2021 Vol. 38, No. 8
Preparation of tetra-needle-like zinc oxide whiskers/natural rubber antibacterial medical composites
2021, 38(8): 2694-2705.
doi: 10.13801/j.cnki.fhclxb.20201102.001
Abstract:
The sodium stearate-tetra-needle-like zinc oxide whiskers (T-ZnOw)/natural rubber (NR) antibacterial medical composites were prepared by introducing the sodium stearate-T-ZnOw ultrasonic dispersion into natural rubber latex (NRL) matrix. The comprehensive mechanical properties, antibacterial properties and thermal stability properties of the composites were systematically studied. The results show that when sodium stearate-T-ZnOw loading of 3wt%, the mechanical properties and thermal stability properties of the composites achieve optimum results. Compared with the pure NR, the shore a hardness, modulus at 300%, tensile strength, tear strength and elongation at break of composites are increased by 8.6%, 25.4%, 20.3%, 25.6% and 6.4%, respectively; The initial thermal degradation temperature (T0) and the termination thermal degradation temperature (Tf) of the composites are increased by 21.2℃ and 5.9℃. When the content of sodium stearate-T-ZnOw exceeds 3wt%, it can inhibit the growth of Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii and Staphylococcus epidermidis in natural rubber latex. It can enter bacterial cells, resulting in cell wall damage, cell leakage, cell death.
The sodium stearate-tetra-needle-like zinc oxide whiskers (T-ZnOw)/natural rubber (NR) antibacterial medical composites were prepared by introducing the sodium stearate-T-ZnOw ultrasonic dispersion into natural rubber latex (NRL) matrix. The comprehensive mechanical properties, antibacterial properties and thermal stability properties of the composites were systematically studied. The results show that when sodium stearate-T-ZnOw loading of 3wt%, the mechanical properties and thermal stability properties of the composites achieve optimum results. Compared with the pure NR, the shore a hardness, modulus at 300%, tensile strength, tear strength and elongation at break of composites are increased by 8.6%, 25.4%, 20.3%, 25.6% and 6.4%, respectively; The initial thermal degradation temperature (T0) and the termination thermal degradation temperature (Tf) of the composites are increased by 21.2℃ and 5.9℃. When the content of sodium stearate-T-ZnOw exceeds 3wt%, it can inhibit the growth of Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii and Staphylococcus epidermidis in natural rubber latex. It can enter bacterial cells, resulting in cell wall damage, cell leakage, cell death.
2021, 38(8): 2706-2714.
doi: 10.13801/j.cnki.fhclxb.20201011.003
Abstract:
TiO2/C-ATP composites consisting of palmerworm-like TiO2 nanorods in-situ growth on the surface of conductive attapulgite (C-ATP) were constructed via a hydrothermal approach. Then TiO2/C-ATP was used as the carrier to uniformly load carbon nitride quantum dots (CNQD) to successfully prepare hierarchical CNQD-TiO2/C-ATP heterojunction photocatalysts. The obtained samples were characterized by XRD, FTIR, SEM/TEM, ultraviolet-visible (UV-Vis-DRS), photoluminescence (PL), Brunauer-emmett-teller (BET) specific area analyzer and photoelectrochemistry. The degradation ability of the sample to tetracycline hydrochloride (TC) was investigated under visible light. The results show that CNQD-TiO2/C-ATP composites dramatically enhance the visible light response, the absorption capacity and the separation of photogenerated electron-hole pairs compared to TiO2/C-ATP and CNQD. After 120 min irradiation, the degradation rate of CNQD-TiO2/C-ATP to remove TC can achieve 88%.
TiO2/C-ATP composites consisting of palmerworm-like TiO2 nanorods in-situ growth on the surface of conductive attapulgite (C-ATP) were constructed via a hydrothermal approach. Then TiO2/C-ATP was used as the carrier to uniformly load carbon nitride quantum dots (CNQD) to successfully prepare hierarchical CNQD-TiO2/C-ATP heterojunction photocatalysts. The obtained samples were characterized by XRD, FTIR, SEM/TEM, ultraviolet-visible (UV-Vis-DRS), photoluminescence (PL), Brunauer-emmett-teller (BET) specific area analyzer and photoelectrochemistry. The degradation ability of the sample to tetracycline hydrochloride (TC) was investigated under visible light. The results show that CNQD-TiO2/C-ATP composites dramatically enhance the visible light response, the absorption capacity and the separation of photogenerated electron-hole pairs compared to TiO2/C-ATP and CNQD. After 120 min irradiation, the degradation rate of CNQD-TiO2/C-ATP to remove TC can achieve 88%.
2021, 38(8): 2715-2723.
doi: 10.13801/j.cnki.fhclxb.20201113.001
Abstract:
The coated bamboo fibres (PUBF) were obtained by using high-reactivity polyurethane (PU) coating agent to coat bamboo fibres (BF), and the mass fraction of isocyanate group (—NCO) in PU coating agent was 14.5wt%. The PUBF/PU casting elastomer composites were prepared by in-stiu polymerization. The BF and PUBF were characterized by FTIR, SEM, XRD and contact angle testing. The results show that the surface of the BF is successfully coated by a thin layer of PU terminated with reactive amino groups (—NH2), which improves the interface compatibility and interfacial bonding between the BF and the casting PU. When the mass fraction of PUBF in the composite is 3wt%, the viscosity of the prepolymer at 80℃ is only 2.2 Pa·s, which is close to the viscosity of the pure PU. The tensile and tear strengths of the corresponding PUBF/PU composite are 38.0 MPa and 82.9 kN/m, respectively, improved by 51.6% and 25.6% compared with the pure casting PU. The BF pre-coated by high-reactivity PU coating agent is suitable for preparing the PUBF/PU composite.
The coated bamboo fibres (PUBF) were obtained by using high-reactivity polyurethane (PU) coating agent to coat bamboo fibres (BF), and the mass fraction of isocyanate group (—NCO) in PU coating agent was 14.5wt%. The PUBF/PU casting elastomer composites were prepared by in-stiu polymerization. The BF and PUBF were characterized by FTIR, SEM, XRD and contact angle testing. The results show that the surface of the BF is successfully coated by a thin layer of PU terminated with reactive amino groups (—NH2), which improves the interface compatibility and interfacial bonding between the BF and the casting PU. When the mass fraction of PUBF in the composite is 3wt%, the viscosity of the prepolymer at 80℃ is only 2.2 Pa·s, which is close to the viscosity of the pure PU. The tensile and tear strengths of the corresponding PUBF/PU composite are 38.0 MPa and 82.9 kN/m, respectively, improved by 51.6% and 25.6% compared with the pure casting PU. The BF pre-coated by high-reactivity PU coating agent is suitable for preparing the PUBF/PU composite.
2021, 38(8): 2724-2736.
doi: 10.13801/j.cnki.fhclxb.20201013.001
Abstract:
To explore how the interaction among factors influences the strength of filling body, and reveal the action mechanism of hydration products from cement materials, a test was designed by Box-Behnken response surface methodology (RSM) for establishing a quadratic polynomial regression model in combination with independent variable parameters of numencial function optimization model. In the design, the added quantities of cement, lime and gypsum were taken as independent variable influence factors, and the compressive strength of cement body as the response target values. Finally, XRD, SEM and EDS analysis methods were utilized to discuss the composition and microstructure morphology of the hydration products from paste samples. The results show that the ANOVA and the response surface of the model jointly explain that the interaction between cement and lime quantities added is the critical factor influencing the strength of filling body. After optimizing the mixture ratio of the composite filling slurry, when the ratio of cement∶lime∶gypsum∶slag∶calcium formate is optimal as 30∶15∶1∶50∶4, the 3 days and 7 days compressive strength values of the cement body are 1.19 MPa and 2.17 MPa, respectively. The relative errors of the model validation tests are 3.25% and 0.93%, which indicates that the model is precise and reliable. The main hydration products of the composite cementitious system are AFt and C-S-H gels, which stagger and overlap closely with age, thus forming a dense 3D spatial network structure support system as the main source of strength for the cemented filling body.
To explore how the interaction among factors influences the strength of filling body, and reveal the action mechanism of hydration products from cement materials, a test was designed by Box-Behnken response surface methodology (RSM) for establishing a quadratic polynomial regression model in combination with independent variable parameters of numencial function optimization model. In the design, the added quantities of cement, lime and gypsum were taken as independent variable influence factors, and the compressive strength of cement body as the response target values. Finally, XRD, SEM and EDS analysis methods were utilized to discuss the composition and microstructure morphology of the hydration products from paste samples. The results show that the ANOVA and the response surface of the model jointly explain that the interaction between cement and lime quantities added is the critical factor influencing the strength of filling body. After optimizing the mixture ratio of the composite filling slurry, when the ratio of cement∶lime∶gypsum∶slag∶calcium formate is optimal as 30∶15∶1∶50∶4, the 3 days and 7 days compressive strength values of the cement body are 1.19 MPa and 2.17 MPa, respectively. The relative errors of the model validation tests are 3.25% and 0.93%, which indicates that the model is precise and reliable. The main hydration products of the composite cementitious system are AFt and C-S-H gels, which stagger and overlap closely with age, thus forming a dense 3D spatial network structure support system as the main source of strength for the cemented filling body.
2021, 38(8): 2737-2746.
doi: 10.13801/j.cnki.fhclxb.20210430.001
Abstract:
The early-age shrinkage, crack resistance and mechanical properties of high strength manufactured sand concrete containing a large amount of high absorbency stone powder were conducted in order to solve the early-age shrinkage and cracking problem of concrete by adding expansion agent, shrinkage reducing agent, polyvinyl alcohol (PVA) fiber, super absorbent polymer (SAP). The mechanism of inhibiting shrinkage and cracking of high strength manufactured sand concrete containing a large amount of high absorbency stone powder was revealed by testing pore structure and microstructure morphology using low-field nuclear magnetic spectroscopy and scanning electron microscope. The test results show that the addition of expansion agent, shrinkage reducing agent, PVA fiber and pre-absorbent SAP can all effectively inhibit the early-age shrinkage and cracking of concrete. Compared with the benchmark group concrete, incorporating pre-absorbent SAP is the best measure to reduce the early-age shrinkage of concrete and the shrinkage strain will be reduced by 93%. The most obvious inhibitory effect on the cracking of concrete is incorporating PVA fiber and the total cracking area can be reduced by 68.26%. The mechanical properties of the concrete are improved because of pre-absorbent SAP and PVA fiber. However, the mechanical properties of concrete have a certain decrease because of incorporating expansion agent and shrinkage reducing agent. SEM images show that SAP can release the pre-absorbed water into the concrete and promote the cement hydration reaction, while the incorporation of PVA fiber improves the internal pore structure of the concrete and has a good filling and bridging effect. The low-field nuclear magnetic resonance experiments show that the mechanism of inhibiting shrinkage and cracking is to improve the pore structure of concrete and enhance the compactness of the interface, thereby reducing early shrinkage and improving crack resistance.
The early-age shrinkage, crack resistance and mechanical properties of high strength manufactured sand concrete containing a large amount of high absorbency stone powder were conducted in order to solve the early-age shrinkage and cracking problem of concrete by adding expansion agent, shrinkage reducing agent, polyvinyl alcohol (PVA) fiber, super absorbent polymer (SAP). The mechanism of inhibiting shrinkage and cracking of high strength manufactured sand concrete containing a large amount of high absorbency stone powder was revealed by testing pore structure and microstructure morphology using low-field nuclear magnetic spectroscopy and scanning electron microscope. The test results show that the addition of expansion agent, shrinkage reducing agent, PVA fiber and pre-absorbent SAP can all effectively inhibit the early-age shrinkage and cracking of concrete. Compared with the benchmark group concrete, incorporating pre-absorbent SAP is the best measure to reduce the early-age shrinkage of concrete and the shrinkage strain will be reduced by 93%. The most obvious inhibitory effect on the cracking of concrete is incorporating PVA fiber and the total cracking area can be reduced by 68.26%. The mechanical properties of the concrete are improved because of pre-absorbent SAP and PVA fiber. However, the mechanical properties of concrete have a certain decrease because of incorporating expansion agent and shrinkage reducing agent. SEM images show that SAP can release the pre-absorbed water into the concrete and promote the cement hydration reaction, while the incorporation of PVA fiber improves the internal pore structure of the concrete and has a good filling and bridging effect. The low-field nuclear magnetic resonance experiments show that the mechanism of inhibiting shrinkage and cracking is to improve the pore structure of concrete and enhance the compactness of the interface, thereby reducing early shrinkage and improving crack resistance.
2021, 38(8): 2747-2757.
doi: 10.13801/j.cnki.fhclxb.20201116.006
Abstract:
Compression tests were carried out on the unit cell of a typical 2.5D woven composite to examine the compression performance. Meanwhile, a high fidelity meso-scale finite element model which was generated in term of the microscopic characterization of the woven architecture was adopted to investigate the internal deformation and progressive failure process of the unit cell. The results indicate that the 2.5D woven composite exhibits nonlinear mechanical response under both the warp and the weft compression, and the compression modulus and strength along warp direction are higher than those in weft direction; The dominate failure modes of warp compression contain transverse cracking of warp yarns, interface debonding between yarns, crushing of weft yarns and the pure matrix cracking; during the weft compression, the crushing and fracture of weft yarns as well as the pure matrix cracking are observed. Moreover, by comparing the experimental and simulation results, the proposed meso-scale model can well predict the stress-strain responses of the 2.5D woven composite under compression loads, as well as accurately simulate the damage initiation and evolution within the woven architecture.
Compression tests were carried out on the unit cell of a typical 2.5D woven composite to examine the compression performance. Meanwhile, a high fidelity meso-scale finite element model which was generated in term of the microscopic characterization of the woven architecture was adopted to investigate the internal deformation and progressive failure process of the unit cell. The results indicate that the 2.5D woven composite exhibits nonlinear mechanical response under both the warp and the weft compression, and the compression modulus and strength along warp direction are higher than those in weft direction; The dominate failure modes of warp compression contain transverse cracking of warp yarns, interface debonding between yarns, crushing of weft yarns and the pure matrix cracking; during the weft compression, the crushing and fracture of weft yarns as well as the pure matrix cracking are observed. Moreover, by comparing the experimental and simulation results, the proposed meso-scale model can well predict the stress-strain responses of the 2.5D woven composite under compression loads, as well as accurately simulate the damage initiation and evolution within the woven architecture.
2021, 38(8): 2383-2395.
doi: 10.13801/j.cnki.fhclxb.20201214.003
Abstract:
Graphene (Gr) has excellent properties such as super-isolation, super-hydrophobicity and super-high specific surface area, making it a revolutionary material for improving the anticorrosion performance of coatings in the 21st century. However, it is easy to agglomerate due to the Van Der Waals force and the high specific surface area between Gr layers, which limits its application in the anti-corrosion coatings. The dispersion modification of Gr can promote its uniform distribution in the coating, which is of great significance to improve the anticorrosive properties of the coating. This paper introduces the structural characteristics of Gr and the anticorrosion mechanism of Gr in coatings, and summarizes the methods of Gr dispersion modification, including the covalent modification of Gr with the small organic molecules, the organic polymers and the inorganic nanoparticles, the non-covalent modification of Gr through the π-π interaction, the hydrogen bonding and the ionic bonding, doping Gr to introduce the new elements and giving it excellent performance, and through the in-situ polymerization to improve the compatibility between Gr and polymer. According to the dispersion principles such as increasing the interlayer steric hindrance of Gr, changing the amphiphilicity of its surface and increasing its compatibility with the polymer, the dispersibility of Gr can be improved remarkable. The uniformly distributed Gr forms a hydrophobic network in the coating, which can effectively improve the corrosion resistance of the coating and expand the application range of the coating. In addition, the paper also analyzed the advantages and disadvantages of various modification methods, and proposed a research direction to further improve the dispersion of Gr and its derivatives; summarized the mechanism of Gr and its derivatives in anti-corrosion coatings, and suggested to strengthen the research on the anti-corrosion mechanism based on experimental exploration in the future.
Graphene (Gr) has excellent properties such as super-isolation, super-hydrophobicity and super-high specific surface area, making it a revolutionary material for improving the anticorrosion performance of coatings in the 21st century. However, it is easy to agglomerate due to the Van Der Waals force and the high specific surface area between Gr layers, which limits its application in the anti-corrosion coatings. The dispersion modification of Gr can promote its uniform distribution in the coating, which is of great significance to improve the anticorrosive properties of the coating. This paper introduces the structural characteristics of Gr and the anticorrosion mechanism of Gr in coatings, and summarizes the methods of Gr dispersion modification, including the covalent modification of Gr with the small organic molecules, the organic polymers and the inorganic nanoparticles, the non-covalent modification of Gr through the π-π interaction, the hydrogen bonding and the ionic bonding, doping Gr to introduce the new elements and giving it excellent performance, and through the in-situ polymerization to improve the compatibility between Gr and polymer. According to the dispersion principles such as increasing the interlayer steric hindrance of Gr, changing the amphiphilicity of its surface and increasing its compatibility with the polymer, the dispersibility of Gr can be improved remarkable. The uniformly distributed Gr forms a hydrophobic network in the coating, which can effectively improve the corrosion resistance of the coating and expand the application range of the coating. In addition, the paper also analyzed the advantages and disadvantages of various modification methods, and proposed a research direction to further improve the dispersion of Gr and its derivatives; summarized the mechanism of Gr and its derivatives in anti-corrosion coatings, and suggested to strengthen the research on the anti-corrosion mechanism based on experimental exploration in the future.
2021, 38(8): 2396-2403.
doi: 10.13801/j.cnki.fhclxb.20210507.001
Abstract:
Metal-organic frameworks (MOFs) antibacterial materials have attracted much attention owing to the advantages such as their large specific surface area, high porosity, adjustable pore size, and good biocompatibility. They are hot materials for the development of efficient and recyclable antibacterial surgical mask. Firstly, this paper analyzed the characteristics of MOFs antibacterial composite materials and their antibacterial mechanism. Then, it summarized the research progress of several types of common MOFs antibacterial composite materials and their fibers based on Ag, Cu, Zn. At last, it discussed the application of MOFs antibacterial functional textiles in the medical treatment and public health, and prospected the potential application value of MOFs antibacterial composite fibers in surgical mask.
Metal-organic frameworks (MOFs) antibacterial materials have attracted much attention owing to the advantages such as their large specific surface area, high porosity, adjustable pore size, and good biocompatibility. They are hot materials for the development of efficient and recyclable antibacterial surgical mask. Firstly, this paper analyzed the characteristics of MOFs antibacterial composite materials and their antibacterial mechanism. Then, it summarized the research progress of several types of common MOFs antibacterial composite materials and their fibers based on Ag, Cu, Zn. At last, it discussed the application of MOFs antibacterial functional textiles in the medical treatment and public health, and prospected the potential application value of MOFs antibacterial composite fibers in surgical mask.
2021, 38(8): 2404-2417.
doi: 10.13801/j.cnki.fhclxb.20210408.001
Abstract:
The increasing popularity of 5G electronic consumer products has brought convenience to people’s life, while there are some problems, such as high risk of electromagnetic interference (EMI) and high power consuming of 5G networks. To solve these problems, it is necessary to develop novel materials with high EMI shielding performance and high-capacity electrode materials. As a new two-dimensional (2D) material, transition metal carbides/nitrides (MXene) have excellent conductivity, low density, hydrophilic surface, 2D layer morphology and tunable surface chemistry, etc. MXene shows promising application prospects in EMI shielding and energy storage due to the facile operation for fabricating films. A lot of MXene-based composite films have been reported recently. Thus in this article, we introduced the preparation methods of MXene nanosheets and MXene-based composite films including their advantages and disadvantages. Secondly, we summarized the research progress of MXene in lithium battery, supercapacitor and EMI shielding fields, and concluded the current mainstream composite materials and the characteristics of MXene composite film in structure and performance. Finally, we proposed critical insights on these scientific challenges and potential solutions. Besides, a future perspective on this technology including other challenges was also described.
The increasing popularity of 5G electronic consumer products has brought convenience to people’s life, while there are some problems, such as high risk of electromagnetic interference (EMI) and high power consuming of 5G networks. To solve these problems, it is necessary to develop novel materials with high EMI shielding performance and high-capacity electrode materials. As a new two-dimensional (2D) material, transition metal carbides/nitrides (MXene) have excellent conductivity, low density, hydrophilic surface, 2D layer morphology and tunable surface chemistry, etc. MXene shows promising application prospects in EMI shielding and energy storage due to the facile operation for fabricating films. A lot of MXene-based composite films have been reported recently. Thus in this article, we introduced the preparation methods of MXene nanosheets and MXene-based composite films including their advantages and disadvantages. Secondly, we summarized the research progress of MXene in lithium battery, supercapacitor and EMI shielding fields, and concluded the current mainstream composite materials and the characteristics of MXene composite film in structure and performance. Finally, we proposed critical insights on these scientific challenges and potential solutions. Besides, a future perspective on this technology including other challenges was also described.
2021, 38(8): 2418-2427.
doi: 10.13801/j.cnki.fhclxb.20210402.002
Abstract:
Bacterial cellulose (BC), an extracellular polysaccharide obtained from microbial fermentation, is an eco-friendly bio-based material, with unique properties, including high purity, high water-holding capacity, excellent tensile strength and bio-compatibility. It shows broad application prospects of many fields such as biomedicine, chemical and food industry. In this review, the structure, unique properties, preparation and modification of BC, are respectively presented. In addition, the research progress of BC composites’ applications in environmental field (adsorption, filtration and photocatalysis) is reviewed. Finally, the existing challenges and future prospects are summarized.
Bacterial cellulose (BC), an extracellular polysaccharide obtained from microbial fermentation, is an eco-friendly bio-based material, with unique properties, including high purity, high water-holding capacity, excellent tensile strength and bio-compatibility. It shows broad application prospects of many fields such as biomedicine, chemical and food industry. In this review, the structure, unique properties, preparation and modification of BC, are respectively presented. In addition, the research progress of BC composites’ applications in environmental field (adsorption, filtration and photocatalysis) is reviewed. Finally, the existing challenges and future prospects are summarized.
2021, 38(8): 2428-2445.
doi: 10.13801/j.cnki.fhclxb.20210425.001
Abstract:
Cellulose is a kind of natural material with the abundant, renewable, and degradable distinction. This article reviews the effects of physical, chemical, biological or combined technologies on cellulose, which can lead to the cellulosic materials, such as cellulose fibers, nanocellulose, and cellulose molecules. Based on cellulose fiber, the cellulose paper substrate with high porosity can be produced by wet papermaking technology. Based on nanocellulose, the nanocellulose membrane substrate with low surface roughness and high transparency can be prepared via vacuum filtration or coating. Based on cellulose molecules, the regenerated cellulose membrane substrate with uniform surface morphology and high transparency can be produced by coating or casting. The commonly used conductive materials (metal conductive materials, polymer conductive materials and carbon based conductive materials, etc.) are further investigated for manufacturing the flexible, light and conductive cellulose substrates by various preparing methods, such as coating, deposition, in-situ polymerization, or self-assembly. The high performance cellulose conductive substrates can effectively construct the flexible electronic devices, which can be applied in the fields of photoelectric conversion, energy storage and electromagnetic shielding. In conclusion, the preparation of flexible electronic devices from natural cellulose is of great significance to expand the applications of cellulose, enhances the utilization value of cellulose, and promotes the further development of flexible electronic devices.
Cellulose is a kind of natural material with the abundant, renewable, and degradable distinction. This article reviews the effects of physical, chemical, biological or combined technologies on cellulose, which can lead to the cellulosic materials, such as cellulose fibers, nanocellulose, and cellulose molecules. Based on cellulose fiber, the cellulose paper substrate with high porosity can be produced by wet papermaking technology. Based on nanocellulose, the nanocellulose membrane substrate with low surface roughness and high transparency can be prepared via vacuum filtration or coating. Based on cellulose molecules, the regenerated cellulose membrane substrate with uniform surface morphology and high transparency can be produced by coating or casting. The commonly used conductive materials (metal conductive materials, polymer conductive materials and carbon based conductive materials, etc.) are further investigated for manufacturing the flexible, light and conductive cellulose substrates by various preparing methods, such as coating, deposition, in-situ polymerization, or self-assembly. The high performance cellulose conductive substrates can effectively construct the flexible electronic devices, which can be applied in the fields of photoelectric conversion, energy storage and electromagnetic shielding. In conclusion, the preparation of flexible electronic devices from natural cellulose is of great significance to expand the applications of cellulose, enhances the utilization value of cellulose, and promotes the further development of flexible electronic devices.
2021, 38(8): 2446-2458.
doi: 10.13801/j.cnki.fhclxb.20210426.004
Abstract:
With the rapid development of modern electronic technology, a large amount of e-waste puts huge pressure on the environment. The cellulose-based flexible conductive composite material has incomparable advantages with traditional petroleum-based conductive products, such as lightweight, degradable, renewable, bio-compatible, and so on. In recent years, paper-based flexible conductive materials have gradually become a research focus in this field. This article reviews the research progress of paper-based flexible conductive materials at home and abroad in recent years, describes the working principle of flexible conductive materials, summarizes the preparation methods and related applications of paper-based flexible conductive materials in detail, and the paper-based flexible conductive materials urgently need to be solved and the future development trend is summarized and prospected.
With the rapid development of modern electronic technology, a large amount of e-waste puts huge pressure on the environment. The cellulose-based flexible conductive composite material has incomparable advantages with traditional petroleum-based conductive products, such as lightweight, degradable, renewable, bio-compatible, and so on. In recent years, paper-based flexible conductive materials have gradually become a research focus in this field. This article reviews the research progress of paper-based flexible conductive materials at home and abroad in recent years, describes the working principle of flexible conductive materials, summarizes the preparation methods and related applications of paper-based flexible conductive materials in detail, and the paper-based flexible conductive materials urgently need to be solved and the future development trend is summarized and prospected.
2021, 38(8): 2459-2478.
doi: 10.13801/j.cnki.fhclxb.20210419.001
Abstract:
Owing to the good structural integrity and excellent comprehensive properties, 3D braided composites have become the preferred materials for some main load-bearing components and high-function parts in aerospace, aviation and national defense fields. However, 3D braided composite structures will inevitably be exposed to harsh environments such as high temperature, low temperature or rapid temperature changes during service. Due to the great difference of thermophysical properties between reinforcement and matrix of 3D braided composite, the dimensional stability and service life of the structure will be seriously threatened. This article gives an overview of the thermophysical properties and temperature effect on the mechanical properties of 3D multi-directional braided composites both at home and abroad in recent years. The research results and progress mainly include three aspects: experiment, theory and numerical simulation. Firstly, the effects of braiding process, braiding parameters, ambient temperature, interface and defects on the thermal conductivity and thermal expansion properties of 3D braided composites were analyzed. Secondly, the differences and relations of different structural geometric models were analyzed based on the micro structure, full-scale and multi-scale models. Finally, the influence mechanism of high/low ambient temperature and different load forms on the failure mode and thermal-mechanical coupling behavior of 3D multi-directional braided composites was discussed, and the focus and development direction of existing research work were summarized.
Owing to the good structural integrity and excellent comprehensive properties, 3D braided composites have become the preferred materials for some main load-bearing components and high-function parts in aerospace, aviation and national defense fields. However, 3D braided composite structures will inevitably be exposed to harsh environments such as high temperature, low temperature or rapid temperature changes during service. Due to the great difference of thermophysical properties between reinforcement and matrix of 3D braided composite, the dimensional stability and service life of the structure will be seriously threatened. This article gives an overview of the thermophysical properties and temperature effect on the mechanical properties of 3D multi-directional braided composites both at home and abroad in recent years. The research results and progress mainly include three aspects: experiment, theory and numerical simulation. Firstly, the effects of braiding process, braiding parameters, ambient temperature, interface and defects on the thermal conductivity and thermal expansion properties of 3D braided composites were analyzed. Secondly, the differences and relations of different structural geometric models were analyzed based on the micro structure, full-scale and multi-scale models. Finally, the influence mechanism of high/low ambient temperature and different load forms on the failure mode and thermal-mechanical coupling behavior of 3D multi-directional braided composites was discussed, and the focus and development direction of existing research work were summarized.
2021, 38(8): 2479-2488.
doi: 10.13801/j.cnki.fhclxb.20201030.008
Abstract:
As the core technology of desalination, reverse osmosis membrane technology has a wide application prospect in desalination of seawater and brackish water, preparation of ultra-pure water, sewage backwater and other fields. However, the “trade-off” effect between permeability and selectivity is still a major challenge to restrict the development of it. In this study, surface functionalized (grafted sulfhydryl group) graphene oxide (GO) was incorporated into m-phenylenediamine aqueous solution. Sulfhydryl grafted graphene oxide (GO-SH)/polyamide (PA) composite membranes were prepared by interfacial polymerization of m-phenylenediamine in aqueous phase and trimesoyl chloride in organic phase. TEM, SEM, EDS, FTIR and NMR were used to characterize the powder after grafting, and 2 g·L−1 NaCl solution was used to test the salt rejection property of the membrane, as well as the setting of pH and reaction time of interface polymerization aqueous phase was optimized. The results show that the GO-SH is more uniformly dispersed in the polyamide, the optimized pH is 11 and the reaction time is 4 min. When the modified powder content is 0.09wt%, composite membrane water flux can be up to 48 L·m−2·h−1 and the salt rejection reaches 99.6%, which are 30% and 2.54% higher than that of the GO/PA membrane in this study. Surface functionalized GO effectively solves the compatibility of inorganic nanoparticles and organic polymers, improves the membrane separation performance, and can be expected to further reduce the operating cost of reverse osmosis projects.
As the core technology of desalination, reverse osmosis membrane technology has a wide application prospect in desalination of seawater and brackish water, preparation of ultra-pure water, sewage backwater and other fields. However, the “trade-off” effect between permeability and selectivity is still a major challenge to restrict the development of it. In this study, surface functionalized (grafted sulfhydryl group) graphene oxide (GO) was incorporated into m-phenylenediamine aqueous solution. Sulfhydryl grafted graphene oxide (GO-SH)/polyamide (PA) composite membranes were prepared by interfacial polymerization of m-phenylenediamine in aqueous phase and trimesoyl chloride in organic phase. TEM, SEM, EDS, FTIR and NMR were used to characterize the powder after grafting, and 2 g·L−1 NaCl solution was used to test the salt rejection property of the membrane, as well as the setting of pH and reaction time of interface polymerization aqueous phase was optimized. The results show that the GO-SH is more uniformly dispersed in the polyamide, the optimized pH is 11 and the reaction time is 4 min. When the modified powder content is 0.09wt%, composite membrane water flux can be up to 48 L·m−2·h−1 and the salt rejection reaches 99.6%, which are 30% and 2.54% higher than that of the GO/PA membrane in this study. Surface functionalized GO effectively solves the compatibility of inorganic nanoparticles and organic polymers, improves the membrane separation performance, and can be expected to further reduce the operating cost of reverse osmosis projects.
2021, 38(8): 2489-2496.
doi: 10.13801/j.cnki.fhclxb.20201030.005
Abstract:
In this paper, from the perspective of surface modification of filter material, how to improve its stability in high humidity environment has been studied. Using polyethylene terephthalate (PET) filter material as the substrate, ethyl orthosilicate (TEOS) as the precursor, and methyltriethoxysilane (MTES) as the low surface energy substance, the sol-gel method was used to generate in-situ on the surface of the filter material SiO2 nanoparticles to prepare modified SiO2 gel-coated filter material. Then, FESEM-EDS, FTIR and a contact angle measuring instrument were used to analyze the changes in the surface chemical composition, wettability and surface morphology of the PET filter material. The results show that SiO2 nanoparticles are formed on the surface after finishing, and the surface is covered with hydrophobic methyl groups after MTES modification treatment. Thus, its hydrophobic property is significantly improved, and its surface water contact angle reaches 154.11°. At the same time, the SiO2 particles are evenly distributed on the surface, and the gel polymer is only deposited at the intersection of the fibers, which ensures air permeability, and the filtration efficiency increases from 97.0595% to 99.2028%, and the filtration quality factor increases by 30%, from 0.02124 to 0.02761.
In this paper, from the perspective of surface modification of filter material, how to improve its stability in high humidity environment has been studied. Using polyethylene terephthalate (PET) filter material as the substrate, ethyl orthosilicate (TEOS) as the precursor, and methyltriethoxysilane (MTES) as the low surface energy substance, the sol-gel method was used to generate in-situ on the surface of the filter material SiO2 nanoparticles to prepare modified SiO2 gel-coated filter material. Then, FESEM-EDS, FTIR and a contact angle measuring instrument were used to analyze the changes in the surface chemical composition, wettability and surface morphology of the PET filter material. The results show that SiO2 nanoparticles are formed on the surface after finishing, and the surface is covered with hydrophobic methyl groups after MTES modification treatment. Thus, its hydrophobic property is significantly improved, and its surface water contact angle reaches 154.11°. At the same time, the SiO2 particles are evenly distributed on the surface, and the gel polymer is only deposited at the intersection of the fibers, which ensures air permeability, and the filtration efficiency increases from 97.0595% to 99.2028%, and the filtration quality factor increases by 30%, from 0.02124 to 0.02761.
2021, 38(8): 2497-2504.
doi: 10.13801/j.cnki.fhclxb.20201111.002
Abstract:
The foamed wood flour-nano-montmorillonite (NMMT)/polypropylene (PP) composites were prepared by the batch foaming method using supercritical CO2 microcellular foaming technology. Effects of NMMT on the microcellular structure and mechanical properties of the composites were explored by investigating crystallization behavior, rheological properties, cell morphology and compression properties. The results show that NMMT accelerates the crystallization rate of the PP matrix in the wood flour/PP composites, and reduces the crystallinity rate. This is beneficial to the formation of foamed homogeneous system and cell growth. The PP molecular chain is inhibited by the NMMT interlayer, resulting in the melt elasticity increasement of the wood flour/PP composites. The phenomena of cell coalescence and collapse are reduced, the average cell diameter of the foamed composites is decreased from 30.4 μm to 20.3 μm, and the uniformity of cell size is obviously improved. The compressive strength and modulus are increased by 187% and 223%, respectively.
The foamed wood flour-nano-montmorillonite (NMMT)/polypropylene (PP) composites were prepared by the batch foaming method using supercritical CO2 microcellular foaming technology. Effects of NMMT on the microcellular structure and mechanical properties of the composites were explored by investigating crystallization behavior, rheological properties, cell morphology and compression properties. The results show that NMMT accelerates the crystallization rate of the PP matrix in the wood flour/PP composites, and reduces the crystallinity rate. This is beneficial to the formation of foamed homogeneous system and cell growth. The PP molecular chain is inhibited by the NMMT interlayer, resulting in the melt elasticity increasement of the wood flour/PP composites. The phenomena of cell coalescence and collapse are reduced, the average cell diameter of the foamed composites is decreased from 30.4 μm to 20.3 μm, and the uniformity of cell size is obviously improved. The compressive strength and modulus are increased by 187% and 223%, respectively.
2021, 38(8): 2505-2516.
doi: 10.13801/j.cnki.fhclxb.20201110.002
Abstract:
A series of melamine phytates/rigid polyurethane foam (MEL-PA/RPUF) composites were prepared by one-step water-blown method with MEL-PA as flame retardant. Thermogravimetric analysis (TG) and thermal analysis kinetics were used to study the thermal stability of the composites and reveal its degradation mechanism. The results show that the char residues of MEL-PA/RPUF gradually increases at 700℃ with the increase of MEL-PA loading. Based on TGA data, the reaction grade n, activation energy E and pre exponential factor A of the main degradation stage for the composites were calculated by the Coats-Redfern and Horowitz-Metzger integration methods. The results show that MEL-PA promotes the initial degradation of the composites in air atmosphere, while the MEL-PA/RPUF composites have higher thermal stability in the high temperature stage, and the two calculation methods have the same law. In N2 atmosphere, MEL-PA30/RPUF (mass fraction of MEL-PA is 10.3wt%) has higher n and E compared with RPUF. The results indicate that the reaction of MEL-PA30/RPUF is more complex and the thermal stability is higher. The mathematical model and experimental analysis by Criado method verify the feasibility of the Coats-Redfern method. The results of thermal degradation kinetics of MEL-PA/RPUF composites provide reference for the analysis of flame retardation performance of RPUF with different flame retardation systems.
A series of melamine phytates/rigid polyurethane foam (MEL-PA/RPUF) composites were prepared by one-step water-blown method with MEL-PA as flame retardant. Thermogravimetric analysis (TG) and thermal analysis kinetics were used to study the thermal stability of the composites and reveal its degradation mechanism. The results show that the char residues of MEL-PA/RPUF gradually increases at 700℃ with the increase of MEL-PA loading. Based on TGA data, the reaction grade n, activation energy E and pre exponential factor A of the main degradation stage for the composites were calculated by the Coats-Redfern and Horowitz-Metzger integration methods. The results show that MEL-PA promotes the initial degradation of the composites in air atmosphere, while the MEL-PA/RPUF composites have higher thermal stability in the high temperature stage, and the two calculation methods have the same law. In N2 atmosphere, MEL-PA30/RPUF (mass fraction of MEL-PA is 10.3wt%) has higher n and E compared with RPUF. The results indicate that the reaction of MEL-PA30/RPUF is more complex and the thermal stability is higher. The mathematical model and experimental analysis by Criado method verify the feasibility of the Coats-Redfern method. The results of thermal degradation kinetics of MEL-PA/RPUF composites provide reference for the analysis of flame retardation performance of RPUF with different flame retardation systems.
2021, 38(8): 2517-2526.
doi: 10.13801/j.cnki.fhclxb.20201022.002
Abstract:
With dodecanol dodecanoate as the phase change material (PCM) and polyvinyl alcohol (PVA) as the supporting material, the dodecanol dodecanoate@PVA thermo-regulated fibers were prepared by emulsion electrospinning technology. The SEM, TEM, DSC, TGA, mini temperature recorder and infrared thermal imager were applied to study the composition of the spinning solution and the surface morphology, latent heat value, thermal stability, temperature regulating properties, mechanical property and water solubility of the electrospun fibers. The results show that with 10.0wt% of PVA and dodecanol dodecanoate∶PVA mass ratio of 50%, the spinning solution has better stability and spinnability. The dodecanol dodecanoate@PVA electrospun fibers have apparent core-sheath structure, and the thermal decomposition temperature of PCM in the fibers is 20℃ higher than the pure PCM, displaying good thermal stability. The latent heat value of dodecanol dodecanoate@PVA electrospun fibers is about 63 J/g, showing good heat storage and temperature regulation performance in cooling process and thermal infrared imaging test. After the crosslinking with glutaraldehyde, the thermal stability of the support material in the electrospun fibers is significantly enhanced, and the mechanical properties and water solubility of the fibers have notable improvement.
With dodecanol dodecanoate as the phase change material (PCM) and polyvinyl alcohol (PVA) as the supporting material, the dodecanol dodecanoate@PVA thermo-regulated fibers were prepared by emulsion electrospinning technology. The SEM, TEM, DSC, TGA, mini temperature recorder and infrared thermal imager were applied to study the composition of the spinning solution and the surface morphology, latent heat value, thermal stability, temperature regulating properties, mechanical property and water solubility of the electrospun fibers. The results show that with 10.0wt% of PVA and dodecanol dodecanoate∶PVA mass ratio of 50%, the spinning solution has better stability and spinnability. The dodecanol dodecanoate@PVA electrospun fibers have apparent core-sheath structure, and the thermal decomposition temperature of PCM in the fibers is 20℃ higher than the pure PCM, displaying good thermal stability. The latent heat value of dodecanol dodecanoate@PVA electrospun fibers is about 63 J/g, showing good heat storage and temperature regulation performance in cooling process and thermal infrared imaging test. After the crosslinking with glutaraldehyde, the thermal stability of the support material in the electrospun fibers is significantly enhanced, and the mechanical properties and water solubility of the fibers have notable improvement.
2021, 38(8): 2527-2537.
doi: 10.13801/j.cnki.fhclxb.20201116.002
Abstract:
The carboxyl-terminated biodegradable polyester elastomer particles (CBEP)/poly (lactic acid) (PLA) composites were prepared by different particle sizes of CBEP blended with PLA. The mechanical, crystallization and degradation properties of the composites were tested, and the effect and mechanism of CBEP on the properties of PLA were studied.The results show that CBEP can significantly improve the toughness of PLA, and the composite specimens appear necking during stretching, especially the elongation at break of the composites with 7.5% (mass ratio to PLA) CBEP-a (particle size of 200 nm) increases from 4.6% of neat PLA to 155%. And the notched impact strength of CBEP/PLA composites is up to 2 times of neat PLA. CBEP can also improve the crystallization properties of PLA, in which the isothermal crystallization half-crystallization time of the composites with 7.5% CBEP-a (particle size of 200 nm) is shortened by 21.4% compared with the neat PLA.The results of the degradation experiments show that the mass loss of the composites with 10% CBEP-a (particle size of 200 nm) in lipase and soil environment is increased from 0.34% and 0.25% of neat PLA to 2.52% and 1.20%, respectively. The CBEP/PLA composites have broad development and application in the fields of biomedicine and environmentally friendly materials.
The carboxyl-terminated biodegradable polyester elastomer particles (CBEP)/poly (lactic acid) (PLA) composites were prepared by different particle sizes of CBEP blended with PLA. The mechanical, crystallization and degradation properties of the composites were tested, and the effect and mechanism of CBEP on the properties of PLA were studied.The results show that CBEP can significantly improve the toughness of PLA, and the composite specimens appear necking during stretching, especially the elongation at break of the composites with 7.5% (mass ratio to PLA) CBEP-a (particle size of 200 nm) increases from 4.6% of neat PLA to 155%. And the notched impact strength of CBEP/PLA composites is up to 2 times of neat PLA. CBEP can also improve the crystallization properties of PLA, in which the isothermal crystallization half-crystallization time of the composites with 7.5% CBEP-a (particle size of 200 nm) is shortened by 21.4% compared with the neat PLA.The results of the degradation experiments show that the mass loss of the composites with 10% CBEP-a (particle size of 200 nm) in lipase and soil environment is increased from 0.34% and 0.25% of neat PLA to 2.52% and 1.20%, respectively. The CBEP/PLA composites have broad development and application in the fields of biomedicine and environmentally friendly materials.
2021, 38(8): 2538-2545.
doi: 10.13801/j.cnki.fhclxb.20201030.009
Abstract:
The styrene, divinylbenzene and KH570 were used as monomers to preparer the cross-link polystyrene microspheres (SiO2/polystyrene hydrophobic composite microspheres), on which the SiO2 rough structure was sucessfully designed via suspension polymerization along with sol-gel reaction in one step. Besides, effects of the oil phase composition, amount of the KH570 and the sol-gel reaction condition on the strength and hydrophobic properties of the SiO2/polystyrene hydrophobic composite microspheres were studied. The results show that the SiO2/polystyrene hydrophobic composite microspheres with durable hydrophobic properties, high strength and ultra-low density could be obtained when the toluene in the oil phase is discarded and the pH value of the system is tuned to 10-11 by ammonia-water at the 50°C reaction stage. The SiO2/polystyrene hydrophobic composite microsphere exhibits the apparent density about 0.9917 g∙cm−3, low crushing rate (2.53% under 69 MPa closure pressure), high initial static water contact angle (as high as 140.7°) and excellent heat resistance (the glass transition temperature and decomposition temperature are up to 160°C and 390°C, respectively). When refluxed in the chelate acid HD and FA that applied in Well A5 in Weizhou X Oil field for 30 days, the static water contact angles on the surface of the SiO2/polystyrene hydrophobic composite microspheres fluctuate only within ±10% and ±7%, respectively. The SiO2/polystyrene hydrophobic composite microsphere shows great potential in deep reservoir as a proppant, which is also suitable for the water control process as a packing material.
The styrene, divinylbenzene and KH570 were used as monomers to preparer the cross-link polystyrene microspheres (SiO2/polystyrene hydrophobic composite microspheres), on which the SiO2 rough structure was sucessfully designed via suspension polymerization along with sol-gel reaction in one step. Besides, effects of the oil phase composition, amount of the KH570 and the sol-gel reaction condition on the strength and hydrophobic properties of the SiO2/polystyrene hydrophobic composite microspheres were studied. The results show that the SiO2/polystyrene hydrophobic composite microspheres with durable hydrophobic properties, high strength and ultra-low density could be obtained when the toluene in the oil phase is discarded and the pH value of the system is tuned to 10-11 by ammonia-water at the 50°C reaction stage. The SiO2/polystyrene hydrophobic composite microsphere exhibits the apparent density about 0.9917 g∙cm−3, low crushing rate (2.53% under 69 MPa closure pressure), high initial static water contact angle (as high as 140.7°) and excellent heat resistance (the glass transition temperature and decomposition temperature are up to 160°C and 390°C, respectively). When refluxed in the chelate acid HD and FA that applied in Well A5 in Weizhou X Oil field for 30 days, the static water contact angles on the surface of the SiO2/polystyrene hydrophobic composite microspheres fluctuate only within ±10% and ±7%, respectively. The SiO2/polystyrene hydrophobic composite microsphere shows great potential in deep reservoir as a proppant, which is also suitable for the water control process as a packing material.
2021, 38(8): 2546-2553.
doi: 10.13801/j.cnki.fhclxb.20201105.002
Abstract:
Flame retardant ethylene-vinyl acetate (EVA) composites were prepared by combination of microencapsulated intumescent flame retardants-ammonium polyphosphate (APP)-pentaerythritol (PER) and organically modified montmorillonite (OMMT). The microencapsulated APP (MCAPP)-microencapsulated PER (MCPER)-OMMT/EVA composites were further characterized through XRD and TEM, confirming OMMT sheets are well dispersed in the matrix as exfoliated or intercalated nanocomposite state. Limiting oxygen index (LOI), TGA, underwriters laboratories 94 vertical burning (UL-94), cone and smoke density test results indicate the synergistic flame retardancy effect between MCAPP-MCPER and OMMT in MCAPP-MCPER-OMMT/EVA composites. Replacing the same amount of MCAPP-MCPER with 3wt% OMMT could improve the LOI value of the MCAPP-MCPER-OMMT/EVA composites from 25.5vol% to 29.5vol%. The UL-94 rating increases from V-2 to V-0. The char residue of MCAPP-MCPER-OMMT/EVA composites is improved from 14.5wt% to 15.9wt% and the smoke density significantly decreases from 154.7 g/s to 97.5 g/s. Besides, the mechanical property of MCAPP-MCPER-OMMT/EVA composites was tested by universal testing machine and dynamic thermomechanical analysis (DMA), the result shows that the flame-retardant MCAPP-MCPER-OMMT/EVA composites has better mechanical properties.
Flame retardant ethylene-vinyl acetate (EVA) composites were prepared by combination of microencapsulated intumescent flame retardants-ammonium polyphosphate (APP)-pentaerythritol (PER) and organically modified montmorillonite (OMMT). The microencapsulated APP (MCAPP)-microencapsulated PER (MCPER)-OMMT/EVA composites were further characterized through XRD and TEM, confirming OMMT sheets are well dispersed in the matrix as exfoliated or intercalated nanocomposite state. Limiting oxygen index (LOI), TGA, underwriters laboratories 94 vertical burning (UL-94), cone and smoke density test results indicate the synergistic flame retardancy effect between MCAPP-MCPER and OMMT in MCAPP-MCPER-OMMT/EVA composites. Replacing the same amount of MCAPP-MCPER with 3wt% OMMT could improve the LOI value of the MCAPP-MCPER-OMMT/EVA composites from 25.5vol% to 29.5vol%. The UL-94 rating increases from V-2 to V-0. The char residue of MCAPP-MCPER-OMMT/EVA composites is improved from 14.5wt% to 15.9wt% and the smoke density significantly decreases from 154.7 g/s to 97.5 g/s. Besides, the mechanical property of MCAPP-MCPER-OMMT/EVA composites was tested by universal testing machine and dynamic thermomechanical analysis (DMA), the result shows that the flame-retardant MCAPP-MCPER-OMMT/EVA composites has better mechanical properties.
2021, 38(8): 2554-2567.
doi: 10.13801/j.cnki.fhclxb.20201209.003
Abstract:
At present, China has made great breakthrough in the development and production of high-performance carbon fiber. In this paper, different batches and grades of domestic ZT7H carbon fibers were selected and processed for desizing and sizing, and then carbon fiber reinforced epoxy resin composites were prepared. The effect of domestic H1 sizing agent on the surface morphology and micro-interface properties of ZT7H carbon fibers was explored, as well as the differences in interface performance of composites made from different grades of carbon fibers. Studies have shown that H1 sizing agent increases the surface roughness and polar component content of carbon fibers, enhancing the micro-interface mechanical properties of the composite before and after hygrothermal treat. At the same time, the weaving method of carbon fiber fabric has a great influence on the static mechanical properties and interface properties of its composites. Experiments have proved that the performance of domestic ZT7H carbon fiber has exceeded Toray T700 carbon fiber, but its product performance stability still needs to be improved.
At present, China has made great breakthrough in the development and production of high-performance carbon fiber. In this paper, different batches and grades of domestic ZT7H carbon fibers were selected and processed for desizing and sizing, and then carbon fiber reinforced epoxy resin composites were prepared. The effect of domestic H1 sizing agent on the surface morphology and micro-interface properties of ZT7H carbon fibers was explored, as well as the differences in interface performance of composites made from different grades of carbon fibers. Studies have shown that H1 sizing agent increases the surface roughness and polar component content of carbon fibers, enhancing the micro-interface mechanical properties of the composite before and after hygrothermal treat. At the same time, the weaving method of carbon fiber fabric has a great influence on the static mechanical properties and interface properties of its composites. Experiments have proved that the performance of domestic ZT7H carbon fiber has exceeded Toray T700 carbon fiber, but its product performance stability still needs to be improved.
2021, 38(8): 2568-2577.
doi: 10.13801/j.cnki.fhclxb.20201015.004
Abstract:
Ex-situ toughening technology is a good solution to improve the toughness of intrinsically brittle thermosetting resin matrix fiber composites. In order to better combine the ex-situ toughening technology with resin transfer molding (RTM) process to prepare high performance bismaleimide (BMI) resin matrix composites, in this paper, based on a new thermoplastic biphenyl polyether ketone (PAEK-B) resin, the phase separation behavior of the PAEK-B in BMI resin and carbon fiber composites, and the rheological properties of PAEK-B/BMI composite resin were studied. The results show that the phase separation behavior of PAEK-B occurs in the injection window temperature of BMI resin for a certain time, and the phase separation structure is maintained in the carbon fiber (CF)/PAEK-B/BMI composites prepared by RTM process. The solution of PAEK-B in the BMI resin is affected by the injection temperature of BMI resin. The initial viscosity of the BMI resin decreases with the increase of injection temperature, but the inflection point time of the PAEK-B/BMI composite resin decreases; The PAEK-B/BMI composite resin accords with the Winter-Chambon criterion. The tanδ of the composite resin has no dependence on the frequency, and the gel activation energy of the composite resin increases with the increase of PAEK-B content.
Ex-situ toughening technology is a good solution to improve the toughness of intrinsically brittle thermosetting resin matrix fiber composites. In order to better combine the ex-situ toughening technology with resin transfer molding (RTM) process to prepare high performance bismaleimide (BMI) resin matrix composites, in this paper, based on a new thermoplastic biphenyl polyether ketone (PAEK-B) resin, the phase separation behavior of the PAEK-B in BMI resin and carbon fiber composites, and the rheological properties of PAEK-B/BMI composite resin were studied. The results show that the phase separation behavior of PAEK-B occurs in the injection window temperature of BMI resin for a certain time, and the phase separation structure is maintained in the carbon fiber (CF)/PAEK-B/BMI composites prepared by RTM process. The solution of PAEK-B in the BMI resin is affected by the injection temperature of BMI resin. The initial viscosity of the BMI resin decreases with the increase of injection temperature, but the inflection point time of the PAEK-B/BMI composite resin decreases; The PAEK-B/BMI composite resin accords with the Winter-Chambon criterion. The tanδ of the composite resin has no dependence on the frequency, and the gel activation energy of the composite resin increases with the increase of PAEK-B content.
2021, 38(8): 2578-2585.
doi: 10.13801/j.cnki.fhclxb.20201015.001
Abstract:
Carbon fiber reinforced polyether ether ketone (CF/PEEK) is a high-performance thermoplastic composite with broad application in aerospace. PEEK has a non-linear behavior related to temperature and strain rate, which makes CF/PEEK have similar mechanical behavior in plane shear direction. In this paper, shear experiments were carried out on CF/PEEK specimens at different temperatures and strain rates. The stress-strain curve was divided into linear and non-linear parts. It is found that temperature and strain rate have a greater influence on the yield stress of CF/PEEK. With the increase of temperature from 20℃ to 130℃, the yield stress decreases by about 66%, and the rate of decrease is fast and then slow. With the increase of strain rate from 10−5 s−1 to 0.1 s−1, the yield stress increases uniformly by about 35%. This phenomenon is fitted into an empirical formula of back stress, and the yield function of the classic elastoplastic constitutive model of thermoplastic composites is modified, which is applied in VUMAT to analysis the shear behavior of CF/PEEK. Compared with the experimental results, it is found that the yield point and the nonlinear stage are in good agreement. However, due to the poor infiltration of fibers and PEEK matrix, CF/PEEK composites have porosity defects inside, which affectes the initial elastic behavior of CF/PEEK composites and resultes in the deviation in the initial loading stage.
Carbon fiber reinforced polyether ether ketone (CF/PEEK) is a high-performance thermoplastic composite with broad application in aerospace. PEEK has a non-linear behavior related to temperature and strain rate, which makes CF/PEEK have similar mechanical behavior in plane shear direction. In this paper, shear experiments were carried out on CF/PEEK specimens at different temperatures and strain rates. The stress-strain curve was divided into linear and non-linear parts. It is found that temperature and strain rate have a greater influence on the yield stress of CF/PEEK. With the increase of temperature from 20℃ to 130℃, the yield stress decreases by about 66%, and the rate of decrease is fast and then slow. With the increase of strain rate from 10−5 s−1 to 0.1 s−1, the yield stress increases uniformly by about 35%. This phenomenon is fitted into an empirical formula of back stress, and the yield function of the classic elastoplastic constitutive model of thermoplastic composites is modified, which is applied in VUMAT to analysis the shear behavior of CF/PEEK. Compared with the experimental results, it is found that the yield point and the nonlinear stage are in good agreement. However, due to the poor infiltration of fibers and PEEK matrix, CF/PEEK composites have porosity defects inside, which affectes the initial elastic behavior of CF/PEEK composites and resultes in the deviation in the initial loading stage.
2021, 38(8): 2586-2594.
doi: 10.13801/j.cnki.fhclxb.20201117.002
Abstract:
Using brominated polystyrene (BPS) as flame retardant, Sb2O3 nanoparticles (nano-Sb2O3) as synergistic flame retardant, polybutylene terephthalate (PBT) as matrix and thermoplastic polyurethane elasticity (TPU) as a toughening component, TPU/nano-Sb2O3-BPS-PBT flame retardant composites were obtained by ball milling dispersion and melt-mixing methods. The mechanical and flame retardant properties of the TPU/nano-Sb2O3-BPS-PBT composites were studied by DSC, tensile, impact and limiting oxygen index (LOI) test. The results show that the TPU can enhance the toughness of the TPU/nano-Sb2O3-BPS-PBT flame retardant composites. With increasing of the mass fraction of TPU, the notched impact strength of the TPU/nano-Sb2O3-BPS-PBT flame retardant composites increases. Furthermore, when the mass fraction of TPU is 9wt%, its impact strength increases by 137% and the elongation at break increases by 340% compared with those of pure PBT, but its tensile strength decreases. The tensile strength of the composites is greater than that of pure PBT when the mass fraction of TPU is 3wt%, which its impact strength is 52% higher than that of the pure PBT. The TPU/nano-Sb2O3-BPS-PBT flame retardant composites reach flame-resistant grade and the composites show superior comprehensive performance.
Using brominated polystyrene (BPS) as flame retardant, Sb2O3 nanoparticles (nano-Sb2O3) as synergistic flame retardant, polybutylene terephthalate (PBT) as matrix and thermoplastic polyurethane elasticity (TPU) as a toughening component, TPU/nano-Sb2O3-BPS-PBT flame retardant composites were obtained by ball milling dispersion and melt-mixing methods. The mechanical and flame retardant properties of the TPU/nano-Sb2O3-BPS-PBT composites were studied by DSC, tensile, impact and limiting oxygen index (LOI) test. The results show that the TPU can enhance the toughness of the TPU/nano-Sb2O3-BPS-PBT flame retardant composites. With increasing of the mass fraction of TPU, the notched impact strength of the TPU/nano-Sb2O3-BPS-PBT flame retardant composites increases. Furthermore, when the mass fraction of TPU is 9wt%, its impact strength increases by 137% and the elongation at break increases by 340% compared with those of pure PBT, but its tensile strength decreases. The tensile strength of the composites is greater than that of pure PBT when the mass fraction of TPU is 3wt%, which its impact strength is 52% higher than that of the pure PBT. The TPU/nano-Sb2O3-BPS-PBT flame retardant composites reach flame-resistant grade and the composites show superior comprehensive performance.
2021, 38(8): 2595-2604.
doi: 10.13801/j.cnki.fhclxb.20201019.002
Abstract:
In order to optimize the hydrated ferric oxide (HFO) loadings of acrylic resin-based HFO composite adsorbents, five composite adsorbents were prepared by regulating FeCl3 concentration, and the HFO loadings were 5.3wt%, 8.6wt%, 12.1wt%, 14.9wt% and 18.5wt% (mass fraction in Fe), respectively. The structure properties of composite adsorbents were analyzed. Furthermore, the adsorption performance of composite adsorbents in removing phosphate were investigated, including adsorption isotherms, adsorption kinetics, effect of pH and coexisting anion, and elution effect. The results show that HFO nanoparticles dispersed into composite adsorbents are amorphous in nature, and the radial distribution of HFO obeys U-type distribution. Moreover, the phosphate adsorption capacity increases with the HFO loadings and then decreases, and the adsorption capacity of the composite adsorbent with HFO loading of 14.9wt% is the maximum (19.04 mg·g−1). The contact time of 240 min is long enough for composite adsorbents to achieve adsorption equilibrium, and the adsorption kinetic curves of the composite adsorbents are fitted well with pseudo-first order kinetic model (R2>0.99). The optimal pH for phosphate adsorption is 6~8. Furthermore, there is no phosphate adsorption by resin when the concentration of SO42− is equal or greater than 600 mg·L−1, while it does not pose any noticeable effect on phosphate adsorption by the loaded HFO nanoparticles. The regeneration efficiencies approach 100% by a binary 5wt% NaOH and 5wt% NaCl solution during 4 continuous adsorption-regeneration cycles. The experiments show that the phosphate adsorption capacity of the composite adsorbents increases with the HFO loadings and then decreases, while there is no significant difference in structure property, adsorption equilibrium time, pH range, effect of coexisting anion, and elution effect.
In order to optimize the hydrated ferric oxide (HFO) loadings of acrylic resin-based HFO composite adsorbents, five composite adsorbents were prepared by regulating FeCl3 concentration, and the HFO loadings were 5.3wt%, 8.6wt%, 12.1wt%, 14.9wt% and 18.5wt% (mass fraction in Fe), respectively. The structure properties of composite adsorbents were analyzed. Furthermore, the adsorption performance of composite adsorbents in removing phosphate were investigated, including adsorption isotherms, adsorption kinetics, effect of pH and coexisting anion, and elution effect. The results show that HFO nanoparticles dispersed into composite adsorbents are amorphous in nature, and the radial distribution of HFO obeys U-type distribution. Moreover, the phosphate adsorption capacity increases with the HFO loadings and then decreases, and the adsorption capacity of the composite adsorbent with HFO loading of 14.9wt% is the maximum (19.04 mg·g−1). The contact time of 240 min is long enough for composite adsorbents to achieve adsorption equilibrium, and the adsorption kinetic curves of the composite adsorbents are fitted well with pseudo-first order kinetic model (R2>0.99). The optimal pH for phosphate adsorption is 6~8. Furthermore, there is no phosphate adsorption by resin when the concentration of SO42− is equal or greater than 600 mg·L−1, while it does not pose any noticeable effect on phosphate adsorption by the loaded HFO nanoparticles. The regeneration efficiencies approach 100% by a binary 5wt% NaOH and 5wt% NaCl solution during 4 continuous adsorption-regeneration cycles. The experiments show that the phosphate adsorption capacity of the composite adsorbents increases with the HFO loadings and then decreases, while there is no significant difference in structure property, adsorption equilibrium time, pH range, effect of coexisting anion, and elution effect.
2021, 38(8): 2605-2615.
doi: 10.13801/j.cnki.fhclxb.20201203.001
Abstract:
In order to study the low-velocity impact response characteristics and damage mechanism of foam filled sandwich structure with folded core, the glass fiber reinforced S-type sandwich panel with folded core was prepared by hot pressing. Sandwich panel was filled by polyurethane foam, and the impact test was carried out on two positions of sandwich panel notes and pedestal through the drop weight testing machine. The research shows that the impact position greatly affects the failure mode of the S-type sandwich panels folded core filled by foam. When the impact position is node, the core of the sandwich panel collapsing and collapsing is mainly caused by the convex side surface wall. When the impact position is node, the core of the sandwich panel collapsing and breaking is mainly caused by the convex side surface wall, and the filling of the foam plays a role in providing torque. When the impact position is the pedestal, the core of the sandwich panel is mainly caused by the tearing of the concave surface wall and the crushing failure of the convex surface wall. The damage of the sandwich panel extends fully along the thickness direction of the plate, resulting in the homogenization of the impact load. Under the same impact energy, the maximum impact load of the node is higher than that of the pedestal, and it is more stable. In addition, the impact displacement caused by the peak load of the node is lower than that of the base impact.
In order to study the low-velocity impact response characteristics and damage mechanism of foam filled sandwich structure with folded core, the glass fiber reinforced S-type sandwich panel with folded core was prepared by hot pressing. Sandwich panel was filled by polyurethane foam, and the impact test was carried out on two positions of sandwich panel notes and pedestal through the drop weight testing machine. The research shows that the impact position greatly affects the failure mode of the S-type sandwich panels folded core filled by foam. When the impact position is node, the core of the sandwich panel collapsing and collapsing is mainly caused by the convex side surface wall. When the impact position is node, the core of the sandwich panel collapsing and breaking is mainly caused by the convex side surface wall, and the filling of the foam plays a role in providing torque. When the impact position is the pedestal, the core of the sandwich panel is mainly caused by the tearing of the concave surface wall and the crushing failure of the convex surface wall. The damage of the sandwich panel extends fully along the thickness direction of the plate, resulting in the homogenization of the impact load. Under the same impact energy, the maximum impact load of the node is higher than that of the pedestal, and it is more stable. In addition, the impact displacement caused by the peak load of the node is lower than that of the base impact.
2021, 38(8): 2616-2624.
doi: 10.13801/j.cnki.fhclxb.20200927.001
Abstract:
Based on the optimization design of ship structure, in view of the current situation that the structural safety margin is too high and the stiffener of stiffened plate is over matched, the concept of the critical stiffness of the stiffener matching was proposed, and the relationship between the stiffness ratio of plate and stiffener was derived. The optimization model of T-type composite stiffener was established. Based on Isight software platform, sensitivity analysis of design variables was carried out to simplify design variables. The Multi-Island genetic algorithm was used to carry out the multivariable optimization design of stiffener. Then, combined with the engineering practice, the design scheme was determined on the basis of the stiffener optimization results. The feasibility of the multivariable optimization design method was verified by the experimental study on the mechanical properties of composite stiffened plates. Research shows that the stiffness ratio formula of the stiffened plate can be used to guide the design of stiffener stiffness matching. In the optimization design of T-type composite reinforcement, the effect of web height on the optimization target is the most obvious. Under the condition of equal stiffness constraint, the optimal design scheme of T-type stiffener can achieve the optimization goal and ensure the better economy.
Based on the optimization design of ship structure, in view of the current situation that the structural safety margin is too high and the stiffener of stiffened plate is over matched, the concept of the critical stiffness of the stiffener matching was proposed, and the relationship between the stiffness ratio of plate and stiffener was derived. The optimization model of T-type composite stiffener was established. Based on Isight software platform, sensitivity analysis of design variables was carried out to simplify design variables. The Multi-Island genetic algorithm was used to carry out the multivariable optimization design of stiffener. Then, combined with the engineering practice, the design scheme was determined on the basis of the stiffener optimization results. The feasibility of the multivariable optimization design method was verified by the experimental study on the mechanical properties of composite stiffened plates. Research shows that the stiffness ratio formula of the stiffened plate can be used to guide the design of stiffener stiffness matching. In the optimization design of T-type composite reinforcement, the effect of web height on the optimization target is the most obvious. Under the condition of equal stiffness constraint, the optimal design scheme of T-type stiffener can achieve the optimization goal and ensure the better economy.
2021, 38(8): 2625-2634.
doi: 10.13801/j.cnki.fhclxb.20201019.001
Abstract:
The temperature distribution along the thickness direction and along the weld line for carbon fiber reinforced polyetheretherketone (CF/PEEK) composite was recorded and optimized. According to the temperature distribution result, the induction welding of CF/PEEK laminates was carried out with appropriate power and heating time, with the help of vacuum bag and properly placed thermal conduction plates. The single lap strength of the welded sample was tested, and the fracture morphology of the weld area was observed and analyzed. The results show that the thermal conduction plates have a good heat dissipation effect around the surfaces of the laminates. The lower the welding power, the more uniform the heating of the welding area, but the heating time will be extended. Under the optimized processing parameters of power of 600 and heating time of 300 s in vacuum bag, and intentionally placed thermal conduction plates above the top surface and along the lateral sides, the single lap shear strength of the part reaches 41.57 MPa.
The temperature distribution along the thickness direction and along the weld line for carbon fiber reinforced polyetheretherketone (CF/PEEK) composite was recorded and optimized. According to the temperature distribution result, the induction welding of CF/PEEK laminates was carried out with appropriate power and heating time, with the help of vacuum bag and properly placed thermal conduction plates. The single lap strength of the welded sample was tested, and the fracture morphology of the weld area was observed and analyzed. The results show that the thermal conduction plates have a good heat dissipation effect around the surfaces of the laminates. The lower the welding power, the more uniform the heating of the welding area, but the heating time will be extended. Under the optimized processing parameters of power of 600 and heating time of 300 s in vacuum bag, and intentionally placed thermal conduction plates above the top surface and along the lateral sides, the single lap shear strength of the part reaches 41.57 MPa.
2021, 38(8): 2635-2645.
doi: 10.13801/j.cnki.fhclxb.20201109.001
Abstract:
Traditional elliptical probabilistic damage imaging uses signal amplitude difference or energy difference as characteristic parameters, which is not sensitive enough to damage identification and has poor noise resistance. In order to improve the sensitivity of damage recognition, it was proposed to use the energy relative variation deviation (ERVD) of wavelet packet as the damage factor. A single Lamb wave mode was excited by an air coupled ultrasonic probe in the composite laminate with an appropriate incidence angle of the probe. Wavelet packet decomposition was used to decompose the collected scanning signal. According to the change of signal characteristics before and after structural damage, a specific frequency band was selected. The calculated damage index was used for elliptical probability damage imaging, and the imaging effects of different damage factors were compared by simulating different environmental noise environments. The experimental results show that the wavelet packet energy ratio deviation as the damage factor has strong sensitivity to damage recognition sensitivity and noise resistance. Using this damage factor for air coupled ultrasound probabilistic damage imaging can improve the location and imaging effect of composite material damage.
Traditional elliptical probabilistic damage imaging uses signal amplitude difference or energy difference as characteristic parameters, which is not sensitive enough to damage identification and has poor noise resistance. In order to improve the sensitivity of damage recognition, it was proposed to use the energy relative variation deviation (ERVD) of wavelet packet as the damage factor. A single Lamb wave mode was excited by an air coupled ultrasonic probe in the composite laminate with an appropriate incidence angle of the probe. Wavelet packet decomposition was used to decompose the collected scanning signal. According to the change of signal characteristics before and after structural damage, a specific frequency band was selected. The calculated damage index was used for elliptical probability damage imaging, and the imaging effects of different damage factors were compared by simulating different environmental noise environments. The experimental results show that the wavelet packet energy ratio deviation as the damage factor has strong sensitivity to damage recognition sensitivity and noise resistance. Using this damage factor for air coupled ultrasound probabilistic damage imaging can improve the location and imaging effect of composite material damage.
2021, 38(8): 2646-2654.
doi: 10.13801/j.cnki.fhclxb.20201111.004
Abstract:
According to the energy band theory, Bi(NO3)3·5H2O was used as bismuth source to synthesize Bi2O3-Bi2WO6 composite photocatalyst materials by hydrothermal calcination. The samples were characterized by means of SEM, XRD, XPS, DRS and EIS, respectively, and the photocatalytic activity was assessed in terms of reduction of U(VI) under visible light irradiation. The results show that the prepared Bi2O3-Bi2WO6 composite materials exhibit enhanced photocatalytic performance for the photo-reduction of U(VI) than the pure Bi2WO6, the optimized photocatalytic efficiency for U(VI) is achieved when the mole ratios of Bi2O3 to Bi2WO6 is 2.4∶1. The improved photocatalytic activity is ascribed to the direct Z-scheme heterojunction between Bi2O3 and Bi2WO6, resulting in the rapid interfacial transfer of photoelectron-hole and wide light response range. This work provides a new idea to design and synthesize the photocatalysts with high visible light activity and understand the enhanced photocatalytic reduction mechanism of U(VI).
According to the energy band theory, Bi(NO3)3·5H2O was used as bismuth source to synthesize Bi2O3-Bi2WO6 composite photocatalyst materials by hydrothermal calcination. The samples were characterized by means of SEM, XRD, XPS, DRS and EIS, respectively, and the photocatalytic activity was assessed in terms of reduction of U(VI) under visible light irradiation. The results show that the prepared Bi2O3-Bi2WO6 composite materials exhibit enhanced photocatalytic performance for the photo-reduction of U(VI) than the pure Bi2WO6, the optimized photocatalytic efficiency for U(VI) is achieved when the mole ratios of Bi2O3 to Bi2WO6 is 2.4∶1. The improved photocatalytic activity is ascribed to the direct Z-scheme heterojunction between Bi2O3 and Bi2WO6, resulting in the rapid interfacial transfer of photoelectron-hole and wide light response range. This work provides a new idea to design and synthesize the photocatalysts with high visible light activity and understand the enhanced photocatalytic reduction mechanism of U(VI).
2021, 38(8): 2655-2665.
doi: 10.13801/j.cnki.fhclxb.20201116.003
Abstract:
In order to study the quasi-static performance of fly ash cenosphere/aluminum (FAC/Al) syntactic foam, quasi-static compression performance tests were conducted on the FAC/Al specimens by using a universal testing machine. The effects of different average particle sizes on the deformation and failure modes and mechanical performance of the aluminum matrix composite foam material specimens were investigated, and the stress-strain curves of the material specimens with different particle sizes under quasi-static load were obtained. And based on the stress-strain curves, the effects of particle sizes on the energy absorption performance of the material were analyzed. And the test results show that the compressive yield strength and energy absorption capacity and the ideal absorption efficiency of the material decrease with the increase of the particle sizes. In addition, by using the least square method to fit based on the stress-strain curves, the constitutive equation of FAC/Al under quasi-static load was given and verified, and the results show that the equation has a good fitting.
In order to study the quasi-static performance of fly ash cenosphere/aluminum (FAC/Al) syntactic foam, quasi-static compression performance tests were conducted on the FAC/Al specimens by using a universal testing machine. The effects of different average particle sizes on the deformation and failure modes and mechanical performance of the aluminum matrix composite foam material specimens were investigated, and the stress-strain curves of the material specimens with different particle sizes under quasi-static load were obtained. And based on the stress-strain curves, the effects of particle sizes on the energy absorption performance of the material were analyzed. And the test results show that the compressive yield strength and energy absorption capacity and the ideal absorption efficiency of the material decrease with the increase of the particle sizes. In addition, by using the least square method to fit based on the stress-strain curves, the constitutive equation of FAC/Al under quasi-static load was given and verified, and the results show that the equation has a good fitting.
2021, 38(8): 2666-2675.
doi: 10.13801/j.cnki.fhclxb.20201110.003
Abstract:
Carbon nanotubes (CNTs) reinforced Al matrix composites were fabricated by spacer-holder method, including in-situ chemical vapor deposition and ball milling process. The mechanical properties and failure mechanisms of the CNTs/Al composite foams were investigated under compression-compression cyclic loading. The results show that the strain-number of cycle curves of the CNTs/Al composite foams is composed of three stages: elastic stage, strain hardening stage and rapid accumulation stage, which is similar to Al foams. Different from Al foams' deformation of layer-by-layer, the main failure modes of CNTs/Al composite foams are the collapse of pores within significant shear deformation bands under fatigue loading and rapid plastic deformation of the specimens. In addition, the fatigue strength of the CNTs/Al composite foams with CNTs content of 2.5wt% and porosity of 60% increases by 92% than Al foams. The CNTs/Al composites exhibit uniform CNTs distribution and good interfacial bonding between CNTs and Al matrix, which guarantees the effective transmission of fatigue loading in the way of shear stress from Al matrix to CNTs, so that the CNTs can give full play to the characteristics of high strength and high toughness, and then improve the fatigue performance.
Carbon nanotubes (CNTs) reinforced Al matrix composites were fabricated by spacer-holder method, including in-situ chemical vapor deposition and ball milling process. The mechanical properties and failure mechanisms of the CNTs/Al composite foams were investigated under compression-compression cyclic loading. The results show that the strain-number of cycle curves of the CNTs/Al composite foams is composed of three stages: elastic stage, strain hardening stage and rapid accumulation stage, which is similar to Al foams. Different from Al foams' deformation of layer-by-layer, the main failure modes of CNTs/Al composite foams are the collapse of pores within significant shear deformation bands under fatigue loading and rapid plastic deformation of the specimens. In addition, the fatigue strength of the CNTs/Al composite foams with CNTs content of 2.5wt% and porosity of 60% increases by 92% than Al foams. The CNTs/Al composites exhibit uniform CNTs distribution and good interfacial bonding between CNTs and Al matrix, which guarantees the effective transmission of fatigue loading in the way of shear stress from Al matrix to CNTs, so that the CNTs can give full play to the characteristics of high strength and high toughness, and then improve the fatigue performance.
2021, 38(8): 2676-2683.
doi: 10.13801/j.cnki.fhclxb.20201019.003
Abstract:
The honeycomb preforms were prepared by vacuum sintering the mixture of ZrO2 toughened Al2O3 ceramic particles (ZTAp) of 1-2 mm, high chromium alloy powder and binder. ZTAp reinforced high chromium cast iron composites were then prepared by pouring high chromium cast iron. The interface microstructure and phase composition of the composites were analyzed by SEM, EDS and XRD. The wear resistance of the composite was evaluated by three-body abrasive wear test. The results show that the matrix of sintered high chromium cast iron is remelted in the process of casting and is metallurgical bonded with cast high chromium cast iron matrix. The interface between ZTAp and metal matrix is compact, and there are no defects such as cracks and pores. The three-body abrasive wear resistance of the composites is more than 3 times of that of high chromium cast iron. The composites are applied to the preparation of grinding roller parts. After 5 000 h of service, the wear loss of the columnar zone and composite zone in the direction of grinding roller radius are 8.2 mm and 5.9 mm, respectively, and the expected service life can be more than twice that of the high chromium cast iron grinding roller.
The honeycomb preforms were prepared by vacuum sintering the mixture of ZrO2 toughened Al2O3 ceramic particles (ZTAp) of 1-2 mm, high chromium alloy powder and binder. ZTAp reinforced high chromium cast iron composites were then prepared by pouring high chromium cast iron. The interface microstructure and phase composition of the composites were analyzed by SEM, EDS and XRD. The wear resistance of the composite was evaluated by three-body abrasive wear test. The results show that the matrix of sintered high chromium cast iron is remelted in the process of casting and is metallurgical bonded with cast high chromium cast iron matrix. The interface between ZTAp and metal matrix is compact, and there are no defects such as cracks and pores. The three-body abrasive wear resistance of the composites is more than 3 times of that of high chromium cast iron. The composites are applied to the preparation of grinding roller parts. After 5 000 h of service, the wear loss of the columnar zone and composite zone in the direction of grinding roller radius are 8.2 mm and 5.9 mm, respectively, and the expected service life can be more than twice that of the high chromium cast iron grinding roller.
2021, 38(8): 2684-2693.
doi: 10.13801/j.cnki.fhclxb.20210513.008
Abstract:
As a comprehensive military fortifications for command, defense, observation, shooting in the battlefield, the porthole of the shelter often becomes the weak point and the protection performance determines the internal personnel security. This paper focused on designing and fabricating the fiber/ceramic interlayer hybrid composite material for protective small arms, and the bulletproof ability of the composites was tested. Firstly, a numerical model of the protective deck produced with fiber/ceramic interlayer hybrid composite was established based on ABAQUS/Explicit. The effects of the different ratio of the hybrid fiber and the homogenous fiber, and the laying angle of fiber on the impact resistance of the composite protective deck were studied. The results indicate that the composites show the best protection when the Kevlar-glass fiber mixed ratio is 0.3-0.7 and the fiber laying angle is 0°/30°/60°/90°/−60°/−30°/0°. Secondly, according to the simulation results, the high strength glass fiber S-2/TDE-85 epoxy composite laminates, SiC ceramics and Kevlar 49 fiber/TDE-85 epoxy composite laminates were stacked successively by combination of winding and hand lay-up techniques to fabricate the fiber/ceramic interlayer hybrid composite material protective deck specimens. Finally, the improved Hopkinson pressure bar device was applied to carry out the projectile impact tests on the protective deck. The results demonstrate that the designed protective deck can withstand the penetration of bullets with an average velocity of 500 m/s, which agrees with the theoretical calculation results.
As a comprehensive military fortifications for command, defense, observation, shooting in the battlefield, the porthole of the shelter often becomes the weak point and the protection performance determines the internal personnel security. This paper focused on designing and fabricating the fiber/ceramic interlayer hybrid composite material for protective small arms, and the bulletproof ability of the composites was tested. Firstly, a numerical model of the protective deck produced with fiber/ceramic interlayer hybrid composite was established based on ABAQUS/Explicit. The effects of the different ratio of the hybrid fiber and the homogenous fiber, and the laying angle of fiber on the impact resistance of the composite protective deck were studied. The results indicate that the composites show the best protection when the Kevlar-glass fiber mixed ratio is 0.3-0.7 and the fiber laying angle is 0°/30°/60°/90°/−60°/−30°/0°. Secondly, according to the simulation results, the high strength glass fiber S-2/TDE-85 epoxy composite laminates, SiC ceramics and Kevlar 49 fiber/TDE-85 epoxy composite laminates were stacked successively by combination of winding and hand lay-up techniques to fabricate the fiber/ceramic interlayer hybrid composite material protective deck specimens. Finally, the improved Hopkinson pressure bar device was applied to carry out the projectile impact tests on the protective deck. The results demonstrate that the designed protective deck can withstand the penetration of bullets with an average velocity of 500 m/s, which agrees with the theoretical calculation results.
