chemical and mechanical damage, The EP-silicone sealant-SiO2 superhydrophobic composite coating with self-repairing property was prepared on the surface of concrete by one-step method. The specific steps were to dissolve the EP, silicone adhesive and nano-SiO2 in anhydrous ethanol solution, and the compound solution would be obtained after 8 h magnetic stirring and 20 min ultrasonic dispersion. Then the superhydrophobic coating with self-repairing performance would be successfully prepared on the surface of concrete by spraying compound solution. When the content of epoxy resin is 2wt%, the content of silicone adhesive is 3wt% and the content of nano-SiO2 is 3wt%, the coating could exhibit optimal superhydrophobic performance. The average contact angle (CA) of the coating is 156°±1.2° and the average slid angle (SA) is 6°±0.8°. After 8 m of abrasion length at a pressure of 2.66 kPa (Sandpaper: 1.7 µm) or 8 h of immerse time in saline (2 mol/L NaCl solution) or acidic environments (pH=3, acetic acid), the coating still maintain superhydrophobicity. The contact angle of the coating remains above 150° after 8 cycles of alkaline damage and self-repair (pH=12, NaOH solution) or 4 cycles of mechanical damage and self-repair. Moreover, the coating also displays excellent self-cleaning and waterproof performance according to the self-cleaning test and waterproof test. The experiments of mechanical and environmental corrosion damage show that the similar structure of the coating can ensure that the micro-nano rough structure of the lower layer maintain superhydrophobicity after the upper layer being damaged. The damage and self-repair experiments show that the coating can be repaired when the coating is heated. This is because the flow of silicone adhesive can promote the migration of low surface energy molecules and nano-SiO2 particles in the coating during the heating process. The simple preparation method, good mechanical wear resistance and excellent self-healing properties of this coating offer the possibility of practical application of superhydrophobic coatings.
2023, 40(10): 5707-5716.
doi: 10.13801/j.cnki.fhclxb.20221228.001
Abstract:
ZIF-7 crystals were in situ grown on graphene oxide (GO) by three synthetic routes, and the resulting graphene oxide/ZIF-7 composites (GZR-n) were characterized by PXRD, FTIR, SEM, TEM, and N2 isothermal adsorption-desorption. The effects of the synthetic routes on the growth, crystallinity, microscopic morphology and pore size of ZIF-7 crystals on GO were investigated. ZIF-7 crystals were grown on the surface and sheet of GO by three synthetic routes. The crystallinity of ZIF-7 crystals on GZR-n was significantly enhanced and some were wrapped by GO. The shape and size of ZIF-7 crystals growing on GZR-n were modulated by the synthesis routes. In particular, the ZIF-7 crystals are spherical particle with a diameter of 50 nm in GZR-II. For GZR-I and GZR-III, the ZIF-7 crystals are regular polyhedron with a size of 200 nm. Additional, their dispersion properties in solvents, adsorption properties and kinetic simulations for organic dyes were explored. GZR-n show good dispersion in methanol and chloroform. Compared with ZIF-7 crystals, the adsorption capacities of GZR-I, GZR-II and GZR-III for methylene blue are increased by 226%, 302% and 278%, respectively. The kinetic simulations indicate that the adsorption of GZR-II and GZR-III for methylene blue are chemisorption and that of GZR-I is physical adsorption.
ZIF-7 crystals were in situ grown on graphene oxide (GO) by three synthetic routes, and the resulting graphene oxide/ZIF-7 composites (GZR-n) were characterized by PXRD, FTIR, SEM, TEM, and N2 isothermal adsorption-desorption. The effects of the synthetic routes on the growth, crystallinity, microscopic morphology and pore size of ZIF-7 crystals on GO were investigated. ZIF-7 crystals were grown on the surface and sheet of GO by three synthetic routes. The crystallinity of ZIF-7 crystals on GZR-n was significantly enhanced and some were wrapped by GO. The shape and size of ZIF-7 crystals growing on GZR-n were modulated by the synthesis routes. In particular, the ZIF-7 crystals are spherical particle with a diameter of 50 nm in GZR-II. For GZR-I and GZR-III, the ZIF-7 crystals are regular polyhedron with a size of 200 nm. Additional, their dispersion properties in solvents, adsorption properties and kinetic simulations for organic dyes were explored. GZR-n show good dispersion in methanol and chloroform. Compared with ZIF-7 crystals, the adsorption capacities of GZR-I, GZR-II and GZR-III for methylene blue are increased by 226%, 302% and 278%, respectively. The kinetic simulations indicate that the adsorption of GZR-II and GZR-III for methylene blue are chemisorption and that of GZR-I is physical adsorption.
2023, 40(10): 5716-5725.
doi: 10.13801/j.cnki.fhclxb.20230202.001
Abstract:
In recent years, flexible pressure sensors with three-dimensional mesh structure show high reversible compressibility and good sensitivity, and their complex network shape is also conducive to the construction of stable conductive network, which is widely used in human health monitoring, wearable devices, medical diagnosis and other fields. In this study, a carbonized wood sponge (CWS)/thermoplastic polyurethane elastomers (TPU) composite pressure sensor with three-dimensional layered structure based on natural balsa wood was designed to construct a stable three-dimensional conductive network and optimize the sensing performance. The catalytic treatment, carbonization process, sensing performance and human applicability of the sensor were characterized. The results show that the carbon yield of the light wood-based CWS/TPU sensor by catalytic treatment and high temperature carbonization can reach 20.15%, the compressive strain can reach at 60%, and the maximum pressure sensing sensitivity can reach 12.87 kPa−1 in the pressure range of 0-4 kPa. Moreover, the sensor still has good sensing stability and environmental stability even after 5000 compression/release cycles, showing good sensing performance. The sensor is successfully used to monitor hand movement, walking and pulse in real time, which shows the potential application value of the sensor in motion and health monitoring.
In recent years, flexible pressure sensors with three-dimensional mesh structure show high reversible compressibility and good sensitivity, and their complex network shape is also conducive to the construction of stable conductive network, which is widely used in human health monitoring, wearable devices, medical diagnosis and other fields. In this study, a carbonized wood sponge (CWS)/thermoplastic polyurethane elastomers (TPU) composite pressure sensor with three-dimensional layered structure based on natural balsa wood was designed to construct a stable three-dimensional conductive network and optimize the sensing performance. The catalytic treatment, carbonization process, sensing performance and human applicability of the sensor were characterized. The results show that the carbon yield of the light wood-based CWS/TPU sensor by catalytic treatment and high temperature carbonization can reach 20.15%, the compressive strain can reach at 60%, and the maximum pressure sensing sensitivity can reach 12.87 kPa−1 in the pressure range of 0-4 kPa. Moreover, the sensor still has good sensing stability and environmental stability even after 5000 compression/release cycles, showing good sensing performance. The sensor is successfully used to monitor hand movement, walking and pulse in real time, which shows the potential application value of the sensor in motion and health monitoring.
2023, 40(10): 5726-5735.
doi: 10.13801/j.cnki.fhclxb.20230310.003
Abstract:
The desalination evaporator based on the solar interface water evaporation technology can realize the desalination and purification of seawater, but the evaporation rate of the evaporator is low at present. In this work, the composite aerogel of polyvinyl alcohol and sodium alginate was prepared by directional freezing. At the same time, carbon nanotubes were used as light absorbing material. The effects of the composition, proportion and content of light absorbing material of the composite aerogel on the evaporation performance of evaporator water were explored. The results show that the composite aerogel evaporator has a light absorption rate of up to 97% and excellent seawater desalination performance. The water evaporation rate under a sun light can reach 2.7 kg·m−2·h−1.In the long-term alternating process of light and darkness, the salt crystals accumulated on the surface of the evaporator will automatically melt and disappear, playing a self-cleaning effect, and can achieve long-term sustainable evaporation. It has broad application prospects in the field of seawater desalination.
The desalination evaporator based on the solar interface water evaporation technology can realize the desalination and purification of seawater, but the evaporation rate of the evaporator is low at present. In this work, the composite aerogel of polyvinyl alcohol and sodium alginate was prepared by directional freezing. At the same time, carbon nanotubes were used as light absorbing material. The effects of the composition, proportion and content of light absorbing material of the composite aerogel on the evaporation performance of evaporator water were explored. The results show that the composite aerogel evaporator has a light absorption rate of up to 97% and excellent seawater desalination performance. The water evaporation rate under a sun light can reach 2.7 kg·m−2·h−1.In the long-term alternating process of light and darkness, the salt crystals accumulated on the surface of the evaporator will automatically melt and disappear, playing a self-cleaning effect, and can achieve long-term sustainable evaporation. It has broad application prospects in the field of seawater desalination.
2023, 40(10): 5736-5749.
doi: 10.13801/j.cnki.fhclxb.20230117.001
Abstract:
The development of renewable, low-cost and environmentally friendly electrode materials with fast ion/electron transfer rate and adjustable surface chemistry is an urgent need for the development of current energy storage devices. In recent years, biomass carbon materials have attracted much attention because of their low cost, renewable and good cycling performance, but their low specific capacitance and energy density affect their practical applications. Here, the biomass waste was transformed into carbon materials with good chemical properties, and the transition metal oxide Fe2O3 was composite by heteroatom-doped biomass carbon materials, taking advantage of the complementary strengths of Fe2O3 and nitrogen doped carbon was used to prepare Fe2O3/nitrogen-doped biomass carbon (NBCs) composite materials by one-step carbonization, showing excellent electrochemical performance. The results show that the specific capacitance of Fe2O3/NBCs as the negative electrode material is 575 F·g−1 at a current density of 1 A·g−1. At the same time, Fe2O3/NBCs-700℃ and NiCoFe-P were used as cathode and cathode materials respectively to assemble asymmetric supercapacitors, achieves an energy density of 33.3 W·h·kg−1 at a power density of 800 W·kg−1. The assembled asymmetric supercapacitors also exhibit excellent cycling stability, maintaining 82.4% capacitance after 3500 cycles. Therefore, Fe2O3/NBCs is a promising electrode material for supercapacitors as negative electrode materials.
The development of renewable, low-cost and environmentally friendly electrode materials with fast ion/electron transfer rate and adjustable surface chemistry is an urgent need for the development of current energy storage devices. In recent years, biomass carbon materials have attracted much attention because of their low cost, renewable and good cycling performance, but their low specific capacitance and energy density affect their practical applications. Here, the biomass waste was transformed into carbon materials with good chemical properties, and the transition metal oxide Fe2O3 was composite by heteroatom-doped biomass carbon materials, taking advantage of the complementary strengths of Fe2O3 and nitrogen doped carbon was used to prepare Fe2O3/nitrogen-doped biomass carbon (NBCs) composite materials by one-step carbonization, showing excellent electrochemical performance. The results show that the specific capacitance of Fe2O3/NBCs as the negative electrode material is 575 F·g−1 at a current density of 1 A·g−1. At the same time, Fe2O3/NBCs-700℃ and NiCoFe-P were used as cathode and cathode materials respectively to assemble asymmetric supercapacitors, achieves an energy density of 33.3 W·h·kg−1 at a power density of 800 W·kg−1. The assembled asymmetric supercapacitors also exhibit excellent cycling stability, maintaining 82.4% capacitance after 3500 cycles. Therefore, Fe2O3/NBCs is a promising electrode material for supercapacitors as negative electrode materials.
2023, 40(10): 5750-5759.
doi: 10.13801/j.cnki.fhclxb.20230117.006
Abstract:
The organic piezoelectric sensor prepared by electrospinning is better flexibility, light weight and breathability than the traditional pressure sensor, which has attracted much attention in the field of wearable sensor research. In this paper, a method of preparing BiCl3/poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) composite film by electrospinning was proposed, and the flexible piezoelectric sensor was designed and prepared with the composite film as the functional layer. After a certain amount of BiCl3 is added, the scanning electron microscope analysis shows that the average diameter of the fiber increases from 619 nm to 1158 nm, and the surface becomes smoother. The X-ray diffraction pattern confirms that β phase content of the composite film has been significantly improved. The piezoelectric response testing results show that the open circuit peak-to-peak voltage (Voc) and short-circuit current (Isc) of P(VDF-TrFE) composite films with 2wt%BiCl3 are 16.8 V and 164 nA. Compared with pure P(VDF-TrFE) piezoelectric film, it is obviously improved 2.15 and 2.24 times. The pressure sensing testing results show that the piezoelectric film is good linear output characteristics under the pressure of 1.28 N. A flexible wearable force sensing keyboard was designed with this film, which could collect fingers pressing force and duration time. And it provides a reference solution on smart fabrics such as flexible keyboard applications.
The organic piezoelectric sensor prepared by electrospinning is better flexibility, light weight and breathability than the traditional pressure sensor, which has attracted much attention in the field of wearable sensor research. In this paper, a method of preparing BiCl3/poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) composite film by electrospinning was proposed, and the flexible piezoelectric sensor was designed and prepared with the composite film as the functional layer. After a certain amount of BiCl3 is added, the scanning electron microscope analysis shows that the average diameter of the fiber increases from 619 nm to 1158 nm, and the surface becomes smoother. The X-ray diffraction pattern confirms that β phase content of the composite film has been significantly improved. The piezoelectric response testing results show that the open circuit peak-to-peak voltage (Voc) and short-circuit current (Isc) of P(VDF-TrFE) composite films with 2wt%BiCl3 are 16.8 V and 164 nA. Compared with pure P(VDF-TrFE) piezoelectric film, it is obviously improved 2.15 and 2.24 times. The pressure sensing testing results show that the piezoelectric film is good linear output characteristics under the pressure of 1.28 N. A flexible wearable force sensing keyboard was designed with this film, which could collect fingers pressing force and duration time. And it provides a reference solution on smart fabrics such as flexible keyboard applications.
2023, 40(10): 5760-5771.
doi: 10.13801/j.cnki.fhclxb.20230104.001
Abstract:
In recent years, serious industrial pollution has led to the growth of various types of bacteria, and pathogenic bacterial infections can be spread rapidly by various means, posing a great risk of infection. Therefore, it is important to develop high-performance antibacterial materials and study their antibacterial mechanisms for application. To address this issue, this work designed a novel nanocomposite bacteriostatic material UiO-66-NHCl by modifying zirconium-based metal-organic backbone material UiO-66-NH2 via sodium chlorite solution, and characterized the structure and chemical composition of metal-organic framework (MOF) composites by using XRD, FTIR, SEM, TEM, EDS and XPS, and the effects of different loading processes on the chlorine loading were also explored, and the antibacterial properties and skin irritation experiments of UiO-66-NHCl composites were investigated. The results show that the active chlorine is introduced on UiO-66-NH2 by impregnation bonding, and the chlorine loading can be increased by changing the chlorine loading ratio (mass ratios m(UiO-66-NH2)∶m(NaClO2)) and chlorination time of UiO-66-NH2 in NaClO2 solution, and the highest chlorine loading is achieved when the chlorine loading ratio is 1∶5 and the chlorination time is 4 h. Under the conditions of high temperature, high humidity and high temperature, it can still maintain 80% of its original chlorine loading and has good stability. The inhibition activity show that the UiO-66-NHCl composites inhibit both Staphylococcus aureus and Escherichia coli compared to the original UiO-66-NH2 material, and the samples with higher chlorine content show higher inhibition effect and no irritation.
In recent years, serious industrial pollution has led to the growth of various types of bacteria, and pathogenic bacterial infections can be spread rapidly by various means, posing a great risk of infection. Therefore, it is important to develop high-performance antibacterial materials and study their antibacterial mechanisms for application. To address this issue, this work designed a novel nanocomposite bacteriostatic material UiO-66-NHCl by modifying zirconium-based metal-organic backbone material UiO-66-NH2 via sodium chlorite solution, and characterized the structure and chemical composition of metal-organic framework (MOF) composites by using XRD, FTIR, SEM, TEM, EDS and XPS, and the effects of different loading processes on the chlorine loading were also explored, and the antibacterial properties and skin irritation experiments of UiO-66-NHCl composites were investigated. The results show that the active chlorine is introduced on UiO-66-NH2 by impregnation bonding, and the chlorine loading can be increased by changing the chlorine loading ratio (mass ratios m(UiO-66-NH2)∶m(NaClO2)) and chlorination time of UiO-66-NH2 in NaClO2 solution, and the highest chlorine loading is achieved when the chlorine loading ratio is 1∶5 and the chlorination time is 4 h. Under the conditions of high temperature, high humidity and high temperature, it can still maintain 80% of its original chlorine loading and has good stability. The inhibition activity show that the UiO-66-NHCl composites inhibit both Staphylococcus aureus and Escherichia coli compared to the original UiO-66-NH2 material, and the samples with higher chlorine content show higher inhibition effect and no irritation.
2023, 40(10): 5772-5781.
doi: 10.13801/j.cnki.fhclxb.20230110.002
Abstract:
The polylactic acid (PLA) has great potential in the preparation of environmentally friendly dielectric materials due to its biodegradability and high strength, but low dielectric constant limits its wide application in this field. The carboxylic multi-walled carbon nanotubes (MWCNTs—COOH), epoxy-based chain extender (ADR) and poly(butylene adipate-co-terephthalate) (PBAT) were introduced into PLA by melt blending to prepare MWCNTs—COOH-ADR-PBAT/PLA composites. The effects of MWCNTs—COOH on the inter-molecular chain interactions, processing, crystallization, dynamic mechanical, mechanical and dielectric properties of the PBAT/PLA reactive compatibilization system were studied by FTIR, Torque rheometer, DSC, DMA, electron universal testing machine, SEM and LCR dielectric measuring instrument, etc. The results show that the carboxyl group in MWCNTs—COOH preferentially reacts with the reactive compatibilizer during the blending process, which reduces the catalytic compatibilization efficiency of the reactive compatibilizer on the interface between PLA and PBAT. At the same time, MWCNTs—COOH preferentially disperse at the two-phase interface under the drive of dynamics and thermodynamics, giving the material a better rigid toughness balance, while significantly improving the dielectric properties of the material. When the MWCNTs—COOH content is 4wt%, the dielectric constant and dielectric loss of MWCNTs—COOH-ADR-PBAT/PLA composite at 100 Hz were 5.35 and 0.06 respectively, and the material had good comprehensive properties.
The polylactic acid (PLA) has great potential in the preparation of environmentally friendly dielectric materials due to its biodegradability and high strength, but low dielectric constant limits its wide application in this field. The carboxylic multi-walled carbon nanotubes (MWCNTs—COOH), epoxy-based chain extender (ADR) and poly(butylene adipate-co-terephthalate) (PBAT) were introduced into PLA by melt blending to prepare MWCNTs—COOH-ADR-PBAT/PLA composites. The effects of MWCNTs—COOH on the inter-molecular chain interactions, processing, crystallization, dynamic mechanical, mechanical and dielectric properties of the PBAT/PLA reactive compatibilization system were studied by FTIR, Torque rheometer, DSC, DMA, electron universal testing machine, SEM and LCR dielectric measuring instrument, etc. The results show that the carboxyl group in MWCNTs—COOH preferentially reacts with the reactive compatibilizer during the blending process, which reduces the catalytic compatibilization efficiency of the reactive compatibilizer on the interface between PLA and PBAT. At the same time, MWCNTs—COOH preferentially disperse at the two-phase interface under the drive of dynamics and thermodynamics, giving the material a better rigid toughness balance, while significantly improving the dielectric properties of the material. When the MWCNTs—COOH content is 4wt%, the dielectric constant and dielectric loss of MWCNTs—COOH-ADR-PBAT/PLA composite at 100 Hz were 5.35 and 0.06 respectively, and the material had good comprehensive properties.
2023, 40(10): 5782-5791.
doi: 10.13801/j.cnki.fhclxb.20230117.004
Abstract:
Due to semi-closed tubular structure and poor ventilation, automobile exhaust gas accumulates in the tunnel, resulting in serious air pollution. In this paper, firstly, a kind of CQDs@TNs composite photocatalyst with visible light response and efficient degradation of NO was prepared by loading carbon quantum dots (CQDs) on the surface of unidimensional TiO2 nanotubes (TNs). Secondly, a super hydrophobic self-cleaning photocatalyst coating was prepared by spraying epoxy resin as the film matrix, introducing low surface energy components and using the above photocatalyst as the photo active component. The microstructure, chemical composition and optical properties of the composite photocatalyst were characterized by SEM, XRD, XPS, Brunauer-Emmett-Teller calculation (BET), PL and UV-Vis, and the NO photodegradation performance was investigated. The microstructure, self-cleaning property and durability of the coating were systematically studied by SEM-EDS, ash adhesion resistance test, UV aging test, water flushing test, sandpaper abrasion test, and the photodegradation property and cyclic degradation performance of NO were also studied. The results show that the coating has good self-cleaning performance and durability, the NO degradation rate reaches 42.9%. Due to its good cycle stability, the coating is expected to be applied to the degradation of NO in tunnels and other semi enclosed environments.
Due to semi-closed tubular structure and poor ventilation, automobile exhaust gas accumulates in the tunnel, resulting in serious air pollution. In this paper, firstly, a kind of CQDs@TNs composite photocatalyst with visible light response and efficient degradation of NO was prepared by loading carbon quantum dots (CQDs) on the surface of unidimensional TiO2 nanotubes (TNs). Secondly, a super hydrophobic self-cleaning photocatalyst coating was prepared by spraying epoxy resin as the film matrix, introducing low surface energy components and using the above photocatalyst as the photo active component. The microstructure, chemical composition and optical properties of the composite photocatalyst were characterized by SEM, XRD, XPS, Brunauer-Emmett-Teller calculation (BET), PL and UV-Vis, and the NO photodegradation performance was investigated. The microstructure, self-cleaning property and durability of the coating were systematically studied by SEM-EDS, ash adhesion resistance test, UV aging test, water flushing test, sandpaper abrasion test, and the photodegradation property and cyclic degradation performance of NO were also studied. The results show that the coating has good self-cleaning performance and durability, the NO degradation rate reaches 42.9%. Due to its good cycle stability, the coating is expected to be applied to the degradation of NO in tunnels and other semi enclosed environments.
2023, 40(10): 5792-5802.
doi: 10.13801/j.cnki.fhclxb.20230314.001
Abstract:
Exploiting adsorbents with excellent adsorption activity, good durability and environment friendly is still the core focus of water pollution treatment. Herein, in this study, sodium alginate (SA), carboxymethyl cellulose (CMC), and graphene oxide (GO) were used as raw materials to frame a SA-CMC-GO composite aerogel with a 3D network structure by a sol-gel and freeze-drying method. The functional group structure and microstructure of SA-CMC-GO composite aerogel were tested and analyzed by SEM, FTIR and XRD. Various parameters affecting the removal of Pb2+ such as pH, temperature and contact time were optimized by using a series of batch adsorption experiments. The results show that the adsorption amount of Pb2+ by the composite aerogel increases with the increase of pH=2-5. The adsorption process is a spontaneous exothermic process and the experimental data of the adsorption process are more fitted to Langmuir isotherm, the theoretical maximum adsorption capacity of Pb2+ on SA-CMC-GO composite aerogel is 272.5 mg·g−1. Adsorption kinetics studies indicate the adsorption of Pb2+ by the SA-CMC-GO composite aerogel shows rapid uptake rates and reaches equilibrium within 60 min. The pseudo-second-order kinetic model coincides with the adsorption behavior of the composite aerogel. Furthermore, the composite aerogel exhibited better reusability for five adsorption and desorption cycles with highly adsorption properties. The results imply that the new SA-CMC-GO composite aerogel could be potentially applied as an effective and rapid adsorbent for Pb2+ removal from aqueous solutions.
Exploiting adsorbents with excellent adsorption activity, good durability and environment friendly is still the core focus of water pollution treatment. Herein, in this study, sodium alginate (SA), carboxymethyl cellulose (CMC), and graphene oxide (GO) were used as raw materials to frame a SA-CMC-GO composite aerogel with a 3D network structure by a sol-gel and freeze-drying method. The functional group structure and microstructure of SA-CMC-GO composite aerogel were tested and analyzed by SEM, FTIR and XRD. Various parameters affecting the removal of Pb2+ such as pH, temperature and contact time were optimized by using a series of batch adsorption experiments. The results show that the adsorption amount of Pb2+ by the composite aerogel increases with the increase of pH=2-5. The adsorption process is a spontaneous exothermic process and the experimental data of the adsorption process are more fitted to Langmuir isotherm, the theoretical maximum adsorption capacity of Pb2+ on SA-CMC-GO composite aerogel is 272.5 mg·g−1. Adsorption kinetics studies indicate the adsorption of Pb2+ by the SA-CMC-GO composite aerogel shows rapid uptake rates and reaches equilibrium within 60 min. The pseudo-second-order kinetic model coincides with the adsorption behavior of the composite aerogel. Furthermore, the composite aerogel exhibited better reusability for five adsorption and desorption cycles with highly adsorption properties. The results imply that the new SA-CMC-GO composite aerogel could be potentially applied as an effective and rapid adsorbent for Pb2+ removal from aqueous solutions.
2023, 40(10): 5803-5810.
doi: 10.13801/j.cnki.fhclxb.20230118.001
Abstract:
Functional emulsion is one of the hot topics because of their functional factors. Bio-macromolecules hyaluronic acid (HA), lysozyme (Lys) and trace metal element zinc can self-assemble to prepare Lys-Zn2+/HA colloidal particles by electrostatic interaction. The effects of different raw material concentration on the properties of colloidal particles were studied to obtain colloidal nanoparticles under optimal assembly conditions. The size and morphology of the colloidal particles were characterized by nanometer particle size analyzer and scanning electron microscope. The results show that the formed colloidal particles have a spherical structure with a particle size of about 300 nm. The colloidal particles have surface activity and can be reassembled at the oil (containing fat-soluble vitamin D3)-water interface to stabilize oil-in-water functional Pickering emulsions. The effects of pH and salt concentration on the properties and emulsifying properties of colloidal particles were investigated in detail. The sustained release properties of the emulsion to trace metals and vitamin D3 functional factors were studied with the optimum emulsion performance. The results show that the emulsion has a certain sustained-release performance for both water-soluble and fat-soluble functional factors and has potential applications in the fields of food, medicine and cosmetics.
Functional emulsion is one of the hot topics because of their functional factors. Bio-macromolecules hyaluronic acid (HA), lysozyme (Lys) and trace metal element zinc can self-assemble to prepare Lys-Zn2+/HA colloidal particles by electrostatic interaction. The effects of different raw material concentration on the properties of colloidal particles were studied to obtain colloidal nanoparticles under optimal assembly conditions. The size and morphology of the colloidal particles were characterized by nanometer particle size analyzer and scanning electron microscope. The results show that the formed colloidal particles have a spherical structure with a particle size of about 300 nm. The colloidal particles have surface activity and can be reassembled at the oil (containing fat-soluble vitamin D3)-water interface to stabilize oil-in-water functional Pickering emulsions. The effects of pH and salt concentration on the properties and emulsifying properties of colloidal particles were investigated in detail. The sustained release properties of the emulsion to trace metals and vitamin D3 functional factors were studied with the optimum emulsion performance. The results show that the emulsion has a certain sustained-release performance for both water-soluble and fat-soluble functional factors and has potential applications in the fields of food, medicine and cosmetics.
2023, 40(10): 5811-5819.
doi: 10.13801/j.cnki.fhclxb.20230720.001
Abstract:
The light absorption and photo-induced carrier recombination of g-C3N4 are the key problems that limit its efficient photocatalytic applications. Herein, carbon dots (CDs) were synthesized using coal pitch as precursor and then the CDs/g-C3N4 composite catalyst was prepared by ultrasonic-assisted method. The structure, optical and photoelectrochemical properties of the catalyst were characterized by TEM, XRD, UV-Vis diffuse reflection spectrum, PL spectrum, EIS test and photocurrent response test. The results show that the regulation of band structure and the formation of interface after the introduction of CDs expand the range of light absorption of the composite photocatalyst, promote the effective separation and migration of photogenerated electrons and holes, and thus facilitate the photocatalytic reaction. Using rhodamine B (RhB) as the model, the photocatalytic activity of CDs/g-C3N4 composite catalyst is significantly higher than that of pure g-C3N4 under visible light irradiation. The degradation rate of RhB can reach 98.6% within 40 min, and the degradation rate constant of CDs/g-C3N4 is 6.8 times that of g-C3N4. The capture of experiment of active species reveals that •O2− plays a major role in the degradation system. In addition, CDs/g-C3N4 composite catalyst exhibit good stability. After 5 cycles, the degradation rate of RhB is still up to 97.5%, which shows a good application prospect in visible light photocatalysis.
The light absorption and photo-induced carrier recombination of g-C3N4 are the key problems that limit its efficient photocatalytic applications. Herein, carbon dots (CDs) were synthesized using coal pitch as precursor and then the CDs/g-C3N4 composite catalyst was prepared by ultrasonic-assisted method. The structure, optical and photoelectrochemical properties of the catalyst were characterized by TEM, XRD, UV-Vis diffuse reflection spectrum, PL spectrum, EIS test and photocurrent response test. The results show that the regulation of band structure and the formation of interface after the introduction of CDs expand the range of light absorption of the composite photocatalyst, promote the effective separation and migration of photogenerated electrons and holes, and thus facilitate the photocatalytic reaction. Using rhodamine B (RhB) as the model, the photocatalytic activity of CDs/g-C3N4 composite catalyst is significantly higher than that of pure g-C3N4 under visible light irradiation. The degradation rate of RhB can reach 98.6% within 40 min, and the degradation rate constant of CDs/g-C3N4 is 6.8 times that of g-C3N4. The capture of experiment of active species reveals that •O2− plays a major role in the degradation system. In addition, CDs/g-C3N4 composite catalyst exhibit good stability. After 5 cycles, the degradation rate of RhB is still up to 97.5%, which shows a good application prospect in visible light photocatalysis.
2023, 40(10): 5820-5829.
doi: 10.13801/j.cnki.fhclxb.20221226.002
Abstract:
In order to study the photo-Fenton properties of FeOCl combined with carbon materials, g-C3N4/FeOCl nanocomposites were prepared by a simple calcination method according to the different composite mass ratios of g-C3N4 and FeCl3·6H2O. Composition, structure, and optical properties of the composite samples tested by XRD, SEM, TEM, XPS, UV-vis DRS, EIS, and transient photocurrent testing. The results show that the g-C3N4/FeOCl composite has a layered nanorod stacking structure with the good light response and carrier separation capability. When the composite ratio of g-C3N4 to FeCl3·6H2O is 1∶20, it exhibits excellent photo-Fenton performance, and the degradation rate of rhodamine B (RhB) reaches 92.4%. And after three cycles, the efficiency of the composite material in degrading RhB remains at 80.1% that showing good stability. Based on the experimental results, the Z-type heterojunction between g-C3N4 and FeOCl was proposed to improve the separation efficiency of photogenerated carriers, and the possible mechanism of photo-Fenton degradation of RhB by Z-type heterojunction was discussed.
In order to study the photo-Fenton properties of FeOCl combined with carbon materials, g-C3N4/FeOCl nanocomposites were prepared by a simple calcination method according to the different composite mass ratios of g-C3N4 and FeCl3·6H2O. Composition, structure, and optical properties of the composite samples tested by XRD, SEM, TEM, XPS, UV-vis DRS, EIS, and transient photocurrent testing. The results show that the g-C3N4/FeOCl composite has a layered nanorod stacking structure with the good light response and carrier separation capability. When the composite ratio of g-C3N4 to FeCl3·6H2O is 1∶20, it exhibits excellent photo-Fenton performance, and the degradation rate of rhodamine B (RhB) reaches 92.4%. And after three cycles, the efficiency of the composite material in degrading RhB remains at 80.1% that showing good stability. Based on the experimental results, the Z-type heterojunction between g-C3N4 and FeOCl was proposed to improve the separation efficiency of photogenerated carriers, and the possible mechanism of photo-Fenton degradation of RhB by Z-type heterojunction was discussed.
2023, 40(10): 5831-5840.
doi: 10.13801/j.cnki.fhclxb.20221226.004
Abstract:
Separators with superior electrolyte property and thermal stability are in urgent need for lithium-ion batteries (LIBs). This work designed a space-confined polymerization method to fabricate an advanced composite separator, in which poly(cyclotriphosphazene-co-4, 4-sulfonyldiphenol) microspheres (PZSMS) grow directly in poly(vinylidene fluoride) (PVDF) membrane as the substrate. To regulate the size and distribution of PZSMS, triethylamine vapor as acid-binding agent is introduced into PVDF membrane separately from the polymeric monomers. The physical-chemical properties and battery performances of PPCS were systematically characterized, such as the structure, tensile strength, electrolyte property and thermal resistance as well as the charge-discharge performance. The results show that under the optimized conditions, the liquid absorbency and ionic conductivity of the composite membrane reach 433% and 1.47 mS/cm, respectively, the tensile strength is greater than 25 MPa, and the thermal shrinkage rate is lower than 2% at 150℃ and 0.5 h, which is better than that of PVDF based membrane and commercial polyethylene (PE) membrane. The LiCoO2/graphite cells with optimized separators exhibit satisfactory discharge capacity retention of 76% at 8.0 C compared with that at 0.5 C and preferable cycling stability with a capacity retention of 97% after 200 cycles. Therefore, PZSMS modified PVDF fibrous membrane prepared by space-confined polymerization method shows a good application prospect in lithium-ion batteries.
Separators with superior electrolyte property and thermal stability are in urgent need for lithium-ion batteries (LIBs). This work designed a space-confined polymerization method to fabricate an advanced composite separator, in which poly(cyclotriphosphazene-co-4, 4-sulfonyldiphenol) microspheres (PZSMS) grow directly in poly(vinylidene fluoride) (PVDF) membrane as the substrate. To regulate the size and distribution of PZSMS, triethylamine vapor as acid-binding agent is introduced into PVDF membrane separately from the polymeric monomers. The physical-chemical properties and battery performances of PPCS were systematically characterized, such as the structure, tensile strength, electrolyte property and thermal resistance as well as the charge-discharge performance. The results show that under the optimized conditions, the liquid absorbency and ionic conductivity of the composite membrane reach 433% and 1.47 mS/cm, respectively, the tensile strength is greater than 25 MPa, and the thermal shrinkage rate is lower than 2% at 150℃ and 0.5 h, which is better than that of PVDF based membrane and commercial polyethylene (PE) membrane. The LiCoO2/graphite cells with optimized separators exhibit satisfactory discharge capacity retention of 76% at 8.0 C compared with that at 0.5 C and preferable cycling stability with a capacity retention of 97% after 200 cycles. Therefore, PZSMS modified PVDF fibrous membrane prepared by space-confined polymerization method shows a good application prospect in lithium-ion batteries.
2023, 40(10): 5841-5848.
doi: 10.13801/j.cnki.fhclxb.20230207.002
Abstract:
To explore a kind of triaxial cross-linked hollow fiber membrane (HFM) with self-cleaning performance, polyacrylonitrile based HFM prepared by wet processing was chemically modified into amidoximated PAN hollow fiber membranes. Then the active groups were coordinated with metal ions (Fe3+) randomly to achieve metal coordinated amidoximation PAN hollow fiber membranes with triaxial cross-linked structure. Preparation process, structural composition, surface morphology, hydrophilic and hydrophobic properties, membrane flux and retention, self-cleaning performance of the hollow fiber membranes were studied. Results show that the amidoximation rate of the membranes increases with the rise of time, temperature and hydroxylamine hydrochloride concentration during the modification process, and the modification levels would affect the crystallinity of the hollow fiber membranes so as to enhance the adsorption of small molecules into the fiber material. Although the Fe ions on the membranes would impact their crystal structure, hydrophilic property and membrane flux, but the triaxial cross-linked structure would promote the retention performance for bovine serum albumin to 88%. Besides, Fenton catalytic system coupled by Fe(III) and H2O2 endows FePAN-HFM with antifouling and self-cleaning properties and the flux recovery rate reaches to 84.6% significantly.
To explore a kind of triaxial cross-linked hollow fiber membrane (HFM) with self-cleaning performance, polyacrylonitrile based HFM prepared by wet processing was chemically modified into amidoximated PAN hollow fiber membranes. Then the active groups were coordinated with metal ions (Fe3+) randomly to achieve metal coordinated amidoximation PAN hollow fiber membranes with triaxial cross-linked structure. Preparation process, structural composition, surface morphology, hydrophilic and hydrophobic properties, membrane flux and retention, self-cleaning performance of the hollow fiber membranes were studied. Results show that the amidoximation rate of the membranes increases with the rise of time, temperature and hydroxylamine hydrochloride concentration during the modification process, and the modification levels would affect the crystallinity of the hollow fiber membranes so as to enhance the adsorption of small molecules into the fiber material. Although the Fe ions on the membranes would impact their crystal structure, hydrophilic property and membrane flux, but the triaxial cross-linked structure would promote the retention performance for bovine serum albumin to 88%. Besides, Fenton catalytic system coupled by Fe(III) and H2O2 endows FePAN-HFM with antifouling and self-cleaning properties and the flux recovery rate reaches to 84.6% significantly.
2023, 40(10): 5848-5858.
doi: 10.13801/j.cnki.fhclxb.20230203.001
Abstract:
In order to study the bonding performance of bamboo scrimber bar-bamboo biochar mortar interface, pull-out tests were carried out on 85 bamboo scrimber bar-bamboo biochar mortar specimens. The effects of surface modification methods of bamboo bar, equivalent diameter of bamboo bar, compressive strength of mortar and bond lengths on the bond properties were also taken into consideration. The different bonding failure modes of the pull-out specimens were observed. The bond-slip curve, bonding strength and slippage were obtained. The failure mechanism was analyzed. A bond-slip constitutive model of bamboo scrimber bar-bamboo biochar mortar interface was established, and the effective surface modification method of bamboo scrimber bar was obtained. The results of the study show that there are three failure modes of the specimens under different initial conditions, including mortar splitting failure, bamboo bar tensile failure and bamboo bar pulled-out failure, among which mortar splitting failure is the most common. The failure process can be divided into micro-slip stage, slip stage, descending stage and residual stage. The bonding strength of the mortar interface can be increased by 13-46 times by modifying the surface of the bamboo bar. The interfacial bonding performance decreases with the increase of bonding length and equivalent diameter, and the effect of mortar strength on bonding strength is not obvious. It is recommended to modify the bamboo scrimber bar through the two methods of sticking sand and coating epoxy mortar. On the basis of ensuring bonding performance, it can improve the peeling of water absorption and expansion of bamboo bands during the maintenance process and the problem of the structure failing in advance. According to the experimental bond-slip curve, the bond-slip constitutive model of bamboo scrimber bar-bamboo biochar mortar treated by sticking sand was proposed. The bond-slip constitutive model can accurately predict the bond behavior between bamboo scrimber bar and mortar. After verification, the model is also applicable to the bonding interface destruction in the test under the other modification of bamboo.
In order to study the bonding performance of bamboo scrimber bar-bamboo biochar mortar interface, pull-out tests were carried out on 85 bamboo scrimber bar-bamboo biochar mortar specimens. The effects of surface modification methods of bamboo bar, equivalent diameter of bamboo bar, compressive strength of mortar and bond lengths on the bond properties were also taken into consideration. The different bonding failure modes of the pull-out specimens were observed. The bond-slip curve, bonding strength and slippage were obtained. The failure mechanism was analyzed. A bond-slip constitutive model of bamboo scrimber bar-bamboo biochar mortar interface was established, and the effective surface modification method of bamboo scrimber bar was obtained. The results of the study show that there are three failure modes of the specimens under different initial conditions, including mortar splitting failure, bamboo bar tensile failure and bamboo bar pulled-out failure, among which mortar splitting failure is the most common. The failure process can be divided into micro-slip stage, slip stage, descending stage and residual stage. The bonding strength of the mortar interface can be increased by 13-46 times by modifying the surface of the bamboo bar. The interfacial bonding performance decreases with the increase of bonding length and equivalent diameter, and the effect of mortar strength on bonding strength is not obvious. It is recommended to modify the bamboo scrimber bar through the two methods of sticking sand and coating epoxy mortar. On the basis of ensuring bonding performance, it can improve the peeling of water absorption and expansion of bamboo bands during the maintenance process and the problem of the structure failing in advance. According to the experimental bond-slip curve, the bond-slip constitutive model of bamboo scrimber bar-bamboo biochar mortar treated by sticking sand was proposed. The bond-slip constitutive model can accurately predict the bond behavior between bamboo scrimber bar and mortar. After verification, the model is also applicable to the bonding interface destruction in the test under the other modification of bamboo.
2023, 40(10): 5860-5871.
doi: 10.13801/j.cnki.fhclxb.20230103.001
Abstract:
In order to improve the mechanical properties and water resistance of magnesium oxychloride cement and solve the problem of resource disposal of abandoned crop highland barley straw, highland barley straw ash (HBSA) prepared by calcination and grinding under certain conditions was used to improve the mechanical properties and water resistance of magnesium oxychloride cement. First of all, the mechanical properties of magnesium oxychloride cement mortar (MOCM) with different HBSA mixing methods and amounts were tested, and the changing laws of the flexural strength, compressive strength, flexural compression ratio and softening coefficient of MOCM were tested respectively. Secondly, the pore structure and microstructure of MOCM were tested and analyzed to further explain the mechanism of the influence of HBSA on the mechanical properties of MOCM. The results show that MOCM can obtain higher mechanical properties and water resistance when HBSA is added with the external mixing method. When the content of HBSA is 5wt%, MOCM has the highest flexural strength and compressive strength; When the content of HBSA is 10wt%, the compressive strength loss of MOCM in saturated state is the smallest, and the water resistance is the best. When HBSA is added with the external mixing method and the content is 10wt%, the proportion of harmful pores and more harmful pores in the pore structure of MOCM is significantly reduced, and the proportion of harmless pores and less harmful pores is significantly increased. The hydration product Mg(OH)2 in MOCM can react with the active SiO2 in HBSA to generate a large number of hydrated magnesium silicate (M-S-H) gel, which effectively fills the harmful pores in MOCM, hinders the transmission and erosion of water, and improves the water resistance of MOCM.
In order to improve the mechanical properties and water resistance of magnesium oxychloride cement and solve the problem of resource disposal of abandoned crop highland barley straw, highland barley straw ash (HBSA) prepared by calcination and grinding under certain conditions was used to improve the mechanical properties and water resistance of magnesium oxychloride cement. First of all, the mechanical properties of magnesium oxychloride cement mortar (MOCM) with different HBSA mixing methods and amounts were tested, and the changing laws of the flexural strength, compressive strength, flexural compression ratio and softening coefficient of MOCM were tested respectively. Secondly, the pore structure and microstructure of MOCM were tested and analyzed to further explain the mechanism of the influence of HBSA on the mechanical properties of MOCM. The results show that MOCM can obtain higher mechanical properties and water resistance when HBSA is added with the external mixing method. When the content of HBSA is 5wt%, MOCM has the highest flexural strength and compressive strength; When the content of HBSA is 10wt%, the compressive strength loss of MOCM in saturated state is the smallest, and the water resistance is the best. When HBSA is added with the external mixing method and the content is 10wt%, the proportion of harmful pores and more harmful pores in the pore structure of MOCM is significantly reduced, and the proportion of harmless pores and less harmful pores is significantly increased. The hydration product Mg(OH)2 in MOCM can react with the active SiO2 in HBSA to generate a large number of hydrated magnesium silicate (M-S-H) gel, which effectively fills the harmful pores in MOCM, hinders the transmission and erosion of water, and improves the water resistance of MOCM.
2023, 40(10): 5871-5883.
doi: 10.13801/j.cnki.fhclxb.20230117.003
Abstract:
In order to prepare a new type of safe, stable and efficient nano silver composite antibacterial agent, silver nanoparticles/chitosan (AgNPs/CS) was biosynthesized by one-step method using Chimonanthus praeco petal extract and chitosan as reducing agent and stabilizing agent, respectively. The optimal preparation procedure was determined by single factor experiment. The products were characterized by UV-vis absorption spectroscopy, TEM and X-ray diffraction, and their antibacterial activity, anti-drug resistance, stability as well as biological safety were comprehensively evaluated. The experimental results show that the AgNPs/CS has the characteristic absorption peak of AgNPs at 451 nm, and the evenly dispersed AgNPs are spherical with average diameter of 12.83 nm, and the crystals have a face-centered cubic structure. The AgNPs/CS show antibacterial activity against aquatic pathogens both in vitro and in vivo, and has excellent anti-drug resistance, biosafety and stability. Therefore, AgNPs/CS is an ideal composite antibacterial agent, which has a prospective application in aquaculture field.
In order to prepare a new type of safe, stable and efficient nano silver composite antibacterial agent, silver nanoparticles/chitosan (AgNPs/CS) was biosynthesized by one-step method using Chimonanthus praeco petal extract and chitosan as reducing agent and stabilizing agent, respectively. The optimal preparation procedure was determined by single factor experiment. The products were characterized by UV-vis absorption spectroscopy, TEM and X-ray diffraction, and their antibacterial activity, anti-drug resistance, stability as well as biological safety were comprehensively evaluated. The experimental results show that the AgNPs/CS has the characteristic absorption peak of AgNPs at 451 nm, and the evenly dispersed AgNPs are spherical with average diameter of 12.83 nm, and the crystals have a face-centered cubic structure. The AgNPs/CS show antibacterial activity against aquatic pathogens both in vitro and in vivo, and has excellent anti-drug resistance, biosafety and stability. Therefore, AgNPs/CS is an ideal composite antibacterial agent, which has a prospective application in aquaculture field.
2023, 40(10): 5885-5892.
doi: 10.13801/j.cnki.fhclxb.20230207.001
Abstract:
In this paper, oxidized hyaluronic acid (OHA) was synthesized by oxidizing hydroxyl groups on hyaluronic acid (HA) with sodium periodate. OHA/HPCS self-healing hydrogel was prepared by using OHA and hydroxypropyl chitosan (HPCS) as raw materials. The aldehyde group on OHA reacted with the amino group of HPCS to form dynamic imine bond through Schiff base reaction. In this paper, the microscopic morphology and properties of OHA/HPCS self-healing hydrogel was characterized by FTIR, UV-vis, SEM, rheology and 1H NMR. OHA/HPCS hydrogels have a porous structure, and the results show that the pore size ranged from 70 to 200 μm by changing the amount of OHA. With the increase of the dosage of OHA, the pores in the OHA/HPCS hydrogels increase, the pore size becomes smaller, the swelling ratio of OHA/HPCS becomes smaller, and the degradation rate becomes slower. OHA/HPCS hydrogel can self-heal within 4 h at room temperature without external stimulation. OHA/HPCS hydrogel can release anticancer drug of gemcitabine in sustained way, with a cumulative release percent of 70%-84% in 12 days. OHA/HPCS hydrogels have the properties of sustained release gemcitabine, indicating that OHA/HPCS hydrogels have potential application prospects in the field of drug release.
In this paper, oxidized hyaluronic acid (OHA) was synthesized by oxidizing hydroxyl groups on hyaluronic acid (HA) with sodium periodate. OHA/HPCS self-healing hydrogel was prepared by using OHA and hydroxypropyl chitosan (HPCS) as raw materials. The aldehyde group on OHA reacted with the amino group of HPCS to form dynamic imine bond through Schiff base reaction. In this paper, the microscopic morphology and properties of OHA/HPCS self-healing hydrogel was characterized by FTIR, UV-vis, SEM, rheology and 1H NMR. OHA/HPCS hydrogels have a porous structure, and the results show that the pore size ranged from 70 to 200 μm by changing the amount of OHA. With the increase of the dosage of OHA, the pores in the OHA/HPCS hydrogels increase, the pore size becomes smaller, the swelling ratio of OHA/HPCS becomes smaller, and the degradation rate becomes slower. OHA/HPCS hydrogel can self-heal within 4 h at room temperature without external stimulation. OHA/HPCS hydrogel can release anticancer drug of gemcitabine in sustained way, with a cumulative release percent of 70%-84% in 12 days. OHA/HPCS hydrogels have the properties of sustained release gemcitabine, indicating that OHA/HPCS hydrogels have potential application prospects in the field of drug release.
2023, 40(10): 5892-5901.
doi: 10.13801/j.cnki.fhclxb.20221213.003
Abstract:
Graphene nanosheets (GNSs) reinforced Al-Mg matrix composite foams (G-AMCFs) were successfully prepared by ball milling and powder metallurgy foaming. The effects of GNSs on pore morphology, microstructure and quasi-static compressive mechanical properties of Al-Mg foams were studied. The results show that the addition of GNSs can increase pore nucleation sites and cause the segregation of MgO around the GNSs. With the increment of GNSs content, the pore size of G-AMCFs increases. The compressive mechanical properties of 0.25wt%G-AMCFs are the best. Compared with Al-Mg foams, the energy absorption capacity, yield strength and plateau stress of 0.25wt%G-AMCFs are increased by 43.6%, 42.9% and 28.1%, respectively. Meanwhile, 0.25wt%G-AMCFs show good ductile deformation behavior. The cell structure with high content of G-AMCFs (0.75wt%) deteriorates which leads to a decrease in mechanical properties, but the yield strength is still higher than that of Al-Mg foams. The enhancement mechanism of composite foams includes dispersion strengthening, load transfer and precipitation strengthening.
Graphene nanosheets (GNSs) reinforced Al-Mg matrix composite foams (G-AMCFs) were successfully prepared by ball milling and powder metallurgy foaming. The effects of GNSs on pore morphology, microstructure and quasi-static compressive mechanical properties of Al-Mg foams were studied. The results show that the addition of GNSs can increase pore nucleation sites and cause the segregation of MgO around the GNSs. With the increment of GNSs content, the pore size of G-AMCFs increases. The compressive mechanical properties of 0.25wt%G-AMCFs are the best. Compared with Al-Mg foams, the energy absorption capacity, yield strength and plateau stress of 0.25wt%G-AMCFs are increased by 43.6%, 42.9% and 28.1%, respectively. Meanwhile, 0.25wt%G-AMCFs show good ductile deformation behavior. The cell structure with high content of G-AMCFs (0.75wt%) deteriorates which leads to a decrease in mechanical properties, but the yield strength is still higher than that of Al-Mg foams. The enhancement mechanism of composite foams includes dispersion strengthening, load transfer and precipitation strengthening.
2023, 40(10): 5903-5916.
doi: 10.13801/j.cnki.fhclxb.20221226.003
Abstract:
For the repair structures of aircraft metal components with one-sided carbon fiber-reinforced polymer (CFRP) patches, the tensile tests on repair specimens with different repair processes (wet lay-up, prepreg and pre-curing methods) and CFRP patch parameters were carried out. The ultimate load, failure mode and interface of the specimens were observed. The three-dimensional (3D) finite element (FE) model had been established. Based on 3D Hashin failure criteria, the damage initiation and evolution in CFRP were simulated. The damages of the adhesive layer and delamination of CFRP were simulated with cohesive zone model. The FE model was validated by experimental and theoretical analysis. The results show that the three repair processes have different interface morphology and failure modes. The wet lay-up method has the best repair effect, 3.3 times of the pre-curing method and 1.3 times of the prepreg method. With the increase of patch thickness, the ultimate load first increases, then decreases, and finally tends to be stable. The failure mode gradually evolves from patch delamination, mixed failure of fiber breakage and adhesive layer damage to adhesive layer shear failure. The best patch thickness is 7 layers, about 1.05 mm in thickness. With the increase of patch length, the ultimate load first increases and then decreases linearly. The damage of the adhesive layer starts from the center and both ends of the joint and evolves to the middle region. The best patch length is 80 mm. The results reported herein could provide useful guidance for the application of aviation maintenance engineering.
For the repair structures of aircraft metal components with one-sided carbon fiber-reinforced polymer (CFRP) patches, the tensile tests on repair specimens with different repair processes (wet lay-up, prepreg and pre-curing methods) and CFRP patch parameters were carried out. The ultimate load, failure mode and interface of the specimens were observed. The three-dimensional (3D) finite element (FE) model had been established. Based on 3D Hashin failure criteria, the damage initiation and evolution in CFRP were simulated. The damages of the adhesive layer and delamination of CFRP were simulated with cohesive zone model. The FE model was validated by experimental and theoretical analysis. The results show that the three repair processes have different interface morphology and failure modes. The wet lay-up method has the best repair effect, 3.3 times of the pre-curing method and 1.3 times of the prepreg method. With the increase of patch thickness, the ultimate load first increases, then decreases, and finally tends to be stable. The failure mode gradually evolves from patch delamination, mixed failure of fiber breakage and adhesive layer damage to adhesive layer shear failure. The best patch thickness is 7 layers, about 1.05 mm in thickness. With the increase of patch length, the ultimate load first increases and then decreases linearly. The damage of the adhesive layer starts from the center and both ends of the joint and evolves to the middle region. The best patch length is 80 mm. The results reported herein could provide useful guidance for the application of aviation maintenance engineering.
2023, 40(10): 5917-5932.
doi: 10.13801/j.cnki.fhclxb.20230213.001
Abstract:
To explore the shear performance and the corresponding mechanisms of carbon fiber reinforced polymer (CFRP) strengthened reinforced concrete (RC) shear walls, a three-dimensional numerical model based on the Hashin damage criteria that captures the CFRP-concrete interface debonding behaviors was developed. Using the proposed model, the influences of shear span ratio, CFRP ratio and wrapping method on the shear capacities of the CFRP-strengthened RC shear wall were investigated. It is found that: (1) The external CFRP strips effectively mitigate the development of the shear primary cracks; (2) The increasing shear span ratio reduces significantly the shear contribution provided by CFRP strips on the CFRP-strengthened RC shear walls; (3) The shear contribution of CFRP is not linearly dependent on the number of CFRP layers. From qualitative to quantification analysis, the influence coefficient of shear span ratio and CFRP layer was introduced based on the numerical calculations. Furthermore, writing in the form of the American Code (ACI 440.2R-17), a calculation formula characterizing the shear contribution of CFRP was established. By comparing with the experimental data, it is noticed that the proposed formula gives more accurate descriptions on the influence of shear span ratio, CFRP ratio and wrapping method on the shear contribution of CFRP. The average absolute error between the prediction results and the experimental results is 8%, thus, verifying the effectiveness of the proposed calculation method.
To explore the shear performance and the corresponding mechanisms of carbon fiber reinforced polymer (CFRP) strengthened reinforced concrete (RC) shear walls, a three-dimensional numerical model based on the Hashin damage criteria that captures the CFRP-concrete interface debonding behaviors was developed. Using the proposed model, the influences of shear span ratio, CFRP ratio and wrapping method on the shear capacities of the CFRP-strengthened RC shear wall were investigated. It is found that: (1) The external CFRP strips effectively mitigate the development of the shear primary cracks; (2) The increasing shear span ratio reduces significantly the shear contribution provided by CFRP strips on the CFRP-strengthened RC shear walls; (3) The shear contribution of CFRP is not linearly dependent on the number of CFRP layers. From qualitative to quantification analysis, the influence coefficient of shear span ratio and CFRP layer was introduced based on the numerical calculations. Furthermore, writing in the form of the American Code (ACI 440.2R-17), a calculation formula characterizing the shear contribution of CFRP was established. By comparing with the experimental data, it is noticed that the proposed formula gives more accurate descriptions on the influence of shear span ratio, CFRP ratio and wrapping method on the shear contribution of CFRP. The average absolute error between the prediction results and the experimental results is 8%, thus, verifying the effectiveness of the proposed calculation method.
2023, 40(10): 5933-5947.
doi: 10.13801/j.cnki.fhclxb.20230222.005
Abstract:
Low velocity impact on the structural free edge would threaten the safety of laminated composite structures. In this paper, experimental and numerical investigations were conducted to study the edge-on impact behaviors of T700/YPH307 composite laminates. Visual inspection, ultrasonic C-scanning, electron microscopy and X-ray computed tomography (CT) technique were performed to detect the post-impact damage status of composite laminates subjected to edge-on impact, which could further reveal 3D spatial distribution of internal damage. Based on the Mohr's theory of fracture plane, a continuum damage mechanics model, considering fracture plane angle within anisotropic materials, was established. And with combination of cohesive zone model, the initiation, propagation and interaction of complicated edge-on impact damage modes, i.e. intra-laminar fiber and matrix failure and inter-laminar delamination, could be characterized in detail. There is a good agreement between numerical and experimental results. It is suggested that failure mechanisms induced by edge-on impact mainly include two distinct characteristics, namely the generation of localized debris wedge beneath the impactor corresponding to peak value of impact force, and the bending fracture of outer plies due to the wedge effect at the stage of stable fluctuations in impact force. Furthermore, it is found that the internal damage would be more serious with the impact energy increasing, while stacking sequence has a relatively small influence on the edge-on impact responses and damage morphology.
Low velocity impact on the structural free edge would threaten the safety of laminated composite structures. In this paper, experimental and numerical investigations were conducted to study the edge-on impact behaviors of T700/YPH307 composite laminates. Visual inspection, ultrasonic C-scanning, electron microscopy and X-ray computed tomography (CT) technique were performed to detect the post-impact damage status of composite laminates subjected to edge-on impact, which could further reveal 3D spatial distribution of internal damage. Based on the Mohr's theory of fracture plane, a continuum damage mechanics model, considering fracture plane angle within anisotropic materials, was established. And with combination of cohesive zone model, the initiation, propagation and interaction of complicated edge-on impact damage modes, i.e. intra-laminar fiber and matrix failure and inter-laminar delamination, could be characterized in detail. There is a good agreement between numerical and experimental results. It is suggested that failure mechanisms induced by edge-on impact mainly include two distinct characteristics, namely the generation of localized debris wedge beneath the impactor corresponding to peak value of impact force, and the bending fracture of outer plies due to the wedge effect at the stage of stable fluctuations in impact force. Furthermore, it is found that the internal damage would be more serious with the impact energy increasing, while stacking sequence has a relatively small influence on the edge-on impact responses and damage morphology.
2023, 40(10): 5948-5957.
doi: 10.13801/j.cnki.fhclxb.20230112.003
Abstract:
To improve the crashworthiness of C-channel carbon fiber reinforced polymer (CFRP) thin-walled structures, the energy absorption characteristics and failure behavior of the structures under axial crushing load were studied. Considering the delamination effect, the progressive damage model of C-channel CFRP thin-walled structure was established. The quadratic stress failure and the nonlinear damage evolution criterion based on the mixed-mode energy method were used to predict the initial interlaminar failure and damage evolution, respectively. For this structure, the hybrid-angle chamfer trigger and steeple trigger were proposed, and the effects of different trigger configurations on the crashworthiness index and failure mode of C-channel CFRP thin-walled structures were compared and analyzed. The results show that the initial peak load corresponding to the hybrid-angle chamfer trigger decreases with the increase of the hybrid angle; The initial peak load can be effectively reduced by reducing the contact area between the hybrid-angle chamfer trigger and the loading plate at the initial crushing stage; The hybrid-angle steeple trigger can improve the failure process and has a positive effect on improving the crashworthiness of the structure.
To improve the crashworthiness of C-channel carbon fiber reinforced polymer (CFRP) thin-walled structures, the energy absorption characteristics and failure behavior of the structures under axial crushing load were studied. Considering the delamination effect, the progressive damage model of C-channel CFRP thin-walled structure was established. The quadratic stress failure and the nonlinear damage evolution criterion based on the mixed-mode energy method were used to predict the initial interlaminar failure and damage evolution, respectively. For this structure, the hybrid-angle chamfer trigger and steeple trigger were proposed, and the effects of different trigger configurations on the crashworthiness index and failure mode of C-channel CFRP thin-walled structures were compared and analyzed. The results show that the initial peak load corresponding to the hybrid-angle chamfer trigger decreases with the increase of the hybrid angle; The initial peak load can be effectively reduced by reducing the contact area between the hybrid-angle chamfer trigger and the loading plate at the initial crushing stage; The hybrid-angle steeple trigger can improve the failure process and has a positive effect on improving the crashworthiness of the structure.
2023, 40(10): 5958-5967.
doi: 10.13801/j.cnki.fhclxb.20221228.004
Abstract:
To evaluate the mechanical properties of ceramic composites affected by coating defects, the SiC coated plain woven C/SiC composite by precursor impregnation and pyrolysis (PIP) process was taken in consideration. Firstly, the observation and statistical analysis of initial defects on SiC coating were performed, then a non-stress oxidation test at 900℃ was conducted, and the damage status of carbon fiber around coating defects was obtained. According to the actual characteristics of the oxidation test, a microscale model of SiC matrix and carbon fiber containing typical coating defects was established. Based on the evolution of oxidation interface under diffusion-controlled reaction mechanism, a simulation on the development of fiber overall damage was carried out and stiffness reduction was calculated. The results show that oxy-gases entered from coating defects diffuse through inner pores of composites and react with carbon fiber, causing tensile modulus reduction in consistency with weight loss, both of which are capable of evaluation on the oxidation extent of composites. The overall damage topography of carbon fiber is determined by the types of coating defects. Under the same distribution scale, damaged zone induced by cracking defects contains larger range of stress concentration compared with that induced by spalling defects. Judgement on the properties of thermal structure at high temperature is supported with the comparison of oxidation damage induced by different coating defects.
To evaluate the mechanical properties of ceramic composites affected by coating defects, the SiC coated plain woven C/SiC composite by precursor impregnation and pyrolysis (PIP) process was taken in consideration. Firstly, the observation and statistical analysis of initial defects on SiC coating were performed, then a non-stress oxidation test at 900℃ was conducted, and the damage status of carbon fiber around coating defects was obtained. According to the actual characteristics of the oxidation test, a microscale model of SiC matrix and carbon fiber containing typical coating defects was established. Based on the evolution of oxidation interface under diffusion-controlled reaction mechanism, a simulation on the development of fiber overall damage was carried out and stiffness reduction was calculated. The results show that oxy-gases entered from coating defects diffuse through inner pores of composites and react with carbon fiber, causing tensile modulus reduction in consistency with weight loss, both of which are capable of evaluation on the oxidation extent of composites. The overall damage topography of carbon fiber is determined by the types of coating defects. Under the same distribution scale, damaged zone induced by cracking defects contains larger range of stress concentration compared with that induced by spalling defects. Judgement on the properties of thermal structure at high temperature is supported with the comparison of oxidation damage induced by different coating defects.
2023, 40(10): 5968-5976.
doi: 10.13801/j.cnki.fhclxb.20221223.003
Abstract:
In order to study the dynamic response of porous metal ceramic functionally graded rectangular plate under low velocity impact, a numerical analysis model based on Hertzian elastic theory and first-order shear deformation plate theory was presented, the analytical solution of response of porous cermet functionally graded rectangular plate under low velocity impact was obtained. According to Hamilton's principle, the equation of motion of functionally graded rectangular plate was derived, a spring-mass (S-M) model with two degrees of freedom was introduced to obtain the time-dependent contact forces during impact, using the Duhamel principle and Navier method to calculate the transverse displacement of porous functionally graded rectangular plate. The results obtained were compared with literature data to verify the validity. On this basis, the influence of related parameters on the impact resistance of functionally graded rectangular plate was compared and analyzed. The results show that with the decrease of porosity, functionally graded index and width to thickness ratio, the maximum transverse displacement of the functionally graded rectangular plate decreases, energy absorption and impact resistance are increased.
In order to study the dynamic response of porous metal ceramic functionally graded rectangular plate under low velocity impact, a numerical analysis model based on Hertzian elastic theory and first-order shear deformation plate theory was presented, the analytical solution of response of porous cermet functionally graded rectangular plate under low velocity impact was obtained. According to Hamilton's principle, the equation of motion of functionally graded rectangular plate was derived, a spring-mass (S-M) model with two degrees of freedom was introduced to obtain the time-dependent contact forces during impact, using the Duhamel principle and Navier method to calculate the transverse displacement of porous functionally graded rectangular plate. The results obtained were compared with literature data to verify the validity. On this basis, the influence of related parameters on the impact resistance of functionally graded rectangular plate was compared and analyzed. The results show that with the decrease of porosity, functionally graded index and width to thickness ratio, the maximum transverse displacement of the functionally graded rectangular plate decreases, energy absorption and impact resistance are increased.
