2021 Vol. 38, No. 6
2021, 38(6): 1629-1650.
doi: 10.13801/j.cnki.fhclxb.20210107.002
Abstract:
Lightweight composite shell structures have the advantages of light weight, high strength and designability, and are widely used in aerospace structures. The lightweight composite shell structures include grid shell structures, stiffened shell structures and sandwich shell structures. This article firstly summarizes these lightweight composite shell structures from the preparation method to the characterization of the mechanical properties. The preparation methods include filament winding process, mold hot pressing process and interlocking assembly process, and the mechanical properties include failure modes, dynamics properties and damping characteristics. Further, the multifunction and intelligence of sandwich structure are summarized briefly. Secondly, the application status of lightweight shell structure is introduced, especially in the aerospace field, including rocket adapters, rocket interstage, satellite central cylinder, missile fairings, aircraft cabins and other structures. Finally, the conclusion is given and the future development directions are discussed.
Lightweight composite shell structures have the advantages of light weight, high strength and designability, and are widely used in aerospace structures. The lightweight composite shell structures include grid shell structures, stiffened shell structures and sandwich shell structures. This article firstly summarizes these lightweight composite shell structures from the preparation method to the characterization of the mechanical properties. The preparation methods include filament winding process, mold hot pressing process and interlocking assembly process, and the mechanical properties include failure modes, dynamics properties and damping characteristics. Further, the multifunction and intelligence of sandwich structure are summarized briefly. Secondly, the application status of lightweight shell structure is introduced, especially in the aerospace field, including rocket adapters, rocket interstage, satellite central cylinder, missile fairings, aircraft cabins and other structures. Finally, the conclusion is given and the future development directions are discussed.
2021, 38(6): 1651-1668.
doi: 10.13801/j.cnki.fhclxb.20210106.001
Abstract:
4D printing is an emerging manufacturing technology, the shape, property, or functionality of the printed structure will change with time under the stimulation of external environment. Smart soft matter is widely used in 4D printing due to its large deformation, multiple excitation response mechanisms and fast response speed, especially shape memory hydrogels and shape memory polymers. At present, the control of rigidity and bending shape of soft composite is two difficult problems in the application of 4D printing, and the establishment of equivalent modulus and curvature prediction models has guiding significance for the design of mechanical properties of 4D printed composite structures. This article gave an overview of the equivalent modulus and bending curvature models of the existing 4D printed composite structures, the elastic modulus prediction models of 4D printed structures under static and dynamic conditions were introduced. Then, the application of Stoney theory, Timoshenko theory and composite material mechanics in flexural curvature modeling of soft composite was emphatically reviewed. In the end, the existing problems of the existing 4D printing soft composite mechanics prediction model and the main development direction were discussed.
4D printing is an emerging manufacturing technology, the shape, property, or functionality of the printed structure will change with time under the stimulation of external environment. Smart soft matter is widely used in 4D printing due to its large deformation, multiple excitation response mechanisms and fast response speed, especially shape memory hydrogels and shape memory polymers. At present, the control of rigidity and bending shape of soft composite is two difficult problems in the application of 4D printing, and the establishment of equivalent modulus and curvature prediction models has guiding significance for the design of mechanical properties of 4D printed composite structures. This article gave an overview of the equivalent modulus and bending curvature models of the existing 4D printed composite structures, the elastic modulus prediction models of 4D printed structures under static and dynamic conditions were introduced. Then, the application of Stoney theory, Timoshenko theory and composite material mechanics in flexural curvature modeling of soft composite was emphatically reviewed. In the end, the existing problems of the existing 4D printing soft composite mechanics prediction model and the main development direction were discussed.
2021, 38(6): 1669-1677.
doi: 10.13801/j.cnki.fhclxb.20210223.004
Abstract:
In the structural design of composite materials, the allowable value is one of the key parameters. The statistic of B basis is usually used as the allowable value of composite materials, and the B basis is the lower limit of 90% confidence with 95% confidence. Accurate calculation of the B basis of composite materials is the guarantee for the safe and reliable application of composite materials. This article summarizes the research progress of the calculation method of the composite material’s B basis, and analyzes in detail the calculation principle, calculation process and applicable conditions of the single-point method and the pooling method. And combined with the project data, the influence of different methods on the calculation results of the B basis is analyzed. Finally, the development trend and expected research direction of the calculation method of composite material B basis are prospected.
In the structural design of composite materials, the allowable value is one of the key parameters. The statistic of B basis is usually used as the allowable value of composite materials, and the B basis is the lower limit of 90% confidence with 95% confidence. Accurate calculation of the B basis of composite materials is the guarantee for the safe and reliable application of composite materials. This article summarizes the research progress of the calculation method of the composite material’s B basis, and analyzes in detail the calculation principle, calculation process and applicable conditions of the single-point method and the pooling method. And combined with the project data, the influence of different methods on the calculation results of the B basis is analyzed. Finally, the development trend and expected research direction of the calculation method of composite material B basis are prospected.
2021, 38(6): 1678-1690.
doi: 10.13801/j.cnki.fhclxb.20210210.004
Abstract:
Developing lithium-ion batteries (LIBs) is a powerful measure to alleviate current energy and environmental problems, but their energy density can no longer meet the high requirements of future energy storage devices. The development of LIBs with high energy density must start from improving the performance of electrode materials. Silicon-based materials have the advantages of high capacity, low cost, and low platform voltage, and are considered to be the most promising anode materials. However, this type of material would undergo a huge volume change (300%) during charging and discharging processes, resulting in serious capacity decline or even failure. In recent years, researchers have begun to focus on improving the performance of silicon-based anodes through structural design and composite modification of the binder in the electrode, and significant results have been achieved. In this paper, the existing problems of silicon-based anodes were briefly introduced, and the types of the binders suitable for silicon-based anodes were summarized. The progress in the design and modification of the binders in silicon-based anodes in recent years was reviewed from the aspects of molecular chain structure design of the binders and enhancement of inter particle force in the electrode. Finally, the development trend and future prospect of the binders for silicon-based anodes were prospected.
Developing lithium-ion batteries (LIBs) is a powerful measure to alleviate current energy and environmental problems, but their energy density can no longer meet the high requirements of future energy storage devices. The development of LIBs with high energy density must start from improving the performance of electrode materials. Silicon-based materials have the advantages of high capacity, low cost, and low platform voltage, and are considered to be the most promising anode materials. However, this type of material would undergo a huge volume change (300%) during charging and discharging processes, resulting in serious capacity decline or even failure. In recent years, researchers have begun to focus on improving the performance of silicon-based anodes through structural design and composite modification of the binder in the electrode, and significant results have been achieved. In this paper, the existing problems of silicon-based anodes were briefly introduced, and the types of the binders suitable for silicon-based anodes were summarized. The progress in the design and modification of the binders in silicon-based anodes in recent years was reviewed from the aspects of molecular chain structure design of the binders and enhancement of inter particle force in the electrode. Finally, the development trend and future prospect of the binders for silicon-based anodes were prospected.
2021, 38(6): 1691-1702.
doi: 10.13801/j.cnki.fhclxb.20210108.001
Abstract:
Collagen (COL) is a green and renewable organic natural polymer material with excellent biocompatibility, biodegradability and low antigenicity. A series of novel collagen-based nanocomposites combining excellent properties of two components could be developed by introducing inorganic nanomaterials with unique functional characteristics into collagen matrix. However, the interface interaction characteristics between inorganic nanomaterials and organic COL have a significant effect on the properties of the corresponding nanocomposites. Therefore, it is necessary to investigate the interface interaction between nanomaterials and COL. This paper systematically reviewed the main research status of the effect of unmodified/modified nanomaterials on the properties of COL-based nanocomposite, and summarized the progress of the interface research between nanomaterials and COL through methods of modern instrumental analysis and molecular dynamics simulation. Moreover, the advantages and disadvantages of the two methods were compared. Finally, the possible future research trend of the interface interaction between nanomaterials and COL matrix was prospected. It is pointed out that the introduction of nanomaterials into the COL matrix to prepare environmentally friendly, multi-functional, high-performance, and widely used COL-based nanocomposites, and the combination of modern instrument analysis methods and computer simulation methods to conduct interface research will be the main research directions in the future.
Collagen (COL) is a green and renewable organic natural polymer material with excellent biocompatibility, biodegradability and low antigenicity. A series of novel collagen-based nanocomposites combining excellent properties of two components could be developed by introducing inorganic nanomaterials with unique functional characteristics into collagen matrix. However, the interface interaction characteristics between inorganic nanomaterials and organic COL have a significant effect on the properties of the corresponding nanocomposites. Therefore, it is necessary to investigate the interface interaction between nanomaterials and COL. This paper systematically reviewed the main research status of the effect of unmodified/modified nanomaterials on the properties of COL-based nanocomposite, and summarized the progress of the interface research between nanomaterials and COL through methods of modern instrumental analysis and molecular dynamics simulation. Moreover, the advantages and disadvantages of the two methods were compared. Finally, the possible future research trend of the interface interaction between nanomaterials and COL matrix was prospected. It is pointed out that the introduction of nanomaterials into the COL matrix to prepare environmentally friendly, multi-functional, high-performance, and widely used COL-based nanocomposites, and the combination of modern instrument analysis methods and computer simulation methods to conduct interface research will be the main research directions in the future.
2021, 38(6): 1703-1723.
doi: 10.13801/j.cnki.fhclxb.20210118.002
Abstract:
At present, cancer is one of the major fatal diseases worldwide, and traditional treatment methods have many drawbacks. New therapeutic methods such as photodynamic therapy (PDT) and photothermal therapy (PTT) have effectively made up for the deficiency of traditional therapeutic methods with the development of nanomaterials. Heterojunction which combines nanomaterials of different compositions into a nanostructure exhibits an excellent performance in photodynamic therapy and photothermal therapy. Heterojunction materials have great application potential in the fields of catalysis, detection, multi-modal imaging and collaborative treatment of tumors due to their inherent peculiarities, including magnetic properties, optical properties and structural design. This article systematically reviews the recent progress of heterojunction materials in single tumor therapy, cooperative therapy and the integration of diagnosis and treatment, and the future development direction of heterojunction materials is also prospected.
At present, cancer is one of the major fatal diseases worldwide, and traditional treatment methods have many drawbacks. New therapeutic methods such as photodynamic therapy (PDT) and photothermal therapy (PTT) have effectively made up for the deficiency of traditional therapeutic methods with the development of nanomaterials. Heterojunction which combines nanomaterials of different compositions into a nanostructure exhibits an excellent performance in photodynamic therapy and photothermal therapy. Heterojunction materials have great application potential in the fields of catalysis, detection, multi-modal imaging and collaborative treatment of tumors due to their inherent peculiarities, including magnetic properties, optical properties and structural design. This article systematically reviews the recent progress of heterojunction materials in single tumor therapy, cooperative therapy and the integration of diagnosis and treatment, and the future development direction of heterojunction materials is also prospected.
2021, 38(6): 1724-1733.
doi: 10.13801/j.cnki.fhclxb.20210210.007
Abstract:
The electrochromic devices (ECDs) can achieve reversible color change under the applied electric field. Generally, an external circuit is necessary to provide driving voltage for ECDs, which limits the practical application to some extent. In recent years, researchers have paid attention to the integration of power supply devices and ECDs to prepare self-powered ECD, and remarkable progress has been made. Various kinds of energy, such as solar energy, chemical energy and mechanical energy, can be used as the driving energy, which effectively meet the needs and greatly promote the development of the ECDs. Here, the progress in self-powered ECDs is reviewed and the practical application of the self-powered ECDs is prospected.
The electrochromic devices (ECDs) can achieve reversible color change under the applied electric field. Generally, an external circuit is necessary to provide driving voltage for ECDs, which limits the practical application to some extent. In recent years, researchers have paid attention to the integration of power supply devices and ECDs to prepare self-powered ECD, and remarkable progress has been made. Various kinds of energy, such as solar energy, chemical energy and mechanical energy, can be used as the driving energy, which effectively meet the needs and greatly promote the development of the ECDs. Here, the progress in self-powered ECDs is reviewed and the practical application of the self-powered ECDs is prospected.
2021, 38(6): 1734-1753.
doi: 10.13801/j.cnki.fhclxb.20210302.005
Abstract:
Wood-plastic composites (WPCs) have been widely utilized in exterior cladding, decking, interior decoration, landscape architecture and automobile interior decoration, etc. WPCs will undergo creep when it is subjected to long-term external forces, which restricts its popularization and application as load-bearing structural materials. This is due to the intrinsic viscoelastic properties of linear or branched macromolecular chains ascribed to their thermodynamic movement. Therefore, increasing the creep resistance of WPCs is an international technique and academic problem needed to be attacked in both industry and academia. Towards a better understanding of creep behavior of WPCs and to improve its creep resistance, this paper reviews the state-of-the-art of the creep characteristics of WPCs. The effects of raw materials, structure, and environmental conditions on the creep resistance of WPCs were discussed. The improving methods for creep resistance of WPCs were summarized and analyzed. The long-term creep test of WPCs is a necessary means to evaluate its durability and safety, but the traditional testing methods are time-consuming and costly. Accelerated testing of creep can be realized by the empirical relationship between creep with time, temperature and external stress. Finally, the applications of Boltzmann superposition principle, time-temperature-stress superposition principle, stepped iso-thermal method and stepped iso-stress method in long-term creep prediction on WPCs were discussed.
Wood-plastic composites (WPCs) have been widely utilized in exterior cladding, decking, interior decoration, landscape architecture and automobile interior decoration, etc. WPCs will undergo creep when it is subjected to long-term external forces, which restricts its popularization and application as load-bearing structural materials. This is due to the intrinsic viscoelastic properties of linear or branched macromolecular chains ascribed to their thermodynamic movement. Therefore, increasing the creep resistance of WPCs is an international technique and academic problem needed to be attacked in both industry and academia. Towards a better understanding of creep behavior of WPCs and to improve its creep resistance, this paper reviews the state-of-the-art of the creep characteristics of WPCs. The effects of raw materials, structure, and environmental conditions on the creep resistance of WPCs were discussed. The improving methods for creep resistance of WPCs were summarized and analyzed. The long-term creep test of WPCs is a necessary means to evaluate its durability and safety, but the traditional testing methods are time-consuming and costly. Accelerated testing of creep can be realized by the empirical relationship between creep with time, temperature and external stress. Finally, the applications of Boltzmann superposition principle, time-temperature-stress superposition principle, stepped iso-thermal method and stepped iso-stress method in long-term creep prediction on WPCs were discussed.
2021, 38(6): 1754-1766.
doi: 10.13801/j.cnki.fhclxb.20201223.002
Abstract:
In order to better isolate or degrade erythromycin, and finally improve the ability to deal with residual erythromycin. Magnetic Fe3O4@polyacrylic acid (Fe3O4@PAA) erythromycin molecularly imprinted polymer (ERYMIP) and photodegradation TiO2@polyacrylic acid erythromycin molecularly imprinted polymer (TiO2@PAA ERYMIP) were prepared, respectively. Scanning electron microscope (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysisand (TG) and magnetic hysteresis loop (MHL) were used to characterize the morphology and structure of the imprinted polymers. Experimental results show that Fe3O4@PAA ERYMIP has superparamagnetic properties and TiO2@PAA ERYMIP has photodegradation performance. The maximum adsorption capacity of Fe3O4@PAA ERYMIP and TiO2@PAA ERYMIP are 958.4 mg·g−1 and 1170.2 mg·g−1, respectively. They have good selectivity compared with other antibiotics. Isothermal adsorption studies find that both Fe3O4@PAA ERYMIP and TiO2@PAA ERYMIP are consistent with Langmuir model. The kinetic studies find that the adsorption processes of Fe3O4@PAA ERYMIP and TiO2@PAA ERYMIP conform to the quasi-secondary and quasi-primary models, respectively.
In order to better isolate or degrade erythromycin, and finally improve the ability to deal with residual erythromycin. Magnetic Fe3O4@polyacrylic acid (Fe3O4@PAA) erythromycin molecularly imprinted polymer (ERYMIP) and photodegradation TiO2@polyacrylic acid erythromycin molecularly imprinted polymer (TiO2@PAA ERYMIP) were prepared, respectively. Scanning electron microscope (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysisand (TG) and magnetic hysteresis loop (MHL) were used to characterize the morphology and structure of the imprinted polymers. Experimental results show that Fe3O4@PAA ERYMIP has superparamagnetic properties and TiO2@PAA ERYMIP has photodegradation performance. The maximum adsorption capacity of Fe3O4@PAA ERYMIP and TiO2@PAA ERYMIP are 958.4 mg·g−1 and 1170.2 mg·g−1, respectively. They have good selectivity compared with other antibiotics. Isothermal adsorption studies find that both Fe3O4@PAA ERYMIP and TiO2@PAA ERYMIP are consistent with Langmuir model. The kinetic studies find that the adsorption processes of Fe3O4@PAA ERYMIP and TiO2@PAA ERYMIP conform to the quasi-secondary and quasi-primary models, respectively.
2021, 38(6): 1767-1774.
doi: 10.13801/j.cnki.fhclxb.20201209.001
Abstract:
Octet-truss is a three-dimensional lattice structure with light configuration and multi-function characteristics. In order to analyze and verify its compression resistance, a method of preparing Octet-truss lattice sandwich panel with continuous fiber was proposed. A set of Octet-truss structure molding tools was designed by this method. Different types of glass fiber and Kevlar fiber specimens were prepared by spatial weaving method and resin curing process, and the axial compression test was carried out. The experimental results show that the mechanical properties of different materials and different sizes of sandwich panels prepared by this method are stable, and the reliability of the preparation process is verified, Combined with the experimental process and electron microscope images, the main failure mode of glass fiber samples is fracture of the struts near the nodes induced by fiber microbuckling, while the Kevlar fiber samples failed by the Euler buckling of the struts.
Octet-truss is a three-dimensional lattice structure with light configuration and multi-function characteristics. In order to analyze and verify its compression resistance, a method of preparing Octet-truss lattice sandwich panel with continuous fiber was proposed. A set of Octet-truss structure molding tools was designed by this method. Different types of glass fiber and Kevlar fiber specimens were prepared by spatial weaving method and resin curing process, and the axial compression test was carried out. The experimental results show that the mechanical properties of different materials and different sizes of sandwich panels prepared by this method are stable, and the reliability of the preparation process is verified, Combined with the experimental process and electron microscope images, the main failure mode of glass fiber samples is fracture of the struts near the nodes induced by fiber microbuckling, while the Kevlar fiber samples failed by the Euler buckling of the struts.
2021, 38(6): 1775-1783.
doi: 10.13801/j.cnki.fhclxb.20200909.004
Abstract:
In order to make full use of the waste generated during the deep processing of red jujube, jujube pit (JP) and linear low density polyethylene (LLDPE) composites were prepared by injection molding method with JP and LLDPE as the main components. The static mechanical properties (tensile, flexural and impact) and dynamic mechanical properties (dynamic viscoelastic, creep behavior and stress relaxation behavior) were fully tested and analyzed. The static mechanical properties analysis show that the tensile and impact strength of JP/LLDPE composites are decreased as the JP contents increase, while the flexural strength of the composites is obviously improved. When the addition contents of JP reach 20wt%, the JP/LLDPE composite exhibit optimal flexural strength, which is 63.57% higher than that of pure LLDPE. Dynamic mechanical analysis confirms that the increase of JP contents is beneficial to improve the rigidity, creep resistance and stress relaxation of JP/LLDPE composites, but the increase of temperature adversely affects the creep resistance and stress relaxation resistance of JP/LLDPE composites.
In order to make full use of the waste generated during the deep processing of red jujube, jujube pit (JP) and linear low density polyethylene (LLDPE) composites were prepared by injection molding method with JP and LLDPE as the main components. The static mechanical properties (tensile, flexural and impact) and dynamic mechanical properties (dynamic viscoelastic, creep behavior and stress relaxation behavior) were fully tested and analyzed. The static mechanical properties analysis show that the tensile and impact strength of JP/LLDPE composites are decreased as the JP contents increase, while the flexural strength of the composites is obviously improved. When the addition contents of JP reach 20wt%, the JP/LLDPE composite exhibit optimal flexural strength, which is 63.57% higher than that of pure LLDPE. Dynamic mechanical analysis confirms that the increase of JP contents is beneficial to improve the rigidity, creep resistance and stress relaxation of JP/LLDPE composites, but the increase of temperature adversely affects the creep resistance and stress relaxation resistance of JP/LLDPE composites.
2021, 38(6): 1784-1794.
doi: 10.13801/j.cnki.fhclxb.20201118.001
Abstract:
The interlayer structure adjusting methods were studied on carbon fiber (CF)/bismaleimide composite materials, conducted respectively by thermoplastic interlaminar toughening and carbon nanotube (CNT) film hybridizing in contrast. The changes of compression properties, dynamic mechanical properties, electrical conductivities and electromagnetic shielding properties of the modified CF composites were analyzed. The results show that thermal compaction processing reduces the thickness of the CNT film significantly, suppressing the local resin-rich of the interlayer CNT region. The compressive strengths of the CNT film-CF hybrid composites are improved, with the fracture morphologies obviously different from that of the CF composites. In comparison, the thermoplastic interlaminar toughened CF composites show much lower compression strengths than the CNT film/CF hybrid composites. Additionally, the interlaminar electrical conductive paths are penetrated by the CNT networks of the hybrid composites, hence the thickness direction conductivities are increased by 3 orders of magnitude. However, the volumetric electrical conductivities of the diverse hybrid composites exhibit an evident “Cannikin Law”. It is noteworthy that the CNT film interlaminar hybrid can dramatically improve the electromagnetic shielding properties of the CF composite, reaching up to 90 dB for the dense CNT film hybrid composite.
The interlayer structure adjusting methods were studied on carbon fiber (CF)/bismaleimide composite materials, conducted respectively by thermoplastic interlaminar toughening and carbon nanotube (CNT) film hybridizing in contrast. The changes of compression properties, dynamic mechanical properties, electrical conductivities and electromagnetic shielding properties of the modified CF composites were analyzed. The results show that thermal compaction processing reduces the thickness of the CNT film significantly, suppressing the local resin-rich of the interlayer CNT region. The compressive strengths of the CNT film-CF hybrid composites are improved, with the fracture morphologies obviously different from that of the CF composites. In comparison, the thermoplastic interlaminar toughened CF composites show much lower compression strengths than the CNT film/CF hybrid composites. Additionally, the interlaminar electrical conductive paths are penetrated by the CNT networks of the hybrid composites, hence the thickness direction conductivities are increased by 3 orders of magnitude. However, the volumetric electrical conductivities of the diverse hybrid composites exhibit an evident “Cannikin Law”. It is noteworthy that the CNT film interlaminar hybrid can dramatically improve the electromagnetic shielding properties of the CF composite, reaching up to 90 dB for the dense CNT film hybrid composite.
2021, 38(6): 1795-1808.
doi: 10.13801/j.cnki.fhclxb.20200826.004
Abstract:
In order to study the effect and mechanism of laying process parameters on the curve trajectory placement quality of prepreg tow, an automated fiber placement simulation test platform was designed and built firstly, and the test of curve trajectory placement was carried out by changing the laying process parameters and laying radius. The laying quality was represented by the measurement and calculation of effective tack width ratio, wrinkle angle and curvature radius ratio and also the results of peeling test of variable laying process parameters. The results show that the curve trajectory placement quality is closely related to the tack and bending stiffness of prepreg tow. With the increase of laying temperature, pressure and tension and the decrease of laying velocity, the tack of prepreg tow increases and the curve trajectory placement quality is improved. Due to the increase of laying temperature, the bending stiffness of the prepreg tow decreases, which can improve the accuracy of laying. However, excessive temperature will cause the tack of the prepreg tow to decrease, make the defect of curve placement obvious. The laying tension will change the stress state of the prepreg tow, thus affecting the accuracy of the laying path. In addition, the smaller the curve placement radius is, the more sensitive the placement quality is to the change of process parameters.
In order to study the effect and mechanism of laying process parameters on the curve trajectory placement quality of prepreg tow, an automated fiber placement simulation test platform was designed and built firstly, and the test of curve trajectory placement was carried out by changing the laying process parameters and laying radius. The laying quality was represented by the measurement and calculation of effective tack width ratio, wrinkle angle and curvature radius ratio and also the results of peeling test of variable laying process parameters. The results show that the curve trajectory placement quality is closely related to the tack and bending stiffness of prepreg tow. With the increase of laying temperature, pressure and tension and the decrease of laying velocity, the tack of prepreg tow increases and the curve trajectory placement quality is improved. Due to the increase of laying temperature, the bending stiffness of the prepreg tow decreases, which can improve the accuracy of laying. However, excessive temperature will cause the tack of the prepreg tow to decrease, make the defect of curve placement obvious. The laying tension will change the stress state of the prepreg tow, thus affecting the accuracy of the laying path. In addition, the smaller the curve placement radius is, the more sensitive the placement quality is to the change of process parameters.
2021, 38(6): 1809-1816.
doi: 10.13801/j.cnki.fhclxb.20201130.001
Abstract:
In this work, continuous carbon fiber (CCF)/polyetheretherketone (PEEK) composites were prepared by using polyethersulfone (PES) as tertiary component and activated PES as surface modifier for CCF respectively. The research focuses on the effects of the preparation process on the properties of the CCF/PEEK composites. The results show that for the CCF/PEEK composites prepared with PES as tertiary component, when 16wt% of CCF is filled, the surface resistance decreases to 107-109 Ω, appearing conductive percolation state, and the friction coefficient reduces to the lowest value of 0.2430. The tensile strength, bending strength and impact strength of CCF/PEEK composites filled with 30wt% of CCF with surface modifier by activated PES are increased to 236.2 MPa, 345.1 MPa and 12.3 kJ/m2 respectively, which are increased by 13.69%, 21.70% and 36.97% respectively, compared with the CCF30/PEEK composites without PES modification, with the good dispersion of CCF and better interface adhesion between PEEK and CCF surface modified by PES. The tribological results indicate that the friction properties of the composites depend not only on the distribution of CCF in the matrix, but also on the interface force between CCF and the matrix.
In this work, continuous carbon fiber (CCF)/polyetheretherketone (PEEK) composites were prepared by using polyethersulfone (PES) as tertiary component and activated PES as surface modifier for CCF respectively. The research focuses on the effects of the preparation process on the properties of the CCF/PEEK composites. The results show that for the CCF/PEEK composites prepared with PES as tertiary component, when 16wt% of CCF is filled, the surface resistance decreases to 107-109 Ω, appearing conductive percolation state, and the friction coefficient reduces to the lowest value of 0.2430. The tensile strength, bending strength and impact strength of CCF/PEEK composites filled with 30wt% of CCF with surface modifier by activated PES are increased to 236.2 MPa, 345.1 MPa and 12.3 kJ/m2 respectively, which are increased by 13.69%, 21.70% and 36.97% respectively, compared with the CCF30/PEEK composites without PES modification, with the good dispersion of CCF and better interface adhesion between PEEK and CCF surface modified by PES. The tribological results indicate that the friction properties of the composites depend not only on the distribution of CCF in the matrix, but also on the interface force between CCF and the matrix.
2021, 38(6): 1817-1824.
doi: 10.13801/j.cnki.fhclxb.20201015.002
Abstract:
Piezoelectric fiber composite faces a challenge of an extremely wide temperature range when it is used in aerospace devices. So it is necessary to investigate the influence of temperature on the strain performance of piezoelectric fiber composite. In this paper, the free strain properties of piezoelectric fiber composites prepared using three kinds of polymer matrices were evaluated from −15℃ to 60℃. The results show that the free strain properties of all piezoelectric fiber composites are strongly dependent on the ambient temperature. The free strain values of piezoelectric fiber composites increase firstly and then decrease with the rising temperature. When the sinusoidal voltage of 0.1 Hz and −500 V-1 000 V is applied, the maximum longitudinal free strain values of the piezoelectric fiber composites with low glass transition temperature (Tg) and high Tg epoxy are 1 416×10−6 and 1 060×10−6 at 40℃, respectively. While the free strain value of the piezoelectric fiber composite with polyurethane reaches 2 361×10−6 at 30℃, which is 66.7% and 122.7% higher than the formers, respectively. The longitudinal free strain values of the piezoelectric fiber composites both with low Tg epoxy and polyurethane reduce about 27.5% as the temperature increases from −15℃ to 40℃. Although the longitudinal free strain of the piezoelectric fiber composite with high Tg epoxy is small, its longitudinal free strain value at −15℃ is only 10.5% lower than that at 40℃, so this kind of composite possesses a high temperature stability in the range of −15-60℃.
Piezoelectric fiber composite faces a challenge of an extremely wide temperature range when it is used in aerospace devices. So it is necessary to investigate the influence of temperature on the strain performance of piezoelectric fiber composite. In this paper, the free strain properties of piezoelectric fiber composites prepared using three kinds of polymer matrices were evaluated from −15℃ to 60℃. The results show that the free strain properties of all piezoelectric fiber composites are strongly dependent on the ambient temperature. The free strain values of piezoelectric fiber composites increase firstly and then decrease with the rising temperature. When the sinusoidal voltage of 0.1 Hz and −500 V-1 000 V is applied, the maximum longitudinal free strain values of the piezoelectric fiber composites with low glass transition temperature (Tg) and high Tg epoxy are 1 416×10−6 and 1 060×10−6 at 40℃, respectively. While the free strain value of the piezoelectric fiber composite with polyurethane reaches 2 361×10−6 at 30℃, which is 66.7% and 122.7% higher than the formers, respectively. The longitudinal free strain values of the piezoelectric fiber composites both with low Tg epoxy and polyurethane reduce about 27.5% as the temperature increases from −15℃ to 40℃. Although the longitudinal free strain of the piezoelectric fiber composite with high Tg epoxy is small, its longitudinal free strain value at −15℃ is only 10.5% lower than that at 40℃, so this kind of composite possesses a high temperature stability in the range of −15-60℃.
2021, 38(6): 1825-1837.
doi: 10.13801/j.cnki.fhclxb.20200827.001
Abstract:
In order to study the axial compression performance of glass fiber reinforced polymer (GFRP)-walled concrete-filled steel tube columns, the static axial compression tests were conducted on a group of non-GFRP constrained specimens and two groups of GFRP constrained specimens. According to the test results, a strong and weak constraint model of the wall column was proposed. Based on the twin-shear unified strength theory, the formula was established to calculate the axial compression bearing capacity of the GFRP-walled concrete-filled steel tube columns. Finally, the theoretical results, obtained through the establishment of the finite element model, were compared with the experimental results. And a parametric analysis was used to study the effect of the yield strength of steel and the strength of concrete on the axial compression performance of the new type wall-filled concrete-filled steel tube columns. The results show that the wall-filled concrete-filled steel tube columns eventually fail due to crushing of the concrete, buckling of the steel tube and excessive deformation of the specimens. At the beginning of the second linear section of the specimen, the steel begins to yield and its strength is fully exerted, which demonstrates that GFRP can effectively improve the peak load of the member, however, the ductility has decreased. The results of the theoretical formula are in agreement with the experimental results. The bearing capacity can be improved by increasing the strength of concrete and the yield strength of the steel. Compared with the strength of concrete, the yield strength of steel bars has a greater influence on the bearing capacity.
In order to study the axial compression performance of glass fiber reinforced polymer (GFRP)-walled concrete-filled steel tube columns, the static axial compression tests were conducted on a group of non-GFRP constrained specimens and two groups of GFRP constrained specimens. According to the test results, a strong and weak constraint model of the wall column was proposed. Based on the twin-shear unified strength theory, the formula was established to calculate the axial compression bearing capacity of the GFRP-walled concrete-filled steel tube columns. Finally, the theoretical results, obtained through the establishment of the finite element model, were compared with the experimental results. And a parametric analysis was used to study the effect of the yield strength of steel and the strength of concrete on the axial compression performance of the new type wall-filled concrete-filled steel tube columns. The results show that the wall-filled concrete-filled steel tube columns eventually fail due to crushing of the concrete, buckling of the steel tube and excessive deformation of the specimens. At the beginning of the second linear section of the specimen, the steel begins to yield and its strength is fully exerted, which demonstrates that GFRP can effectively improve the peak load of the member, however, the ductility has decreased. The results of the theoretical formula are in agreement with the experimental results. The bearing capacity can be improved by increasing the strength of concrete and the yield strength of the steel. Compared with the strength of concrete, the yield strength of steel bars has a greater influence on the bearing capacity.
2021, 38(6): 1838-1846.
doi: 10.13801/j.cnki.fhclxb.20200810.001
Abstract:
WF/HDPE composites were prepared by melt extrusion with poplar fiber (WF) as reinforcing material, high density polyethylene (HDPE) as matrix and maleic anhydride grafted polyethylene (MAPE) as coupling agent. The addition amount of WF, the addition amount of coupling agent and the extrusion temperature were selected as independent variables, and the impact strength, bending strength and tensile strength of the specimen were selected as the response value. The experiment was designed by Box-Behnken Design method and the secondary mathematical model of mechanical strength of WF/HDPE composites was established by the response surface method to optimize the extrusion process of the composites. The results show that the optimum levels of WF addition, MAPE addition and extrusion temperature are 47.37wt%, 4.23wt% and 173.69℃, respectively. The corresponding impact strength, bending strength and tensile strength of WF/HDPE composite are 4.06 kJ·m−2, 43.79 MPa and 28.59 MPa. The error between the predicted value of the model and the measured value is less than 5%, which well reflects the relationship between the mechanical properties and the factors of extrusion process of the WF/HDPE composites.
WF/HDPE composites were prepared by melt extrusion with poplar fiber (WF) as reinforcing material, high density polyethylene (HDPE) as matrix and maleic anhydride grafted polyethylene (MAPE) as coupling agent. The addition amount of WF, the addition amount of coupling agent and the extrusion temperature were selected as independent variables, and the impact strength, bending strength and tensile strength of the specimen were selected as the response value. The experiment was designed by Box-Behnken Design method and the secondary mathematical model of mechanical strength of WF/HDPE composites was established by the response surface method to optimize the extrusion process of the composites. The results show that the optimum levels of WF addition, MAPE addition and extrusion temperature are 47.37wt%, 4.23wt% and 173.69℃, respectively. The corresponding impact strength, bending strength and tensile strength of WF/HDPE composite are 4.06 kJ·m−2, 43.79 MPa and 28.59 MPa. The error between the predicted value of the model and the measured value is less than 5%, which well reflects the relationship between the mechanical properties and the factors of extrusion process of the WF/HDPE composites.
2021, 38(6): 1847-1858.
doi: 10.13801/j.cnki.fhclxb.20200824.001
Abstract:
To improve its structural performance, the multi-objective optimization of adhesively bonded single-lap joints of carbon fiber reinforced polymer (CFRP) laminates was carried out based on genetic algorithm. Firstly, finite element (FE) models were constructed using 3D Hashin damage criteria and triangle cohesive zone model (CZM), those well capture the intra-laminar, inter-laminar and adhesive damages during the tensile loads, respectively. And its effectiveness was verified through experiments. Secondly, using the Latin hypercube sampling (LHS) method and polynomial response surface method (RSM), a multi-objective optimization agent model with tensile strength and shear strength as the objective function was established based on lap the length, the adhesive thickness and the width of the bonded parts. Finally, the tensile strength and shear strength agent model was optimized to obtain Pareto solution set based on genetic algorithm (GA), and the Pareto solution set was sequenced by technique for order preference by similarity to ideal solution (TOPSIS) method to obtain the optimized single-bonded joint structure design scheme. The result shows that the experimental measurements of tensile load tests concur with the numerical predictions and validate the FE models. The tensile strength and shear strength of the adhesively bonded single-lap joints of CFRP laminates have a significant correlation with the lap length, the thickness of the adhesive layer and the width of the bonded parts. Compared with the numerical simulation results, the error of the quadratic response surface proxy model results is less than 2.3%. Compared with the conventional single lap bonding structure, the tensile strength and shear strength are increased by 2.65% and 17.24%, respectively.
To improve its structural performance, the multi-objective optimization of adhesively bonded single-lap joints of carbon fiber reinforced polymer (CFRP) laminates was carried out based on genetic algorithm. Firstly, finite element (FE) models were constructed using 3D Hashin damage criteria and triangle cohesive zone model (CZM), those well capture the intra-laminar, inter-laminar and adhesive damages during the tensile loads, respectively. And its effectiveness was verified through experiments. Secondly, using the Latin hypercube sampling (LHS) method and polynomial response surface method (RSM), a multi-objective optimization agent model with tensile strength and shear strength as the objective function was established based on lap the length, the adhesive thickness and the width of the bonded parts. Finally, the tensile strength and shear strength agent model was optimized to obtain Pareto solution set based on genetic algorithm (GA), and the Pareto solution set was sequenced by technique for order preference by similarity to ideal solution (TOPSIS) method to obtain the optimized single-bonded joint structure design scheme. The result shows that the experimental measurements of tensile load tests concur with the numerical predictions and validate the FE models. The tensile strength and shear strength of the adhesively bonded single-lap joints of CFRP laminates have a significant correlation with the lap length, the thickness of the adhesive layer and the width of the bonded parts. Compared with the numerical simulation results, the error of the quadratic response surface proxy model results is less than 2.3%. Compared with the conventional single lap bonding structure, the tensile strength and shear strength are increased by 2.65% and 17.24%, respectively.
2021, 38(6): 1859-1869.
doi: 10.13801/j.cnki.fhclxb.20200825.001
Abstract:
The isolation devices and dampers in architectural structure have large force and deformation under strong earthquake or wind, which requires high damping coefficient of damping material, suitable temperature matching with outdoor environment, and large damping temperature range. Currently, polyurethane damping materials are difficult to satisfy the above-mentioned performance indexes simultaneously, therefore they can not be widely used in structure engineering. In this paper, glass fiber, graphene, tetra-needle like ZnO whiskers (T-ZnOw) and hindered phenol were selected to improve the damping, mechanical properties and temperature properties. Through orthogonal design, polyurethane with different additions were prepared. And the robustness of loss peak value (tanδmax), damping temperature range (ΔT0.5) and glass transition temperature (Tg) were analyzed based on the dynamic thermomechanical analysis (DMA) test. According to the degree of importance of each index, weight assignment was carried out. The optimization scheme was obtained based on analytic hierarchy process (AHP), which is a multi-index weighting evaluation method. The validation test shows that tanδmax is 1.24, ΔT0.5 is 57℃, and Tg is 21.8℃.Compared with the initial group, the improvement rate of tanδmax reaches 16.98 %, and the improvement rate of ΔT0.5 reaches 46.91 %.
The isolation devices and dampers in architectural structure have large force and deformation under strong earthquake or wind, which requires high damping coefficient of damping material, suitable temperature matching with outdoor environment, and large damping temperature range. Currently, polyurethane damping materials are difficult to satisfy the above-mentioned performance indexes simultaneously, therefore they can not be widely used in structure engineering. In this paper, glass fiber, graphene, tetra-needle like ZnO whiskers (T-ZnOw) and hindered phenol were selected to improve the damping, mechanical properties and temperature properties. Through orthogonal design, polyurethane with different additions were prepared. And the robustness of loss peak value (tanδmax), damping temperature range (ΔT0.5) and glass transition temperature (Tg) were analyzed based on the dynamic thermomechanical analysis (DMA) test. According to the degree of importance of each index, weight assignment was carried out. The optimization scheme was obtained based on analytic hierarchy process (AHP), which is a multi-index weighting evaluation method. The validation test shows that tanδmax is 1.24, ΔT0.5 is 57℃, and Tg is 21.8℃.Compared with the initial group, the improvement rate of tanδmax reaches 16.98 %, and the improvement rate of ΔT0.5 reaches 46.91 %.
2021, 38(6): 1870-1881.
doi: 10.13801/j.cnki.fhclxb.20200904.001
Abstract:
In engineering practice, glass fiber reinforced polymer (GFRP)-concrete composite beams usually fail as a result of larger damages, and hence it is of great significance to study the damage process. In order to study the damage characteristics of such components, four-point bending loading tests were carried out for a GFRP I-beam and six GFRP-concrete composite beams connected by different bolts, and the whole process was monitored by an acoustic emission (AE) device. On the basis of the phase-space reconstruction of the AE energy signals, the fractal dimension of AE energy signals were calculated in each loading stage. The results show that the time serials of AE energy is of fractal characteristics. The dimension can well describe the complete damage stages; The evolution of the fractal dimension curve of AE energy time series is summarized: the mode in pure bending section is “early peak” to “low amplitude fluctuation”; the mode in shear span area is “low amplitude fluctuation” to “continuous high amplitude fluctuation”; by comparing the phenomenon of loading process of test beam with the evolution of fractal dimension value, the “sustained high amplitude fluctuation” of the fractal dimension can be regarded as the precursor of the instability of the test beam. According to the dimension, the possibility of “early warning” was proposed. Early warning points can be identified when there is enduring high-amplitude fluctuation for corresponding fractal dimension. The bearing capacity of the structure has reached about 70% of the allowable extreme, suggesting necessary intensified monitor.
In engineering practice, glass fiber reinforced polymer (GFRP)-concrete composite beams usually fail as a result of larger damages, and hence it is of great significance to study the damage process. In order to study the damage characteristics of such components, four-point bending loading tests were carried out for a GFRP I-beam and six GFRP-concrete composite beams connected by different bolts, and the whole process was monitored by an acoustic emission (AE) device. On the basis of the phase-space reconstruction of the AE energy signals, the fractal dimension of AE energy signals were calculated in each loading stage. The results show that the time serials of AE energy is of fractal characteristics. The dimension can well describe the complete damage stages; The evolution of the fractal dimension curve of AE energy time series is summarized: the mode in pure bending section is “early peak” to “low amplitude fluctuation”; the mode in shear span area is “low amplitude fluctuation” to “continuous high amplitude fluctuation”; by comparing the phenomenon of loading process of test beam with the evolution of fractal dimension value, the “sustained high amplitude fluctuation” of the fractal dimension can be regarded as the precursor of the instability of the test beam. According to the dimension, the possibility of “early warning” was proposed. Early warning points can be identified when there is enduring high-amplitude fluctuation for corresponding fractal dimension. The bearing capacity of the structure has reached about 70% of the allowable extreme, suggesting necessary intensified monitor.
2021, 38(6): 1882-1889.
doi: 10.13801/j.cnki.fhclxb.20200922.005
Abstract:
A facie solid-state route has been employed to synthesize LiNi0.8Co0.1Mn0.1O2 material with superior electrochemical performance by varying the oxygen flow rate during the calcination process, and the effect of different oxygen flow rates on the structure and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 has also been investigated. It reveals that the LiNi0.8Co0.1Mn0.1O2 material synthesized under a flow rate of 0.1 L/min has the lowest degree of cation mixing among all samples and large d-space. The 0.1 L/min sample shows a discharge capacity of 174 mA·h·g−1 after 100 cycles at 1 C, corresponding to the capacity retention rate of 98.3%. A retention rate as high as 96.8% is achieved at 2 C, and good performance is also obtained in high cut-off votage test. Moreover, we confirm that low oxygen-flow rate can lead to high degree of cation mixing because of high content of Ni2+, and high oxygen-flow rate can decrease the d-spacing of LiNi0.8Co0.1Mn0.1O2 material, thereby being harmful for the Li+ intercalation/deintercalation.
A facie solid-state route has been employed to synthesize LiNi0.8Co0.1Mn0.1O2 material with superior electrochemical performance by varying the oxygen flow rate during the calcination process, and the effect of different oxygen flow rates on the structure and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 has also been investigated. It reveals that the LiNi0.8Co0.1Mn0.1O2 material synthesized under a flow rate of 0.1 L/min has the lowest degree of cation mixing among all samples and large d-space. The 0.1 L/min sample shows a discharge capacity of 174 mA·h·g−1 after 100 cycles at 1 C, corresponding to the capacity retention rate of 98.3%. A retention rate as high as 96.8% is achieved at 2 C, and good performance is also obtained in high cut-off votage test. Moreover, we confirm that low oxygen-flow rate can lead to high degree of cation mixing because of high content of Ni2+, and high oxygen-flow rate can decrease the d-spacing of LiNi0.8Co0.1Mn0.1O2 material, thereby being harmful for the Li+ intercalation/deintercalation.
2021, 38(6): 1890-1904.
doi: 10.13801/j.cnki.fhclxb.20201010.001
Abstract:
Carbon supported cerium doped zinc oxide composite material was prepared using bamboo as carbon source, ZnCl2 as zinc source, Ce(NO3)3·6H2O as cerium source, in one-pot method. These materials were fully characterized by XRD, FTIR, SEM, EDS, BET, XPS, UV-Vis diffuse reflection spectrum (DRS) and photoluminescence spectroscopy (PL). Their properties in photocatalytic degradation of organic dyes were studied at the same time. The optimized preparing condition of the material was obtained as follows: impregnation ratio of ZnCl2 to bamboo is 3∶10 by mass, calcination temperature is 500℃ and the addition amount of ZnCl2 is 2.5% of bamboo. The degradation rates of methylene blue (MB) under sunlight and ultraviolet are 92.2% and 93.7%, respectively, under the following condition: dark adsorption time 20 min, illumination time 120 min, 50 mL MB (10 mg·L−1) and catalyst amount 40 mg. Moreover, kinetic studies of the reaction proved that the photocatalytic degradation of MB catalyzed by this material follows the first order reaction kinetics principle. And the catalyst can be reused several times.
Carbon supported cerium doped zinc oxide composite material was prepared using bamboo as carbon source, ZnCl2 as zinc source, Ce(NO3)3·6H2O as cerium source, in one-pot method. These materials were fully characterized by XRD, FTIR, SEM, EDS, BET, XPS, UV-Vis diffuse reflection spectrum (DRS) and photoluminescence spectroscopy (PL). Their properties in photocatalytic degradation of organic dyes were studied at the same time. The optimized preparing condition of the material was obtained as follows: impregnation ratio of ZnCl2 to bamboo is 3∶10 by mass, calcination temperature is 500℃ and the addition amount of ZnCl2 is 2.5% of bamboo. The degradation rates of methylene blue (MB) under sunlight and ultraviolet are 92.2% and 93.7%, respectively, under the following condition: dark adsorption time 20 min, illumination time 120 min, 50 mL MB (10 mg·L−1) and catalyst amount 40 mg. Moreover, kinetic studies of the reaction proved that the photocatalytic degradation of MB catalyzed by this material follows the first order reaction kinetics principle. And the catalyst can be reused several times.
2021, 38(6): 1905-1913.
doi: 10.13801/j.cnki.fhclxb.20200923.002
Abstract:
High-temperature saturated steam was firstly applied to pre-treat fresh moso bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) culms with high moisture content, and then bamboo fibers were extracted from the thermal treated bamboo culms by rolling. And then the microstructure, chemical composition, mechanical behavior, and hygroscopic properties of the extracted fibers were analyzed by using optical microscopy, nanoindentation (NI) and so forth. Results indicate that the vascular bundles and parenchymatous cells in bamboo culms have been effectively seperated due to the degradation of hemicellulose after the steam and mechanical treatment. The degradation of hemicelluloses, increaed relative lignin content and cellulose crystallinity (CrI) upon thermal treatment make a major contribution to the reduced hygroscopicity and increase of reduced elastic modulus (Er) and hardness (H) of fiber cell walls. The maximum tensile strength and modulus of bamboo fibers are 765 MPa and 24.8 GPa, respectively, which are not obviously affected by steam treatment. However, there are some differences in the properties of bamboo fibers extracted from different parts in bamboo culms. The dimensions of fibers from outerlayer are larger than that of inner layer and the tensile properties of fibers from bamboo culms without nodes are higher than that of bamboo culms near the nodes. Thus, multilayer extraction and classifiedutilization of bamboo fibers should be considered in its potential application.
High-temperature saturated steam was firstly applied to pre-treat fresh moso bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) culms with high moisture content, and then bamboo fibers were extracted from the thermal treated bamboo culms by rolling. And then the microstructure, chemical composition, mechanical behavior, and hygroscopic properties of the extracted fibers were analyzed by using optical microscopy, nanoindentation (NI) and so forth. Results indicate that the vascular bundles and parenchymatous cells in bamboo culms have been effectively seperated due to the degradation of hemicellulose after the steam and mechanical treatment. The degradation of hemicelluloses, increaed relative lignin content and cellulose crystallinity (CrI) upon thermal treatment make a major contribution to the reduced hygroscopicity and increase of reduced elastic modulus (Er) and hardness (H) of fiber cell walls. The maximum tensile strength and modulus of bamboo fibers are 765 MPa and 24.8 GPa, respectively, which are not obviously affected by steam treatment. However, there are some differences in the properties of bamboo fibers extracted from different parts in bamboo culms. The dimensions of fibers from outerlayer are larger than that of inner layer and the tensile properties of fibers from bamboo culms without nodes are higher than that of bamboo culms near the nodes. Thus, multilayer extraction and classifiedutilization of bamboo fibers should be considered in its potential application.
2021, 38(6): 1914-1921.
doi: 10.13801/j.cnki.fhclxb.20200928.006
Abstract:
Based on Al2O3 modified expanded perlite (mEP), floating visible-light responsive photocatalysts Ag2CrO4-g-C3N4-TiO2/mEP were prepared via a sol-gel-impregnation deposition method. The synthesized photocatalysts were characterized using XRD, N2 adsorption/desorption, FESEM-EDS, XPS and UV-vis DRS. The results show that the concentration of Ag2CrO4 has influence on the crystal structure and specific surface area of the photocatalysts. High concentration of Ag2CrO4 could form agglomerated particles on the surface of the photocatalyst which are not conductive to the adsorption and photocatalytic inactivation of algae. When the theoretical molar ratio of Ag2CrO4/TiO2 is 0.05 and the initial algal cell concentration of Microcystis aeruginosa is 2.75×106 cells/mL, the removal rate of algal after adsorption for 8 h was 10.3%. Under the synergistic effect of adsorption and photocatalysis, the removal rate of algal could reach 81.88%. The inactivation of algae cell mainly ascribed to the attack by the photo-generated holes (h+). The removal rate of algae could reach to 72.19% after three successive cycles which indicated the stability of the photocatalst.
Based on Al2O3 modified expanded perlite (mEP), floating visible-light responsive photocatalysts Ag2CrO4-g-C3N4-TiO2/mEP were prepared via a sol-gel-impregnation deposition method. The synthesized photocatalysts were characterized using XRD, N2 adsorption/desorption, FESEM-EDS, XPS and UV-vis DRS. The results show that the concentration of Ag2CrO4 has influence on the crystal structure and specific surface area of the photocatalysts. High concentration of Ag2CrO4 could form agglomerated particles on the surface of the photocatalyst which are not conductive to the adsorption and photocatalytic inactivation of algae. When the theoretical molar ratio of Ag2CrO4/TiO2 is 0.05 and the initial algal cell concentration of Microcystis aeruginosa is 2.75×106 cells/mL, the removal rate of algal after adsorption for 8 h was 10.3%. Under the synergistic effect of adsorption and photocatalysis, the removal rate of algal could reach 81.88%. The inactivation of algae cell mainly ascribed to the attack by the photo-generated holes (h+). The removal rate of algae could reach to 72.19% after three successive cycles which indicated the stability of the photocatalst.
2021, 38(6): 1922-1928.
doi: 10.13801/j.cnki.fhclxb.20201030.001
Abstract:
Flexible Ti3C2Tx MXene/polyvinyl alcohol (PVA) composites with high dielectric constant were fabricated by using the solution casting method with two-dimensional transition metal carbide Ti3C2Tx MXene as the filler and non-ferroelectric and biodegradable polyvinyl alcohol (PVA) as the matrix. The effect of Ti3C2Tx MXene loading on the dielectric properties of the composites were investigated. The variation of dielectric properties of the Ti3C2Tx MXene/PVA composites conforms to the percolation theory. With the increase of Ti3C2Tx MXene loading, the dielectric constant of Ti3C2Tx MXene/PVA composites first increases and then decreases. The composites show a dielectric constant up to 577.3 at 20 Hz frequency with Ti3C2Tx MXene loading of 20wt%, a 5 398% increase compared with that of the neat PVA matrix. When the Ti3C2Tx MXene loading exceeds 20wt%, the dielectric constant of the Ti3C2Tx MXene/PVA composites decreases sharply and the dielectric loss increases rapidly, showing obvious percolation behavior.
Flexible Ti3C2Tx MXene/polyvinyl alcohol (PVA) composites with high dielectric constant were fabricated by using the solution casting method with two-dimensional transition metal carbide Ti3C2Tx MXene as the filler and non-ferroelectric and biodegradable polyvinyl alcohol (PVA) as the matrix. The effect of Ti3C2Tx MXene loading on the dielectric properties of the composites were investigated. The variation of dielectric properties of the Ti3C2Tx MXene/PVA composites conforms to the percolation theory. With the increase of Ti3C2Tx MXene loading, the dielectric constant of Ti3C2Tx MXene/PVA composites first increases and then decreases. The composites show a dielectric constant up to 577.3 at 20 Hz frequency with Ti3C2Tx MXene loading of 20wt%, a 5 398% increase compared with that of the neat PVA matrix. When the Ti3C2Tx MXene loading exceeds 20wt%, the dielectric constant of the Ti3C2Tx MXene/PVA composites decreases sharply and the dielectric loss increases rapidly, showing obvious percolation behavior.
2021, 38(6): 1929-1938.
doi: 10.13801/j.cnki.fhclxb.20200924.001
Abstract:
In this paper, SA@Fe3O4/L-met used sodium alginate (SA) as matrix precursor material, with magnetic composite gel balls obtained by immobilizing iron trioxide (Fe3O4) and L-methionine (L-met) by ion cross-linking. The influence of pH, dosage and initial concentration on Pb(Ⅱ) adsorption was explored. The results show that at pH=5, the dosage is 0.5 g·L−1, the initial concentration is 20 mg·L−1, SA@Fe3O4/L-met can achieve better adsorption efficiency for Pb(Ⅱ), and the maximum adsorption amount can reach 328.02 mg·g−1, much larger than the adsorption capacity of SA@Fe3O4 and SA, 142.5 mg·g−1 and 152.8 mg·g−1. Studies on adsorption kinetics and thermodynamics show that the adsorption process is aligned with the second-order kinetic equation and Langmuir equation to a greater degree of fit, and the reaction process is a process of entropy increase and heat absorption. The structure and performance of the gel sphere were characterized by using SEM, XPS and VSM. It was found that the amino groups, carboxyl groups and hydroxyl groups in the gel ball participating in the reaction process, combining with Pb(Ⅱ), and there also exists ion exchange. After 5 times of desorption, the adsorption capacity of the material can still reach 210.5 mg·g−1, which is an ideal environmentally friendly adsorbent.
In this paper, SA@Fe3O4/L-met used sodium alginate (SA) as matrix precursor material, with magnetic composite gel balls obtained by immobilizing iron trioxide (Fe3O4) and L-methionine (L-met) by ion cross-linking. The influence of pH, dosage and initial concentration on Pb(Ⅱ) adsorption was explored. The results show that at pH=5, the dosage is 0.5 g·L−1, the initial concentration is 20 mg·L−1, SA@Fe3O4/L-met can achieve better adsorption efficiency for Pb(Ⅱ), and the maximum adsorption amount can reach 328.02 mg·g−1, much larger than the adsorption capacity of SA@Fe3O4 and SA, 142.5 mg·g−1 and 152.8 mg·g−1. Studies on adsorption kinetics and thermodynamics show that the adsorption process is aligned with the second-order kinetic equation and Langmuir equation to a greater degree of fit, and the reaction process is a process of entropy increase and heat absorption. The structure and performance of the gel sphere were characterized by using SEM, XPS and VSM. It was found that the amino groups, carboxyl groups and hydroxyl groups in the gel ball participating in the reaction process, combining with Pb(Ⅱ), and there also exists ion exchange. After 5 times of desorption, the adsorption capacity of the material can still reach 210.5 mg·g−1, which is an ideal environmentally friendly adsorbent.
2021, 38(6): 1939-1949.
doi: 10.13801/j.cnki.fhclxb.20200922.004
Abstract:
In order to explore the feasibility of preparing high-efficiency adsorption material with agricultural waste corncobs as raw material to remove heavy metal ions from aqueous solution, a large number of carboxyl groups with strong affinity for heavy metal ions were grafted onto the surface of corncobs using atom transfer radical polymerization (ATRP) technology to obtain the sodium acrylate-corncobs graft copolymers (MC-g-PGMA-g-PAA-Na). Thermogravimetry, fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray energy spectrum (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize MC-g-PGMA-g-PAA-Na before and after adsorption of Ni2+ for studying its adsorption mechanism. The results show that MC-g-PGMA-g-PAA-Na can effectively remove Ni2+ in aqueous solution. The carboxyl content in MC-g-PGMA-g-PAA-Na reaches 6.02 mmol·g−1 and is 35.4 times that before modification. It is proved that when MC-g-PGMA-g-PAA-Na is contacted with a solution containing Ni2+, the carboxyl groups contained in MC-g-PGMA-g-PAA-Na act on Ni2+ to adsorb Ni2+ in the solution and form carboxylic acid nickel. The valence of Ni2+ do not change before and after adsorption. The coordination mode of carboxyl and Ni2+ is mainly a bidentate bridge. At the same time, all Na+ contained in MC-g-PGMA-g-PAA-Na are released into the solution, indicating that the process of adsorption of Ni2+ in the solution is accompanied by cation exchange between Na+ and Ni2+.
In order to explore the feasibility of preparing high-efficiency adsorption material with agricultural waste corncobs as raw material to remove heavy metal ions from aqueous solution, a large number of carboxyl groups with strong affinity for heavy metal ions were grafted onto the surface of corncobs using atom transfer radical polymerization (ATRP) technology to obtain the sodium acrylate-corncobs graft copolymers (MC-g-PGMA-g-PAA-Na). Thermogravimetry, fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray energy spectrum (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize MC-g-PGMA-g-PAA-Na before and after adsorption of Ni2+ for studying its adsorption mechanism. The results show that MC-g-PGMA-g-PAA-Na can effectively remove Ni2+ in aqueous solution. The carboxyl content in MC-g-PGMA-g-PAA-Na reaches 6.02 mmol·g−1 and is 35.4 times that before modification. It is proved that when MC-g-PGMA-g-PAA-Na is contacted with a solution containing Ni2+, the carboxyl groups contained in MC-g-PGMA-g-PAA-Na act on Ni2+ to adsorb Ni2+ in the solution and form carboxylic acid nickel. The valence of Ni2+ do not change before and after adsorption. The coordination mode of carboxyl and Ni2+ is mainly a bidentate bridge. At the same time, all Na+ contained in MC-g-PGMA-g-PAA-Na are released into the solution, indicating that the process of adsorption of Ni2+ in the solution is accompanied by cation exchange between Na+ and Ni2+.
2021, 38(6): 1950-1959.
doi: 10.13801/j.cnki.fhclxb.20200921.001
Abstract:
The chitosan (CS)-polylactic acid (PLA) spinning solution was prepared using a composite solution of trifluoroacetic acid (TFA) and dichloromethane (DCM) as the solvent, and CS and PLA as the solute. Electrospinning and template coiling were used to prepare CS-PLA composite nerve conduit, and the comprehensive properties of CS-PLA composites were investigated. By characterizing the structure and properties of composites, the molecular interactions in CS and PLA systems were analyzed. Furthermore, through the co-cultivation experiments of composite nerve conduit and Schwann cells, the best system components for Schwann cells to grow and adhere to the inner wall of the catheter were proposed and verified. The results show that CS and PLA molecules are bonded by hydrogen bonds in the composite material, and the various hydrogen bond contributions are in the order of OH...OH>OH...N>OH...ether O. With the increase of PLA content, the thermal performance and thermal stability of the composites are increased, the tensile strength is increased by 197.7%, and the breaking elongation is increased by 53.7%. With the increase of CS content, the hydrophilicity and cell compatibility of the composites gradually increase. When the component ratio of CS∶PLA is 3∶1, the size of the grooves and micropores is the most favorable for Schwann cell adhesion.
The chitosan (CS)-polylactic acid (PLA) spinning solution was prepared using a composite solution of trifluoroacetic acid (TFA) and dichloromethane (DCM) as the solvent, and CS and PLA as the solute. Electrospinning and template coiling were used to prepare CS-PLA composite nerve conduit, and the comprehensive properties of CS-PLA composites were investigated. By characterizing the structure and properties of composites, the molecular interactions in CS and PLA systems were analyzed. Furthermore, through the co-cultivation experiments of composite nerve conduit and Schwann cells, the best system components for Schwann cells to grow and adhere to the inner wall of the catheter were proposed and verified. The results show that CS and PLA molecules are bonded by hydrogen bonds in the composite material, and the various hydrogen bond contributions are in the order of OH...OH>OH...N>OH...ether O. With the increase of PLA content, the thermal performance and thermal stability of the composites are increased, the tensile strength is increased by 197.7%, and the breaking elongation is increased by 53.7%. With the increase of CS content, the hydrophilicity and cell compatibility of the composites gradually increase. When the component ratio of CS∶PLA is 3∶1, the size of the grooves and micropores is the most favorable for Schwann cell adhesion.
2021, 38(6): 1960-1973.
doi: 10.13801/j.cnki.fhclxb.20200928.002
Abstract:
In this paper, MnO2-polydopamine (PDA)/polyvinyl alcohol (PVA) and MnO2-PVA-5-fluorouracil (5-Fu)/PVA composite microspheres were prepared by electrospinning. Specifically, dopamine (DA) and KMnO4 were added to the PVA solution, where a redox reaction happened between DA and KMnO4 to form PDA and MnO2. Thus, the MnO2-PDA/PVA microspheres were prepared by electrospinning the MnO2-PDA/PVA solution. MnO2-PDA-5-Fu/PVA microspheres were prepared by electrospinning the MnO2-PDA-5-Fu/PVA solution, which was prepared by directly dissolving 5-Fu in the MnO2-PDA/PVA solution. The water stability of the electrospun microspheres was given by a glutaraldehyde crosslinking method. The composite microspheres have excellent photothermal conversion, controlled drug release and good biosafety, which were used to prevent the recurrence of tumor after the operation. The photothermal conversion efficiency of MnO2-PDA-5-Fu/PVA microspheres reaches 24.5% under the irradiation of 808 nm NIR laser, which can achieve the efficient tumor thermal ablation; on the other hand, the released 5-Fu can kill the residual tumor cells after operation. This study confirms the application potential of the microspheres in the field of preventing tumor recurrence, and provides a new strategy for the design of multifunctional composite nanomaterials.
In this paper, MnO2-polydopamine (PDA)/polyvinyl alcohol (PVA) and MnO2-PVA-5-fluorouracil (5-Fu)/PVA composite microspheres were prepared by electrospinning. Specifically, dopamine (DA) and KMnO4 were added to the PVA solution, where a redox reaction happened between DA and KMnO4 to form PDA and MnO2. Thus, the MnO2-PDA/PVA microspheres were prepared by electrospinning the MnO2-PDA/PVA solution. MnO2-PDA-5-Fu/PVA microspheres were prepared by electrospinning the MnO2-PDA-5-Fu/PVA solution, which was prepared by directly dissolving 5-Fu in the MnO2-PDA/PVA solution. The water stability of the electrospun microspheres was given by a glutaraldehyde crosslinking method. The composite microspheres have excellent photothermal conversion, controlled drug release and good biosafety, which were used to prevent the recurrence of tumor after the operation. The photothermal conversion efficiency of MnO2-PDA-5-Fu/PVA microspheres reaches 24.5% under the irradiation of 808 nm NIR laser, which can achieve the efficient tumor thermal ablation; on the other hand, the released 5-Fu can kill the residual tumor cells after operation. This study confirms the application potential of the microspheres in the field of preventing tumor recurrence, and provides a new strategy for the design of multifunctional composite nanomaterials.
2021, 38(6): 1974-1983.
doi: 10.13801/j.cnki.fhclxb.20200831.002
Abstract:
The interaction between the composite laminate structure and the mold during the autoclave curing process was studied to improve the manufacturing accuracy. Considering the joint effect of frictional force and adhesive force at the contact interface between the mold and the component, a numerical calculation model for curing strain and stress of the composite laminate structure was improved and compared with the existing experimental results. The spring element was introduced to establish a finite element model of the curing process and used to verify the analytical model. Finally, the influencing factors of curing deformation were explored through the analytical model. The results show that the analytical forecast model established has high calculation accuracy and practicability. The finite element model considering the role of the mold can better predict the deformation trend of the laminate. Through analytical model exploration, it is found that the length of the laminate, the mold material and the surface condition will have an effect on the interlayer slip during the curing process, which has a better guiding significance for the formulation of process conditions.
The interaction between the composite laminate structure and the mold during the autoclave curing process was studied to improve the manufacturing accuracy. Considering the joint effect of frictional force and adhesive force at the contact interface between the mold and the component, a numerical calculation model for curing strain and stress of the composite laminate structure was improved and compared with the existing experimental results. The spring element was introduced to establish a finite element model of the curing process and used to verify the analytical model. Finally, the influencing factors of curing deformation were explored through the analytical model. The results show that the analytical forecast model established has high calculation accuracy and practicability. The finite element model considering the role of the mold can better predict the deformation trend of the laminate. Through analytical model exploration, it is found that the length of the laminate, the mold material and the surface condition will have an effect on the interlayer slip during the curing process, which has a better guiding significance for the formulation of process conditions.
