2018 Vol. 35, No. 11
2018, 35(11): 2919-2926.
doi: 10.13801/j.cnki.fhclxb.20180122.003
Abstract:
In order to increase the distribution of diamond particles and the thermal conductivity of polyacrylonitrile(PAN) copolymers, the diamond/PAN hybrid composite fibers were obtained via electrospinning using PAN and different sized diamonds as raw materials. The effects of different contents and various sizes of diamond on the morphology and thermal properties of diamond/PAN composite fibers were studied with changing the mass fraction of diamond addition. The results show that electrospinning can give the ability to deliver microdiamonds in the form of well-dispersed particles into the polymer matrix, and the stability and continuity of the spinning are greatly affected by the particle size of the diamonds. The size of diamond of 0.5-1 μm can be effectively coated in the diamond/PAN fiber, and the thermal conductivity of diamond/PAN fibers reaches 1.923 W/(m·K) when the actual mass fraction of diamond is 38.5wt%. However, when the size of diamond particles is greater than 1-2 μm, the stability of the spinning is poor. As a result, it will lead to the diamond being little or not even appearing in the diamond/PAN fibers.
In order to increase the distribution of diamond particles and the thermal conductivity of polyacrylonitrile(PAN) copolymers, the diamond/PAN hybrid composite fibers were obtained via electrospinning using PAN and different sized diamonds as raw materials. The effects of different contents and various sizes of diamond on the morphology and thermal properties of diamond/PAN composite fibers were studied with changing the mass fraction of diamond addition. The results show that electrospinning can give the ability to deliver microdiamonds in the form of well-dispersed particles into the polymer matrix, and the stability and continuity of the spinning are greatly affected by the particle size of the diamonds. The size of diamond of 0.5-1 μm can be effectively coated in the diamond/PAN fiber, and the thermal conductivity of diamond/PAN fibers reaches 1.923 W/(m·K) when the actual mass fraction of diamond is 38.5wt%. However, when the size of diamond particles is greater than 1-2 μm, the stability of the spinning is poor. As a result, it will lead to the diamond being little or not even appearing in the diamond/PAN fibers.
2018, 35(11): 2927-2934.
doi: 10.13801/j.cnki.fhclxb.20180126.002
Abstract:
Two kinds of lanthanide metal-organic frameworks such as terbium benzene-1,3,5-tricarboxylate (Tb(BTC)) and europium benzene-1,3,5-tricarboxylate (Eu(BTC)) were synthesized by hydrothermal method. 1,4-bis(2-trifluoromethyl-4-aminophenoxy)benzene (6FAPB) and 1,2,3,4-cyclobutane dianhydride (CBDA) as the monomers of polyimide (PI), the Tb(BTC)/PI and Eu(BTC)/PI composites containing 7wt% Tb(BTC) or Eu(BTC) (mass fraction) were prepared by the in-situ polymerization. The structure and properties of the Tb(BTC)/PI and Eu(BTC)/PI composites were characterized by FTIR, UV-visible spectrometer (UV-vis), TGA, XRD, SEM, universal tensile testing machine and gas permeabilities testing. These experimental results show that Tb(BTC) and Eu(BTC) contain very few pore structures, belonging to the mesoporous range, and exhibit high thermal stabilities. The introduction of Tb(BTC) and Eu(BTC) improves the thermal and mechanical properties of PI(6FAPB-CBDA). The glass transition temperatures increase from 351.9℃ of pure PI(6FAPB-CBDA) to 358.0℃ and 354.8℃, and the 5% thermal decomposition temperatures increase from 431.6℃ to 447.8℃ and 441.1℃. The tensile strengths of Tb(BTC)/PI and Eu(BTC)/PI composites increase from 60.8 MPa to 77.7 MPa and 70.4 MPa, and the Young's modulus increase from 1.54 GPa to 2.80 GPa and 2.17 GPa, respectively. However, the optical transmittances at 500 nm of Tb(BTC)/PI and Eu(BTC)/PI composites reduce from 82.3% to 23.0% and 24.2%. The results of gas permeability testing show that both of Tb(BTC) and Eu(BTC) can improve the gas permeabilities of the PI-(6FAPB-CBDA) membrane. The effect of Eu(BTC) is better than Tb(BTC). The permeabilities of H2, O2, N2 and CO2 of Eu(TBC)/PI composite are 119.23, 15.02, 3.21 and 90.35 Barrer, respectively, and O2/N2 is 4.68, CO2/N2 is 28.15.
Two kinds of lanthanide metal-organic frameworks such as terbium benzene-1,3,5-tricarboxylate (Tb(BTC)) and europium benzene-1,3,5-tricarboxylate (Eu(BTC)) were synthesized by hydrothermal method. 1,4-bis(2-trifluoromethyl-4-aminophenoxy)benzene (6FAPB) and 1,2,3,4-cyclobutane dianhydride (CBDA) as the monomers of polyimide (PI), the Tb(BTC)/PI and Eu(BTC)/PI composites containing 7wt% Tb(BTC) or Eu(BTC) (mass fraction) were prepared by the in-situ polymerization. The structure and properties of the Tb(BTC)/PI and Eu(BTC)/PI composites were characterized by FTIR, UV-visible spectrometer (UV-vis), TGA, XRD, SEM, universal tensile testing machine and gas permeabilities testing. These experimental results show that Tb(BTC) and Eu(BTC) contain very few pore structures, belonging to the mesoporous range, and exhibit high thermal stabilities. The introduction of Tb(BTC) and Eu(BTC) improves the thermal and mechanical properties of PI(6FAPB-CBDA). The glass transition temperatures increase from 351.9℃ of pure PI(6FAPB-CBDA) to 358.0℃ and 354.8℃, and the 5% thermal decomposition temperatures increase from 431.6℃ to 447.8℃ and 441.1℃. The tensile strengths of Tb(BTC)/PI and Eu(BTC)/PI composites increase from 60.8 MPa to 77.7 MPa and 70.4 MPa, and the Young's modulus increase from 1.54 GPa to 2.80 GPa and 2.17 GPa, respectively. However, the optical transmittances at 500 nm of Tb(BTC)/PI and Eu(BTC)/PI composites reduce from 82.3% to 23.0% and 24.2%. The results of gas permeability testing show that both of Tb(BTC) and Eu(BTC) can improve the gas permeabilities of the PI-(6FAPB-CBDA) membrane. The effect of Eu(BTC) is better than Tb(BTC). The permeabilities of H2, O2, N2 and CO2 of Eu(TBC)/PI composite are 119.23, 15.02, 3.21 and 90.35 Barrer, respectively, and O2/N2 is 4.68, CO2/N2 is 28.15.
2018, 35(11): 2935-2941.
doi: 10.13801/j.cnki.fhclxb.20180115.003
Abstract:
Rapid ultra violet (UV)-curable acrylate resin system used at ultra-low temperature (liquid nitrogen) were prepared by using polyetherketone cardo (PEKC) as the filler, and their curing behavior and tolerance of liquid nitrogen temperature were studied. The gel fraction and curing shrinkage of PEKC/acrylate resin system were measured; then the coefficient of linear thermal expansion (α) of the cured PEKC/acrylate resin systems was characterized by DMA to determine its dimensional stability as the temperature varied from -150 to 50℃; finally, the tensile properties and lap shear strengths at room temperature and liquid nitrogen temperature were also investigated and analyzed to confirm their ultra-low temperature tolerance. The results indicate that, PEKC/acrylate resin systems with 0-4% (mass ratio to the acrylate resin) PEKC content can be efficiently rapidly cured in 5 s as the gel fraction reaches more than 80%. When the mass ratio of PEKC to acrylate resin systems increases from 0 to 4%, the α of PEKC/acrylate resin systems decreases from 6.71×10-5℃-1 to 5.29×10-5℃-1 with decreasing the volume shrinkage from 25.61% to 6.24% and the linear shrinkage from 1.78% to 0.41%. Additionally, the toughness of the PEKC/acrylate resin systems increases as the elongation at break of the acrylate resin systems gradually increases, and the tensile strength of PEKC/acrylate resin systems is more than 20 MPa. The lap shear strength of PEKC/acrylate resin system with 3% (mass ratio to the acrylate resin system) PEKC content at room temperature and liquid nitrogen temperature are 17.48 MPa and 17.23 MPa, respectively.
Rapid ultra violet (UV)-curable acrylate resin system used at ultra-low temperature (liquid nitrogen) were prepared by using polyetherketone cardo (PEKC) as the filler, and their curing behavior and tolerance of liquid nitrogen temperature were studied. The gel fraction and curing shrinkage of PEKC/acrylate resin system were measured; then the coefficient of linear thermal expansion (α) of the cured PEKC/acrylate resin systems was characterized by DMA to determine its dimensional stability as the temperature varied from -150 to 50℃; finally, the tensile properties and lap shear strengths at room temperature and liquid nitrogen temperature were also investigated and analyzed to confirm their ultra-low temperature tolerance. The results indicate that, PEKC/acrylate resin systems with 0-4% (mass ratio to the acrylate resin) PEKC content can be efficiently rapidly cured in 5 s as the gel fraction reaches more than 80%. When the mass ratio of PEKC to acrylate resin systems increases from 0 to 4%, the α of PEKC/acrylate resin systems decreases from 6.71×10-5℃-1 to 5.29×10-5℃-1 with decreasing the volume shrinkage from 25.61% to 6.24% and the linear shrinkage from 1.78% to 0.41%. Additionally, the toughness of the PEKC/acrylate resin systems increases as the elongation at break of the acrylate resin systems gradually increases, and the tensile strength of PEKC/acrylate resin systems is more than 20 MPa. The lap shear strength of PEKC/acrylate resin system with 3% (mass ratio to the acrylate resin system) PEKC content at room temperature and liquid nitrogen temperature are 17.48 MPa and 17.23 MPa, respectively.
2018, 35(11): 2942-2949.
doi: 10.13801/j.cnki.fhclxb.20180123.002
Abstract:
A novel urushiol-based benzoxazine (UB) was synthesized from urushiol, furfuryl amine and paraformaldehyde, and its structure was characterized. Subsequently, silaned graphene oxide (SGO) and UB and bismaleimide were blended and cured to prepare SGO/urushiol-based benzoxazine-bismaleimide copolymer resin (UBB) composites. The structure and morphologies of SGO/UBB composite were characterized by FTIR, XRD and SEM. The results show that SGO is uniformly dispersed and crosslinked in urushiol based benzoxazine-bismaleimide copolymer resin, and the interfacial compatibility of the two resins is better. The thermal stability and mechanical properties of the copolymer resin are improved by SGO remarkably. When the additive amount of SGO is 0.5wt%, the 5% mass loss temperature and char yield (800℃) of SGO/UBB composite are 441.2℃ and 44.3%, respectively, which are much higher than those of the pure copolymer resin (399.0℃ and 39.2%). When the additive mass ratio of SGO is 0.3%, comparing pure copolymer resin, the Young's modulus and tensile strength of SGO/UBB composite increase by 115.4% and 309.9% and reach 962.8 MPa and 29.1 MPa, respectively. The water absorption of SGO/UBB composite is low.
A novel urushiol-based benzoxazine (UB) was synthesized from urushiol, furfuryl amine and paraformaldehyde, and its structure was characterized. Subsequently, silaned graphene oxide (SGO) and UB and bismaleimide were blended and cured to prepare SGO/urushiol-based benzoxazine-bismaleimide copolymer resin (UBB) composites. The structure and morphologies of SGO/UBB composite were characterized by FTIR, XRD and SEM. The results show that SGO is uniformly dispersed and crosslinked in urushiol based benzoxazine-bismaleimide copolymer resin, and the interfacial compatibility of the two resins is better. The thermal stability and mechanical properties of the copolymer resin are improved by SGO remarkably. When the additive amount of SGO is 0.5wt%, the 5% mass loss temperature and char yield (800℃) of SGO/UBB composite are 441.2℃ and 44.3%, respectively, which are much higher than those of the pure copolymer resin (399.0℃ and 39.2%). When the additive mass ratio of SGO is 0.3%, comparing pure copolymer resin, the Young's modulus and tensile strength of SGO/UBB composite increase by 115.4% and 309.9% and reach 962.8 MPa and 29.1 MPa, respectively. The water absorption of SGO/UBB composite is low.
2018, 35(11): 2950-2957.
doi: 10.13801/j.cnki.fhclxb.20180316.002
Abstract:
A new kind of bipolar plate for proton exchange membrane fuel cell was prepared by compression molding method, using polyvinyl butyral (PVB) modified phenolic resin (PF) as binder and expanded graphite as the first conductive filler. The effects of PVB to PF mass ratio, the modified resin content and addition of carbon black on the conductivity, flexural strength of the expanded graphite/PF-PVB composite bipolar plate were also investigated. The results show that, when the mass fraction of resin is fixed at 30wt%, the expanded graphite/PF-PVB composite bipolar plate posses the highest in-plane conductivity(192.3 S/cm) and flexural strength(47.25 MPa) with the PVB:PF=0.5, which is increased by 12.3% and 14.2% respectively compared to the expanded graphite/PF composite bipolar plate samples without PVB addition. When PVB:PF=0.5, with the mass fraction of resin increase from 25wt% to 45wt%, the conductivity of the expanded graphite/PF-PVB composite bipolar plate declines while flexural strength increases. Further add carbon black to improve the conductivity of the expanded graphite/PF-PVB composite bipolar plate, when resin mass fraction at 45 wt%, the sample with 4 wt% carbon black shows the best in-plane conductivity (137 S/cm) and best area specific resistance (14.4 mΩ·cm2).
A new kind of bipolar plate for proton exchange membrane fuel cell was prepared by compression molding method, using polyvinyl butyral (PVB) modified phenolic resin (PF) as binder and expanded graphite as the first conductive filler. The effects of PVB to PF mass ratio, the modified resin content and addition of carbon black on the conductivity, flexural strength of the expanded graphite/PF-PVB composite bipolar plate were also investigated. The results show that, when the mass fraction of resin is fixed at 30wt%, the expanded graphite/PF-PVB composite bipolar plate posses the highest in-plane conductivity(192.3 S/cm) and flexural strength(47.25 MPa) with the PVB:PF=0.5, which is increased by 12.3% and 14.2% respectively compared to the expanded graphite/PF composite bipolar plate samples without PVB addition. When PVB:PF=0.5, with the mass fraction of resin increase from 25wt% to 45wt%, the conductivity of the expanded graphite/PF-PVB composite bipolar plate declines while flexural strength increases. Further add carbon black to improve the conductivity of the expanded graphite/PF-PVB composite bipolar plate, when resin mass fraction at 45 wt%, the sample with 4 wt% carbon black shows the best in-plane conductivity (137 S/cm) and best area specific resistance (14.4 mΩ·cm2).
2018, 35(11): 2958-2965.
doi: 10.13801/j.cnki.fhclxb.20180202.003
Abstract:
Disorder mesoporous carbon (DOMC) and order mesoporous carbon (OMC) were added into polyimide (PI) to fabricate DOMC/PI and OMC/PI hybrid membranes via in-situ polymerization. Many analysis methods, including FTIR, TEM, SEM and XRD were employed to explore the morphology of DOMC or OMC and the effect of their addition on the morphology of the hybrid membranes. The permeation of CO2 and N2 was studied using the novel membranes. Due to the porous structure of carbon materials and the interaction between CO2 molecules and mesoporous carbon, addition of DOMC and OMC does not only increase the free volume of polymeric membrane, but also improve the selective adsorption of membrane for CO2. The addition of DOMC or OMC enhances both the gas permeabilities of two pure gases (CO2 and N2) and the CO2 selectivity of membranes. With addition content of DOMC and OMC increasing, both the gas permeabilities of two pure gases and the CO2 selectivity of membranes increase first and then decrease. DOMC has more porous structures and a larger specific surface area compared with OMC, therefor, both CO2 and N2 permeability of DOMC/PI hybrid membrane are better than those of OMC/PI hybrid membrane. The two hybrid membranes show the similar CO2/N2 selectivity.
Disorder mesoporous carbon (DOMC) and order mesoporous carbon (OMC) were added into polyimide (PI) to fabricate DOMC/PI and OMC/PI hybrid membranes via in-situ polymerization. Many analysis methods, including FTIR, TEM, SEM and XRD were employed to explore the morphology of DOMC or OMC and the effect of their addition on the morphology of the hybrid membranes. The permeation of CO2 and N2 was studied using the novel membranes. Due to the porous structure of carbon materials and the interaction between CO2 molecules and mesoporous carbon, addition of DOMC and OMC does not only increase the free volume of polymeric membrane, but also improve the selective adsorption of membrane for CO2. The addition of DOMC or OMC enhances both the gas permeabilities of two pure gases (CO2 and N2) and the CO2 selectivity of membranes. With addition content of DOMC and OMC increasing, both the gas permeabilities of two pure gases and the CO2 selectivity of membranes increase first and then decrease. DOMC has more porous structures and a larger specific surface area compared with OMC, therefor, both CO2 and N2 permeability of DOMC/PI hybrid membrane are better than those of OMC/PI hybrid membrane. The two hybrid membranes show the similar CO2/N2 selectivity.
2018, 35(11): 2966-2972.
doi: 10.13801/j.cnki.fhclxb.20180310.001
Abstract:
The synergistic flame retardant system consisting of cage pentaerythritol phosphate (PEPA) and expandable graphite (EG) was added to the natural rubber (NR) to prepare EG-PEPA/NR composites. The effects of PEPA and EG with different mass ratios on the flame retardancy and mechanical properties of EG-PEPA/NR composites were investigated by limiting oxygen index(LOI) and vertical combustion(UL-94) test, thermogravimetric analysis, cone calorimetry, tensile test and carbon residue SEM and FTIR. The results show that the flame retardancy and mechanical properties of EG-PEPA/NR composites perform the best when PEPA to EG with the mass ratio of 33:7 are added to NR. Its LOI reaches 28.1% and the UL-94 reaches V-0 level. The amount of carbon residue increases from 27.5% to 33.6% at 600℃. The peaks of total heat release and heat release rate are 96.2 MJ·m-2 and 512.4 kW·m-2, respectively, decreasing by 22.2% and 40.3% compared to the pure NR sample. The tensile strength and elongation of EG-PEPA/NR at break also reach 13.8 MPa and 368%, respectively.
The synergistic flame retardant system consisting of cage pentaerythritol phosphate (PEPA) and expandable graphite (EG) was added to the natural rubber (NR) to prepare EG-PEPA/NR composites. The effects of PEPA and EG with different mass ratios on the flame retardancy and mechanical properties of EG-PEPA/NR composites were investigated by limiting oxygen index(LOI) and vertical combustion(UL-94) test, thermogravimetric analysis, cone calorimetry, tensile test and carbon residue SEM and FTIR. The results show that the flame retardancy and mechanical properties of EG-PEPA/NR composites perform the best when PEPA to EG with the mass ratio of 33:7 are added to NR. Its LOI reaches 28.1% and the UL-94 reaches V-0 level. The amount of carbon residue increases from 27.5% to 33.6% at 600℃. The peaks of total heat release and heat release rate are 96.2 MJ·m-2 and 512.4 kW·m-2, respectively, decreasing by 22.2% and 40.3% compared to the pure NR sample. The tensile strength and elongation of EG-PEPA/NR at break also reach 13.8 MPa and 368%, respectively.
2018, 35(11): 2973-2978.
doi: 10.13801/j.cnki.fhclxb.20180326.001
Abstract:
Multi-walled carbon nanotubes (MWCNTs) treated with mixed acids were used to reinforce the bisphenol A cyanate ester-novolac cyanate ester(BCE-NCE) resin. The microstructure of the MWCNTs/BCE-NCE composites was characterized by SEM and TEM. The thermal performances of the MWCNTs/BCE-NCE composites were investigated by DSC, DMA and TG/DTA. The mechanical properties of the MWCNTs/BCE-NCE composites were investigated by electronic tension machine. The dielectric properties of the MWCNTs/BCE-NCE resin were investigated by cavity resonator method. The results show that the dispersion properties of the treated MWCNTs in the BCE-NCE resin matrix are improved compared with the untreated analogue. MWCNTs have little effect on the BCE-NCE resin thermodynamic properties. Upon addition of 0.8wt% MWCNTs to the BCE-NCE resin, the glass transition temperature(Tg) of the cured MWCNTs/BCE-NCE composites changes from 298℃ to 285℃, maintaining a relatively high value. The BCE-NCE resin impact strength of 0.6wt% MWCNTs is 11.40 kJ/m2, and the toughness increases by 40.7%. The dielectric constant and dielectric loss of MWCNTs/BCE-NCE composites increase obviously. Upon addition of 0.8wt% of MWCNTs to the resin, the dielectric constant is 5.1 and dielectric loss is 0.032 under 1 GHz frequency. Therefore, the MWCNTs/BCE-NCE composites may be suitable for future applications involving high performance composites and electronic industry.
Multi-walled carbon nanotubes (MWCNTs) treated with mixed acids were used to reinforce the bisphenol A cyanate ester-novolac cyanate ester(BCE-NCE) resin. The microstructure of the MWCNTs/BCE-NCE composites was characterized by SEM and TEM. The thermal performances of the MWCNTs/BCE-NCE composites were investigated by DSC, DMA and TG/DTA. The mechanical properties of the MWCNTs/BCE-NCE composites were investigated by electronic tension machine. The dielectric properties of the MWCNTs/BCE-NCE resin were investigated by cavity resonator method. The results show that the dispersion properties of the treated MWCNTs in the BCE-NCE resin matrix are improved compared with the untreated analogue. MWCNTs have little effect on the BCE-NCE resin thermodynamic properties. Upon addition of 0.8wt% MWCNTs to the BCE-NCE resin, the glass transition temperature(Tg) of the cured MWCNTs/BCE-NCE composites changes from 298℃ to 285℃, maintaining a relatively high value. The BCE-NCE resin impact strength of 0.6wt% MWCNTs is 11.40 kJ/m2, and the toughness increases by 40.7%. The dielectric constant and dielectric loss of MWCNTs/BCE-NCE composites increase obviously. Upon addition of 0.8wt% of MWCNTs to the resin, the dielectric constant is 5.1 and dielectric loss is 0.032 under 1 GHz frequency. Therefore, the MWCNTs/BCE-NCE composites may be suitable for future applications involving high performance composites and electronic industry.
2018, 35(11): 2979-2986.
doi: 10.13801/j.cnki.fhclxb.20180428.001
Abstract:
The surface of polyacrylonitrile(PAN)-based carbon fibre was modified by high energy laser beam. SEM, EDS, FTIR, XRD, and tensile testing machine were used to characterize the morphology, change of composition, phase structure, and mechanical properties of carbon fibre before and after modification. The effect of laser beam on changes of carbon fibre microstructure was systematically studied to explore the mechanisms of laser beam on carbon fibre. The results show that surface roughness, specific surface area and infiltration of carbon fibre are improved after laser surface modification. When the power is higher, scanning speed becomes lower, carbon fibre wettability exhibits better. There are no changes in chemical composition, microstructure and type of functional groups of the modified carbon fibre. The type of functional group of modified carbon fibre is not changed, which indicates that process of laser modification is mainly based on physical process. The laser modification does not change the microstructure of carbon fiber. A slight decrease in microcrystalline size is beneficial to improve to the interfacial adhesion properties between carbon fiber and epoxy resin. The tensile strength, impact strength of modified carbon fibre/epoxy resin composites are also improved. When the mass fraction of carbon fibre is 0.2wt% and modified power is 150 W, the tensile strength of carbon fibre/epoxy resin composite increases by 59%, and the impact strength increases by 52%.
The surface of polyacrylonitrile(PAN)-based carbon fibre was modified by high energy laser beam. SEM, EDS, FTIR, XRD, and tensile testing machine were used to characterize the morphology, change of composition, phase structure, and mechanical properties of carbon fibre before and after modification. The effect of laser beam on changes of carbon fibre microstructure was systematically studied to explore the mechanisms of laser beam on carbon fibre. The results show that surface roughness, specific surface area and infiltration of carbon fibre are improved after laser surface modification. When the power is higher, scanning speed becomes lower, carbon fibre wettability exhibits better. There are no changes in chemical composition, microstructure and type of functional groups of the modified carbon fibre. The type of functional group of modified carbon fibre is not changed, which indicates that process of laser modification is mainly based on physical process. The laser modification does not change the microstructure of carbon fiber. A slight decrease in microcrystalline size is beneficial to improve to the interfacial adhesion properties between carbon fiber and epoxy resin. The tensile strength, impact strength of modified carbon fibre/epoxy resin composites are also improved. When the mass fraction of carbon fibre is 0.2wt% and modified power is 150 W, the tensile strength of carbon fibre/epoxy resin composite increases by 59%, and the impact strength increases by 52%.
2018, 35(11): 2987-2993.
doi: 10.13801/j.cnki.fhclxb.20180130.002
Abstract:
The composite, with polyamide 6(PA6) as the matrix, graphene microchip(GNPmc) as the thermal filler, nano Ag as the laser reinforced filler, was prepared using torque rheometer and marked by 16.2 W laser power on the surface. The effect of amount of nano Ag on the thermal conductivity of GNPmc/PA6 composites and composition and content of the elements and residual carbon before and after laser marking were researched. The study finds that when the content of nano Ag is 1.5 g, the thermal conductivity of nano Ag-GNPmc/PA6 composite is 0.55 W/(m·K), the laser marker image is the clearest, the depth of laser marker image is 414.9 μm, the content of C decreases to 82.17% and O increases to 14.27%, amorphous C content increases a lot and residual C rate is 6.27%.
The composite, with polyamide 6(PA6) as the matrix, graphene microchip(GNPmc) as the thermal filler, nano Ag as the laser reinforced filler, was prepared using torque rheometer and marked by 16.2 W laser power on the surface. The effect of amount of nano Ag on the thermal conductivity of GNPmc/PA6 composites and composition and content of the elements and residual carbon before and after laser marking were researched. The study finds that when the content of nano Ag is 1.5 g, the thermal conductivity of nano Ag-GNPmc/PA6 composite is 0.55 W/(m·K), the laser marker image is the clearest, the depth of laser marker image is 414.9 μm, the content of C decreases to 82.17% and O increases to 14.27%, amorphous C content increases a lot and residual C rate is 6.27%.
2018, 35(11): 2994-3000.
doi: 10.13801/j.cnki.fhclxb.20180409.003
Abstract:
In order to improve the interface properties of composites, nanocarbons with different morphologies were deposited onto the surface of carbon fiber (CF) by controlling the process parameters using microwave plasma enhanced chemical vapor deposition (MPECVD) method. And then the multi-scale reinforcement was introduced into the interface layer of the CF/epoxy (EP) composites. Effects of different MPECVD technological parameters on the structural morphology of nanocarbon were researched by FESEM. The morphologies of nanocarbon on the interfacial shear strength (IFSS) were also studied by single fiber fragmentation test. And then, the relationship between interfacial properties and the micro-structure of interface region of nanocarbon-CF/EP was discussed. The results show that the morphologies of nanocarbon are changed significantly with the increase in deposition power. When the deposited power reaches 700 W, IFSS of nanocarbon-CF/EP composite increases by 118.85%, reaching 112.38 MPa.
In order to improve the interface properties of composites, nanocarbons with different morphologies were deposited onto the surface of carbon fiber (CF) by controlling the process parameters using microwave plasma enhanced chemical vapor deposition (MPECVD) method. And then the multi-scale reinforcement was introduced into the interface layer of the CF/epoxy (EP) composites. Effects of different MPECVD technological parameters on the structural morphology of nanocarbon were researched by FESEM. The morphologies of nanocarbon on the interfacial shear strength (IFSS) were also studied by single fiber fragmentation test. And then, the relationship between interfacial properties and the micro-structure of interface region of nanocarbon-CF/EP was discussed. The results show that the morphologies of nanocarbon are changed significantly with the increase in deposition power. When the deposited power reaches 700 W, IFSS of nanocarbon-CF/EP composite increases by 118.85%, reaching 112.38 MPa.
2018, 35(11): 3001-3007.
doi: 10.13801/j.cnki.fhclxb.20180131.001
Abstract:
In order to obtain the influence of laser ablation on the electrical properties of quartz fiber/cyanate composite and reveal the influencing mechanism, it is great significance for the evaluation and analysis of wave transmission performance and thermal protection design under extreme harsh thermal environment. Using laser as an external heat flow loading method, the laser ablation experiment of quartz/cyanate composite was carried out in this paper, and the dielectric constant before and after the experiment was tested. In order to analyze the change mechanism of dielectric constant, the quartz fiber/cyanate composite surface products after laser ablation and quartz fiber/cyanate composite were tested by transmission infrared spectroscopy and XRD. The ablation surface of quartz fiber/cyanate composite irradiated by laser was observed by SEM. The thermal weight loss of cyanate and quartz fibers were also tested. The results show that the dielectric constant is about 6 and nearly 1 time higher than the initial state in the range of 7-18 GHz. The influence mechanism of laser ablation on the electrical properties of quartz fiber/cyanate composite is as follows:The absorption of laser energy makes the cyanate thermal decomposition and cracking, the formation of carbon black, which is conductive ability and the chain state in situ on surface, the dielectric constant of the ablation sample increases, the radar wave absorption capacity of quartz fiber/cyanate composite that is ablation state will be enhanced under this condition. At the same time, the rough surface and the loose state formed by ablation will enhance the reflection and scattering of electromagnetic wave, which can further weaken the radar wave transmission capability.
In order to obtain the influence of laser ablation on the electrical properties of quartz fiber/cyanate composite and reveal the influencing mechanism, it is great significance for the evaluation and analysis of wave transmission performance and thermal protection design under extreme harsh thermal environment. Using laser as an external heat flow loading method, the laser ablation experiment of quartz/cyanate composite was carried out in this paper, and the dielectric constant before and after the experiment was tested. In order to analyze the change mechanism of dielectric constant, the quartz fiber/cyanate composite surface products after laser ablation and quartz fiber/cyanate composite were tested by transmission infrared spectroscopy and XRD. The ablation surface of quartz fiber/cyanate composite irradiated by laser was observed by SEM. The thermal weight loss of cyanate and quartz fibers were also tested. The results show that the dielectric constant is about 6 and nearly 1 time higher than the initial state in the range of 7-18 GHz. The influence mechanism of laser ablation on the electrical properties of quartz fiber/cyanate composite is as follows:The absorption of laser energy makes the cyanate thermal decomposition and cracking, the formation of carbon black, which is conductive ability and the chain state in situ on surface, the dielectric constant of the ablation sample increases, the radar wave absorption capacity of quartz fiber/cyanate composite that is ablation state will be enhanced under this condition. At the same time, the rough surface and the loose state formed by ablation will enhance the reflection and scattering of electromagnetic wave, which can further weaken the radar wave transmission capability.
2018, 35(11): 3008-3018.
doi: 10.13801/j.cnki.fhclxb.20180122.001
Abstract:
The nano SiO2/low density polyethylene(LDPE) composites were deep mixing by a parallel twin-screw extruder, the effect of the process on the dispersion and direct current breakdown strength and space charge characteristics of nano SiO2 particles in nano SiO2/LDPE composite system were investigated by SEM, direct current breakdown strength test and variable temperature space charge test, comprehensively evaluated dispersion improvement and the effect of the mechanical shear degradation on the electrical properties of nano SiO2/LDPE composites in molten state. The results show that with the increase of mixing times, nano SiO2 particles are dispersed more uniformly in the LDPE; the direct current breakdown strength of deep mixing increases to 433.1 kV/mm at room temperature compared with single mixing; With the increase of mixing times, the ability to restrain the space charge becomes stronger at low temperature, but the inhibition ability becomes worse at high temperature above 60℃. The increase of mixing times improves the dispersion of nano SiO2 particles and increases the interface with the LDPE matrix, meanwhile, the nano SiO2 particles also increase the thickness of the lamellae of the composites, increase the crystallinity, increase the interface area and mechanical properties with the improvement of the dispersibility, both of them promote the improvement of electrical properties. However due to the degradation of material caused by deep mixing, the increase of structural defects affects the space charge suppression performance in the high temperature region of nano SiO2/LDPE composites.
The nano SiO2/low density polyethylene(LDPE) composites were deep mixing by a parallel twin-screw extruder, the effect of the process on the dispersion and direct current breakdown strength and space charge characteristics of nano SiO2 particles in nano SiO2/LDPE composite system were investigated by SEM, direct current breakdown strength test and variable temperature space charge test, comprehensively evaluated dispersion improvement and the effect of the mechanical shear degradation on the electrical properties of nano SiO2/LDPE composites in molten state. The results show that with the increase of mixing times, nano SiO2 particles are dispersed more uniformly in the LDPE; the direct current breakdown strength of deep mixing increases to 433.1 kV/mm at room temperature compared with single mixing; With the increase of mixing times, the ability to restrain the space charge becomes stronger at low temperature, but the inhibition ability becomes worse at high temperature above 60℃. The increase of mixing times improves the dispersion of nano SiO2 particles and increases the interface with the LDPE matrix, meanwhile, the nano SiO2 particles also increase the thickness of the lamellae of the composites, increase the crystallinity, increase the interface area and mechanical properties with the improvement of the dispersibility, both of them promote the improvement of electrical properties. However due to the degradation of material caused by deep mixing, the increase of structural defects affects the space charge suppression performance in the high temperature region of nano SiO2/LDPE composites.
2018, 35(11): 3019-3033.
doi: 10.13801/j.cnki.fhclxb.20180322.003
Abstract:
The inorganic nano ZnO and montmorillonite (MMT) particles were doped in low density polyethylene(LDPE). The effects of inorganic nano particles on the dielectric properties LDPE were discussed. The nano ZnO/LDPE and nano MMT/LDPE composites with different crystal habits were prepared using melt blending polymerization with different cooling methods. The samples were characterization using FTIR, polarizing microscopy (PLM), SEM, DSC and thermally stimulated current (TSC), and the alternating curren breakdown characteristics of nano ZnO/LDPE and nano MMT/LDPE composites was studied. The results indicate that doping proper mass fraction of the inorganic nanoparticles touched by the surface can avoid the agglomeration effectively. It can raise the crystallization rate and improve the crystalline texture of nano ZnO/LDPE and nano MMT/LDPE composites. The inorganic nano particles doping would increase the density and depth of LDPE. Inside the sample would form the interface "localization state" owing to the charge carrier is trapping. The breakdown field strength of nano ZnO/LDPE and MMT/LDPE composites prepared by oil cooling are 13.6% and 14.4% higher than that of the composites prepared by natural air cooling. When the content of the nano particles doped is 3wt%, the breakdown strength of the composites appeares the highest values; the breakdown strength of ZnO/LDPE composite is 0.68% higher than that of MMT/LDPE composite. The conductivity experimental results show that the nano ZnO/LDPE composite conductivity is relatively lower than that of MMT/LDPE composite. The dielectric properties tests show that the nano ZnO/LDPE and MMT/LDPE composites dielectric constant decreases, and the tangent value of dielectric loss angle is improved in the range of 1-105 Hz test frequency.
The inorganic nano ZnO and montmorillonite (MMT) particles were doped in low density polyethylene(LDPE). The effects of inorganic nano particles on the dielectric properties LDPE were discussed. The nano ZnO/LDPE and nano MMT/LDPE composites with different crystal habits were prepared using melt blending polymerization with different cooling methods. The samples were characterization using FTIR, polarizing microscopy (PLM), SEM, DSC and thermally stimulated current (TSC), and the alternating curren breakdown characteristics of nano ZnO/LDPE and nano MMT/LDPE composites was studied. The results indicate that doping proper mass fraction of the inorganic nanoparticles touched by the surface can avoid the agglomeration effectively. It can raise the crystallization rate and improve the crystalline texture of nano ZnO/LDPE and nano MMT/LDPE composites. The inorganic nano particles doping would increase the density and depth of LDPE. Inside the sample would form the interface "localization state" owing to the charge carrier is trapping. The breakdown field strength of nano ZnO/LDPE and MMT/LDPE composites prepared by oil cooling are 13.6% and 14.4% higher than that of the composites prepared by natural air cooling. When the content of the nano particles doped is 3wt%, the breakdown strength of the composites appeares the highest values; the breakdown strength of ZnO/LDPE composite is 0.68% higher than that of MMT/LDPE composite. The conductivity experimental results show that the nano ZnO/LDPE composite conductivity is relatively lower than that of MMT/LDPE composite. The dielectric properties tests show that the nano ZnO/LDPE and MMT/LDPE composites dielectric constant decreases, and the tangent value of dielectric loss angle is improved in the range of 1-105 Hz test frequency.
2018, 35(11): 3034-3043.
doi: 10.13801/j.cnki.fhclxb.20180316.003
Abstract:
In order to further improve the electrical tree resistance of low density polyethylene (LDPE), montmorillonite (MMT)-SiO2/LDPE multi-element composite was prepared by melt blending with the organic MMT and surface modified SiO2 as the inorganic nanofiller. The molecular chain interaction of filler and LDPE matrix was characterized by FTIR. The effects of inorganic fillers on crystallization behavior, crystallization morphology and the electrical tree resistance property of LDPE were investigated. The research results indicate that inorganic fillers are mixed in LDPE in the form of physical entanglement through the long chain of modifier and LDPE matrix. The heterogeneous nucleation of nano-SiO2 forms small crystal structure which impedes the development of electrical trees, the MMT dispersed in amorphous region has a blocking effect on the development of electrical trees. The combination makes the development path of the electrical trees in the MMT-SiO2/LDPE multi-element composite more torturous, resulting in the electrical tree resistance of the MMT-SiO2/LDPE multi-element composite being better than MMT/LDPE and SiO2/LDPE composites.
In order to further improve the electrical tree resistance of low density polyethylene (LDPE), montmorillonite (MMT)-SiO2/LDPE multi-element composite was prepared by melt blending with the organic MMT and surface modified SiO2 as the inorganic nanofiller. The molecular chain interaction of filler and LDPE matrix was characterized by FTIR. The effects of inorganic fillers on crystallization behavior, crystallization morphology and the electrical tree resistance property of LDPE were investigated. The research results indicate that inorganic fillers are mixed in LDPE in the form of physical entanglement through the long chain of modifier and LDPE matrix. The heterogeneous nucleation of nano-SiO2 forms small crystal structure which impedes the development of electrical trees, the MMT dispersed in amorphous region has a blocking effect on the development of electrical trees. The combination makes the development path of the electrical trees in the MMT-SiO2/LDPE multi-element composite more torturous, resulting in the electrical tree resistance of the MMT-SiO2/LDPE multi-element composite being better than MMT/LDPE and SiO2/LDPE composites.
2018, 35(11): 3044-3050.
doi: 10.13801/j.cnki.fhclxb.20180227.002
Abstract:
The extrusion method was applied to prepare rice husk/high density polyethylene (HDPE) and rice husk biochar/HDPE composites. The morphological properties of the rice husk/HDPE and rice husk biochar/HDPE composites were evaluated by SEM and XRD analysis, the mechanical properties and creep resistance of composites were also observed and compared. The results show that the combination of rice husk/HDPE composites is so different from rice husk biochar/HDPE composites:rice husk/HDPE composites show that the husk is covered by HDPE, rice husk biochar/HDPE composites show HDPE is embedded in the pores of rice husk biochar; The XRD shows that both rice husk and rice husk biocar can affect the intensity of the peaks of the composites but have little effect on the crystallite structure; And whether it is bending, tensile or creep resistance, rice husk biochar/HDPE composites are much stronger than those of rice husk/HDPE composites.
The extrusion method was applied to prepare rice husk/high density polyethylene (HDPE) and rice husk biochar/HDPE composites. The morphological properties of the rice husk/HDPE and rice husk biochar/HDPE composites were evaluated by SEM and XRD analysis, the mechanical properties and creep resistance of composites were also observed and compared. The results show that the combination of rice husk/HDPE composites is so different from rice husk biochar/HDPE composites:rice husk/HDPE composites show that the husk is covered by HDPE, rice husk biochar/HDPE composites show HDPE is embedded in the pores of rice husk biochar; The XRD shows that both rice husk and rice husk biocar can affect the intensity of the peaks of the composites but have little effect on the crystallite structure; And whether it is bending, tensile or creep resistance, rice husk biochar/HDPE composites are much stronger than those of rice husk/HDPE composites.
2018, 35(11): 3051-3061.
doi: 10.13801/j.cnki.fhclxb.20180404.003
Abstract:
Polyhedral oligomeric silsesquioxane/ploy (L-Lactic acid) (POSS/PLLA) composites were prepared by blending POSS and PLLA with different molecular mass in dichloromethane solvent. The crystallization morphology, crystallization behavior and thermal properties of POSS/PLLA composites were studied by polarizing microscope (POM), DSC, XRD and TGA. The results show that the crystallization temperatures of POSS/PLLA composites increase to about 110℃ and their crystallization ability increases. The initial thermal decomposition temperature and the terminate thermal decomposition temperature of the POSS/PLLA composites increase and the temperature corresponding to the maximum decomposition rate is between 373℃ and 379℃, which indicates that their thermal stability is improved. When the content of POSS is lower, the nucleation plays a dominant role. When the content of POSS is higher, it hinders the movement of PLLA chains. And the blocking effect of POSS is stronger for high molecular weight PLLA. The cross extinction phenomenon and the ring band crystal morphology appear in POSS/PLLA composites and PLLA are seen obviously during isothermal crystalization. The spherulite in the cooling process produces cracks, which is related to the brittleness of PLLA.
Polyhedral oligomeric silsesquioxane/ploy (L-Lactic acid) (POSS/PLLA) composites were prepared by blending POSS and PLLA with different molecular mass in dichloromethane solvent. The crystallization morphology, crystallization behavior and thermal properties of POSS/PLLA composites were studied by polarizing microscope (POM), DSC, XRD and TGA. The results show that the crystallization temperatures of POSS/PLLA composites increase to about 110℃ and their crystallization ability increases. The initial thermal decomposition temperature and the terminate thermal decomposition temperature of the POSS/PLLA composites increase and the temperature corresponding to the maximum decomposition rate is between 373℃ and 379℃, which indicates that their thermal stability is improved. When the content of POSS is lower, the nucleation plays a dominant role. When the content of POSS is higher, it hinders the movement of PLLA chains. And the blocking effect of POSS is stronger for high molecular weight PLLA. The cross extinction phenomenon and the ring band crystal morphology appear in POSS/PLLA composites and PLLA are seen obviously during isothermal crystalization. The spherulite in the cooling process produces cracks, which is related to the brittleness of PLLA.
2018, 35(11): 3062-3072.
doi: 10.13801/j.cnki.fhclxb.20180126.001
Abstract:
Polycarbonate/acrylonitrile styrene acrylate (PC/ASA) composites modified with two kinds of synergistic flame-retardant systems, p-bis-(diphenylphosphoryloxy)-benzol (BDPB)-silsesquioxanes, phenyl, hydroxy-terminated(SPH) and BDPB-organically modified montmorillonite(OMMT), respectively, were prepared by melt compounding. The microstructure、combustion behavior and dynamic mechanical properties were investigated by XRD, TG, limiting oxygen index(LOI), SEM, XPS and DMA test. The results indicate that the BDPB-SPH and BDPB-OMMT flame-retardant systems exhibit a synergistic effect. The BDPB-SPH-PC/ASA and BDPB-OMMT-PC/ASA composites could reach V-0 rating in vertical burning test (UL-94), and the LOI of the composites reach 30.4% and 31.2%, respectively. The residual of BDPB-SPH-PC/ASA and BDPB-OMMT-PC/ASA could increase to 12.43% and 14.24%, respectively. With the loading of BDPB-SPH and BDPB-OMMT flame-retardant systems, the microstructure of residual layer becomes more compact. BDPB, SPH and OMMT tend to accumulate at the surface during combustion, which could promote the formation of stable layer and as a result enhance the flame retardant properties. The glass transition temperature(Tg) of BDPB-SPH-PC/ASA and BDPB-OMMT-PC/ASA composites shift to low temperature, and the storage modulus of the composites are enhanced before Tg.
Polycarbonate/acrylonitrile styrene acrylate (PC/ASA) composites modified with two kinds of synergistic flame-retardant systems, p-bis-(diphenylphosphoryloxy)-benzol (BDPB)-silsesquioxanes, phenyl, hydroxy-terminated(SPH) and BDPB-organically modified montmorillonite(OMMT), respectively, were prepared by melt compounding. The microstructure、combustion behavior and dynamic mechanical properties were investigated by XRD, TG, limiting oxygen index(LOI), SEM, XPS and DMA test. The results indicate that the BDPB-SPH and BDPB-OMMT flame-retardant systems exhibit a synergistic effect. The BDPB-SPH-PC/ASA and BDPB-OMMT-PC/ASA composites could reach V-0 rating in vertical burning test (UL-94), and the LOI of the composites reach 30.4% and 31.2%, respectively. The residual of BDPB-SPH-PC/ASA and BDPB-OMMT-PC/ASA could increase to 12.43% and 14.24%, respectively. With the loading of BDPB-SPH and BDPB-OMMT flame-retardant systems, the microstructure of residual layer becomes more compact. BDPB, SPH and OMMT tend to accumulate at the surface during combustion, which could promote the formation of stable layer and as a result enhance the flame retardant properties. The glass transition temperature(Tg) of BDPB-SPH-PC/ASA and BDPB-OMMT-PC/ASA composites shift to low temperature, and the storage modulus of the composites are enhanced before Tg.
2018, 35(11): 3073-3080.
doi: 10.13801/j.cnki.fhclxb.20180319.009
Abstract:
Modified multi-walled carbon nanotubes suspension(MWCNTs-NH2(M)) was prepared by modifying on MWCNTs-NH2. MWCNTs-COOH and MWCNTs-NH2(M) were dispersed in epoxy(EP) respectively, multiscale MWCNTs-carbon fiber/EP(MWCNTs-CF/EP) composites were successfully manufactured by hot-melt method. The effect of MWCNTs on modulus, toughness of EP and interfacial shear strength (IFSS) between EP and CF was investigated, the reactions between MWCNTs and the sizing agent of CF were analysed, and the mechanical properties of multiscale MWCNTs-CF/EP composites were evaluated. The results indicate that functional MWCNTs can strengthen modulus and toughness of EP more effectively. The IFSSs are improved due to the chemical reactions between -COOH or -NH2 grafted on the MWCNTs surface and the epoxy group in the sizing agent of CF. The multiscale MWCNTs-CF/EP composites show an improved mechanical behavior and this effect is more evident with MWCNTs-NH2(M) compared to MWCNTs-COOH, the 0° compressive strength, 90° compressive strength, flexural strength, flexural modulus, compression strength after impact(CAI) of multiscale MWCNTs-CF/EP composites can be enhanced by 16.7%, 16.3%, 40.9%, 30.3%, 20.6%, respectively when the mass fraction of MWCNTs-NH2(M) is 1wt%.
Modified multi-walled carbon nanotubes suspension(MWCNTs-NH2(M)) was prepared by modifying on MWCNTs-NH2. MWCNTs-COOH and MWCNTs-NH2(M) were dispersed in epoxy(EP) respectively, multiscale MWCNTs-carbon fiber/EP(MWCNTs-CF/EP) composites were successfully manufactured by hot-melt method. The effect of MWCNTs on modulus, toughness of EP and interfacial shear strength (IFSS) between EP and CF was investigated, the reactions between MWCNTs and the sizing agent of CF were analysed, and the mechanical properties of multiscale MWCNTs-CF/EP composites were evaluated. The results indicate that functional MWCNTs can strengthen modulus and toughness of EP more effectively. The IFSSs are improved due to the chemical reactions between -COOH or -NH2 grafted on the MWCNTs surface and the epoxy group in the sizing agent of CF. The multiscale MWCNTs-CF/EP composites show an improved mechanical behavior and this effect is more evident with MWCNTs-NH2(M) compared to MWCNTs-COOH, the 0° compressive strength, 90° compressive strength, flexural strength, flexural modulus, compression strength after impact(CAI) of multiscale MWCNTs-CF/EP composites can be enhanced by 16.7%, 16.3%, 40.9%, 30.3%, 20.6%, respectively when the mass fraction of MWCNTs-NH2(M) is 1wt%.
2018, 35(11): 3081-3087.
doi: 10.13801/j.cnki.fhclxb.20180319.011
Abstract:
Sulfonated poly (ether ether ketone) (SPEEK) was obtained by modifying poly(ether ether ketone) (PEEK) with concentrated H2SO4. the SPEEK/BBA-BBE-BMI composites were cast-molded, with bismaleimide (BMI) resin as the matrix, 3,3'-diallyl bisphenol A(BBA) and bisphenol A diallyl ether(BBE) as the reactive diluent, SPEEK as the modifier. The effects of SPEEK on the composites were studied. The micro-structure and mechanical properties of the SPEEK/BBA-BBE-BMI composites were examined. The results show that SPEEK produces better modification effect and obvious characteristic peaks of sulfonic acid groups appear in FTIR. SEM and EDS analysis reveale that the micro-structure changes clearly and the content of sulfur element is higher. The micro-structure of SPEEK/BBA-BBE-BMI composite displays that the SPEEK exhibits a porous two-phase structure with a diameter of about 2 μm in the matrix. The "honeycomb" structure changes the fracture morphology from brittle to ductile fracture. The irregular divergence occurre when the breakage encounters the SPEEK component, and this change could supply the composite more excellent properties. The results of mechanical properties for composite indicate that the flexural strength and impact strength of SPEEK/BBA-BBE-BMI composite with 5wt% SPEEK are the best (147.93 MPa and 15.74 kJ/mm2), 49.47% and 66.21% higher than that of the matrix, respectively.
Sulfonated poly (ether ether ketone) (SPEEK) was obtained by modifying poly(ether ether ketone) (PEEK) with concentrated H2SO4. the SPEEK/BBA-BBE-BMI composites were cast-molded, with bismaleimide (BMI) resin as the matrix, 3,3'-diallyl bisphenol A(BBA) and bisphenol A diallyl ether(BBE) as the reactive diluent, SPEEK as the modifier. The effects of SPEEK on the composites were studied. The micro-structure and mechanical properties of the SPEEK/BBA-BBE-BMI composites were examined. The results show that SPEEK produces better modification effect and obvious characteristic peaks of sulfonic acid groups appear in FTIR. SEM and EDS analysis reveale that the micro-structure changes clearly and the content of sulfur element is higher. The micro-structure of SPEEK/BBA-BBE-BMI composite displays that the SPEEK exhibits a porous two-phase structure with a diameter of about 2 μm in the matrix. The "honeycomb" structure changes the fracture morphology from brittle to ductile fracture. The irregular divergence occurre when the breakage encounters the SPEEK component, and this change could supply the composite more excellent properties. The results of mechanical properties for composite indicate that the flexural strength and impact strength of SPEEK/BBA-BBE-BMI composite with 5wt% SPEEK are the best (147.93 MPa and 15.74 kJ/mm2), 49.47% and 66.21% higher than that of the matrix, respectively.
2018, 35(11): 3088-3096.
doi: 10.13801/j.cnki.fhclxb.20180716.002
Abstract:
It is one of the main causes of GFRP composite windturbine blades failure that the blade shimmy leads to the formation and growth of interlayer sliding cracks.The stress intensity factor K is an important parameter for the interlayer fracture toughness.It is also one of the important indicators for the safety assessment of surface cracks.On the basis of experiments, a new method for deriving K values from the displacement of the GFRP composite blade surface was proposed in this paper.The correctness of the theory was verified by experiments.It is proved by the comparison between experiment and simulation that it is feasible to study the interlaminar fracture toughness response through the surface displacement of the GFRP composite blades shimmy.This study provides a new idea and method for the strength prediction of GFRP composite windturbine blades.
It is one of the main causes of GFRP composite windturbine blades failure that the blade shimmy leads to the formation and growth of interlayer sliding cracks.The stress intensity factor K is an important parameter for the interlayer fracture toughness.It is also one of the important indicators for the safety assessment of surface cracks.On the basis of experiments, a new method for deriving K values from the displacement of the GFRP composite blade surface was proposed in this paper.The correctness of the theory was verified by experiments.It is proved by the comparison between experiment and simulation that it is feasible to study the interlaminar fracture toughness response through the surface displacement of the GFRP composite blades shimmy.This study provides a new idea and method for the strength prediction of GFRP composite windturbine blades.
2018, 35(11): 3097-3105.
doi: 10.13801/j.cnki.fhclxb.20180227.001
Abstract:
TiB2-TiC/Fe composite coatings were fabricated on the surface of Q235 steel via plasma cladding by used Ti, B4C, and Fe55 as precursor materials. The phase composition, structure, microhardness and friction wear resistance of TiB2-TiC/Fe coatings were analyzed, and the wear mechanism was also discussed. The results show that the TiB2-TiC/Fe composite coatings mainly consist of TiB2, TiC and α-Fe. TiB2 phase presents rectangle or multilateral shape, and TiC phase is irregular patch shape. With the increase of ceramic content in TiB2-TiC/Fe composite coatings, the sizes of TiB2 and TiC enlarge gradually and the TiB2-TiC/Fe composite coatings are closely and metallurgically combined with Q235 steel substrate. The wear resistance and hardness of TiB2-TiC/Fe composite coatings can improve with the increasing of ceramic contents in the coatings, while the wear resistance declines when ceramic content increases to some extent (35wt%) in TiB2-TiC/Fe composite coatings. The wear mechanism of TiB2-TiC/Fe composite coatings are mainly abrasive and delaminate wear. The plasma cladding coating with 30wt% ceramic content has lower wearing volume, and the wear resistance of the coating is 7 times to that of Q235 steel. When the content of Ti+B4C continues to increase, the size and defects of ceramic phase increase and the wear resistance of the coatings reduces eventually.
TiB2-TiC/Fe composite coatings were fabricated on the surface of Q235 steel via plasma cladding by used Ti, B4C, and Fe55 as precursor materials. The phase composition, structure, microhardness and friction wear resistance of TiB2-TiC/Fe coatings were analyzed, and the wear mechanism was also discussed. The results show that the TiB2-TiC/Fe composite coatings mainly consist of TiB2, TiC and α-Fe. TiB2 phase presents rectangle or multilateral shape, and TiC phase is irregular patch shape. With the increase of ceramic content in TiB2-TiC/Fe composite coatings, the sizes of TiB2 and TiC enlarge gradually and the TiB2-TiC/Fe composite coatings are closely and metallurgically combined with Q235 steel substrate. The wear resistance and hardness of TiB2-TiC/Fe composite coatings can improve with the increasing of ceramic contents in the coatings, while the wear resistance declines when ceramic content increases to some extent (35wt%) in TiB2-TiC/Fe composite coatings. The wear mechanism of TiB2-TiC/Fe composite coatings are mainly abrasive and delaminate wear. The plasma cladding coating with 30wt% ceramic content has lower wearing volume, and the wear resistance of the coating is 7 times to that of Q235 steel. When the content of Ti+B4C continues to increase, the size and defects of ceramic phase increase and the wear resistance of the coatings reduces eventually.
2018, 35(11): 3106-3113.
doi: 10.13801/j.cnki.fhclxb.20180305.001
Abstract:
In order to investigate the effects of re-melting temperature on the interface characteristics and mechanical properties of WCP/Fe composites, the WCP/Fe composites were prepared by powder sintering and the interface of the composites were re-melted at the different temperatures. The research provides a theoretical basis for the interface structure design and the application of particle reinforced metal matrix composites. The results show that a phase transition reaction occurs from WC to W2C with the increase of the re-melting temperature, and W2C reacts with Fe to generate the solid Fe3W3C phase. Besides, the width of interface reaction zone increases with the increase of the re-melting temperature. The interfacial morphology is transformed from discontinuous cycle to a continuous cycle and then to serration shape. The compressive strength of the WCP/Fe composites exhibits the trend of increasing and then decreasing. When re-melting temperature is 1 300℃, the interface width is 13.5 μm and the interface reaction zone appears in continuous cycle shape. The internal compressive cracks of the composites are not inclined to initiate and propagation. Meanwhile, the compression strength of composites is 386 MPa when it reaches the maximum.
In order to investigate the effects of re-melting temperature on the interface characteristics and mechanical properties of WCP/Fe composites, the WCP/Fe composites were prepared by powder sintering and the interface of the composites were re-melted at the different temperatures. The research provides a theoretical basis for the interface structure design and the application of particle reinforced metal matrix composites. The results show that a phase transition reaction occurs from WC to W2C with the increase of the re-melting temperature, and W2C reacts with Fe to generate the solid Fe3W3C phase. Besides, the width of interface reaction zone increases with the increase of the re-melting temperature. The interfacial morphology is transformed from discontinuous cycle to a continuous cycle and then to serration shape. The compressive strength of the WCP/Fe composites exhibits the trend of increasing and then decreasing. When re-melting temperature is 1 300℃, the interface width is 13.5 μm and the interface reaction zone appears in continuous cycle shape. The internal compressive cracks of the composites are not inclined to initiate and propagation. Meanwhile, the compression strength of composites is 386 MPa when it reaches the maximum.
2018, 35(11): 3114-3121.
doi: 10.13801/j.cnki.fhclxb.20180123.001
Abstract:
TiB2/Al-Si composite samples were produced by selective laser melting (SLM), following by different heat treatments. The microstructures and mechanical properties of in-situ TiB2/Al-Si composites before and after different heat treatments were analyzed by XRD, SEM, electron back-scattered diffraction (EBSD), EDS and tensile tests. The results indicate that the as-prepared SLM TiB2/Al-Si composites have ultra-fine microstructures and high mechanical properties due to the high cooling rate of SLM and the existence of nano TiB2 particles. The average grain size is 1.1 μm, and TiB2/Al-Si composites show high yield strength of 262 MPa, high tensile strength of 435 MPa and excellent elongation of 11.88%. For the TiB2/Al-Si composites after different heat treatments, the mechanical properties reach its best after the direct artificial aging (150℃/12 h). The tensile strength of the TiB2/Al-Si composites reaches 488 MPa which increases by 53 MPa, and the elongation decreases to 7.2%.
TiB2/Al-Si composite samples were produced by selective laser melting (SLM), following by different heat treatments. The microstructures and mechanical properties of in-situ TiB2/Al-Si composites before and after different heat treatments were analyzed by XRD, SEM, electron back-scattered diffraction (EBSD), EDS and tensile tests. The results indicate that the as-prepared SLM TiB2/Al-Si composites have ultra-fine microstructures and high mechanical properties due to the high cooling rate of SLM and the existence of nano TiB2 particles. The average grain size is 1.1 μm, and TiB2/Al-Si composites show high yield strength of 262 MPa, high tensile strength of 435 MPa and excellent elongation of 11.88%. For the TiB2/Al-Si composites after different heat treatments, the mechanical properties reach its best after the direct artificial aging (150℃/12 h). The tensile strength of the TiB2/Al-Si composites reaches 488 MPa which increases by 53 MPa, and the elongation decreases to 7.2%.
2018, 35(11): 3122-3129.
doi: 10.13801/j.cnki.fhclxb.20180308.002
Abstract:
Preparation of Al2O3 sol and ZrO2 and CeO2 ceramic powder based on sol-gel method were prepared. The ceramic powders were dispersed in Al2O3 sol to form the composite slurry, then ZrO2/Al2O3 and ZrO2-CeO2/Al2O3 composite ceramic coatings were prepared on the surface of superalloy GH3039 substrate by XRD, SEM, EDS and DSC to study the influence of different ceramic powder on thermal shock resistance of composite sol-gel coating at 900℃. The results indicate that the pure Al2O3 coating without any ceramic powder has a large number of macro crack, bad surface integrity and easy peeling during the process of sintering; when the ZrO2 ceramic powder is added into the Al2O3 sol, the structure of the ZrO2/Al2O3 composite ceramic coating has no obvious macro crack and the adhesion between the coating and the substrate increases significantly; when CeO2:ZrO2=1:10 (molar ratio), CeO2 can stabilize the phase transition under high temperature, which can prevent the transition from t-ZrO2 to m-ZrO2. The ceramic particles are dispersed homogeneously in the Al2O3 network film and present the structure of coated ZrO2-CeO2 particles covered with nano Al2O3 particles. This structure makes the thermal shock resistance and spalling resistance of Al2O3 composite ceramic coating more excellent than the ZrO2/Al2O3 composite ceramic coating. ZrO2-CeO2/Al2O3 composite ceramic coatings can solve the thermal coefficient mismatch problem between matrix and Al2O3 coating so as to further improve the performance of matrix thermal shock and prolongs lifetime of the superalloy GH3039.
Preparation of Al2O3 sol and ZrO2 and CeO2 ceramic powder based on sol-gel method were prepared. The ceramic powders were dispersed in Al2O3 sol to form the composite slurry, then ZrO2/Al2O3 and ZrO2-CeO2/Al2O3 composite ceramic coatings were prepared on the surface of superalloy GH3039 substrate by XRD, SEM, EDS and DSC to study the influence of different ceramic powder on thermal shock resistance of composite sol-gel coating at 900℃. The results indicate that the pure Al2O3 coating without any ceramic powder has a large number of macro crack, bad surface integrity and easy peeling during the process of sintering; when the ZrO2 ceramic powder is added into the Al2O3 sol, the structure of the ZrO2/Al2O3 composite ceramic coating has no obvious macro crack and the adhesion between the coating and the substrate increases significantly; when CeO2:ZrO2=1:10 (molar ratio), CeO2 can stabilize the phase transition under high temperature, which can prevent the transition from t-ZrO2 to m-ZrO2. The ceramic particles are dispersed homogeneously in the Al2O3 network film and present the structure of coated ZrO2-CeO2 particles covered with nano Al2O3 particles. This structure makes the thermal shock resistance and spalling resistance of Al2O3 composite ceramic coating more excellent than the ZrO2/Al2O3 composite ceramic coating. ZrO2-CeO2/Al2O3 composite ceramic coatings can solve the thermal coefficient mismatch problem between matrix and Al2O3 coating so as to further improve the performance of matrix thermal shock and prolongs lifetime of the superalloy GH3039.
2018, 35(11): 3130-3136.
doi: 10.13801/j.cnki.fhclxb.20180209.009
Abstract:
In order to improve the oxidation behavior of C/C composites in a wide range of temperature, a new SiC/Si-B4C coating was developed. The oxidation resistant mechanism of the SiC/Si-B4C coated composites was studied by thermogravimetric analysis in the temperature range from room temperature to 1 500℃. After oxidation at 1 500℃ in air for 2 h, the mass gain of sample is 2.21%. The oxidation behaviors of SiC, Si and B4C were also studied in the temperature range from 500℃ to 1 500℃, respectively, and the effective oxidation resistant temperature ranges of SiC, Si and B4C were explained. By analyses of oxidation kinetics, activation energies for the oxidation of SiC and Si are 196.7 kJ/mol and 167.3 kJ/mol, respectively. Because of the synergistic oxidation resistant mechanism of SiC, Si and B4C, the SiC/Si-B4C coating shows self-healing ability and excellent oxidation resistance in the temperature range from 600℃ to 1 500℃.
In order to improve the oxidation behavior of C/C composites in a wide range of temperature, a new SiC/Si-B4C coating was developed. The oxidation resistant mechanism of the SiC/Si-B4C coated composites was studied by thermogravimetric analysis in the temperature range from room temperature to 1 500℃. After oxidation at 1 500℃ in air for 2 h, the mass gain of sample is 2.21%. The oxidation behaviors of SiC, Si and B4C were also studied in the temperature range from 500℃ to 1 500℃, respectively, and the effective oxidation resistant temperature ranges of SiC, Si and B4C were explained. By analyses of oxidation kinetics, activation energies for the oxidation of SiC and Si are 196.7 kJ/mol and 167.3 kJ/mol, respectively. Because of the synergistic oxidation resistant mechanism of SiC, Si and B4C, the SiC/Si-B4C coating shows self-healing ability and excellent oxidation resistance in the temperature range from 600℃ to 1 500℃.
2018, 35(11): 3137-3145.
doi: 10.13801/j.cnki.fhclxb.20180130.001
Abstract:
The magnesium oxysulfate whiskers (MgOSW) were modified by silane coupling agent 3-triethoxysilylpropylamine(KH550), and the modified whiskers dispersion liquid was prepared by ultrasonic technology. MgOSW/natural rubber (NR) composites were developed by the blending modified whiskers dispersion liquid with the NR latex. The morphology, mechanical properties, flammability properties and thermalstability properties of the KH550-MgOSW/NR composites were investigated. The results show that modified MgOSW have good compatibility with NR latex matrix. The properties of KH550-MgOSW/NR composites are improved by the incorporation of modified MgOSW into NR matrix.When modified whiskers mass ratio to NR is 4%, the performances of KH550-MgOSW/NR composites achieve optimum results. Compared with pure NR, the modulus at 300%, tensile strength, tear strength, elongation at break and crosslink density of KH550-MgOSW/NR composites are increased by 25.0%, 36.8%, 37.3%, 11.4%, 44.2%, respectively. The flame retardant grade of composites increases from FV-1 to FV-0. The initial thermal degradation temperature (T0), maximum thermal degradation temperature (Tp), and termination of thermal degradation temperature (TTf) of KH550-MgOSW/NR composites markedly increase 6.2℃, 5.2℃ and 4.1℃, respectively, compared to NR.
The magnesium oxysulfate whiskers (MgOSW) were modified by silane coupling agent 3-triethoxysilylpropylamine(KH550), and the modified whiskers dispersion liquid was prepared by ultrasonic technology. MgOSW/natural rubber (NR) composites were developed by the blending modified whiskers dispersion liquid with the NR latex. The morphology, mechanical properties, flammability properties and thermalstability properties of the KH550-MgOSW/NR composites were investigated. The results show that modified MgOSW have good compatibility with NR latex matrix. The properties of KH550-MgOSW/NR composites are improved by the incorporation of modified MgOSW into NR matrix.When modified whiskers mass ratio to NR is 4%, the performances of KH550-MgOSW/NR composites achieve optimum results. Compared with pure NR, the modulus at 300%, tensile strength, tear strength, elongation at break and crosslink density of KH550-MgOSW/NR composites are increased by 25.0%, 36.8%, 37.3%, 11.4%, 44.2%, respectively. The flame retardant grade of composites increases from FV-1 to FV-0. The initial thermal degradation temperature (T0), maximum thermal degradation temperature (Tp), and termination of thermal degradation temperature (TTf) of KH550-MgOSW/NR composites markedly increase 6.2℃, 5.2℃ and 4.1℃, respectively, compared to NR.
2018, 35(11): 3146-3153.
doi: 10.13801/j.cnki.fhclxb.20180109.001
Abstract:
A nature bio-template strategy was implemented to synthesize nano Ag-Au particles and display ordered arrays on butterfly wings. By a convenient procedure, the butterfly wings were immersed in ethylenediamine to increase the reactive sites on the chitin component (e.g. -CONH-and -OH functional groups), in which nano Ag particles can in situ come into being and further serve as the active sites for succedent Au deposition. The 30-50 nm solid spherical, 50-80 nm hollow spherical, irregular Ag-Au particles are loaded both on the wings' surface layer and inside the ordered array nanostructure homogeneously. This work not only replicates the fine structure of the butterfly wing, but also regulates the shape of nano Ag-Au particles. The preparation method of liquid phase impregnation based on natural biological templates provides an important reference for the effective preparation of the Ag-Au/butterfly wing composites with fine graded structure and multi-component functional nanostructures.
A nature bio-template strategy was implemented to synthesize nano Ag-Au particles and display ordered arrays on butterfly wings. By a convenient procedure, the butterfly wings were immersed in ethylenediamine to increase the reactive sites on the chitin component (e.g. -CONH-and -OH functional groups), in which nano Ag particles can in situ come into being and further serve as the active sites for succedent Au deposition. The 30-50 nm solid spherical, 50-80 nm hollow spherical, irregular Ag-Au particles are loaded both on the wings' surface layer and inside the ordered array nanostructure homogeneously. This work not only replicates the fine structure of the butterfly wing, but also regulates the shape of nano Ag-Au particles. The preparation method of liquid phase impregnation based on natural biological templates provides an important reference for the effective preparation of the Ag-Au/butterfly wing composites with fine graded structure and multi-component functional nanostructures.
2018, 35(11): 3154-3161.
doi: 10.13801/j.cnki.fhclxb.20180310.003
Abstract:
Surface-nickeled polyimide (PI-Ni) fibers with high tensile strength, high conductivity and high-temperature stability were successfully prepared by using high-strength PI fiber as the matrix via a surface-modification ion-exchange and electroless nickel plating method. The prepared PI-Ni fibers were characterized by SEM, XRD, EDS, mechanical test, electrical conductivity measurement, adhesion test and TGA, respectively. The results indicate that the coated metal layer on the PI-Ni fibers is amorphous Ni-P alloy, which has smooth, detect-free and compact surface morphologies. The PI-Ni fiber is prepared with the tensile strength up to 1.2 GPa, surface resistivity of 1.76×10-4 Ω·cm, and 5%-weight-loss temperature of 611℃, which is a high-performance organic conductive fiber.
Surface-nickeled polyimide (PI-Ni) fibers with high tensile strength, high conductivity and high-temperature stability were successfully prepared by using high-strength PI fiber as the matrix via a surface-modification ion-exchange and electroless nickel plating method. The prepared PI-Ni fibers were characterized by SEM, XRD, EDS, mechanical test, electrical conductivity measurement, adhesion test and TGA, respectively. The results indicate that the coated metal layer on the PI-Ni fibers is amorphous Ni-P alloy, which has smooth, detect-free and compact surface morphologies. The PI-Ni fiber is prepared with the tensile strength up to 1.2 GPa, surface resistivity of 1.76×10-4 Ω·cm, and 5%-weight-loss temperature of 611℃, which is a high-performance organic conductive fiber.
2018, 35(11): 3162-3171.
doi: 10.13801/j.cnki.fhclxb.20180205.002
Abstract:
The rice straw/magnesium oxychloride cement (MOC) inorganic light composites were prepared with hydrogen peroxide solution as the foaming agent, MnO2 as the excitation agent, calcium stearate as the stabilizing foam agent, polyacrylamide as the thickening agent. The effect of straw size and adding quantity on the dispersion of straw in the slurry and its effect on the strength, toughness, crack resistance and water absorption of straw/MOC composites were discussed. The results show that the straw size and the amount of addition have a great influence on the straw dispersion and strength of straw/MOC composites. When the straw size is smaller than 250 μm and the quantity is 0.9% mass ratio of straw to MOC, the straw dispersion is the best, the compressive strength (11.26 MPa), bending strength (3.97 MPa) and anti-crack of straw/MOC composites are the largest. SEM analysis show that there are weak layer between straw and the matrix because the poor cementing quality. When the straw size is too large or straw quantity is too much, per unit volume of the straw/MOC composites will be introduced more weak interfacial bonding part. As a result, the overall performance of the sample will be affected.
The rice straw/magnesium oxychloride cement (MOC) inorganic light composites were prepared with hydrogen peroxide solution as the foaming agent, MnO2 as the excitation agent, calcium stearate as the stabilizing foam agent, polyacrylamide as the thickening agent. The effect of straw size and adding quantity on the dispersion of straw in the slurry and its effect on the strength, toughness, crack resistance and water absorption of straw/MOC composites were discussed. The results show that the straw size and the amount of addition have a great influence on the straw dispersion and strength of straw/MOC composites. When the straw size is smaller than 250 μm and the quantity is 0.9% mass ratio of straw to MOC, the straw dispersion is the best, the compressive strength (11.26 MPa), bending strength (3.97 MPa) and anti-crack of straw/MOC composites are the largest. SEM analysis show that there are weak layer between straw and the matrix because the poor cementing quality. When the straw size is too large or straw quantity is too much, per unit volume of the straw/MOC composites will be introduced more weak interfacial bonding part. As a result, the overall performance of the sample will be affected.
2018, 35(11): 3172-3179.
doi: 10.13801/j.cnki.fhclxb.20180202.002
Abstract:
A series of nano TiO2 photocatalytic dispersed solutions were prepared by using deionized water as a medium, sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (DBS), ployvinylpynolidone (PVP), cetyl trimethyl ammonium bromide (CTAB), polyacrylic acid sodium (PAAS) surfactant as the dispersant, respectively. The TiO2 dispersed solutions were used as a finishing agent for the polyester sea-island filament needle punched nonwoven (PFN-NWF) to prepare TiO2/PFN-NWF photocatalytic composites through the twice dip-padding technique. The morphology, structure and properties of TiO2 solutions and TiO2/PFN-NWF photocatalytic composites were investigated. The capsicol and formaldehyde solution was used as a model contaminant to evaluate the photocatalytic activity of the TiO2/PFN-NWF composites. The results indicate that the dispersion system of TiO2 significantly affected by acidity-basicity of solution and dispersant, and the dispersivity of TiO2 solution can be effectively improved by addition of PAAS. The TiO2 is well immobilized on the surface of PFN-NWF and has good load fastness, the load rate of TiO2/PFN-NWF composites could be achieved 4.79%. The TiO2/PFN-NWF composites also have excellent catalytic performance. The capsicol (2 mL) drops on the surface of TiO2/PFN-NWF composites can be completely degraded under natural light irradiation for 60 min. The degradation ratio of formaldehyde is 95.98% under xenon lamp (300 W) irradiation for 3 h, and this ratio is remained above 90.19% after five cycles.
A series of nano TiO2 photocatalytic dispersed solutions were prepared by using deionized water as a medium, sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (DBS), ployvinylpynolidone (PVP), cetyl trimethyl ammonium bromide (CTAB), polyacrylic acid sodium (PAAS) surfactant as the dispersant, respectively. The TiO2 dispersed solutions were used as a finishing agent for the polyester sea-island filament needle punched nonwoven (PFN-NWF) to prepare TiO2/PFN-NWF photocatalytic composites through the twice dip-padding technique. The morphology, structure and properties of TiO2 solutions and TiO2/PFN-NWF photocatalytic composites were investigated. The capsicol and formaldehyde solution was used as a model contaminant to evaluate the photocatalytic activity of the TiO2/PFN-NWF composites. The results indicate that the dispersion system of TiO2 significantly affected by acidity-basicity of solution and dispersant, and the dispersivity of TiO2 solution can be effectively improved by addition of PAAS. The TiO2 is well immobilized on the surface of PFN-NWF and has good load fastness, the load rate of TiO2/PFN-NWF composites could be achieved 4.79%. The TiO2/PFN-NWF composites also have excellent catalytic performance. The capsicol (2 mL) drops on the surface of TiO2/PFN-NWF composites can be completely degraded under natural light irradiation for 60 min. The degradation ratio of formaldehyde is 95.98% under xenon lamp (300 W) irradiation for 3 h, and this ratio is remained above 90.19% after five cycles.
2018, 35(11): 3180-3188.
doi: 10.13801/j.cnki.fhclxb.20180316.004
Abstract:
A novel cellulose nanofibers(CNF) aerogels were prepared based on the spherical cellulose nanofiber gel modified with 3-(2-aminoethylamino) propylmethyldimethoxysilane (AEAPMDS) in combination by solvent displacement and freeze drying. The change of its N content was investigated under different reaction conditions. The resultant spherical nano cellulose aerogels were characterized with respect to microscopic morphology, structural characteristics, mechanical properties and CO2 adsorption properties. The results show that the best preparation condition of the AEAPMDS-CNF aerogel is for 10 h at 90℃ and 12wt% AEAPMDS. The prepared AEAPMDS-CNF aerogel is a mesoporous material with 3D network pore structure, light mass (ρ ≤ 0.0573 g·cm-3) and high porosity (ε>90%). Its compressive strength can reach 0.46 MPa with a high CO2 adsorption capacity of up to 1.54 mmol·g-1. It is a promising material for CO2 adsorption in the future.
A novel cellulose nanofibers(CNF) aerogels were prepared based on the spherical cellulose nanofiber gel modified with 3-(2-aminoethylamino) propylmethyldimethoxysilane (AEAPMDS) in combination by solvent displacement and freeze drying. The change of its N content was investigated under different reaction conditions. The resultant spherical nano cellulose aerogels were characterized with respect to microscopic morphology, structural characteristics, mechanical properties and CO2 adsorption properties. The results show that the best preparation condition of the AEAPMDS-CNF aerogel is for 10 h at 90℃ and 12wt% AEAPMDS. The prepared AEAPMDS-CNF aerogel is a mesoporous material with 3D network pore structure, light mass (ρ ≤ 0.0573 g·cm-3) and high porosity (ε>90%). Its compressive strength can reach 0.46 MPa with a high CO2 adsorption capacity of up to 1.54 mmol·g-1. It is a promising material for CO2 adsorption in the future.
2018, 35(11): 3189-3195.
doi: 10.13801/j.cnki.fhclxb.20180319.010
Abstract:
In order to utilize the magnetic responsiveness of Fe3O4 and the excellent photocatalytic activity of graphite carbon nitride (g-C3N4), high temperature thermal polymerization method was used to prepare g-C3N4 with urea as a precursor. The magnetic separation Fe3O4/g-C3N4 composite photocatalyst was synthesized by hydrothermal method. The obtained samples were characterized by TEM, XRD, TGA, BET and vibrating sample magnetometer (VSM) to investigate the morphology, crystalline phase, specific surface area, composition and saturation magnetization of Fe3O4/g-C3N4 composites. The adsorption and photocatalytic properties of Fe3O4/g-C3N4 composites were evaluated by the adsorption and photocatalytic degradation of dye methylene blue (MB) under simulated sunlight. The results show that the specific surface area of magnetic separation Fe3O4/g-C3N4 composites is large compared with g-C3N4, up to 71.89 m2/g. Fe3O4/g-C3N4 composites possess good magnetic, and the intensity of saturation magnetic field reaches to 18.79 emu/g, which is enough for magnetic separation and recovery. The removal rate of MB reaches to 56.54% under irradiation for 240 min. Fe3O4/g-C3N4 composites not only exhibit good adsorption and photocatalytic activity and magnetic, but also can be recovered easily by external magnetic field.
In order to utilize the magnetic responsiveness of Fe3O4 and the excellent photocatalytic activity of graphite carbon nitride (g-C3N4), high temperature thermal polymerization method was used to prepare g-C3N4 with urea as a precursor. The magnetic separation Fe3O4/g-C3N4 composite photocatalyst was synthesized by hydrothermal method. The obtained samples were characterized by TEM, XRD, TGA, BET and vibrating sample magnetometer (VSM) to investigate the morphology, crystalline phase, specific surface area, composition and saturation magnetization of Fe3O4/g-C3N4 composites. The adsorption and photocatalytic properties of Fe3O4/g-C3N4 composites were evaluated by the adsorption and photocatalytic degradation of dye methylene blue (MB) under simulated sunlight. The results show that the specific surface area of magnetic separation Fe3O4/g-C3N4 composites is large compared with g-C3N4, up to 71.89 m2/g. Fe3O4/g-C3N4 composites possess good magnetic, and the intensity of saturation magnetic field reaches to 18.79 emu/g, which is enough for magnetic separation and recovery. The removal rate of MB reaches to 56.54% under irradiation for 240 min. Fe3O4/g-C3N4 composites not only exhibit good adsorption and photocatalytic activity and magnetic, but also can be recovered easily by external magnetic field.
2018, 35(11): 3196-3204.
doi: 10.13801/j.cnki.fhclxb.20180310.002
Abstract:
Graphene oxide/organo-modified bentonite(GO/OM-Bent) composites were prepared by the synthesis of GO, Bent and cetyltrimethyl ammonium bromide (CTAB), then the composites were used to treat Cd(Ⅱ)-containing wastewater at a concentration of 10 mg·L-1. The effects of GO content in GO/OM-Bent composite, pH value, GO/OM-Bent composite dosage, reaction time, initial concentration of cadmium and coexisting ions on adsorption of Cd(Ⅱ) by GO/OM-Bent composite were investigated by batch test. The adsorption results of GO/OM-Bent composites are balanced at 120 min with the best effect on Cd(Ⅱ) adsorption under the optimal condition:the pH value is 6, the mass fraction of GO is 30wt%, the GO/OM-Bent composite dosage is 200 mg·L-1; Under the same conditions, the adsorption capacity of GO/OM-Bent composite is 12.01 mg·g-1 and 5.39 mg·g-1 higher than that of OM-Bent and GO, respectively; the pseudo-second-order kinetics model can well describe the adsorption process and the adsorption isotherm conforms to the Langmuir model. At 303 K, the maximum adsorption capacity of GO/OM-Bent composite on Cd(Ⅱ) could be reached 133.33 mg·g-1. The results of desorption test shows that the adsorption efficiency of Cd(Ⅱ) remains as high as 83.5% after 5 cycles of adsorption-desorption, indicating that GO/OM-Bent composite has good cyclic regeneration performance.
Graphene oxide/organo-modified bentonite(GO/OM-Bent) composites were prepared by the synthesis of GO, Bent and cetyltrimethyl ammonium bromide (CTAB), then the composites were used to treat Cd(Ⅱ)-containing wastewater at a concentration of 10 mg·L-1. The effects of GO content in GO/OM-Bent composite, pH value, GO/OM-Bent composite dosage, reaction time, initial concentration of cadmium and coexisting ions on adsorption of Cd(Ⅱ) by GO/OM-Bent composite were investigated by batch test. The adsorption results of GO/OM-Bent composites are balanced at 120 min with the best effect on Cd(Ⅱ) adsorption under the optimal condition:the pH value is 6, the mass fraction of GO is 30wt%, the GO/OM-Bent composite dosage is 200 mg·L-1; Under the same conditions, the adsorption capacity of GO/OM-Bent composite is 12.01 mg·g-1 and 5.39 mg·g-1 higher than that of OM-Bent and GO, respectively; the pseudo-second-order kinetics model can well describe the adsorption process and the adsorption isotherm conforms to the Langmuir model. At 303 K, the maximum adsorption capacity of GO/OM-Bent composite on Cd(Ⅱ) could be reached 133.33 mg·g-1. The results of desorption test shows that the adsorption efficiency of Cd(Ⅱ) remains as high as 83.5% after 5 cycles of adsorption-desorption, indicating that GO/OM-Bent composite has good cyclic regeneration performance.
2018, 35(11): 3205-3211.
doi: 10.13801/j.cnki.fhclxb.20180822.001
Abstract:
The high purity metal organic frameworks MIL-101 was prepared by the solvent hot method using 2-methyl imidazole instead of HF acid in this experiment. Ni/MIL101 composite was prepared from the successful load of Ni by the method of excessive impregnation and liquid phase reduction. The product structure, morphology, specific surface area and pore size and thermal stability were characterized via XRD, SEM, BET, TG, FIRT. The hydrogen diffusion coefficient and hydrogen absorption enthalpy of MIL-101 and Ni/MIL-101 composite were measured to investigate the hydrogen storage capacity. The results show that Ni/MIL-101 composite is successfully prepared by this method. The product is a metal skeleton compound with two kinds of pore structure, and the load of Ni can reduce the hydrogen absorption enthalpy of Ni/MIL-101 composite, and the hydrogen diffusion coefficient of Ni/MIL-101 composite reaches 7.6373×10-7 cm/s, which improves the hydrogen storage capacity of MIL-101.
The high purity metal organic frameworks MIL-101 was prepared by the solvent hot method using 2-methyl imidazole instead of HF acid in this experiment. Ni/MIL101 composite was prepared from the successful load of Ni by the method of excessive impregnation and liquid phase reduction. The product structure, morphology, specific surface area and pore size and thermal stability were characterized via XRD, SEM, BET, TG, FIRT. The hydrogen diffusion coefficient and hydrogen absorption enthalpy of MIL-101 and Ni/MIL-101 composite were measured to investigate the hydrogen storage capacity. The results show that Ni/MIL-101 composite is successfully prepared by this method. The product is a metal skeleton compound with two kinds of pore structure, and the load of Ni can reduce the hydrogen absorption enthalpy of Ni/MIL-101 composite, and the hydrogen diffusion coefficient of Ni/MIL-101 composite reaches 7.6373×10-7 cm/s, which improves the hydrogen storage capacity of MIL-101.
2018, 35(11): 3212-3218.
doi: 10.13801/j.cnki.fhclxb.20180302.001
Abstract:
Using Fe(NO3)39H2O, H3PO4, HNO3 as the raw materials, the semi-sphere FePO4 precursors were prepared by liquid phase crystallization method, and then the sphere LiFePO4/C composite was synthesized by high temperature solid phase method. The corrosive Al foils were characterized by SEM, metalloscope and feeler gauge. The corrosive Al foils were used as the current collector of cathode LiFePO4/C composite of Li ion battery. The result shows that the surface of corrosive Al foil have 3D dense ordered micro square porous and possessing dense tunnels in the inner and the thickness of Al foil is decreased by 14.29%.The initial discharge capacity at 0.1 C is 153 mAh·g-1 and the electrode react resistance is 51.12 Ω. LiFePO4/C composite has good rate property and cycle stability.
Using Fe(NO3)39H2O, H3PO4, HNO3 as the raw materials, the semi-sphere FePO4 precursors were prepared by liquid phase crystallization method, and then the sphere LiFePO4/C composite was synthesized by high temperature solid phase method. The corrosive Al foils were characterized by SEM, metalloscope and feeler gauge. The corrosive Al foils were used as the current collector of cathode LiFePO4/C composite of Li ion battery. The result shows that the surface of corrosive Al foil have 3D dense ordered micro square porous and possessing dense tunnels in the inner and the thickness of Al foil is decreased by 14.29%.The initial discharge capacity at 0.1 C is 153 mAh·g-1 and the electrode react resistance is 51.12 Ω. LiFePO4/C composite has good rate property and cycle stability.
2018, 35(11): 3219-3226.
doi: 10.13801/j.cnki.fhclxb.20180205.001
Abstract:
In order to improve the electrochemical performance of lithium ion battery, a porous conductive current collector was fabricated mixing multiwalled carbon nanotubes (MWCNTs) and cellulose fibers through vacuum filtration method. The cellulose fibers were used as the matrix and MWCNTs as the conductive agent. The porous conductive paper of MWCNTs/paper fiber was used as cathode current collector instead of copper foil. The hollow Si microsphere doped with MWCNTs was used as active materials. FESEM was used for characterization. The results show that active substances of hollow Si-MWCNTs are well dispersed in network of MWCNTs conductive paper, which ensures the structural stability and chemical stability at the same time. The results show excellent cyclic stability and higher specific capacity, and also reversible. The capacity of the lithium ion battery reachs 1 300 mAh/g after 30 cycles at a rate of 0.02 C. The capacity still maintain 330 mAh/g at the current density of 3 C. When the current density reduces to 0.25 C, the capacity can be restored to as high as 1 150 mAh/g.
In order to improve the electrochemical performance of lithium ion battery, a porous conductive current collector was fabricated mixing multiwalled carbon nanotubes (MWCNTs) and cellulose fibers through vacuum filtration method. The cellulose fibers were used as the matrix and MWCNTs as the conductive agent. The porous conductive paper of MWCNTs/paper fiber was used as cathode current collector instead of copper foil. The hollow Si microsphere doped with MWCNTs was used as active materials. FESEM was used for characterization. The results show that active substances of hollow Si-MWCNTs are well dispersed in network of MWCNTs conductive paper, which ensures the structural stability and chemical stability at the same time. The results show excellent cyclic stability and higher specific capacity, and also reversible. The capacity of the lithium ion battery reachs 1 300 mAh/g after 30 cycles at a rate of 0.02 C. The capacity still maintain 330 mAh/g at the current density of 3 C. When the current density reduces to 0.25 C, the capacity can be restored to as high as 1 150 mAh/g.
2018, 35(11): 3227-3234.
doi: 10.13801/j.cnki.fhclxb.20180329.003
Abstract:
MnO2 nanorods-reduced graphene composite modified glassy carbon electrode (MnO2 NRs-ErGO/GCE) was prepared for the detection of amaranth using electrochemical reduction method. The surface morphology and crystal structure of the modified materials were characterized by SEM and XRD. The electrochemical behavior of amaranth on the bare electrode, ErGO/GCE and MnO2 NRs-ErGO/GCE modified electrodes were investigated by cyclic voltammetry, respectively. The determination conditions (including pH value, accumulation potential, and accumulation time) were optimized systematically. The results show that MnO2 NRs-ErGO increases the electrochemical active area of GCE and improves the electrochemical oxidation reaction of amaranth significantly. Under the optimum detection conditions, the peak current is found to be linear with amaranth concentrations in the range from 2.0×10-8-1.0×10-5 mol/L and 1.0×10-5-4.0×10-4 mol/L with a low detection limit of 1.0×10-8 mol/L. The satisfactory results are obtained in the analysis of actual beverage samples by using the proposed modified electrode.
MnO2 nanorods-reduced graphene composite modified glassy carbon electrode (MnO2 NRs-ErGO/GCE) was prepared for the detection of amaranth using electrochemical reduction method. The surface morphology and crystal structure of the modified materials were characterized by SEM and XRD. The electrochemical behavior of amaranth on the bare electrode, ErGO/GCE and MnO2 NRs-ErGO/GCE modified electrodes were investigated by cyclic voltammetry, respectively. The determination conditions (including pH value, accumulation potential, and accumulation time) were optimized systematically. The results show that MnO2 NRs-ErGO increases the electrochemical active area of GCE and improves the electrochemical oxidation reaction of amaranth significantly. Under the optimum detection conditions, the peak current is found to be linear with amaranth concentrations in the range from 2.0×10-8-1.0×10-5 mol/L and 1.0×10-5-4.0×10-4 mol/L with a low detection limit of 1.0×10-8 mol/L. The satisfactory results are obtained in the analysis of actual beverage samples by using the proposed modified electrode.
