2019 Vol. 36, No. 9
2019, 36(9): 1995-2001.
doi: 10.13801/j.cnki.fhclxb.20181210.004
Abstract:
The polysiloxane/polyphenylene sulfide (PVS/PPS) nonwoven composite separator was first fabricated by employing polyvinylsilsesquioxane (PVS) polymer as the coating material and PPS nonwoven as the substrate. The physical properties, electrochemical behavior and battery performance of the separator were systematically investigated. Compared with polyolefin separator (PP/PE/PP), the PVS/PPS composite separator is discovered to display highly developed microporous structure, superior electrolyte wettability, higher ionic conductivity and enhanced compatibility with electrode. These behaviors can be helpful for weaken ohmic polarization degree in case of charging/discharging, which finally endows battery with higher discharge specific capacity and outstanding cyclic stability (retention rate is ahout 100%). The PVS/PPS composite separator can exhibit excellent heat resistance and dimensional stability even after thermal treatment at 250℃ for 1 h. Accordingly, there is a promising prospect for PPS nonwoven-based composite separator in the development of the high power lithium ion battery.
The polysiloxane/polyphenylene sulfide (PVS/PPS) nonwoven composite separator was first fabricated by employing polyvinylsilsesquioxane (PVS) polymer as the coating material and PPS nonwoven as the substrate. The physical properties, electrochemical behavior and battery performance of the separator were systematically investigated. Compared with polyolefin separator (PP/PE/PP), the PVS/PPS composite separator is discovered to display highly developed microporous structure, superior electrolyte wettability, higher ionic conductivity and enhanced compatibility with electrode. These behaviors can be helpful for weaken ohmic polarization degree in case of charging/discharging, which finally endows battery with higher discharge specific capacity and outstanding cyclic stability (retention rate is ahout 100%). The PVS/PPS composite separator can exhibit excellent heat resistance and dimensional stability even after thermal treatment at 250℃ for 1 h. Accordingly, there is a promising prospect for PPS nonwoven-based composite separator in the development of the high power lithium ion battery.
2019, 36(9): 2002-2012.
doi: 10.13801/j.cnki.fhclxb.20190122.002
Abstract:
The modified basalt short fiber (BSF) and aramid pulp (AP) were used to reinforce chloroprene rubber (CR) to obtain BSF-AP/CR composites with high modulus and strength. The effects of BSF and AP on the basic physical properties, dynamic mechanical properties and dynamic stiffness of the BSF-AP/CR composites were systematically studied. FTIR tests show that the γ-aminopropyl triethoxysilane (KH550) is reacted with the surface groups of BSF, and the SEM observation finds that the BSF has good compatibility with rubber, easy to disperse and orientate, while the AP is anchored in the rubber matrix, and the orientation degree is worse than that of BSF. With the decrease of the mass ratio of BSF to AP, the tensile strength, elongation at break and flexural properties of the BSF-AP/CR composites reduce, but the tear strength and wear resistance are improved. The dynamic stiffness of the BSF-AP/CR composites was tested by elastomer material testing system (MTS). The MTS shows that the lower the mass ratio of BSF and AP is, the greater the dynamic stiffness of BSF-AP/CR composites is, indicating AP contributes greatly to the dynamic stiffness of BSF-AP/CR composites. The dynamic mechanical properties reveals that the more the amount of AP is, the higher the storage modulus (G') of BSF-AP/CR composites is and the more obvious Payne effect is however, the smaller the damping factor is, indicating that AP has good modulus lag balance effect. When the mass ratio of BSF to AP is 10:10, there is better comprehensive performance for the BSF-AP/CR composites.
The modified basalt short fiber (BSF) and aramid pulp (AP) were used to reinforce chloroprene rubber (CR) to obtain BSF-AP/CR composites with high modulus and strength. The effects of BSF and AP on the basic physical properties, dynamic mechanical properties and dynamic stiffness of the BSF-AP/CR composites were systematically studied. FTIR tests show that the γ-aminopropyl triethoxysilane (KH550) is reacted with the surface groups of BSF, and the SEM observation finds that the BSF has good compatibility with rubber, easy to disperse and orientate, while the AP is anchored in the rubber matrix, and the orientation degree is worse than that of BSF. With the decrease of the mass ratio of BSF to AP, the tensile strength, elongation at break and flexural properties of the BSF-AP/CR composites reduce, but the tear strength and wear resistance are improved. The dynamic stiffness of the BSF-AP/CR composites was tested by elastomer material testing system (MTS). The MTS shows that the lower the mass ratio of BSF and AP is, the greater the dynamic stiffness of BSF-AP/CR composites is, indicating AP contributes greatly to the dynamic stiffness of BSF-AP/CR composites. The dynamic mechanical properties reveals that the more the amount of AP is, the higher the storage modulus (G') of BSF-AP/CR composites is and the more obvious Payne effect is however, the smaller the damping factor is, indicating that AP has good modulus lag balance effect. When the mass ratio of BSF to AP is 10:10, there is better comprehensive performance for the BSF-AP/CR composites.
2019, 36(9): 2013-2022.
doi: 10.13801/j.cnki.fhclxb.20181210.003
Abstract:
The epoxy resin-urea-formaldehyde (E-51-UF) microcapsules were synthesized by one-step in-situ polymerization with UF resin as the shell and E-51 as the core material. The structure, surface morphology, heat resistance and particle size distribution of E-51-UF microcapsules were characterized by FTIR, SEM, TG and particle size analyzer. The E-51-UF@2-methylimidazole (2-MI) composite microcapsules were prepared by blending E-51-UF microcapsules as the core and 2-MI as the shell. The E-51-UF@2-MI composite microcapsules were filled in the epoxy resin matrix and E-51-UF@2-MI microcapsules/E-51 composite samples were prepared for the tensile, bending and trapezoidal double cantilever beam (TDCB). The electronic universal testing machine was used to test the properties of the samples. The effects of the mass fraction of E-51-UF@2-MI composite microcapsules on the mechanical properties and self-healing properties of E-51-UF@2-MI microcapsules/E-51 composites were analyzed. The results show that the prepared E-51-UF microcapsules have a regular spherical structure with an average particle size of 130 μm and a heat resistant temperature of 364℃. When the mass fraction of E-51-UF@2-MI microcapsules is 10wt%, the tensile strength of E-51-UF@2-MI composite microcapsules/E-51 composites reaches a maximum of 31.17 MPa, the bending strength is 66.77 MPa and the maximum self-healing ratio is 90.1%.
The epoxy resin-urea-formaldehyde (E-51-UF) microcapsules were synthesized by one-step in-situ polymerization with UF resin as the shell and E-51 as the core material. The structure, surface morphology, heat resistance and particle size distribution of E-51-UF microcapsules were characterized by FTIR, SEM, TG and particle size analyzer. The E-51-UF@2-methylimidazole (2-MI) composite microcapsules were prepared by blending E-51-UF microcapsules as the core and 2-MI as the shell. The E-51-UF@2-MI composite microcapsules were filled in the epoxy resin matrix and E-51-UF@2-MI microcapsules/E-51 composite samples were prepared for the tensile, bending and trapezoidal double cantilever beam (TDCB). The electronic universal testing machine was used to test the properties of the samples. The effects of the mass fraction of E-51-UF@2-MI composite microcapsules on the mechanical properties and self-healing properties of E-51-UF@2-MI microcapsules/E-51 composites were analyzed. The results show that the prepared E-51-UF microcapsules have a regular spherical structure with an average particle size of 130 μm and a heat resistant temperature of 364℃. When the mass fraction of E-51-UF@2-MI microcapsules is 10wt%, the tensile strength of E-51-UF@2-MI composite microcapsules/E-51 composites reaches a maximum of 31.17 MPa, the bending strength is 66.77 MPa and the maximum self-healing ratio is 90.1%.
2019, 36(9): 2023-2030.
doi: 10.13801/j.cnki.fhclxb.20190227.002
Abstract:
Vascular self-lubrication epoxy resin (VAEP) and carbon fiber (CF)/VAEP composites were prepared by the vaporization of sacrificial components (VaSC) technology and vacuum immerse mode. With methyl silicone oil as a lubricant, polylactide (PLA) was used as the sacrificial components, CF was used as the reinforcing components, which was woven into PLA-CF fabric by the measure of warp and weft weave. The morphology of the CF/VAEP composites of section, friction surface and transfer film surface were characterized by SEM. The mechanical properties and tribological properties of the CF/VAEP composites were tested by electronic universal testing machine and high-speed block-on-ring wear tester. The results show that the vascular structure and CF enhance the lubrication and mechanical properties of epoxy resin (EP). Compared with the pure EP, when the radial direction vascular density of the VAEP is 8 pores/10 mm, the friction coefficient and wear rate are reduced by 67.95% and 85.71%, respectively. Compared with the same radial direction vascular density of VAEP, when the radial direction vascular density of the CF/VAEP composites is 8 pores/10 mm and warp to weft ratio of CF tow is 8/4, the tensile strength, tensile modulus, bending strength and bending modulus of the CF/VAEP vascular self-lubricating composites are increased by 203.33%, 44.16%, 325.78%, 311.37%, respectively.
Vascular self-lubrication epoxy resin (VAEP) and carbon fiber (CF)/VAEP composites were prepared by the vaporization of sacrificial components (VaSC) technology and vacuum immerse mode. With methyl silicone oil as a lubricant, polylactide (PLA) was used as the sacrificial components, CF was used as the reinforcing components, which was woven into PLA-CF fabric by the measure of warp and weft weave. The morphology of the CF/VAEP composites of section, friction surface and transfer film surface were characterized by SEM. The mechanical properties and tribological properties of the CF/VAEP composites were tested by electronic universal testing machine and high-speed block-on-ring wear tester. The results show that the vascular structure and CF enhance the lubrication and mechanical properties of epoxy resin (EP). Compared with the pure EP, when the radial direction vascular density of the VAEP is 8 pores/10 mm, the friction coefficient and wear rate are reduced by 67.95% and 85.71%, respectively. Compared with the same radial direction vascular density of VAEP, when the radial direction vascular density of the CF/VAEP composites is 8 pores/10 mm and warp to weft ratio of CF tow is 8/4, the tensile strength, tensile modulus, bending strength and bending modulus of the CF/VAEP vascular self-lubricating composites are increased by 203.33%, 44.16%, 325.78%, 311.37%, respectively.
2019, 36(9): 2031-2041.
doi: 10.13801/j.cnki.fhclxb.20181226.001
Abstract:
In order to systemically investigate the effects of nano SiO2 on the alternating current/direct current (AC/DC) breakdown strength and AC/DC electrical treeing resistance properties of cross-linked polyethylene (XLPE), nano SiO2/XLPE composites with 0.5wt% and 1wt% nano SiO2 were prepared using parallel twin screw extrude. With untreated XLPE and commercial DC cable XLPE insulation as references, the doping effects of nano SiO2 on the electrical tree initiation and growth characteristics under AC voltage and periodic grounded DC voltage as well as the AC/DC breakdown strength of XLPE were tested. The experimental results indicate that the DC breakdown strength of commercial DC cable XLPE insulation is similar to that of the untreated XLPE, but the periodic grounded DC electrical tree initiation is more difficult and the tree growth speed is much slower than that of untreated XLPE. With the increase of nano SiO2 content, its effect on improving AC/DC breakdown strength and inhibiting AC/DC electrical tree initiation are increased. The 1wt% nano SiO2/XLPE composite has the significant inhibition effect on the imitation and growth of the periodic grounded DC electrical tree, and its tree initiation and growth properties are both superior to the commercial cable material. The AC breakdown strength and the initiation voltage of AC electrical tree of 1wt% nano SiO2/XLPE composite are both higher than that of untreated XLPE, but the inhibition on the growth of AC electrical tree is limited to the early stage of tree propagation. After the electrical tree exceeds a certain length, the growth rate of electrical tree in the 1wt% nano SiO2/XLPE composite exceeds that of untreated XLPE.
In order to systemically investigate the effects of nano SiO2 on the alternating current/direct current (AC/DC) breakdown strength and AC/DC electrical treeing resistance properties of cross-linked polyethylene (XLPE), nano SiO2/XLPE composites with 0.5wt% and 1wt% nano SiO2 were prepared using parallel twin screw extrude. With untreated XLPE and commercial DC cable XLPE insulation as references, the doping effects of nano SiO2 on the electrical tree initiation and growth characteristics under AC voltage and periodic grounded DC voltage as well as the AC/DC breakdown strength of XLPE were tested. The experimental results indicate that the DC breakdown strength of commercial DC cable XLPE insulation is similar to that of the untreated XLPE, but the periodic grounded DC electrical tree initiation is more difficult and the tree growth speed is much slower than that of untreated XLPE. With the increase of nano SiO2 content, its effect on improving AC/DC breakdown strength and inhibiting AC/DC electrical tree initiation are increased. The 1wt% nano SiO2/XLPE composite has the significant inhibition effect on the imitation and growth of the periodic grounded DC electrical tree, and its tree initiation and growth properties are both superior to the commercial cable material. The AC breakdown strength and the initiation voltage of AC electrical tree of 1wt% nano SiO2/XLPE composite are both higher than that of untreated XLPE, but the inhibition on the growth of AC electrical tree is limited to the early stage of tree propagation. After the electrical tree exceeds a certain length, the growth rate of electrical tree in the 1wt% nano SiO2/XLPE composite exceeds that of untreated XLPE.
2019, 36(9): 2042-2050.
doi: 10.13801/j.cnki.fhclxb.20181224.001
Abstract:
To improve the interfacial compatibility as well as enhance the dielectric properties of polyvinylidene fluoride (PVDF) based inorganic composite, the BaTiO3 nanoparticles were coated using Ag decorated inorganic layer polydopamine (PDA). Subsequently the BaTiO3@PDA-Ag particle was introduced the dielectric polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)) matrix and BaTiO3@PDA-Ag/P(VDF-HFP) composite films were prepared using a solution casting mothed. FTIR and XPS were employed to detect the structures and monographs of the BaTiO3@PDA-Ag/P(VDF-HFP) composites, and the wide range frequency dielectric spectrometer and ferroelectric property testing system were used to compare the dielectric and polarizing properties of the BaTiO3@PDA-Ag/P(VDF-HFP) composite films under various electric fields. In the BaTiO3@PDA-Ag/P(VDF-HFP) composite film with 20wt% BaTiO3@PDA-Ag particles, a high dielectric constant of 25 and low loss of 0.1, a large electric displacement of 6.2 μC·cm-2 under 175 M·Vm-1, and a considerable high discharging energy density of 6.9 J·cm-3 under 200 M·Vm-1 are obtained. Considering its favorable interface and considerable electric performances, the core-shell structure of the BaTiO3@PDA-Ag/P(VDF-HFP) composite provides a reference to the future research of this sorts of composites for energy storage devices.
To improve the interfacial compatibility as well as enhance the dielectric properties of polyvinylidene fluoride (PVDF) based inorganic composite, the BaTiO3 nanoparticles were coated using Ag decorated inorganic layer polydopamine (PDA). Subsequently the BaTiO3@PDA-Ag particle was introduced the dielectric polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)) matrix and BaTiO3@PDA-Ag/P(VDF-HFP) composite films were prepared using a solution casting mothed. FTIR and XPS were employed to detect the structures and monographs of the BaTiO3@PDA-Ag/P(VDF-HFP) composites, and the wide range frequency dielectric spectrometer and ferroelectric property testing system were used to compare the dielectric and polarizing properties of the BaTiO3@PDA-Ag/P(VDF-HFP) composite films under various electric fields. In the BaTiO3@PDA-Ag/P(VDF-HFP) composite film with 20wt% BaTiO3@PDA-Ag particles, a high dielectric constant of 25 and low loss of 0.1, a large electric displacement of 6.2 μC·cm-2 under 175 M·Vm-1, and a considerable high discharging energy density of 6.9 J·cm-3 under 200 M·Vm-1 are obtained. Considering its favorable interface and considerable electric performances, the core-shell structure of the BaTiO3@PDA-Ag/P(VDF-HFP) composite provides a reference to the future research of this sorts of composites for energy storage devices.
2019, 36(9): 2051-2058.
doi: 10.13801/j.cnki.fhclxb.20181218.002
Abstract:
The ZrO2/polyvinylidene fluoride (PVDF) composites were prepared via melting method. The morphology and structure of ZrO2/PVDF composites were analyzed by SEM, XRD and FTIR. The results show that the ZrO2/PVDF composites with the uniformly distributed ZrO2 are mainly composed of a large number of α phases and a small amount of γ phase. In addition, dielectric constant ε' of ZrO2/PVDF composites increases with the increase of ZrO2 content by dielectric spectroscopy (BDS) and the dielectric loss tanδ value keeps a constant, indicating that the dielectric properties of ZrO2/PVDF composites can be significantly improved by adding ZrO2. By calculating the dielectric modulus M″ and activation energy of ZrO2/PVDF composites, the glass transition peaks, defect peaks and interfacial polarization peaks have been observed. The activation energy of ZrO2/PVDF composite increases with the addition of ZrO2.
The ZrO2/polyvinylidene fluoride (PVDF) composites were prepared via melting method. The morphology and structure of ZrO2/PVDF composites were analyzed by SEM, XRD and FTIR. The results show that the ZrO2/PVDF composites with the uniformly distributed ZrO2 are mainly composed of a large number of α phases and a small amount of γ phase. In addition, dielectric constant ε' of ZrO2/PVDF composites increases with the increase of ZrO2 content by dielectric spectroscopy (BDS) and the dielectric loss tanδ value keeps a constant, indicating that the dielectric properties of ZrO2/PVDF composites can be significantly improved by adding ZrO2. By calculating the dielectric modulus M″ and activation energy of ZrO2/PVDF composites, the glass transition peaks, defect peaks and interfacial polarization peaks have been observed. The activation energy of ZrO2/PVDF composite increases with the addition of ZrO2.
2019, 36(9): 2059-2066.
doi: 10.13801/j.cnki.fhclxb.20181220.001
Abstract:
The accelerated aging tests of alkali-ultraviolet circulation of glass fiber/epoxy vinlester (GF/EVE) composites used in wind power project were carried out. The change of moisture absorption rate, micro morphology, surface element content, initial decomposition temperature and erosion mass loss rate of the CF/EVE composite samples were investigated to reveal the aging mechanism of GF/EVE composites in alkali-ultraviolet circulation aging and the change of erosion resistance of GF/EVE composites under different cyclic aging cycles. The results show that the coaction of photo-oxidative, hydrolysis reaction and water diffusion causes the surface resin of the GF/EVE composites aging degradation and fiber decomposition and also causes fiber and resin matrix to debond. The breakdown of resin molecular chain and the decrease of resin crosslinking density cause the decline of initial decomposition temperature of resin under circulation aging. The erosion mass loss rate decreases by 2.06% at the first aging cycle and the erosion mass loss rate increases by 32.8% at the end of aging.
The accelerated aging tests of alkali-ultraviolet circulation of glass fiber/epoxy vinlester (GF/EVE) composites used in wind power project were carried out. The change of moisture absorption rate, micro morphology, surface element content, initial decomposition temperature and erosion mass loss rate of the CF/EVE composite samples were investigated to reveal the aging mechanism of GF/EVE composites in alkali-ultraviolet circulation aging and the change of erosion resistance of GF/EVE composites under different cyclic aging cycles. The results show that the coaction of photo-oxidative, hydrolysis reaction and water diffusion causes the surface resin of the GF/EVE composites aging degradation and fiber decomposition and also causes fiber and resin matrix to debond. The breakdown of resin molecular chain and the decrease of resin crosslinking density cause the decline of initial decomposition temperature of resin under circulation aging. The erosion mass loss rate decreases by 2.06% at the first aging cycle and the erosion mass loss rate increases by 32.8% at the end of aging.
2019, 36(9): 2067-2075.
doi: 10.13801/j.cnki.fhclxb.20181115.001
Abstract:
Submicrometer-sized cobalt hydroxystannate (CHS) flame retardant was prepared via coprecipitation method and applied to flexible polyvinyl chloride (PVC) to obtained CHS/PVC composites. The flame retardancy, thermal stability and mechanical properties of CHS/PVC composites were investigated by limiting oxygen index (LOI), cone calorimeter, TG analysis and universal tensile tests. The results show that the CHS effectively enhances the flame retardancy and maintains the mechanical property of CHS/PVC composites. Compared with blank PVC, when the mass ratio of CHS to PVC is 10%, the LOI of CHS/PVC composite is increased by 2.3%, the peaks of heat release rate and smoke production rate are reduced by 39.6% and 57.4%, respectively. The enhancement for CHS/PVC composites in flame retardation mainly attributes to the water dehydration from CHS when heating which dilutes heat. On the other hand, the CoCl2 generated during the combustion process can effectively catalyze the early decomposition of PVC and then a denser and continuous residual charlayer is formed, thereby the combustion of PVC is effectively suppress.
Submicrometer-sized cobalt hydroxystannate (CHS) flame retardant was prepared via coprecipitation method and applied to flexible polyvinyl chloride (PVC) to obtained CHS/PVC composites. The flame retardancy, thermal stability and mechanical properties of CHS/PVC composites were investigated by limiting oxygen index (LOI), cone calorimeter, TG analysis and universal tensile tests. The results show that the CHS effectively enhances the flame retardancy and maintains the mechanical property of CHS/PVC composites. Compared with blank PVC, when the mass ratio of CHS to PVC is 10%, the LOI of CHS/PVC composite is increased by 2.3%, the peaks of heat release rate and smoke production rate are reduced by 39.6% and 57.4%, respectively. The enhancement for CHS/PVC composites in flame retardation mainly attributes to the water dehydration from CHS when heating which dilutes heat. On the other hand, the CoCl2 generated during the combustion process can effectively catalyze the early decomposition of PVC and then a denser and continuous residual charlayer is formed, thereby the combustion of PVC is effectively suppress.
2019, 36(9): 2076-2085.
doi: 10.13801/j.cnki.fhclxb.20181121.003
Abstract:
A kind of high-rigidity epoxy resin (5182 resin) was designed and its stiffness enhancement mechanisms in crosslinking network, the heat resistance properties and mechanical properties of epoxy resin were investigated. The results show that the stiffness of crosslinking network of 5182 resin is improved through stiff imide structure and more cross-linked points, the glass transition temperature is 228℃, and tensile modulus reaches 4 375 MPa. High-modulus carbon fiber (Domestic BHM3 and Toray M40J) reinforced high-rigidity 5182 resin composites were prepared, the interface properties, microstructure and the mechanical properties of high-modulus carbon fiber/high-rigidity epoxy resin composites were evaluated. Due to increasing modulus of resin and transferring of interface damage from carbon fiber surface to the resin area, high modulus carbon fiber/high-rigidity epoxy composites shows the highest interfacial shear strength (106.8 MPa) and excellent mechanical performance, especially flexible properties and interlaminar shear strength.
A kind of high-rigidity epoxy resin (5182 resin) was designed and its stiffness enhancement mechanisms in crosslinking network, the heat resistance properties and mechanical properties of epoxy resin were investigated. The results show that the stiffness of crosslinking network of 5182 resin is improved through stiff imide structure and more cross-linked points, the glass transition temperature is 228℃, and tensile modulus reaches 4 375 MPa. High-modulus carbon fiber (Domestic BHM3 and Toray M40J) reinforced high-rigidity 5182 resin composites were prepared, the interface properties, microstructure and the mechanical properties of high-modulus carbon fiber/high-rigidity epoxy resin composites were evaluated. Due to increasing modulus of resin and transferring of interface damage from carbon fiber surface to the resin area, high modulus carbon fiber/high-rigidity epoxy composites shows the highest interfacial shear strength (106.8 MPa) and excellent mechanical performance, especially flexible properties and interlaminar shear strength.
2019, 36(9): 2086-2092.
doi: 10.13801/j.cnki.fhclxb.20181122.004
Abstract:
Sodium montmorillonite (MMT) was modified by octadecyl trimethyl ammonium chloride (OTAC) via cation exchange and organic montmorillonite (OMMT) was got. Polyurethane elastomer (PUE) was synthesized taking 4,4'-diphenylmethane diisocyanate (MDI) and polypropylene glycol (PPG) as the raw materials and 1,4-butanediol (BDO) as chain extender, and then OMMT/PUE composite was prepared by the prepolymer method. The results of FTIR and XRD show that the characteristic peaks of -CH2(2 921 cm-1 and 1 469 cm-1) appear and indicate that the new groups have been introduced into the layers of OMMT, the intercalation quantity of OTAC is about 24% by the heat resistance of MMT and OMMT, and the interlayer spacing of OMMT is 0.7 nm larger than that of MMT. The analytical results of SEM and XRD of OMMT/PUE composites reveal that proper OMMT disperses evenly in the PUE matrix, and OMMT is peeled completely. This phenomenon can be explained by two main reasons, i.e. one is the strong interaction between OTAC molecular and soft segments of PUE, and the other is the interface interaction amid the active groups of OMMT and PUE matrix. The test results of mechanical properties of OMMT/PUE composites display that the maximum tensile strength, elongation at break and breaking tensile strength of OMMT/PUE composite are 37%, 28% and 34% higher than that of PUE matrix, respectively, when the content of OMMT is 3wt%, and the mechanical properties of OMMT/PUE composites are significantly improved.
Sodium montmorillonite (MMT) was modified by octadecyl trimethyl ammonium chloride (OTAC) via cation exchange and organic montmorillonite (OMMT) was got. Polyurethane elastomer (PUE) was synthesized taking 4,4'-diphenylmethane diisocyanate (MDI) and polypropylene glycol (PPG) as the raw materials and 1,4-butanediol (BDO) as chain extender, and then OMMT/PUE composite was prepared by the prepolymer method. The results of FTIR and XRD show that the characteristic peaks of -CH2(2 921 cm-1 and 1 469 cm-1) appear and indicate that the new groups have been introduced into the layers of OMMT, the intercalation quantity of OTAC is about 24% by the heat resistance of MMT and OMMT, and the interlayer spacing of OMMT is 0.7 nm larger than that of MMT. The analytical results of SEM and XRD of OMMT/PUE composites reveal that proper OMMT disperses evenly in the PUE matrix, and OMMT is peeled completely. This phenomenon can be explained by two main reasons, i.e. one is the strong interaction between OTAC molecular and soft segments of PUE, and the other is the interface interaction amid the active groups of OMMT and PUE matrix. The test results of mechanical properties of OMMT/PUE composites display that the maximum tensile strength, elongation at break and breaking tensile strength of OMMT/PUE composite are 37%, 28% and 34% higher than that of PUE matrix, respectively, when the content of OMMT is 3wt%, and the mechanical properties of OMMT/PUE composites are significantly improved.
2019, 36(9): 2093-2100.
doi: 10.13801/j.cnki.fhclxb.20181206.001
Abstract:
The influence of the hybrid process and the composite process on the mechanical properties of hybrid coir-hemp/polypropylene (PP) composites was discussed by orthogonal analysis. The results show that the mechanical properties of hybrid coir-hemp/PP composites after hybrid treatment are greatly improved compared with that of hemp/PP composites under the same composite conditions. The mass ratio between coir fiber and hemp fiber has the greatest influence on the mechanical properties of hybrid coir-hemp/PP composites, and the mechanical properties of the hybrid coir-hemp/PP composites increase linearly with the increase of the coir fiber content; the mass fraction of PP fiber in reinforced needle-punched felt has great influence on the flexural strength of the hybrid coir-hemp/PP composites. The bending strength of the hybrid coir-hemp/PP composites decreases with the increase of the PP fiber content on the initial, and then increases with the increase of PP fiber content, while the tensile strength of the hybrid coir-hemp/PP composites decreases linearly with the increases of PP fiber. The mechanical properties of the hybrid coir-hemp/PP composites decrease with the increase of the composite lamination temperature.
The influence of the hybrid process and the composite process on the mechanical properties of hybrid coir-hemp/polypropylene (PP) composites was discussed by orthogonal analysis. The results show that the mechanical properties of hybrid coir-hemp/PP composites after hybrid treatment are greatly improved compared with that of hemp/PP composites under the same composite conditions. The mass ratio between coir fiber and hemp fiber has the greatest influence on the mechanical properties of hybrid coir-hemp/PP composites, and the mechanical properties of the hybrid coir-hemp/PP composites increase linearly with the increase of the coir fiber content; the mass fraction of PP fiber in reinforced needle-punched felt has great influence on the flexural strength of the hybrid coir-hemp/PP composites. The bending strength of the hybrid coir-hemp/PP composites decreases with the increase of the PP fiber content on the initial, and then increases with the increase of PP fiber content, while the tensile strength of the hybrid coir-hemp/PP composites decreases linearly with the increases of PP fiber. The mechanical properties of the hybrid coir-hemp/PP composites decrease with the increase of the composite lamination temperature.
2019, 36(9): 2101-2109.
doi: 10.13801/j.cnki.fhclxb.20190121.002
Abstract:
The polyimide fiber/epoxy (PI/EP) composite laminates were prepared by hot-melt method combined with autoclave molding technology using high strength and high modulus PI fiber as reinforcement and aviation grade EP as matrix. The mechanical properties and failure morphology of the PI/EP composites were analyzed. The results show that PI fiber exhibits good interfacial bonding strength with epoxy resin. The interlaminar shear strength of the PI/EP composites is 65.2 MPa and the in-plane shear strength is 68.6 MPa; The PI/EP composites possess excellent mechanical properties because of good interface bonding integration condition, the longitudinal tensile strength is up to 1 835 MPa and the flexural strength is 834 MPa. The longitudinal tensile failure form of the PI/EP composites is explosion damage of filament. The high strength and high modulus PI fiber has excellent toughness and high elongation, so the time of failure becomes longer when the PI/EP composites are subjected to great tensile stress. The longitudinal compression failure form is 45° kinking band. The high strength and high modulus PI/EP composites provides a new material selection scheme for advanced aerospace composites.
The polyimide fiber/epoxy (PI/EP) composite laminates were prepared by hot-melt method combined with autoclave molding technology using high strength and high modulus PI fiber as reinforcement and aviation grade EP as matrix. The mechanical properties and failure morphology of the PI/EP composites were analyzed. The results show that PI fiber exhibits good interfacial bonding strength with epoxy resin. The interlaminar shear strength of the PI/EP composites is 65.2 MPa and the in-plane shear strength is 68.6 MPa; The PI/EP composites possess excellent mechanical properties because of good interface bonding integration condition, the longitudinal tensile strength is up to 1 835 MPa and the flexural strength is 834 MPa. The longitudinal tensile failure form of the PI/EP composites is explosion damage of filament. The high strength and high modulus PI fiber has excellent toughness and high elongation, so the time of failure becomes longer when the PI/EP composites are subjected to great tensile stress. The longitudinal compression failure form is 45° kinking band. The high strength and high modulus PI/EP composites provides a new material selection scheme for advanced aerospace composites.
2019, 36(9): 2110-2118.
doi: 10.13801/j.cnki.fhclxb.20181023.004
Abstract:
According to hierarchical structural design idea, a high-performance polymethylallyl imide (PMI) foam was added between the unidirectional carbon fiber reinforced resin composite to prepare hierarchical composite honeycomb structure. The out-of-plane compressive performance of hierarchical composite honeycomb structures were studied, including the theoretical prediction and experimental verification of the out-of-plane compressive performance of hierarchical composite honeycomb structures. The relationship between the out-of-plane compressive properties of hierarchical composite honeycomb structure and the structural equivalent density was studied. The three-point bending performance of hierarchical composite honeycomb structure was studied, including theoretical prediction and experimental verification. The failure mode of the structure was predicted by theoretical research, the failure mode mechanism diagram was drawn, and the theoretical prediction results were verified by three-point bending test.
According to hierarchical structural design idea, a high-performance polymethylallyl imide (PMI) foam was added between the unidirectional carbon fiber reinforced resin composite to prepare hierarchical composite honeycomb structure. The out-of-plane compressive performance of hierarchical composite honeycomb structures were studied, including the theoretical prediction and experimental verification of the out-of-plane compressive performance of hierarchical composite honeycomb structures. The relationship between the out-of-plane compressive properties of hierarchical composite honeycomb structure and the structural equivalent density was studied. The three-point bending performance of hierarchical composite honeycomb structure was studied, including theoretical prediction and experimental verification. The failure mode of the structure was predicted by theoretical research, the failure mode mechanism diagram was drawn, and the theoretical prediction results were verified by three-point bending test.
2019, 36(9): 2119-2130.
doi: 10.13801/j.cnki.fhclxb.20181203.001
Abstract:
The Bi2WO6 semiconductor possesses excellent photocatalytic performance due to its nontoxicity, strong oxidizing power and visible-light responsiveness. However, the small specific surface area and poor adsorption capacity limit its practical applications. The taking advantage of strong adsorption abilities of attapulgite clay to prepare attapulgite/Bi2WO6 photocatalytic composite by adjusting the temperature and time of hydrothermal reaction, the mass ratio, and the pH value of the precursor solution. The as-prepared photocatalyst was characterized by XRD, SEM, N2 adsorption-desorption measurements and UV-visible diffused reflectance spectra (UV-vis DRS). The results show that the attapulgite/Bi2WO6 photocatalytic composite has 3D nanospheres hierarchical structure and exhibit a better photocatalytic activity for Rhodamine B under visible light while it is prepared under hydrothermal reaction at 180℃ for 18 h, the mass ratio of attapulgite clay to Bi2WO6 is 6%, and the initial pH=1 for the precursor solution of attapulgite/Bi2WO6 photocatalytic composite.
The Bi2WO6 semiconductor possesses excellent photocatalytic performance due to its nontoxicity, strong oxidizing power and visible-light responsiveness. However, the small specific surface area and poor adsorption capacity limit its practical applications. The taking advantage of strong adsorption abilities of attapulgite clay to prepare attapulgite/Bi2WO6 photocatalytic composite by adjusting the temperature and time of hydrothermal reaction, the mass ratio, and the pH value of the precursor solution. The as-prepared photocatalyst was characterized by XRD, SEM, N2 adsorption-desorption measurements and UV-visible diffused reflectance spectra (UV-vis DRS). The results show that the attapulgite/Bi2WO6 photocatalytic composite has 3D nanospheres hierarchical structure and exhibit a better photocatalytic activity for Rhodamine B under visible light while it is prepared under hydrothermal reaction at 180℃ for 18 h, the mass ratio of attapulgite clay to Bi2WO6 is 6%, and the initial pH=1 for the precursor solution of attapulgite/Bi2WO6 photocatalytic composite.
2019, 36(9): 2131-2138.
doi: 10.13801/j.cnki.fhclxb.20181212.001
Abstract:
By introducing β-tricalcium phosphate (β-TCP) particles into the magnesium matrix alloy, the mechanical and corrosion degradation properties of the composite could be adjusted to meet the service requirements of different implantation sites. In this study, on the basis of mechanical stirring casting, the melt of Mg matrix composite was assisted by ultrasonic treatment, and the β-TCP/Mg-Zn-Ca biodegradable composite was prepared with the β-TCP content of 1% (mass ratio), Zn content of 3% (mass ratio) and Ca content of 0.2% (mass ratio). The effects of ultrasonic treatment on the microstructure, mechanical properties and corrosion behavior of the β-TCP/Mg-Zn-Ca composite were analyzed. The results show that the ultrasonic treatment can refine the microstructure and facilitate the uniform dispersion of the β-TCP particles in the matrix alloy. The corrosion resistance of the β-TCP/Mg-Zn-Ca composites is improved after ultrasonic treatment; The yield strength, ultimate tensile strength and elongation of the as-extruded β-TCP/Mg-Zn-Ca composite after ultrasonic treatment are 211.54 MPa, 334.32 MPa, and 7.28%, respectively, which increase by 8.44%, 4.67% and 17.99%, respectively, compared with the unsonicated β-TCP/Mg-Zn-Ca composite.
By introducing β-tricalcium phosphate (β-TCP) particles into the magnesium matrix alloy, the mechanical and corrosion degradation properties of the composite could be adjusted to meet the service requirements of different implantation sites. In this study, on the basis of mechanical stirring casting, the melt of Mg matrix composite was assisted by ultrasonic treatment, and the β-TCP/Mg-Zn-Ca biodegradable composite was prepared with the β-TCP content of 1% (mass ratio), Zn content of 3% (mass ratio) and Ca content of 0.2% (mass ratio). The effects of ultrasonic treatment on the microstructure, mechanical properties and corrosion behavior of the β-TCP/Mg-Zn-Ca composite were analyzed. The results show that the ultrasonic treatment can refine the microstructure and facilitate the uniform dispersion of the β-TCP particles in the matrix alloy. The corrosion resistance of the β-TCP/Mg-Zn-Ca composites is improved after ultrasonic treatment; The yield strength, ultimate tensile strength and elongation of the as-extruded β-TCP/Mg-Zn-Ca composite after ultrasonic treatment are 211.54 MPa, 334.32 MPa, and 7.28%, respectively, which increase by 8.44%, 4.67% and 17.99%, respectively, compared with the unsonicated β-TCP/Mg-Zn-Ca composite.
2019, 36(9): 2139-2146.
doi: 10.13801/j.cnki.fhclxb.20181122.001
Abstract:
A novel Sm3+-SrTiO3/TiO2 composite nanofibers were synthesized by one-step hydrothermal technique. By this way, TiO2 nanofibers could serve as the both substrate and reactant. Moreover, not only doping of Sm3+ into SrTiO3 but also in-situ growth of SrTiO3 on skeleton of TiO2 could be simultaneously satisfied. The as-synthesized Sm3+-SrTiO3/TiO2 composite nanofibers were characterized by XRD, XPS, FESEM and HRTEM. The photocatalytic activity was evaluated by the degradation of rhodamine B and p-chloro phenol. The results show that rare earth Sm3+ ions are doped into the SrTiO3 lattice and replace Sr2+ in SrTiO3, forming an impurity level in forbidden band. The range of the light absorption by SrTiO3 is enlarged. Meanwhile, the defects are introduced into SrTiO3 lattice, acting as trapping cites of photogenerated electrons and hence reducing the recombination of charge carrier. The additionally, the heterojunction between SrTiO3 and TiO2 is beneficial for the electronic-hole separation. With these regards, Sm3+ doped SrTiO3/TiO2 composite nanofibers exhibit highly photocatalytic activity under visible light.
A novel Sm3+-SrTiO3/TiO2 composite nanofibers were synthesized by one-step hydrothermal technique. By this way, TiO2 nanofibers could serve as the both substrate and reactant. Moreover, not only doping of Sm3+ into SrTiO3 but also in-situ growth of SrTiO3 on skeleton of TiO2 could be simultaneously satisfied. The as-synthesized Sm3+-SrTiO3/TiO2 composite nanofibers were characterized by XRD, XPS, FESEM and HRTEM. The photocatalytic activity was evaluated by the degradation of rhodamine B and p-chloro phenol. The results show that rare earth Sm3+ ions are doped into the SrTiO3 lattice and replace Sr2+ in SrTiO3, forming an impurity level in forbidden band. The range of the light absorption by SrTiO3 is enlarged. Meanwhile, the defects are introduced into SrTiO3 lattice, acting as trapping cites of photogenerated electrons and hence reducing the recombination of charge carrier. The additionally, the heterojunction between SrTiO3 and TiO2 is beneficial for the electronic-hole separation. With these regards, Sm3+ doped SrTiO3/TiO2 composite nanofibers exhibit highly photocatalytic activity under visible light.
2019, 36(9): 2147-2154.
doi: 10.13801/j.cnki.fhclxb.20190301.002
Abstract:
Novel photocatalysts reduced graphene oxide (RGO)-MIL-68(Fe) were synthesized via an electrostatically derived self-assembly of MIL-68(Fe) with graphene, followed by solvothermal approach. The as-prepared RGO-MIL-68(Fe) composites were characterized by XRD, FESEM and UV-vis diffuse reflectance spectra (UV-vis DRS). The photocatalytic activity for reduction of Cr(Ⅵ) over RGO-MIL-68(Fe) composites were investigated under visible light irradiations using ammonium oxalate ((NH4)2C2O4) as a sac-rificial agent. The results show that the reduction of Cr(Ⅵ) over MIL-68(Fe) can be significantly increased by loading RGO. An optimum activity is achieved over 1wt%RGO-MIL-68(Fe) composite, giving a corresponding Cr(Ⅵ) reduction ratio of 81% after 60 min under visible light irradiation. Combining with photoelectrochemical analyses, it can be revealed that the introduction of RGO will minimize the recombination of photogenerated electron-hole pairs.
Novel photocatalysts reduced graphene oxide (RGO)-MIL-68(Fe) were synthesized via an electrostatically derived self-assembly of MIL-68(Fe) with graphene, followed by solvothermal approach. The as-prepared RGO-MIL-68(Fe) composites were characterized by XRD, FESEM and UV-vis diffuse reflectance spectra (UV-vis DRS). The photocatalytic activity for reduction of Cr(Ⅵ) over RGO-MIL-68(Fe) composites were investigated under visible light irradiations using ammonium oxalate ((NH4)2C2O4) as a sac-rificial agent. The results show that the reduction of Cr(Ⅵ) over MIL-68(Fe) can be significantly increased by loading RGO. An optimum activity is achieved over 1wt%RGO-MIL-68(Fe) composite, giving a corresponding Cr(Ⅵ) reduction ratio of 81% after 60 min under visible light irradiation. Combining with photoelectrochemical analyses, it can be revealed that the introduction of RGO will minimize the recombination of photogenerated electron-hole pairs.
Preparation and microstructure of Fe3Al/Al2O3 composites reinforced by surface modified carbon fiber
2019, 36(9): 2155-2162.
doi: 10.13801/j.cnki.fhclxb.20181213.002
Abstract:
The short carbon fiber (CFs)/Fe3Al-Al2O3 composites were prepared by a sol-gel dispersing method and a subsequent hot-pressing process. The Cu coating and SiC coating applied to CFs were fabricated by electrochemistry and in-situ reaction method, respectively. The effects of Cu coating and SiC coating applied to carbon fiber on the microstructure, phase composition, mechanical properties and fracture behavior of CFs/Fe3Al-Al2O3 composites were investigated. The results show that the CFs/Fe3Al-Al2O3 composites fabricated from the as-received CFs exhibit low density and the flexural strength is only 239.0 MPa comparable with matrix due to the CFs severely eroded in Fe3Al-Al2O3 matrix. The Cu coating applied to CFs can effectively protect CFs eroded by matrix, improve sintering compactness and cause strong bonding between the fiber and matrix that cause high flexural strength, however, the length of fibers extending from the matrix is short during the fracture process. The CFs/Fe3Al-Al2O3 composites fabricated from SiC coating exhibite homogeneous microstructure, the coating onto fiber is integrated and soft bondings between fiber and matrix result in the fiber with SiC coating extending from matrix or SiC coating remained in the pull-out holes. The weak interaction between the fiber with SiC coating and matrix greatly promotes fiber debonding and extending from matrix to promote toughening and progressive failure mechanisms in the CFs/Fe3Al-Al2O3 composites.
The short carbon fiber (CFs)/Fe3Al-Al2O3 composites were prepared by a sol-gel dispersing method and a subsequent hot-pressing process. The Cu coating and SiC coating applied to CFs were fabricated by electrochemistry and in-situ reaction method, respectively. The effects of Cu coating and SiC coating applied to carbon fiber on the microstructure, phase composition, mechanical properties and fracture behavior of CFs/Fe3Al-Al2O3 composites were investigated. The results show that the CFs/Fe3Al-Al2O3 composites fabricated from the as-received CFs exhibit low density and the flexural strength is only 239.0 MPa comparable with matrix due to the CFs severely eroded in Fe3Al-Al2O3 matrix. The Cu coating applied to CFs can effectively protect CFs eroded by matrix, improve sintering compactness and cause strong bonding between the fiber and matrix that cause high flexural strength, however, the length of fibers extending from the matrix is short during the fracture process. The CFs/Fe3Al-Al2O3 composites fabricated from SiC coating exhibite homogeneous microstructure, the coating onto fiber is integrated and soft bondings between fiber and matrix result in the fiber with SiC coating extending from matrix or SiC coating remained in the pull-out holes. The weak interaction between the fiber with SiC coating and matrix greatly promotes fiber debonding and extending from matrix to promote toughening and progressive failure mechanisms in the CFs/Fe3Al-Al2O3 composites.
2019, 36(9): 2163-2168.
doi: 10.13801/j.cnki.fhclxb.20190402.001
Abstract:
The ZrB2-SiC composite coatings were prepared on C/C composites by slurry painting. The phase composition and microstructure of the as-prepared ZrB2-SiC/(C/C) composites were analyzed by XRD spectroscopy and SEM, and the static oxidation behavior at 1 200℃ and 1 500℃ were also investigated. The results show that the ZrB2-SiC coatings are compact and uniform without obvious pores and cracks. After static oxidizing at 1 200℃ for 60 min, the mass loss rate of the as-prepared ZrB2-SiC/(C/C) composites is only about 2.4%. At 1 500℃, the mass loss rate increases to about 15%, but it is still lower than that of C/C composites without anti-oxidation coatings(~35%). In the static oxidation process, the significantly improved oxidation resistance of the as-prepared ZrB2-SiC/(C/C) composites is attributed to the generated glassy SiO2 film containing high melting point particles such as ZrO2.
The ZrB2-SiC composite coatings were prepared on C/C composites by slurry painting. The phase composition and microstructure of the as-prepared ZrB2-SiC/(C/C) composites were analyzed by XRD spectroscopy and SEM, and the static oxidation behavior at 1 200℃ and 1 500℃ were also investigated. The results show that the ZrB2-SiC coatings are compact and uniform without obvious pores and cracks. After static oxidizing at 1 200℃ for 60 min, the mass loss rate of the as-prepared ZrB2-SiC/(C/C) composites is only about 2.4%. At 1 500℃, the mass loss rate increases to about 15%, but it is still lower than that of C/C composites without anti-oxidation coatings(~35%). In the static oxidation process, the significantly improved oxidation resistance of the as-prepared ZrB2-SiC/(C/C) composites is attributed to the generated glassy SiO2 film containing high melting point particles such as ZrO2.
2019, 36(9): 2169-2175.
doi: 10.13801/j.cnki.fhclxb.20181201.001
Abstract:
In order to improve the performance for photocatalytic hydrogen production of Cu2ZnSnS4, the Cu2ZnSnS4 photocatalytic materials were made by hydrothermal method, then Cu2ZnSnS4-CdS composite was made by adding Cd(CH3COO)2·2H2O and Na2S by hydrothermal method again. XRD, SEM, TEM, Raman and XPS were used to characterize the structure, morphology and the valence of elements of Cu2ZnSnS4-CdS composite. And the pohotocatalytic hydrogen production was test in xenon lamp. The results show that Cu2ZnSnS4-CdS composite is successfully prepared with better crystallization properties. The Cu2ZnSnS4-CdS composite is made with blocky granular and spheric particles. More than 95% of the Cd and S atoms (atomic ratio of 1:1) in the Cu2ZnSnS4-CdS composite surface show that the spheric particles are CdS which are grown on the furface of Cu2ZnSnS4. The results show that the pohotocatalytic hydrogen production of Cu2ZnSnS4-CdS composite is about 296.17 μmol(g·h)-1, whitch is better than Cu2ZnSnS4 and CdS.
In order to improve the performance for photocatalytic hydrogen production of Cu2ZnSnS4, the Cu2ZnSnS4 photocatalytic materials were made by hydrothermal method, then Cu2ZnSnS4-CdS composite was made by adding Cd(CH3COO)2·2H2O and Na2S by hydrothermal method again. XRD, SEM, TEM, Raman and XPS were used to characterize the structure, morphology and the valence of elements of Cu2ZnSnS4-CdS composite. And the pohotocatalytic hydrogen production was test in xenon lamp. The results show that Cu2ZnSnS4-CdS composite is successfully prepared with better crystallization properties. The Cu2ZnSnS4-CdS composite is made with blocky granular and spheric particles. More than 95% of the Cd and S atoms (atomic ratio of 1:1) in the Cu2ZnSnS4-CdS composite surface show that the spheric particles are CdS which are grown on the furface of Cu2ZnSnS4. The results show that the pohotocatalytic hydrogen production of Cu2ZnSnS4-CdS composite is about 296.17 μmol(g·h)-1, whitch is better than Cu2ZnSnS4 and CdS.
2019, 36(9): 2176-2186.
doi: 10.13801/j.cnki.fhclxb.20181220.002
Abstract:
The magnetic mesoporous TiO2/graphene oxide (Fe3O4@TiO2/GO) composites were prepared by the synthesis of graphene oxide (GO), nano Fe3O4 and tetrabutyl titanate (TBOT), then the Fe3O4@TiO2/GO composites were used to treat U(Ⅵ)-containing waste water at a concentration of 10 mg·L-1. The effects of mass fraction of GO in Fe3O4@TiO2/GO composites, initial pH of solution, the dosage of Fe3O4@TiO2/GO composites, reaction time, initial uranium concentration and coexisting ions on U(Ⅵ) adsorption on Fe3O4@TiO2/GO composites were investigated. The results show that the Fe3O4@TiO2/GO composites has the best adsorption for U(Ⅵ) when the pH value is 6, the mass fraction of GO is 60wt% and the Fe3O4@TiO2/GO composites dosage is 10 mg, under the same conditions, the adsorption capacity of U(Ⅵ) is 10.99 mg·g-1 and 1.91 mg·g-1 higher than that of Fe3O4@TiO2 composites and GO, respectively. The adsorption results of the Fe3O4@TiO2/GO composites are balanced at 180 min, and the pseudo-second-order kinetics model and the Freundlich adsorption isotherm model are good descriptions of the adsorption of the Fe3O4@TiO2/GO composites for U(Ⅵ) process. The results of desorption experiments show that the adsorption efficiency of the Fe3O4@TiO2/GO composites for U(Ⅵ) remains as high as 90.86% after 5 cycles of adsorption-desorption, indicating that the Fe3O4@TiO2/GO composites have higher recycling performance.
The magnetic mesoporous TiO2/graphene oxide (Fe3O4@TiO2/GO) composites were prepared by the synthesis of graphene oxide (GO), nano Fe3O4 and tetrabutyl titanate (TBOT), then the Fe3O4@TiO2/GO composites were used to treat U(Ⅵ)-containing waste water at a concentration of 10 mg·L-1. The effects of mass fraction of GO in Fe3O4@TiO2/GO composites, initial pH of solution, the dosage of Fe3O4@TiO2/GO composites, reaction time, initial uranium concentration and coexisting ions on U(Ⅵ) adsorption on Fe3O4@TiO2/GO composites were investigated. The results show that the Fe3O4@TiO2/GO composites has the best adsorption for U(Ⅵ) when the pH value is 6, the mass fraction of GO is 60wt% and the Fe3O4@TiO2/GO composites dosage is 10 mg, under the same conditions, the adsorption capacity of U(Ⅵ) is 10.99 mg·g-1 and 1.91 mg·g-1 higher than that of Fe3O4@TiO2 composites and GO, respectively. The adsorption results of the Fe3O4@TiO2/GO composites are balanced at 180 min, and the pseudo-second-order kinetics model and the Freundlich adsorption isotherm model are good descriptions of the adsorption of the Fe3O4@TiO2/GO composites for U(Ⅵ) process. The results of desorption experiments show that the adsorption efficiency of the Fe3O4@TiO2/GO composites for U(Ⅵ) remains as high as 90.86% after 5 cycles of adsorption-desorption, indicating that the Fe3O4@TiO2/GO composites have higher recycling performance.
2019, 36(9): 2187-2195.
doi: 10.13801/j.cnki.fhclxb.20190109.004
Abstract:
The nano crystalline cellulose (NCC)/ZnO nano hybrids were prepared with a procedure of in-situ polymerization using NCC as a morphological-inducing template, and Zn acetate (Zn(CH3COO)2·2H2O) as a Zn source, respectively. The NCC/ZnO nano hybrids were then carbonized at 550℃ to obtain biochar/ZnO composites. The morphology, crystal structure, pore texture and light absorption performance of biochar/ZnO composites influenced by a mass ratio of biochar to ZnO (0.03:1, 0.17:1, 0.67:1) were characterized by TEM, XRD, BET and UV-Vis spectroscopy. The adsorption-photocatalysis performance of biochar/ZnO composites was investigated through removing methylene blue (MB) under UV light irradiation, and the mechanism of biochar/ZnO composites was further studied. The results indicate that the NCC transforms to biochar with graphite crystallite and skeleton structure after a carbonization process at 550℃. The nano ZnO particles are uniformly deposited on the surface of biochar, and then the biochar/ZnO composites are obtained. The obtained biochar/ZnO composites exhibit higher surface area and better absorbability compared with the neat nano ZnO. And the biochar improves the separation of photogenerated electrons and holes of ZnO. The biochar/ZnO composites remove MB with a synergistic effect of adsorption and photocatalysis. In particular, the biochar/ZnO composite has an average pore diameter of 188.99 nm, and a specific surface area of 33.51 m2/g respectively at the mass ratio of 0.17:1 (biochar to ZnO). Consequently, the biochar/ZnO composite has an optimum degradation efficiency to MB, corresponding to 99.8% degradation rate of MB after the absorption for 30 min in dark condition and continuous irradiation for 20 min under 500 W UV light at room temperature.
The nano crystalline cellulose (NCC)/ZnO nano hybrids were prepared with a procedure of in-situ polymerization using NCC as a morphological-inducing template, and Zn acetate (Zn(CH3COO)2·2H2O) as a Zn source, respectively. The NCC/ZnO nano hybrids were then carbonized at 550℃ to obtain biochar/ZnO composites. The morphology, crystal structure, pore texture and light absorption performance of biochar/ZnO composites influenced by a mass ratio of biochar to ZnO (0.03:1, 0.17:1, 0.67:1) were characterized by TEM, XRD, BET and UV-Vis spectroscopy. The adsorption-photocatalysis performance of biochar/ZnO composites was investigated through removing methylene blue (MB) under UV light irradiation, and the mechanism of biochar/ZnO composites was further studied. The results indicate that the NCC transforms to biochar with graphite crystallite and skeleton structure after a carbonization process at 550℃. The nano ZnO particles are uniformly deposited on the surface of biochar, and then the biochar/ZnO composites are obtained. The obtained biochar/ZnO composites exhibit higher surface area and better absorbability compared with the neat nano ZnO. And the biochar improves the separation of photogenerated electrons and holes of ZnO. The biochar/ZnO composites remove MB with a synergistic effect of adsorption and photocatalysis. In particular, the biochar/ZnO composite has an average pore diameter of 188.99 nm, and a specific surface area of 33.51 m2/g respectively at the mass ratio of 0.17:1 (biochar to ZnO). Consequently, the biochar/ZnO composite has an optimum degradation efficiency to MB, corresponding to 99.8% degradation rate of MB after the absorption for 30 min in dark condition and continuous irradiation for 20 min under 500 W UV light at room temperature.
2019, 36(9): 2196-2203.
doi: 10.13801/j.cnki.fhclxb.20181221.001
Abstract:
In order to investigate the effects of the different carbonization temperatures on the electrocatalytic hydrogen evolution properties of the Co-Mn-doped carbon aerogel (Co-Mn/CA), the Co-Mn/CA was prepared by hydrothermal method using resource-rich and renewable lignocellulose as a carbon source, cobalt acetate tetrahydrate as a cobalt source, and manganese acetate tetrahydrate as a manganese source. The results reveal that after carbonization, the surface morphology of the cellulose aerogel changes from a laminated structure to a porous structure, which increases the active sites and electrocatalytic hydrogen evolution activity. After characterizing the structure by XRD and N2 adsorption and desorption, it shows that CA product after carbonization is almost amorphous carbon and the CA after carbonization at 900℃(CA-900) has the largest specific surface area and total pore volume of 958 m2·g-1 and 0.33 cm3g-1, respectively. The electrochemical performance tests show that the Co-Mn/CA-900 has the best electrocatalyst hydrogen evolution reaction (HER) activity. In 1 mol/L KOH electrolyte, it has an overpotential of 175 mV at a current density of 50 mA·cm-2 and the pressure drop is only 7% after chronopotential test for 10 h, which indicates superior electrocatalytic hydrogen evolution stability.
In order to investigate the effects of the different carbonization temperatures on the electrocatalytic hydrogen evolution properties of the Co-Mn-doped carbon aerogel (Co-Mn/CA), the Co-Mn/CA was prepared by hydrothermal method using resource-rich and renewable lignocellulose as a carbon source, cobalt acetate tetrahydrate as a cobalt source, and manganese acetate tetrahydrate as a manganese source. The results reveal that after carbonization, the surface morphology of the cellulose aerogel changes from a laminated structure to a porous structure, which increases the active sites and electrocatalytic hydrogen evolution activity. After characterizing the structure by XRD and N2 adsorption and desorption, it shows that CA product after carbonization is almost amorphous carbon and the CA after carbonization at 900℃(CA-900) has the largest specific surface area and total pore volume of 958 m2·g-1 and 0.33 cm3g-1, respectively. The electrochemical performance tests show that the Co-Mn/CA-900 has the best electrocatalyst hydrogen evolution reaction (HER) activity. In 1 mol/L KOH electrolyte, it has an overpotential of 175 mV at a current density of 50 mA·cm-2 and the pressure drop is only 7% after chronopotential test for 10 h, which indicates superior electrocatalytic hydrogen evolution stability.
2019, 36(9): 2204-2211.
doi: 10.13801/j.cnki.fhclxb.20181107.001
Abstract:
To facilitate Kaolin which was used to remove Cu2+ from waste water, the stripped Kaolin was prepared by ball milling and the Fe3O4/Kaolin magnetic composite was prepared by oxidative precipitation method. The morphology and composition of Fe3O4/Kaolin magnetic composite were characterized by laser particle size analyzer, SEM and XRD, respectively. The saturation adsorption capacity and magnetic separation recovery of Cu2+ was tested. It is demonstrated that 3.0 g Fe3O4 is the optimal amount as additive in Fe3O4/Kaolin magnetic composite to achieve improved adsorption ability (17.98 mg/g). The saturation magnetization reaches about 16.19 emu/g by hysteresis loop, which shows excellent magnetic response. In addition, the adsorption data of the Fe3O4/Kaolin magnetic composite were fitted by Langmuir and Freundlich adsorption isotherm. It is found that the adsorption behavior of Fe3O4/Kaolin for Cu2+ is basically consistent with the Langmuir adsorption isotherm model and the Freundlich adsorption isotherm model, indicating both monolayer adsorption and multi-layer adsorption are existed in the adsorption behavior of the Fe3O4/Kaolin magnetic composite for Cu2+.
To facilitate Kaolin which was used to remove Cu2+ from waste water, the stripped Kaolin was prepared by ball milling and the Fe3O4/Kaolin magnetic composite was prepared by oxidative precipitation method. The morphology and composition of Fe3O4/Kaolin magnetic composite were characterized by laser particle size analyzer, SEM and XRD, respectively. The saturation adsorption capacity and magnetic separation recovery of Cu2+ was tested. It is demonstrated that 3.0 g Fe3O4 is the optimal amount as additive in Fe3O4/Kaolin magnetic composite to achieve improved adsorption ability (17.98 mg/g). The saturation magnetization reaches about 16.19 emu/g by hysteresis loop, which shows excellent magnetic response. In addition, the adsorption data of the Fe3O4/Kaolin magnetic composite were fitted by Langmuir and Freundlich adsorption isotherm. It is found that the adsorption behavior of Fe3O4/Kaolin for Cu2+ is basically consistent with the Langmuir adsorption isotherm model and the Freundlich adsorption isotherm model, indicating both monolayer adsorption and multi-layer adsorption are existed in the adsorption behavior of the Fe3O4/Kaolin magnetic composite for Cu2+.
2019, 36(9): 2212-2219.
doi: 10.13801/j.cnki.fhclxb.20181203.002
Abstract:
In order to research the dispersion effect of the different cellulose nanofibrils (CNFs) on the untreated multi-walled carbon nanotubes (MWCNTs), the CNFs with different carboxyl content and form were isolated from bamboo powder by 2,2,6,6-tetramethylpiperidin-1-oxyl radical (TEMPO) oxidation method with the different amount of NaClO added. The obtained different CNFs were used to disperse untreated MWCNTs as a dispersant, subsequently, the amount of MWCNTs dispersed in the different CNFs suspensions was measured with the Beer-Lambert law. The dispersion effect of the different CNFs on MWCNTs was evaluated by atomic force microscopy (AFM), laser particle size analyzer (LPSA) and so on. The results show that the carboxyl content of CNFs increases and the cross section diameter of CNFs decreases with the increase of NaClO added during TEMPO oxidizing. At the same time, the research also indicates that the dispersion amount of MWCNTs increases with the increase of the carboxyl content of CNFs. When the carboxyl content of CNFs increases from 0.635 mmol/g to 1.646 mmol/g, the percent of MWCNTs dispersed in the CNFs suspension increases from 19% to 39%. The different CNFs/MWCNTs suspensions show that the particle dispersion index (PDI) values of the particle size distribution are less than 0.3, and the absolute values of Zeta potential are higher than 30 mV, which proves that the MWCNTs could be well dispersed by the different CNFs. The CNFs/MWCNTs composite films display that the tensile stress increases and resistivity decreases with the increase of carboxyl group of the CNFs, when the carboxyl content of CNFs is 1.646 mmol/L, the tensile stress of CNFs/MWCNTs composite film can reach 91 MPa, and the resistivity is as low as 0.1460 Ωcm.
In order to research the dispersion effect of the different cellulose nanofibrils (CNFs) on the untreated multi-walled carbon nanotubes (MWCNTs), the CNFs with different carboxyl content and form were isolated from bamboo powder by 2,2,6,6-tetramethylpiperidin-1-oxyl radical (TEMPO) oxidation method with the different amount of NaClO added. The obtained different CNFs were used to disperse untreated MWCNTs as a dispersant, subsequently, the amount of MWCNTs dispersed in the different CNFs suspensions was measured with the Beer-Lambert law. The dispersion effect of the different CNFs on MWCNTs was evaluated by atomic force microscopy (AFM), laser particle size analyzer (LPSA) and so on. The results show that the carboxyl content of CNFs increases and the cross section diameter of CNFs decreases with the increase of NaClO added during TEMPO oxidizing. At the same time, the research also indicates that the dispersion amount of MWCNTs increases with the increase of the carboxyl content of CNFs. When the carboxyl content of CNFs increases from 0.635 mmol/g to 1.646 mmol/g, the percent of MWCNTs dispersed in the CNFs suspension increases from 19% to 39%. The different CNFs/MWCNTs suspensions show that the particle dispersion index (PDI) values of the particle size distribution are less than 0.3, and the absolute values of Zeta potential are higher than 30 mV, which proves that the MWCNTs could be well dispersed by the different CNFs. The CNFs/MWCNTs composite films display that the tensile stress increases and resistivity decreases with the increase of carboxyl group of the CNFs, when the carboxyl content of CNFs is 1.646 mmol/L, the tensile stress of CNFs/MWCNTs composite film can reach 91 MPa, and the resistivity is as low as 0.1460 Ωcm.
2019, 36(9): 2220-2226.
doi: 10.13801/j.cnki.fhclxb.20181213.001
Abstract:
The regenerated high-density polyethylene(HDPE), salix wood powder and waste tire rubber powder were used as the raw materials, and sulfur-containing coupling agent Si69 as the interface compatibilizer, wood powder/rubber-plastic ternary composites were prepared by molding method. The influences of Si69 on the mechanical properties and heat resistance of wood powder/rubber-plastic ternary composites were investigated, the waste tire rubber powder surface characteristics before and after Si69 modification and the microstructure of wood powder/rubber-plastic ternary composites were analyzed by FTIR and SEM. The results show that Si69 has a chemical reaction with waste tire rubber powder. When the contents of Si69 is 5wt%, the interfacial compatibility of wood powder/rubber-plastic ternary composites is better, mechanical properties and heat resistance are good, the flexural strength, flexural modulus and tensile strength are increased by 13.85%, 7.24%, 6.63%, respectively, which compared with no adding Si69; The vicat softening temperature and heat deformation temperature of wood powder/rubber-plastic composites are increased by 6.95℃ and 8.70℃, respectively. Heat resistance of wood powder/rubber-plastic composites is improved by Si69 to some extent. When the contents of Si69 is 7wt%, the notched impact strength of wood powder/rubber-plastic ternary composites can reach 3.99 k·Jm-2.
The regenerated high-density polyethylene(HDPE), salix wood powder and waste tire rubber powder were used as the raw materials, and sulfur-containing coupling agent Si69 as the interface compatibilizer, wood powder/rubber-plastic ternary composites were prepared by molding method. The influences of Si69 on the mechanical properties and heat resistance of wood powder/rubber-plastic ternary composites were investigated, the waste tire rubber powder surface characteristics before and after Si69 modification and the microstructure of wood powder/rubber-plastic ternary composites were analyzed by FTIR and SEM. The results show that Si69 has a chemical reaction with waste tire rubber powder. When the contents of Si69 is 5wt%, the interfacial compatibility of wood powder/rubber-plastic ternary composites is better, mechanical properties and heat resistance are good, the flexural strength, flexural modulus and tensile strength are increased by 13.85%, 7.24%, 6.63%, respectively, which compared with no adding Si69; The vicat softening temperature and heat deformation temperature of wood powder/rubber-plastic composites are increased by 6.95℃ and 8.70℃, respectively. Heat resistance of wood powder/rubber-plastic composites is improved by Si69 to some extent. When the contents of Si69 is 7wt%, the notched impact strength of wood powder/rubber-plastic ternary composites can reach 3.99 k·Jm-2.
