2019 Vol. 36, No. 1
2019, 36(1): 1-6.
doi: 10.13801/j.cnki.fhclxb.20180511.002
Abstract:
The carbon nanotubes (CNTs)/epoxy composites were fabricated via 3D-printing technology and dip coating method. Superior shielding effectiveness of 39.2 dB and conductivity of 35 S/m (2 mm of sample thickness) were achieved with only 2.86vol% CNTs loading in CNTs/epoxy composites. The absorption electromagnetic interference shielding effectiveness accounts for 98% of the total electromagnetic interference shielding effectiveness, confirming that absorption is the primary shielding mechanism rather than reflection in CNTs/epoxy composites, certifying the proposed model. It is worth noting that the flexural properties of CNTs/epoxy composites are better than those of the original 3D-printed epoxy. The research provides creative new ideas and methods for the preparation of polymer matrix composites with excellent electromagnetic shielding performance.
The carbon nanotubes (CNTs)/epoxy composites were fabricated via 3D-printing technology and dip coating method. Superior shielding effectiveness of 39.2 dB and conductivity of 35 S/m (2 mm of sample thickness) were achieved with only 2.86vol% CNTs loading in CNTs/epoxy composites. The absorption electromagnetic interference shielding effectiveness accounts for 98% of the total electromagnetic interference shielding effectiveness, confirming that absorption is the primary shielding mechanism rather than reflection in CNTs/epoxy composites, certifying the proposed model. It is worth noting that the flexural properties of CNTs/epoxy composites are better than those of the original 3D-printed epoxy. The research provides creative new ideas and methods for the preparation of polymer matrix composites with excellent electromagnetic shielding performance.
Preparation and properties of calcium alginate/polypropylene non-woven composite filtration membrane
2019, 36(1): 7-12.
doi: 10.13801/j.cnki.fhclxb.20180502.008
Abstract:
Polypropylene non-woven supported calcium alginate (CaAlg/PP) hydrogel composite filtration membranes were fabricated without porogen. The morphology, structure and thermal stability of the CaAlg/PP membranes were characterized by SEM and TG. The antiswelling property, dyes adsorption and dyes rejection properties of the CaAlg/PP membranes were researched. The results show that the antiswelling properties of CaAlg/PP membrane are greatly improved compared with free-standing CaAlg hydrogel filtration membrane. When the concentration of sodium chloride is 1 g·L-1, the flux of the CaAlg/PP membrane reaches 9.5 L(m2·h)-1 under 0.1 MPa and the rejection of brilliant blue is 98.3%. The pressure resistant performance of CaAlg/PP membrane is far better than CaAlg filtration membrane and can be reused multiple times after Ca2+ cross-linking. The adsorption rate of anionic dyes is low, reducing the CaAlg/PP membrane fouling. The CaAlg/PP membrane can be used in dye desalination with a low salt concentration.
Polypropylene non-woven supported calcium alginate (CaAlg/PP) hydrogel composite filtration membranes were fabricated without porogen. The morphology, structure and thermal stability of the CaAlg/PP membranes were characterized by SEM and TG. The antiswelling property, dyes adsorption and dyes rejection properties of the CaAlg/PP membranes were researched. The results show that the antiswelling properties of CaAlg/PP membrane are greatly improved compared with free-standing CaAlg hydrogel filtration membrane. When the concentration of sodium chloride is 1 g·L-1, the flux of the CaAlg/PP membrane reaches 9.5 L(m2·h)-1 under 0.1 MPa and the rejection of brilliant blue is 98.3%. The pressure resistant performance of CaAlg/PP membrane is far better than CaAlg filtration membrane and can be reused multiple times after Ca2+ cross-linking. The adsorption rate of anionic dyes is low, reducing the CaAlg/PP membrane fouling. The CaAlg/PP membrane can be used in dye desalination with a low salt concentration.
2019, 36(1): 13-19.
doi: 10.13801/j.cnki.fhclxb.20181112.003
Abstract:
Ni0.5Co0.5Fe2O4 ferrite nanopowders prepared by the hydro-thermal method were used to toughen cyanate ester-epoxy resin (CE-EP). The effect of Ni0.5Co0.5Fe2O4 ferrite on the curing reaction, mechanical properties and thermal stability of the CE-EP resins was studied. The XRD and SEM results indicate that the synthesized Ni0.5Co0.5Fe2O4 ferrite has good crystallinity, purity and block shape, and its particle size is about 20 nm. The performance study shows that the addition of Ni0.5Co0.5Fe2O4 ferrite has little effect on the curing reaction speed between CE and EP, and does not change the curing mechanism of the resin matrix. Compared with the pure resin system, the Ni0.5Co0.5Fe2O4 ferrite/CE-EP composites obviously improve their toughness on the basis of maintaining the glass transition temperature (Tg) of the CE-EP resins. When the Ni0.5Co0.5Fe2O4 ferrite content is 3wt%, the impact strength and the bending strength of Ni0.5Co0.5Fe2O4 ferrite/CE-EP composites reach the maximum, which are increased by 65% and 30.3% compared with the pure resin matrix, respectively. However, the thermal decomposition temperature of the Ni0.5Co0.5Fe2O4 ferrite/CE-EP composites decreases slightly, which may be due to the catalytic effect of the Ni0.5Co0.5Fe2O4 ferrite on the decomposition of the resin matrix.
Ni0.5Co0.5Fe2O4 ferrite nanopowders prepared by the hydro-thermal method were used to toughen cyanate ester-epoxy resin (CE-EP). The effect of Ni0.5Co0.5Fe2O4 ferrite on the curing reaction, mechanical properties and thermal stability of the CE-EP resins was studied. The XRD and SEM results indicate that the synthesized Ni0.5Co0.5Fe2O4 ferrite has good crystallinity, purity and block shape, and its particle size is about 20 nm. The performance study shows that the addition of Ni0.5Co0.5Fe2O4 ferrite has little effect on the curing reaction speed between CE and EP, and does not change the curing mechanism of the resin matrix. Compared with the pure resin system, the Ni0.5Co0.5Fe2O4 ferrite/CE-EP composites obviously improve their toughness on the basis of maintaining the glass transition temperature (Tg) of the CE-EP resins. When the Ni0.5Co0.5Fe2O4 ferrite content is 3wt%, the impact strength and the bending strength of Ni0.5Co0.5Fe2O4 ferrite/CE-EP composites reach the maximum, which are increased by 65% and 30.3% compared with the pure resin matrix, respectively. However, the thermal decomposition temperature of the Ni0.5Co0.5Fe2O4 ferrite/CE-EP composites decreases slightly, which may be due to the catalytic effect of the Ni0.5Co0.5Fe2O4 ferrite on the decomposition of the resin matrix.
2019, 36(1): 20-27.
doi: 10.13801/j.cnki.fhclxb.20180502.009
Abstract:
Graphene oxide (GO) was prepared by the modified Hummers method with graphite powder as the raw material. The GO/polyamic acid (PAA) precursor was synthesized by in-situ polymerization, and further imidized into GO/polyimide(PI) film by heating. The GO was characterized by XRD, Raman, FTIR and AFM, and the structure of PI films at different curing temperatures was studied. Then, the water vapor transmission rate and mechanical properties of GO/PI film were tested. The results reveal that the GO has a single layer structure with its thickness of 1.26 nm. The GO/PI composite film exhibites good water resistance performance. The water vapor transmission rate of the GO/PI composite film (thickness of the film is 50 μm) containing 0.025wt% GO is as low as 56.7 g(m2·d)-1. The mechanical properties measurements suggest that the tensile strength and the elongation at break of the 0.025wt%GO/PI composite film are 150.8 MPa and 13.5%, respectively, increasing by 18.8% and 66.7% as compared to that of PI film (126.9 MPa and 8.1%).
Graphene oxide (GO) was prepared by the modified Hummers method with graphite powder as the raw material. The GO/polyamic acid (PAA) precursor was synthesized by in-situ polymerization, and further imidized into GO/polyimide(PI) film by heating. The GO was characterized by XRD, Raman, FTIR and AFM, and the structure of PI films at different curing temperatures was studied. Then, the water vapor transmission rate and mechanical properties of GO/PI film were tested. The results reveal that the GO has a single layer structure with its thickness of 1.26 nm. The GO/PI composite film exhibites good water resistance performance. The water vapor transmission rate of the GO/PI composite film (thickness of the film is 50 μm) containing 0.025wt% GO is as low as 56.7 g(m2·d)-1. The mechanical properties measurements suggest that the tensile strength and the elongation at break of the 0.025wt%GO/PI composite film are 150.8 MPa and 13.5%, respectively, increasing by 18.8% and 66.7% as compared to that of PI film (126.9 MPa and 8.1%).
Preparation and flame retardant properties of phosphorus-boron hybrid polymer/epoxy resin composites
2019, 36(1): 28-38.
doi: 10.13801/j.cnki.fhclxb.20180404.001
Abstract:
A containing phosphorus-boron hybrid polymer (PDCP-DGB) was synthesized by step-reaction polymerization using phenyl dichlorophosphate (PDCP) and boric diglyceride (DGB) as the raw materials. A series of PDCP-DGB/epoxy resin (EP) flame retardant composites were prepared by crosslinking and curing between PDCP-DGB and EP blends. The structure of PDCP-DGB was characterized by FTIR and nuclear magnetic resonance. The PDCP-DGB/EP composites were investigated by gel permeation chromatography (GPC), TG, limit oxygen index (LOI), microscale combustion calorimeter, SEM and XPS. The results indicate that with the increase of mass fraction of PDCP-DGB, the temperature of maximum decomposition rate of PDCP-DGB/EP composite, the residual mass rate and the LOI improve, but the smoke density level, maximum smoke density, peak value of heat release rate (PHRR) and total heat release (THR) decrease. PDCP-DGB is conducive to improve the thermal stability and flame retardant properties of PDCP-DGB/EP composite and has little influence on the mechanical properties of PDCP-DGB/EP composites. When the mass fraction of PDCP-DGB reaches 15wt%, the LOI reaches 28.3%, which is 47.4% higher than that of the pure EP, the vertical burning (UL-94) reaches V-0 level, the THR and PHRR decrease by 28% and 23%, respectively, the residual mass rate increases by 5.11%. SEM images show that the carbon residue surface of PDCP-DGB/EP composites is well improved, which is dense, continuous and smooth.
A containing phosphorus-boron hybrid polymer (PDCP-DGB) was synthesized by step-reaction polymerization using phenyl dichlorophosphate (PDCP) and boric diglyceride (DGB) as the raw materials. A series of PDCP-DGB/epoxy resin (EP) flame retardant composites were prepared by crosslinking and curing between PDCP-DGB and EP blends. The structure of PDCP-DGB was characterized by FTIR and nuclear magnetic resonance. The PDCP-DGB/EP composites were investigated by gel permeation chromatography (GPC), TG, limit oxygen index (LOI), microscale combustion calorimeter, SEM and XPS. The results indicate that with the increase of mass fraction of PDCP-DGB, the temperature of maximum decomposition rate of PDCP-DGB/EP composite, the residual mass rate and the LOI improve, but the smoke density level, maximum smoke density, peak value of heat release rate (PHRR) and total heat release (THR) decrease. PDCP-DGB is conducive to improve the thermal stability and flame retardant properties of PDCP-DGB/EP composite and has little influence on the mechanical properties of PDCP-DGB/EP composites. When the mass fraction of PDCP-DGB reaches 15wt%, the LOI reaches 28.3%, which is 47.4% higher than that of the pure EP, the vertical burning (UL-94) reaches V-0 level, the THR and PHRR decrease by 28% and 23%, respectively, the residual mass rate increases by 5.11%. SEM images show that the carbon residue surface of PDCP-DGB/EP composites is well improved, which is dense, continuous and smooth.
2019, 36(1): 39-50.
doi: 10.13801/j.cnki.fhclxb.20180524.002
Abstract:
Graphene/iron phthalocyanine(G/FePc) composites were prepared by co-grinding and hot-press molding. The microstructure of G/FePc composites was examined by SEM and the interaction between G and FePc was examined by XPS. It's found that FePc is uniformly absorbed on G and G/FePc composites form layer-like structure after solidification, which improves the heat resistance and wave absorbing properties. The effect of G content on the heat resistance and electromagnetic properties of G/FePc composites was further explored by TGA and vector network analysis, and the wave absorbing properties of G/FePc composites were simulated. The results show that the heat resistance and wave absorbing properties of G/FePc composites increase with G content increasing. When the G content is 5%(mass ratio), the char yield reaches 62.2% at 1 000℃, the maximum reflectivity reaches -30.5 dB with the thickness of 3.5 mm and bandwidth of reflectivity less than -10 dB is 1.38 GHz.
Graphene/iron phthalocyanine(G/FePc) composites were prepared by co-grinding and hot-press molding. The microstructure of G/FePc composites was examined by SEM and the interaction between G and FePc was examined by XPS. It's found that FePc is uniformly absorbed on G and G/FePc composites form layer-like structure after solidification, which improves the heat resistance and wave absorbing properties. The effect of G content on the heat resistance and electromagnetic properties of G/FePc composites was further explored by TGA and vector network analysis, and the wave absorbing properties of G/FePc composites were simulated. The results show that the heat resistance and wave absorbing properties of G/FePc composites increase with G content increasing. When the G content is 5%(mass ratio), the char yield reaches 62.2% at 1 000℃, the maximum reflectivity reaches -30.5 dB with the thickness of 3.5 mm and bandwidth of reflectivity less than -10 dB is 1.38 GHz.
2019, 36(1): 51-59.
doi: 10.13801/j.cnki.fhclxb.20180404.002
Abstract:
The continuous carbon fiber reinforced polyamide 6 (CF/PA6) unidirectional prepreg of 60 mm width was prepared by a molten impregnation method. A structure of CF/PA6 composites rectangular box was then manufactured by hot stamping method. The results show that the fiber spread width shows a linear relationship with the wrap angle. The large pretension force should be avoided due to the high pulling force which will be accumulated and result in the fiber's breaking up. The high pulling speed results in pool impregnation quality. The pre-heating of CF can improve the pool impregnation quality under high pulling speed. In hot stamping, the pre-consolidation is necessary and the desirable preheating temperature and forming temperature are in the range of 260-280℃ and 130-160℃, respectively.
The continuous carbon fiber reinforced polyamide 6 (CF/PA6) unidirectional prepreg of 60 mm width was prepared by a molten impregnation method. A structure of CF/PA6 composites rectangular box was then manufactured by hot stamping method. The results show that the fiber spread width shows a linear relationship with the wrap angle. The large pretension force should be avoided due to the high pulling force which will be accumulated and result in the fiber's breaking up. The high pulling speed results in pool impregnation quality. The pre-heating of CF can improve the pool impregnation quality under high pulling speed. In hot stamping, the pre-consolidation is necessary and the desirable preheating temperature and forming temperature are in the range of 260-280℃ and 130-160℃, respectively.
2019, 36(1): 60-68.
doi: 10.13801/j.cnki.fhclxb.20180428.003
Abstract:
The self-made lignin-based charring agent with phosphorus (Lig-P) and ammonium polyphosphate (APP) were used for the preparation of flame retardant poly(lactic acid) (PLA), and organic montmorillonite (OMMT) was also incorporated into flame retardant PLA, and the synergistic effect of OMMT on the flame retardant properties of PLA was studied in detail. The flame retardancy, thermal degradation and fire performance of the Lig-P-APP-OMMT/PLA composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimetric test and TGA, respectively. The analysis results show that there is significantly synergistic effect between OMMT and Lig-P-APP for Lig-P-APP-OMMT/PLA composites, in which the LOI value of PLA increase from 27% to 32%, accompanied with the PLA passing V-0 rating in UL-94 test at 3wt% of OMMT substitution for Lig-P-APP. The peak thermal degradation rate of Lig-P-APP-OMMT/PLA flame retardant composites reduces, and its charring residue at 800℃ increases by nearly 50%. Cone calorimetry results indicate that the heat release rate of Lig-P-APP-OMMT/PLA flame retardant composites dramatically reduces, and the peak heat release rate (PHRR), the peak smoke produce rate (PSPR) and the total smoke production (TSP) decrease by 26.4%, 60% and 26.3%, respectively with the optimum loading of 3wt% OMMT. The incorporation of OMMT benefits to the formation of much more compact and more graphitic char layer during the combustion of Lig-P-APP-OMMT/PLA flame retardant composites.
The self-made lignin-based charring agent with phosphorus (Lig-P) and ammonium polyphosphate (APP) were used for the preparation of flame retardant poly(lactic acid) (PLA), and organic montmorillonite (OMMT) was also incorporated into flame retardant PLA, and the synergistic effect of OMMT on the flame retardant properties of PLA was studied in detail. The flame retardancy, thermal degradation and fire performance of the Lig-P-APP-OMMT/PLA composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimetric test and TGA, respectively. The analysis results show that there is significantly synergistic effect between OMMT and Lig-P-APP for Lig-P-APP-OMMT/PLA composites, in which the LOI value of PLA increase from 27% to 32%, accompanied with the PLA passing V-0 rating in UL-94 test at 3wt% of OMMT substitution for Lig-P-APP. The peak thermal degradation rate of Lig-P-APP-OMMT/PLA flame retardant composites reduces, and its charring residue at 800℃ increases by nearly 50%. Cone calorimetry results indicate that the heat release rate of Lig-P-APP-OMMT/PLA flame retardant composites dramatically reduces, and the peak heat release rate (PHRR), the peak smoke produce rate (PSPR) and the total smoke production (TSP) decrease by 26.4%, 60% and 26.3%, respectively with the optimum loading of 3wt% OMMT. The incorporation of OMMT benefits to the formation of much more compact and more graphitic char layer during the combustion of Lig-P-APP-OMMT/PLA flame retardant composites.
2019, 36(1): 69-76.
doi: 10.13801/j.cnki.fhclxb.20180503.001
Abstract:
A new type nanofiber separator with coaxial structure for lithium ion battery was constructed through electrospinning method. Polyether imide (PEI) was adopted as the core layer material due to its high heat-resistance and high strength, and polyvinylidene fluoride (PVDF) with excellent electrolyte affinity and interfacial stability was adopted as the shell layer material. The structure and performances of PEI-PVDF coaxial separator were investigated by SEM, TEM, TGA, electrochemical workstation, and battery test system. The results show that PEI-PVDF coaxial fiber has a clear core-shell structure. Compared with the commercial separator, it has excellent thermal stability and does not shrink after treated at 180℃ for 2 h. The liquid electrolyte absorption rate also increases greatly, and reaches up to 520%. The electrochemical stability window is up to 5.0 V. The ionic conductivity is 2.3 mS·cm-1. The lithium ion battery assembled with PEI-PVDF coaxial separator still show the specific discharge capacity of 107 mAh·g-1 at discharge current density of 8 C. In the recovery at 0.2 C rate, the specific capacity retain 95.4% of its original specific capacity. The coulombic efficiency of the batteries is 92.5% after 100 cycles of charge and discharge. The characteristics of the high rate and high heat resistance of the PEI-PVDF separator show that it is a kind of high power, high safety separator for lithium ion battery.
A new type nanofiber separator with coaxial structure for lithium ion battery was constructed through electrospinning method. Polyether imide (PEI) was adopted as the core layer material due to its high heat-resistance and high strength, and polyvinylidene fluoride (PVDF) with excellent electrolyte affinity and interfacial stability was adopted as the shell layer material. The structure and performances of PEI-PVDF coaxial separator were investigated by SEM, TEM, TGA, electrochemical workstation, and battery test system. The results show that PEI-PVDF coaxial fiber has a clear core-shell structure. Compared with the commercial separator, it has excellent thermal stability and does not shrink after treated at 180℃ for 2 h. The liquid electrolyte absorption rate also increases greatly, and reaches up to 520%. The electrochemical stability window is up to 5.0 V. The ionic conductivity is 2.3 mS·cm-1. The lithium ion battery assembled with PEI-PVDF coaxial separator still show the specific discharge capacity of 107 mAh·g-1 at discharge current density of 8 C. In the recovery at 0.2 C rate, the specific capacity retain 95.4% of its original specific capacity. The coulombic efficiency of the batteries is 92.5% after 100 cycles of charge and discharge. The characteristics of the high rate and high heat resistance of the PEI-PVDF separator show that it is a kind of high power, high safety separator for lithium ion battery.
2019, 36(1): 77-84.
doi: 10.13801/j.cnki.fhclxb.20180423.001
Abstract:
In order to improve the aspergillus niger corrosion resistance of eucalyptus/polyvinyl chloride (PVC) composites, TiO2 was added to prepare TiO2-eucalyptus/PVC composites. The TiO2-eucalyptus/PVC composites were subjected to the mold accelerated corrosion test, the accelerated corrosion conditions:the temperature was 28℃ and the humidity was 85%. The color difference, mechanical properties, water absorption performance, the functional groups, microtopography and thermal stability of TiO2-eucalyptus/PVC composites before and after corrosion were tested and analyzed. The results show that TiO2 can improve the mold corrosion resistance of eucalyptus/PVC composite. The TiO2-eucalyptus/PVC composites present less mold phase when the TiO2 adding amount is 2wt% after corrosion. The color difference and water absorption of TiO2-eucalyptus/PVC composites decrease by 69.32% and 13.33% respectively in comparison to the composites without TiO2. And the tensile strength, impact strength, bending strength and bending modulus of TiO2-eucalyptus/PVC composites increase by 31.17%, 39.44%, 40.75% and 10.99%, respectively. The 2wt%TiO2-eucalyptus/PVC composite obtained at higher thermal decomposition temperature in each stage indicates the better thermal stability. The more TiO2 content will affect the interface of eucalyptus fiber and PVC, making it to be more susceptible to mold corrosion.
In order to improve the aspergillus niger corrosion resistance of eucalyptus/polyvinyl chloride (PVC) composites, TiO2 was added to prepare TiO2-eucalyptus/PVC composites. The TiO2-eucalyptus/PVC composites were subjected to the mold accelerated corrosion test, the accelerated corrosion conditions:the temperature was 28℃ and the humidity was 85%. The color difference, mechanical properties, water absorption performance, the functional groups, microtopography and thermal stability of TiO2-eucalyptus/PVC composites before and after corrosion were tested and analyzed. The results show that TiO2 can improve the mold corrosion resistance of eucalyptus/PVC composite. The TiO2-eucalyptus/PVC composites present less mold phase when the TiO2 adding amount is 2wt% after corrosion. The color difference and water absorption of TiO2-eucalyptus/PVC composites decrease by 69.32% and 13.33% respectively in comparison to the composites without TiO2. And the tensile strength, impact strength, bending strength and bending modulus of TiO2-eucalyptus/PVC composites increase by 31.17%, 39.44%, 40.75% and 10.99%, respectively. The 2wt%TiO2-eucalyptus/PVC composite obtained at higher thermal decomposition temperature in each stage indicates the better thermal stability. The more TiO2 content will affect the interface of eucalyptus fiber and PVC, making it to be more susceptible to mold corrosion.
2019, 36(1): 85-95.
doi: 10.13801/j.cnki.fhclxb.20180417.002
Abstract:
In order to save energy consumption and time of the pre-oxidation process and optimize the performance of polyacrylonitrile(PAN) pre-oxidized fiber, PAN precursor could cyclize in advance with modification with H2O2. The unmodified and modified PAN precursor treated at different temperatures was analyzed by FTIR and XPS, et al. The results show that the modification with H2O2 aqueous solution at 60℃ induces nitrile of the PAN precursor to cyclize and terminal ring structure tautomerizes, hence it brings about imine and quasi-aromatic primary amine. With the increase of the modification temperature, the content and conjugation degree of the imine of modified PAN precursor is promoted. In the process of the simulated stabilization, quasi-aromatic primary amine of the modified PAN precursor could induce adjacent nitrile to cyclize at lower temperature. The modified PAN precursor with NH3H2O as additives experiences the same pre-oxidation process as the unmodified PAN precursor. The former can reach suited pre-oxidation degree within a short time and the radial structure of PAN pre-oxidized fiber becomes more uniform, so that the PAN pre-oxidized fiber which has higher thermostability can be obtained.
In order to save energy consumption and time of the pre-oxidation process and optimize the performance of polyacrylonitrile(PAN) pre-oxidized fiber, PAN precursor could cyclize in advance with modification with H2O2. The unmodified and modified PAN precursor treated at different temperatures was analyzed by FTIR and XPS, et al. The results show that the modification with H2O2 aqueous solution at 60℃ induces nitrile of the PAN precursor to cyclize and terminal ring structure tautomerizes, hence it brings about imine and quasi-aromatic primary amine. With the increase of the modification temperature, the content and conjugation degree of the imine of modified PAN precursor is promoted. In the process of the simulated stabilization, quasi-aromatic primary amine of the modified PAN precursor could induce adjacent nitrile to cyclize at lower temperature. The modified PAN precursor with NH3H2O as additives experiences the same pre-oxidation process as the unmodified PAN precursor. The former can reach suited pre-oxidation degree within a short time and the radial structure of PAN pre-oxidized fiber becomes more uniform, so that the PAN pre-oxidized fiber which has higher thermostability can be obtained.
2019, 36(1): 96-103.
doi: 10.13801/j.cnki.fhclxb.20180411.003
Abstract:
The rice straw fiber and acrylonitrile-butadiene-styrene(ABS) were used as the raw materials, the acticarbon, Al2O3, SiO2 were used as the modifiers, respectively, the straw fiber/ABS composites were prepared via mixing molding process, The thermogravimetric-mass spectrometry combined instrument was used to compare and analyse the volatile organic compounds(VOC) release of straw fiber/ABS composites, and the effect of VOC release from composites by several different kinds of modifiers was researched. The results show that ABS and straw fibers can release CH2O, C2H4O and C3H4O during the pyrolysis. The main source of the release of benzene and alkanes such as C6H6, C7H8 and C8H8 is ABS; the addition of activated carbon could significantly reduce the VOC release of straw fiber/ABS composites, and the total VOC release decreases by 55.5%. Al2O3 and SiO2 can obviously reduce the release content of benzene in the straw fiber/ABS composite, the content of benzene is 32.4% and 30.9%, respectively. However, metal impurities such as Fe and Cu can catalyze the generation of aldehydes, resulting in increasing VOC emissions by 11.8% and 235.7%, respectively.
The rice straw fiber and acrylonitrile-butadiene-styrene(ABS) were used as the raw materials, the acticarbon, Al2O3, SiO2 were used as the modifiers, respectively, the straw fiber/ABS composites were prepared via mixing molding process, The thermogravimetric-mass spectrometry combined instrument was used to compare and analyse the volatile organic compounds(VOC) release of straw fiber/ABS composites, and the effect of VOC release from composites by several different kinds of modifiers was researched. The results show that ABS and straw fibers can release CH2O, C2H4O and C3H4O during the pyrolysis. The main source of the release of benzene and alkanes such as C6H6, C7H8 and C8H8 is ABS; the addition of activated carbon could significantly reduce the VOC release of straw fiber/ABS composites, and the total VOC release decreases by 55.5%. Al2O3 and SiO2 can obviously reduce the release content of benzene in the straw fiber/ABS composite, the content of benzene is 32.4% and 30.9%, respectively. However, metal impurities such as Fe and Cu can catalyze the generation of aldehydes, resulting in increasing VOC emissions by 11.8% and 235.7%, respectively.
2019, 36(1): 104-113.
doi: 10.13801/j.cnki.fhclxb.20180502.002
Abstract:
In the operation of power system, the electric field in high voltage direct current cable accessories was easily distorted and even leades to insulation failure, which was caused by the conductivity of composite insulation materials mismatched. In order to solve this problem, the nano TiO2/liquid silicone rubber (LSR) composites with different components for cable accessories insulation were prepared, and the microstructure and dielectric properties were tested. The results show that nano TiO2 particles disperse uniformly in LSR matrix. With the increase of TiO2 nanoparticles doping content, the relative permittivity and dielectric loss constant of nano TiO2/LSR composites are increased, while the breakdown strength decreases. The conductivity of nano TiO2/LSR composites is approximately equal to that of cable ontology insulation crosslinked polyethylene (XLPE), when the nano TiO2 doping content is 4wt%. Moreover, the trend of the conductivity changes of the two materials is basically the same, as the electric field strength increases. The pulsed electroacoustic apparatus (PEA) test result shows that 4wt% TiO2/LSR composites accumulated space charge is the least. The doping of TiO2 nanoparticles improves the electric field dependent coefficient of conductivity of cable access-ories insulation, and it can inhibit the accumulation of space charge to some extent. It makes the composite insulation achieve a good match, which can promote the electric field distribution uniform in the direct current cables accessories composite insulation.
In the operation of power system, the electric field in high voltage direct current cable accessories was easily distorted and even leades to insulation failure, which was caused by the conductivity of composite insulation materials mismatched. In order to solve this problem, the nano TiO2/liquid silicone rubber (LSR) composites with different components for cable accessories insulation were prepared, and the microstructure and dielectric properties were tested. The results show that nano TiO2 particles disperse uniformly in LSR matrix. With the increase of TiO2 nanoparticles doping content, the relative permittivity and dielectric loss constant of nano TiO2/LSR composites are increased, while the breakdown strength decreases. The conductivity of nano TiO2/LSR composites is approximately equal to that of cable ontology insulation crosslinked polyethylene (XLPE), when the nano TiO2 doping content is 4wt%. Moreover, the trend of the conductivity changes of the two materials is basically the same, as the electric field strength increases. The pulsed electroacoustic apparatus (PEA) test result shows that 4wt% TiO2/LSR composites accumulated space charge is the least. The doping of TiO2 nanoparticles improves the electric field dependent coefficient of conductivity of cable access-ories insulation, and it can inhibit the accumulation of space charge to some extent. It makes the composite insulation achieve a good match, which can promote the electric field distribution uniform in the direct current cables accessories composite insulation.
2019, 36(1): 114-121.
doi: 10.13801/j.cnki.fhclxb.20180322.002
Abstract:
Continuous carbon fiber reinforced polyamide 6 (CF/PA6) unidirectional laminates with three different isothermal crystallization time were prepared. The tensile tests of 0° and 90°, the bending and interlaminar shear tests before and after water absorption of CF/PA6 composites were then respectively performed. The results show that the strength (and modulus) of 0° and 90° tensile, bending and interlaminar shear of CF/PA6 composites are decreased by 10%-37% (0-0.6%), 35%-46% (62%-64%), 53%-61% (16%-28%) and 5%-31%, respectively. The effect mechanism of water absorption on the properties of CF/PA6 composite is given with the help of further characterization methods of SEM and metallographic microscopy.
Continuous carbon fiber reinforced polyamide 6 (CF/PA6) unidirectional laminates with three different isothermal crystallization time were prepared. The tensile tests of 0° and 90°, the bending and interlaminar shear tests before and after water absorption of CF/PA6 composites were then respectively performed. The results show that the strength (and modulus) of 0° and 90° tensile, bending and interlaminar shear of CF/PA6 composites are decreased by 10%-37% (0-0.6%), 35%-46% (62%-64%), 53%-61% (16%-28%) and 5%-31%, respectively. The effect mechanism of water absorption on the properties of CF/PA6 composite is given with the help of further characterization methods of SEM and metallographic microscopy.
2019, 36(1): 122-132.
doi: 10.13801/j.cnki.fhclxb.20180502.003
Abstract:
Material testing system (MTS) and spilt Hopkinson pressure bar (SHPB) were employed to investigate the mechanical response and the failure modes of 2D plain laminated composites (2DWCs), 3D orthogonal woven composites (3DOWCs) and 3D braided composites (3DBCs), respectively. From the stress-strain curve results, the strain rate effect, strain rate sensitivity and energy absorption properties of the three kinds of the composites under different strain rates compression could be concluded. The damage mechanism was also studied. It is found that all kinds of composites have obvious strain rate effect. And when subjected to out-plane compressive loading, 2DWCs shows the highest stiffness, strength, and rate sensitivity, 3DBCs shows the weakest. However, in case that the strain rate is greater than 1 500 s-1, the 3DBCs have the highest energy absorption capacity, while 2DWCs has the lowest. 2DWCs and 3DOWCs happens shear fracture failure, the failure mode of 3DBCs is mainly in the form of collapse. When loaded with in-plane compression, 2DWCs has the maximum compressive stiffness and the minimum energy absorption capacity, and delamination occurs. 3DOWCs has the highest compressive strength. 3DBCs has the maximum failure strain and strain rate sensitivity, and the failure form is the loaded face expansion damage.
Material testing system (MTS) and spilt Hopkinson pressure bar (SHPB) were employed to investigate the mechanical response and the failure modes of 2D plain laminated composites (2DWCs), 3D orthogonal woven composites (3DOWCs) and 3D braided composites (3DBCs), respectively. From the stress-strain curve results, the strain rate effect, strain rate sensitivity and energy absorption properties of the three kinds of the composites under different strain rates compression could be concluded. The damage mechanism was also studied. It is found that all kinds of composites have obvious strain rate effect. And when subjected to out-plane compressive loading, 2DWCs shows the highest stiffness, strength, and rate sensitivity, 3DBCs shows the weakest. However, in case that the strain rate is greater than 1 500 s-1, the 3DBCs have the highest energy absorption capacity, while 2DWCs has the lowest. 2DWCs and 3DOWCs happens shear fracture failure, the failure mode of 3DBCs is mainly in the form of collapse. When loaded with in-plane compression, 2DWCs has the maximum compressive stiffness and the minimum energy absorption capacity, and delamination occurs. 3DOWCs has the highest compressive strength. 3DBCs has the maximum failure strain and strain rate sensitivity, and the failure form is the loaded face expansion damage.
2019, 36(1): 133-138.
doi: 10.13801/j.cnki.fhclxb.20180726.004
Abstract:
Low-density ablative thermal protection material is a key candidate material for spacecraft thermal protection systems. Its excellent high-temperature mechanical properties are the key to structural integrity of thermal protection structures under aerodynamic thermal loading. In this paper, the low-density ablation thermal protection composite of multiphase fibers reinforced phenolic resin composite was used to carry out compression experiments at high temperatures to obtain the variation law of the compressive strength with temperature. The influence of force load, pyrolysis and oxidation reaction on compressive strength was analysised by thermogravity and SEM. Two kinds toughening mechanisms of soft phase carbon layer bridging and fiber debonding and pull-out are revealed, which provides experimental data support for the application of the composite in thermal protection systems.
Low-density ablative thermal protection material is a key candidate material for spacecraft thermal protection systems. Its excellent high-temperature mechanical properties are the key to structural integrity of thermal protection structures under aerodynamic thermal loading. In this paper, the low-density ablation thermal protection composite of multiphase fibers reinforced phenolic resin composite was used to carry out compression experiments at high temperatures to obtain the variation law of the compressive strength with temperature. The influence of force load, pyrolysis and oxidation reaction on compressive strength was analysised by thermogravity and SEM. Two kinds toughening mechanisms of soft phase carbon layer bridging and fiber debonding and pull-out are revealed, which provides experimental data support for the application of the composite in thermal protection systems.
2019, 36(1): 139-146.
doi: 10.13801/j.cnki.fhclxb.20180420.002
Abstract:
The surface porous Ti-hydroxyapatite(HA)/Ti-Ag gradient biocomposites were prepared by spark plasma sintering technology. The effects of different HA contents on the microstructure, interface bonding, surface pore characteristics, mechanical properties and in vitro biological activity of the surface porous Ti-HA/Ti-Ag composites were investigated. The results show that the matrix alloys of the composites are mainly consisted of α-Ti and Ti2Ag phases. The surface porous layers are mainly consisted of α-Ti, HA phases and a few reaction phases of CaO, CaTiO3, Ti5P3. A stable metallurgical bonding on matrix alloys and surface porous layers of the composites could be observed. With increasing of HA contents, the reaction phases of surface porous layers are increased and the bonding degree of interface is deterioration. The average porosity and pore size of surface layers are appeared in a slowly increasing trend. As a result, the average compressive strength and compressive elastic modulus of the surface porous Ti-HA/Ti-Ag composites are decreased. Therefore, the mechanical properties of the composites are reduced at higher HA contents. In vitro bioactivity tests show that lots of bone-like apatite are deposited on the surface porous Ti-HA/Ti-Ag gradient biocomposites after soaking in SBF for 7 days and the apatite formation ability is significant enhanced with increasing of HA contents.
The surface porous Ti-hydroxyapatite(HA)/Ti-Ag gradient biocomposites were prepared by spark plasma sintering technology. The effects of different HA contents on the microstructure, interface bonding, surface pore characteristics, mechanical properties and in vitro biological activity of the surface porous Ti-HA/Ti-Ag composites were investigated. The results show that the matrix alloys of the composites are mainly consisted of α-Ti and Ti2Ag phases. The surface porous layers are mainly consisted of α-Ti, HA phases and a few reaction phases of CaO, CaTiO3, Ti5P3. A stable metallurgical bonding on matrix alloys and surface porous layers of the composites could be observed. With increasing of HA contents, the reaction phases of surface porous layers are increased and the bonding degree of interface is deterioration. The average porosity and pore size of surface layers are appeared in a slowly increasing trend. As a result, the average compressive strength and compressive elastic modulus of the surface porous Ti-HA/Ti-Ag composites are decreased. Therefore, the mechanical properties of the composites are reduced at higher HA contents. In vitro bioactivity tests show that lots of bone-like apatite are deposited on the surface porous Ti-HA/Ti-Ag gradient biocomposites after soaking in SBF for 7 days and the apatite formation ability is significant enhanced with increasing of HA contents.
2019, 36(1): 147-158.
doi: 10.13801/j.cnki.fhclxb.20180510.002
Abstract:
The heterogeneous catalyst of magnetism is low cost, little hazardous, high efficient and easy separation from aqueous solutions. The Fe3O4/MnO2 magnetic bimetal oxide catalyst prepared via hydrothermal method shows a better performance in activating 2KHSO5·KHSO4·K2SO4 for Rhodamine B (Rh B) degradation in aqueous solutions. Different quality of magnetic microspheres Fe3O4 and nanowire MnO2 loaded together, synthesizing Fe3O4/MnO2 catalyst with three different Fe3O4:MnO2 mass ratios, which are 1:3, 2:3, 1:1. The characterizations of XRD, SEM and TEM show that two metallic oxide are loaded together. Compared with the catalytic performances of three Fe3O4/MnO2 magnetic bimetal oxide catalysts according to activate 2KHSO5·KHSO4·K2SO4 for Rh B degradation in aqueous solutions, founding the Fe3O4/MnO2(2:3) catalyst has the best catalytic activity. According to investigating the effects of reaction parameters on Rh B degradation on Fe3O4/MnO2(2:3) catalyst, the best conditions of Rh B degradation in aqueous solutions are 10 mg/L Rh B, 0.4 g/L Fe3O4/MnO2, 0.3 g/L 2KHSO5·KHSO4·K2SO4 and pH=8. After three cyclic utilizations, the 2:3 Fe3O4/MnO2 magnetic bimetal oxide catalyst still have a good performance. SO4- plays an important role in degrading Rh B in aqueous solutions.
The heterogeneous catalyst of magnetism is low cost, little hazardous, high efficient and easy separation from aqueous solutions. The Fe3O4/MnO2 magnetic bimetal oxide catalyst prepared via hydrothermal method shows a better performance in activating 2KHSO5·KHSO4·K2SO4 for Rhodamine B (Rh B) degradation in aqueous solutions. Different quality of magnetic microspheres Fe3O4 and nanowire MnO2 loaded together, synthesizing Fe3O4/MnO2 catalyst with three different Fe3O4:MnO2 mass ratios, which are 1:3, 2:3, 1:1. The characterizations of XRD, SEM and TEM show that two metallic oxide are loaded together. Compared with the catalytic performances of three Fe3O4/MnO2 magnetic bimetal oxide catalysts according to activate 2KHSO5·KHSO4·K2SO4 for Rh B degradation in aqueous solutions, founding the Fe3O4/MnO2(2:3) catalyst has the best catalytic activity. According to investigating the effects of reaction parameters on Rh B degradation on Fe3O4/MnO2(2:3) catalyst, the best conditions of Rh B degradation in aqueous solutions are 10 mg/L Rh B, 0.4 g/L Fe3O4/MnO2, 0.3 g/L 2KHSO5·KHSO4·K2SO4 and pH=8. After three cyclic utilizations, the 2:3 Fe3O4/MnO2 magnetic bimetal oxide catalyst still have a good performance. SO4- plays an important role in degrading Rh B in aqueous solutions.
2019, 36(1): 159-166.
doi: 10.13801/j.cnki.fhclxb.20180613.003
Abstract:
The short carbon fiber (CFs) reinforced AZ91 Mg matrix composites with different CFs volume fractions (10vol%, 15vol%, 20vol%) were fabricated by stir-casting method. The cast CFs/AZ91 composites were extruded into bars with three different extrusion ratios at 250℃ and 350℃, respectively. During the hot extrusion, grains of the AZ91 matrix are refined due to the dynamic recrystallizaiton while the CFs distribute parallel to the extrusion direction. With increasing of the extrusion temperature and extrusion ratio, the porosity ratio of the CFs/AZ91 composites is reduced effectively and the recrystalled grains grow up accompanied by the improvement of the microstructure homogeneity. The tensile properties of CFs/AZ91 composites are improved due to the improved microstructure whereas the fiber fractures obviously during extrusion, which will restrict the further improvement of the mechanical properties. The CFs/AZ91 composite extruded with small extrusion ratio at lower temperature has better damping capabilities than those of the composites extruded with high extrusion ratio and higher temperature.
The short carbon fiber (CFs) reinforced AZ91 Mg matrix composites with different CFs volume fractions (10vol%, 15vol%, 20vol%) were fabricated by stir-casting method. The cast CFs/AZ91 composites were extruded into bars with three different extrusion ratios at 250℃ and 350℃, respectively. During the hot extrusion, grains of the AZ91 matrix are refined due to the dynamic recrystallizaiton while the CFs distribute parallel to the extrusion direction. With increasing of the extrusion temperature and extrusion ratio, the porosity ratio of the CFs/AZ91 composites is reduced effectively and the recrystalled grains grow up accompanied by the improvement of the microstructure homogeneity. The tensile properties of CFs/AZ91 composites are improved due to the improved microstructure whereas the fiber fractures obviously during extrusion, which will restrict the further improvement of the mechanical properties. The CFs/AZ91 composite extruded with small extrusion ratio at lower temperature has better damping capabilities than those of the composites extruded with high extrusion ratio and higher temperature.
2019, 36(1): 167-177.
doi: 10.13801/j.cnki.fhclxb.20180511.001
Abstract:
An electron beam was applied to remelt TiC/Ti composite coating prepared by mechanical alloying (MA) method. The microstructure and wear resistance of the coatings were analyzed after electron beam remelting with different scanning velocities. The results show that when the scanning velocity is between 5 mm/s and 15 mm/s, the hardness and wear resistance of TiC/Ti composite coatings are significantly improved due to elimination of the pores and cracks through remelting process. Remelting defects appear inside the coating when the scanning velocity is too fast (20 mm/s). With the increase of scanning velocity from 5 mm/s to 15 mm/s, TiC phase in the TiC/Ti composite coating changes from coarse dendritic crystals to short rod-like and granular crystals gradually, enhancing the dispersion strengthening effect and solid solution strengthening effect. The hardness of TiC/Ti composite coatings increase from HV 554 (before remelting) to HV 783, and the wear rate of the coating decreases from 5.93×10-4 mm3(N·m)-1 to 1.75×10-4 mm3(N·m)-1 with the increase of scanning velocity. The remelted TiC/Ti composite coating reaches the best performance at the scanning velocity of 15 mm/s.
An electron beam was applied to remelt TiC/Ti composite coating prepared by mechanical alloying (MA) method. The microstructure and wear resistance of the coatings were analyzed after electron beam remelting with different scanning velocities. The results show that when the scanning velocity is between 5 mm/s and 15 mm/s, the hardness and wear resistance of TiC/Ti composite coatings are significantly improved due to elimination of the pores and cracks through remelting process. Remelting defects appear inside the coating when the scanning velocity is too fast (20 mm/s). With the increase of scanning velocity from 5 mm/s to 15 mm/s, TiC phase in the TiC/Ti composite coating changes from coarse dendritic crystals to short rod-like and granular crystals gradually, enhancing the dispersion strengthening effect and solid solution strengthening effect. The hardness of TiC/Ti composite coatings increase from HV 554 (before remelting) to HV 783, and the wear rate of the coating decreases from 5.93×10-4 mm3(N·m)-1 to 1.75×10-4 mm3(N·m)-1 with the increase of scanning velocity. The remelted TiC/Ti composite coating reaches the best performance at the scanning velocity of 15 mm/s.
2019, 36(1): 178-185.
doi: 10.13801/j.cnki.fhclxb.20180606.001
Abstract:
Mg/ZK60 laminated composites were fabricated by accumulative roll-bonding at 300℃ using the pure Mg and ZK60 alloy. After the bonding rolling process, grains of the Mg layers and ZK60 layers are refined obviously. The grain size decreases slightly and the microstructure becomes more homogeneous with increasing of accumulative roll-bonding cycles. The thicknesses of both Mg layer and ZK60 layer decrease gradually with increasing of the accumulative roll-bonding(ARB) cycles. After two ARB cycles, an obvious wavy structure can be observed in the laminated Mg/ZK60 composite and both the Mg layer and ZK60 layer show typical basal plane texture with the {0001} plane slightly incline to rolling direction. The ultimate tensile strength and yield strength locate between the pure Mg and ZK60 alloy sheets. As similar as the tensile properties, the damping capability of Mg/ZK60 laminated composite is between Mg and ZK60 while the composite having similar damping behavior as that of ZK60 sheet at elevated temperature.
Mg/ZK60 laminated composites were fabricated by accumulative roll-bonding at 300℃ using the pure Mg and ZK60 alloy. After the bonding rolling process, grains of the Mg layers and ZK60 layers are refined obviously. The grain size decreases slightly and the microstructure becomes more homogeneous with increasing of accumulative roll-bonding cycles. The thicknesses of both Mg layer and ZK60 layer decrease gradually with increasing of the accumulative roll-bonding(ARB) cycles. After two ARB cycles, an obvious wavy structure can be observed in the laminated Mg/ZK60 composite and both the Mg layer and ZK60 layer show typical basal plane texture with the {0001} plane slightly incline to rolling direction. The ultimate tensile strength and yield strength locate between the pure Mg and ZK60 alloy sheets. As similar as the tensile properties, the damping capability of Mg/ZK60 laminated composite is between Mg and ZK60 while the composite having similar damping behavior as that of ZK60 sheet at elevated temperature.
2019, 36(1): 186-191.
doi: 10.13801/j.cnki.fhclxb.20180428.004
Abstract:
Polyimide modified C/C (C/C-PI) composites were fabricated by needling technology, chemical vapor infiltration (CVI), vacuum impregnation and curing process. The flexural properties, heat conducting properties and thermal expansion properties of C/C-PI composites were investigated. The results indicate that C/C-PI composites show a better flexural strength of 120.75 MPa in XY direction and 40.33 MPa in Z direction which are 17.92% and 20.57% higher than C/C composite. The thermal conductivities of C/C-PI composites do not change significantly with temperature, and reach the maximum values of 29.88 W(m·℃)-1 in XY direction and 9.93 W(m·℃)-1 in Z direction, which are 47.02% and 56.12% lower than C/C composites, respectively. As the test temperature continues to rise, the thermal conductivities of C/C-PI and C/C composites are decreasing gradually. The coefficients of linear expansion of C/C-PI composites increase linearly with the increase of temperature and the values maintain under 4×10-6 K-1. In particularly, C/C-PI composites have a lower linear expansion coefficient in XY direction in comparison with Z direction, which can meet the requirement of dimension stability of thermal structure parts.
Polyimide modified C/C (C/C-PI) composites were fabricated by needling technology, chemical vapor infiltration (CVI), vacuum impregnation and curing process. The flexural properties, heat conducting properties and thermal expansion properties of C/C-PI composites were investigated. The results indicate that C/C-PI composites show a better flexural strength of 120.75 MPa in XY direction and 40.33 MPa in Z direction which are 17.92% and 20.57% higher than C/C composite. The thermal conductivities of C/C-PI composites do not change significantly with temperature, and reach the maximum values of 29.88 W(m·℃)-1 in XY direction and 9.93 W(m·℃)-1 in Z direction, which are 47.02% and 56.12% lower than C/C composites, respectively. As the test temperature continues to rise, the thermal conductivities of C/C-PI and C/C composites are decreasing gradually. The coefficients of linear expansion of C/C-PI composites increase linearly with the increase of temperature and the values maintain under 4×10-6 K-1. In particularly, C/C-PI composites have a lower linear expansion coefficient in XY direction in comparison with Z direction, which can meet the requirement of dimension stability of thermal structure parts.
2019, 36(1): 192-199.
doi: 10.13801/j.cnki.fhclxb.20180509.002
Abstract:
Acrylic acid functionalized nano graphene oxide (FAGO)/acrylate composite emulsion was prepared by seed emulsion polymerization via using sodium allyl sulfonate (ALS) as polymerizable emulsifier. The structure of GO and FAGO were confirmed by FTIR and XRD, the morphology of GO, FAGO and nano FAGO/acrylate composite emulsions were observed by SEM and TEM. The results show that the carboxyl group on acrylic acid reacts with GO hydroxyl to form ester bond. The edge of FAGO is distorted and has more local folds, the system of irregularities increase significantly compared to GO. And the nano FAGO/acrylate composite latex particles are regularly spherical. The nano particle size potential analyzer test results show that the nano FAGO/acrylate composite emulsion size is uniform, well-disperse. With the increases of the amount of ALS, the particle size of the latex particles gradually decreases, its dispersion index (PDI) first decreases and then increases, the corresponding Zeta potential gradually increases, the viscosity of the emulsion gradually increases, and the water resistance of latex film becomes worse. When the amount of ALS is 0.8wt%, the nano FAGO/acrylate composite emulsion obtains the best overall performance.
Acrylic acid functionalized nano graphene oxide (FAGO)/acrylate composite emulsion was prepared by seed emulsion polymerization via using sodium allyl sulfonate (ALS) as polymerizable emulsifier. The structure of GO and FAGO were confirmed by FTIR and XRD, the morphology of GO, FAGO and nano FAGO/acrylate composite emulsions were observed by SEM and TEM. The results show that the carboxyl group on acrylic acid reacts with GO hydroxyl to form ester bond. The edge of FAGO is distorted and has more local folds, the system of irregularities increase significantly compared to GO. And the nano FAGO/acrylate composite latex particles are regularly spherical. The nano particle size potential analyzer test results show that the nano FAGO/acrylate composite emulsion size is uniform, well-disperse. With the increases of the amount of ALS, the particle size of the latex particles gradually decreases, its dispersion index (PDI) first decreases and then increases, the corresponding Zeta potential gradually increases, the viscosity of the emulsion gradually increases, and the water resistance of latex film becomes worse. When the amount of ALS is 0.8wt%, the nano FAGO/acrylate composite emulsion obtains the best overall performance.
2019, 36(1): 200-206.
doi: 10.13801/j.cnki.fhclxb.20180420.001
Abstract:
The photocatalysts of TiO2-ZnO composite hollow microspheres were obtained by using Ti(SO4)2 and Zn(NO3)2 as raw materials through hydrothermal method. The structures and properties of as-prepared TiO2-ZnO samples were characterized by FTIR, XRD, SEM, UV-Vis diffuse reflection spectrum (UV-Vis DRS), XPS and N2 adsorption-desorption analysis. Methylene blue (MB), as a photocatalytic degradation target, was used to evaluate the photocatalytic performance of the prepared photocatalysts. The results show that the prepared TiO2-ZnO photocatalyst has a hollow microsphere structure with a particle size of 1-2 μm and a specific surface area of 30.46 m2/g. The light absorption ability of ZnO is improved by the addition of TiO2 and reduces the electron hole recombination rate effectively. Under high pressure Hg lamp irradiation, the photocatalytic activity of TiO2-ZnO composite hollow microspheres is higher than that of pure ZnO, and the TiO2-ZnO sample with Zn(NO3)2:Ti(SO4)2 molar ratio of 1:0.7 has the best photocatalytic activity among all the samples. The degradation rate of MB can reach 95.8% in 60 min, and the photocatalytic degradation rate of TiO2-ZnO composite hollow microspheres is 4.3 times that of ZnO.
The photocatalysts of TiO2-ZnO composite hollow microspheres were obtained by using Ti(SO4)2 and Zn(NO3)2 as raw materials through hydrothermal method. The structures and properties of as-prepared TiO2-ZnO samples were characterized by FTIR, XRD, SEM, UV-Vis diffuse reflection spectrum (UV-Vis DRS), XPS and N2 adsorption-desorption analysis. Methylene blue (MB), as a photocatalytic degradation target, was used to evaluate the photocatalytic performance of the prepared photocatalysts. The results show that the prepared TiO2-ZnO photocatalyst has a hollow microsphere structure with a particle size of 1-2 μm and a specific surface area of 30.46 m2/g. The light absorption ability of ZnO is improved by the addition of TiO2 and reduces the electron hole recombination rate effectively. Under high pressure Hg lamp irradiation, the photocatalytic activity of TiO2-ZnO composite hollow microspheres is higher than that of pure ZnO, and the TiO2-ZnO sample with Zn(NO3)2:Ti(SO4)2 molar ratio of 1:0.7 has the best photocatalytic activity among all the samples. The degradation rate of MB can reach 95.8% in 60 min, and the photocatalytic degradation rate of TiO2-ZnO composite hollow microspheres is 4.3 times that of ZnO.
2019, 36(1): 207-212.
doi: 10.13801/j.cnki.fhclxb.20180509.001
Abstract:
The ZnS/reduced graphene oxide (ZnS/RGO) composites were synthesized via a one-pot hydrothermal synthesis. The effects of solvent (ethanol, water) on the morphology and structure of ZnS/RGO composites were analyzed by XRD, FTIR, Raman and SEM. The results show that small ZnS particles uniformly disperse on the graphene sheet when using ethanol as the solvent during the formation of ZnS nanoparticles and the reduction of graphene oxide (GO) occur simultaneously. The photocatalytic activity of the prepared ZnS/RGO composite was examined by the degradation of Methylene blue (MB). The experimental results suggest that the designed ZnS/RGO composite possess superior photocatalytic activity, which is 3.7 fold higher reaction rates for MB degradation than that of the pure ZnS nanoparticles. Graphene, as a good electron collector and transporter to reduce the photoinduced electron-hole pair recombination, can greatly improve the photocatalytic activity of ZnS/RGO composites.
The ZnS/reduced graphene oxide (ZnS/RGO) composites were synthesized via a one-pot hydrothermal synthesis. The effects of solvent (ethanol, water) on the morphology and structure of ZnS/RGO composites were analyzed by XRD, FTIR, Raman and SEM. The results show that small ZnS particles uniformly disperse on the graphene sheet when using ethanol as the solvent during the formation of ZnS nanoparticles and the reduction of graphene oxide (GO) occur simultaneously. The photocatalytic activity of the prepared ZnS/RGO composite was examined by the degradation of Methylene blue (MB). The experimental results suggest that the designed ZnS/RGO composite possess superior photocatalytic activity, which is 3.7 fold higher reaction rates for MB degradation than that of the pure ZnS nanoparticles. Graphene, as a good electron collector and transporter to reduce the photoinduced electron-hole pair recombination, can greatly improve the photocatalytic activity of ZnS/RGO composites.
2019, 36(1): 213-221.
doi: 10.13801/j.cnki.fhclxb.20180503.002
Abstract:
Magnetic CuFe2O4/cellulose nano crystals (CuFe2O4/CNC) composite was presented via a facile one-step solvothermal method. The catalytic reduction of 4-nitrophenol (4-NP) was tested with the addition of NaBH4. The results show that the prepared superparamagnetic CuFe2O4/CNC composite is a cubic spinel crystal structure with the nano particle size of 10 nm, presenting the saturation magnetization of 33.15 emu·g-1. Compared with CuFe2O4 nano particles, the CuFe2O4/CNC composite shows a higher specific surface area of 89.9 m2·g-1 (the specific surface area of CuFe2O4 nano particles is 53.9 m2·g-1). The CNC helps to improve the monodispersity of CuFe2O4 nano particles and absorbs 4-NP to facilitate the mass transfer rate positively. The CuFe2O4/CNC composite is conducted to catalytic reduction of 4-NP. The dynamic kinetics of the catalytic reduction is the first order process. When 0.2 g CNC is added, CuFe2O4/CNC composite can catalyze the reduction of 4-NP (100 μL, 0.005 mol·L-1) within 25 s, showing a high catalytic activity. The conversion rate of 4-NP can still reach 90% even after 5 cycles.
Magnetic CuFe2O4/cellulose nano crystals (CuFe2O4/CNC) composite was presented via a facile one-step solvothermal method. The catalytic reduction of 4-nitrophenol (4-NP) was tested with the addition of NaBH4. The results show that the prepared superparamagnetic CuFe2O4/CNC composite is a cubic spinel crystal structure with the nano particle size of 10 nm, presenting the saturation magnetization of 33.15 emu·g-1. Compared with CuFe2O4 nano particles, the CuFe2O4/CNC composite shows a higher specific surface area of 89.9 m2·g-1 (the specific surface area of CuFe2O4 nano particles is 53.9 m2·g-1). The CNC helps to improve the monodispersity of CuFe2O4 nano particles and absorbs 4-NP to facilitate the mass transfer rate positively. The CuFe2O4/CNC composite is conducted to catalytic reduction of 4-NP. The dynamic kinetics of the catalytic reduction is the first order process. When 0.2 g CNC is added, CuFe2O4/CNC composite can catalyze the reduction of 4-NP (100 μL, 0.005 mol·L-1) within 25 s, showing a high catalytic activity. The conversion rate of 4-NP can still reach 90% even after 5 cycles.
2019, 36(1): 222-233.
doi: 10.13801/j.cnki.fhclxb.20180412.002
Abstract:
A series Fe-modified mesoporous SiO2 (Fe-SiO2) composites were successfully synthesized via one-step method. Fe species can be co-precipitated with the siliceous species in the mildly acidic aqueous solutions that contain the template and aluminum chloride. The structure, morphology and chemical composition of Fe-SiO2 composites were characterized by XRD, N2 physisorption, FTIR, UV-vis, SEM and EDS techniques. The obtained mesoporous Fe-SiO2 composites was then used to adsorb and synergetic catalytic degrade organic methylene blue (MB) from wastewater. The effects of the initial Fe content in the reaction solution on the structure and property of Fe-SiO2 composites were thoroughly investigated. The results show that the mesoporous Fe-SiO2 synthesized with relatively low Fe content (rFe:Si ≤ 0.05) has a well-ordered mesostructure and large surface area (860-889 m2·g-1), and Fe species are highly dispersed in the framework of the SiO2. At high Fe content (rFe:Si=0.1), the obtained mesoporous Fe-SiO2 has a reduced surface areas of 526 m2·g-1, and Fe species are existing in the matrix of SiO2 as the both framework and extra-framework forms. All of the mesoporous Fe-SiO2 composites show high adsorption capacities and the superior heterogeneous Fenton-like catalytic activities for the removal of MB from aqueous solutions. Among them, the Fe-SiO2 sample synthesized with the rFe:Si of 0.05 presents the best performance. It can remove 213 mgg-1 of high concentrated MB (250 mg·L-1) by adsorption and synergetic catalytic degradation.
A series Fe-modified mesoporous SiO2 (Fe-SiO2) composites were successfully synthesized via one-step method. Fe species can be co-precipitated with the siliceous species in the mildly acidic aqueous solutions that contain the template and aluminum chloride. The structure, morphology and chemical composition of Fe-SiO2 composites were characterized by XRD, N2 physisorption, FTIR, UV-vis, SEM and EDS techniques. The obtained mesoporous Fe-SiO2 composites was then used to adsorb and synergetic catalytic degrade organic methylene blue (MB) from wastewater. The effects of the initial Fe content in the reaction solution on the structure and property of Fe-SiO2 composites were thoroughly investigated. The results show that the mesoporous Fe-SiO2 synthesized with relatively low Fe content (rFe:Si ≤ 0.05) has a well-ordered mesostructure and large surface area (860-889 m2·g-1), and Fe species are highly dispersed in the framework of the SiO2. At high Fe content (rFe:Si=0.1), the obtained mesoporous Fe-SiO2 has a reduced surface areas of 526 m2·g-1, and Fe species are existing in the matrix of SiO2 as the both framework and extra-framework forms. All of the mesoporous Fe-SiO2 composites show high adsorption capacities and the superior heterogeneous Fenton-like catalytic activities for the removal of MB from aqueous solutions. Among them, the Fe-SiO2 sample synthesized with the rFe:Si of 0.05 presents the best performance. It can remove 213 mgg-1 of high concentrated MB (250 mg·L-1) by adsorption and synergetic catalytic degradation.
2019, 36(1): 234-244.
doi: 10.13801/j.cnki.fhclxb.20180530.004
Abstract:
A Fe3O4@ion imprinted poly(Styrene-3-(2-amino triethylenetetramine)-2-hydroxypropyl methacrylate-divinylbenzene) (Fe3O4@ⅡP(St-HPMA-DVB)) magnetic composite was synthesized via ultrasonic assisted suspension polymerization with perchlorate (ClO4-) as the ion imprinting template. The Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite was characterized by TEM, vibrating sample magnetometer (VSM), TGA, XRD, elemental analysis (EA). The effect of the usage amount of crosslinking agent DVB while preparation on the structure and performance of Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite was investigated. The results show that the Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite has an average size of 500-2 000 nm, which increases with the increase of the amount of DVB. The saturation magnetization intensity is 9.77-12.78 emu/g, which decreases with the increase of the amount of DVB. The addition of DVB is beneficial to the formation and stability of the ion imprinted cavity of Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite. The effects of solution pH value, initial concentration of ClO4-, and adsorption time on the adsorption properties of ClO4- in aqueous solutions were investigated. The results show that the adsorption capability is affected significantly by solution pH value and reaches the maximum at pH=3.0. The best adsorption capacity and selectivity of Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite to ClO4- can be obtained when the usage amount of DVB is 0.5 g for synthesis. The adsorption mechanisms may be including both ion exchange and electrostatic interaction. The isothermal adsorption curves mainly obey the Langmuir mode with the maximum adsorption capacity (qm, c=76.9-111.1 mg/g) much higher than that of none-ion imprinted polymer magnetic material Fe3O4@non-ion imprinted poly(NIP)(St-HPMA-DVB) magnetic composite (qm, c=62.5 mg/g). The adsorption kinetic studies show that the adsorption processes reach the equilibrium within 10 min and the kinetic data are well fitted to the pseudo-second-order model. There is almost no interference by the coexisting components in water for the adsorption of ClO4-, with imprinting factor α at 1.8, and selectivity factor β lager than 5.8 for several kinds of common co-existing anions, respectively. The Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite is an ideal candidate for adsorption and recycle ClO4- from aqueous solution.
A Fe3O4@ion imprinted poly(Styrene-3-(2-amino triethylenetetramine)-2-hydroxypropyl methacrylate-divinylbenzene) (Fe3O4@ⅡP(St-HPMA-DVB)) magnetic composite was synthesized via ultrasonic assisted suspension polymerization with perchlorate (ClO4-) as the ion imprinting template. The Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite was characterized by TEM, vibrating sample magnetometer (VSM), TGA, XRD, elemental analysis (EA). The effect of the usage amount of crosslinking agent DVB while preparation on the structure and performance of Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite was investigated. The results show that the Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite has an average size of 500-2 000 nm, which increases with the increase of the amount of DVB. The saturation magnetization intensity is 9.77-12.78 emu/g, which decreases with the increase of the amount of DVB. The addition of DVB is beneficial to the formation and stability of the ion imprinted cavity of Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite. The effects of solution pH value, initial concentration of ClO4-, and adsorption time on the adsorption properties of ClO4- in aqueous solutions were investigated. The results show that the adsorption capability is affected significantly by solution pH value and reaches the maximum at pH=3.0. The best adsorption capacity and selectivity of Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite to ClO4- can be obtained when the usage amount of DVB is 0.5 g for synthesis. The adsorption mechanisms may be including both ion exchange and electrostatic interaction. The isothermal adsorption curves mainly obey the Langmuir mode with the maximum adsorption capacity (qm, c=76.9-111.1 mg/g) much higher than that of none-ion imprinted polymer magnetic material Fe3O4@non-ion imprinted poly(NIP)(St-HPMA-DVB) magnetic composite (qm, c=62.5 mg/g). The adsorption kinetic studies show that the adsorption processes reach the equilibrium within 10 min and the kinetic data are well fitted to the pseudo-second-order model. There is almost no interference by the coexisting components in water for the adsorption of ClO4-, with imprinting factor α at 1.8, and selectivity factor β lager than 5.8 for several kinds of common co-existing anions, respectively. The Fe3O4@ⅡP(St-HPMA-DVB) magnetic composite is an ideal candidate for adsorption and recycle ClO4- from aqueous solution.
2019, 36(1): 245-253.
doi: 10.13801/j.cnki.fhclxb.20180417.001
Abstract:
The applicabilities of two high-strength synthetic fibers for engineered fiber/cement composites were researched, with hydrophilic aramid fiber and hydrophobic ultra-high molecular weight polyethylene (UHMWPE) fiber. The results show that engineered aramid fiber/cement composites have no strain-hardening ability and present single crack failure pattern under uniaxial tensile load, and engineered UHMWPE fiber/cement composites show strain-hardening ability and multi cracking pattern. The UHMWPE fiber is more suitable for fiber/cement producing compared with aramid fiber. With the decrease of matrix water-to-binder ratio, the tensile strength of engineered UHMWPE fiber/cement composites increases but the strain-hardening ability decreases. It is suggested that when producing engineered UHMWPE fiber/cement composites, coordination of fiber tensile strength and fiber-matrix bond strength should be considered.
The applicabilities of two high-strength synthetic fibers for engineered fiber/cement composites were researched, with hydrophilic aramid fiber and hydrophobic ultra-high molecular weight polyethylene (UHMWPE) fiber. The results show that engineered aramid fiber/cement composites have no strain-hardening ability and present single crack failure pattern under uniaxial tensile load, and engineered UHMWPE fiber/cement composites show strain-hardening ability and multi cracking pattern. The UHMWPE fiber is more suitable for fiber/cement producing compared with aramid fiber. With the decrease of matrix water-to-binder ratio, the tensile strength of engineered UHMWPE fiber/cement composites increases but the strain-hardening ability decreases. It is suggested that when producing engineered UHMWPE fiber/cement composites, coordination of fiber tensile strength and fiber-matrix bond strength should be considered.
2019, 36(1): 254-260.
doi: 10.13801/j.cnki.fhclxb.20180428.002
Abstract:
Graphite carbonitride (g-C3N4) was prepared from melamine and hydrothermally treated with hydrochloric acid to obtain acid-activated g-C3N4. The effects of hydrochloric acid activation on the structure and morphology of g-C3N4 and the electrochemical performance of g-C3N4/S cathode composites were investigated experimentally. The experimental results show that g-C3N4 layer spacing does not change significantly after hydrochloric acid activation. With the increase of hydrochloric acid concentration, the specific surface area of the g-C3N4 sample first increases and then decreases. When the concentration of hydrochloric acid is 2.5wt%, the maximum specific surface area is 86.1 m2·g-1, which is 5-6 times higher than untreated g-C3N4 of 13 m2·g-1. The specific capacity and cycle performance of hydrochloric acid activated g-C3N4/S cathode composites also increase first and then decrease. When the concentration of hydrochloric acid is 2.5wt%, the specific capacity and cycle performance of the hydrochloric acid activated g-C3N4/S cathode composite sample are the best, and the specific capacity is 1 538 mAh·g-1. After 50 cycles, its capacity holding rate is 77.8%. The electrochemical performance and specific surface area of hydrochloric acid activated g-C3N4/S cathode composites show a strong correlation.
Graphite carbonitride (g-C3N4) was prepared from melamine and hydrothermally treated with hydrochloric acid to obtain acid-activated g-C3N4. The effects of hydrochloric acid activation on the structure and morphology of g-C3N4 and the electrochemical performance of g-C3N4/S cathode composites were investigated experimentally. The experimental results show that g-C3N4 layer spacing does not change significantly after hydrochloric acid activation. With the increase of hydrochloric acid concentration, the specific surface area of the g-C3N4 sample first increases and then decreases. When the concentration of hydrochloric acid is 2.5wt%, the maximum specific surface area is 86.1 m2·g-1, which is 5-6 times higher than untreated g-C3N4 of 13 m2·g-1. The specific capacity and cycle performance of hydrochloric acid activated g-C3N4/S cathode composites also increase first and then decrease. When the concentration of hydrochloric acid is 2.5wt%, the specific capacity and cycle performance of the hydrochloric acid activated g-C3N4/S cathode composite sample are the best, and the specific capacity is 1 538 mAh·g-1. After 50 cycles, its capacity holding rate is 77.8%. The electrochemical performance and specific surface area of hydrochloric acid activated g-C3N4/S cathode composites show a strong correlation.
2019, 36(1): 261-268.
doi: 10.13801/j.cnki.fhclxb.20180511.003
Abstract:
Ethylene vinyl acetate (EVA) with 18%(mass ratio) of vinyl acetate was blended with silicone rubber (SR) in the mixer, then the other rubber components were added in the roll-milling to prepare un-vulcanized EVA/SR rubber composites, then they were vulcanized to produce EVA/SR viscoelastic damping composites with wider effective temperature range. The effects of different contents of EVA on the mechanical properties, processability, damping characteristics and thermal properties of EVA/SR composites were studied by capillary rheometer, rubber processing analyzer (RPA), DMA and DSC. The results show that adding more EVA can significantly improve the hardness and modulus and tear strength of SR. Meanwhile, the tensile strength and elongation at break are still high remaining within the range of SR application requirements, and EVA/SR is sheared thinner. The compound exhibits distinct Payne effect in strain scanning by increasing its amplitude. The effects of EVA content and vulcanization can be analyzed by Kraus model. EVA micro-cluster is dispersed in chemically crosslink network SR together filled with silica forming multiple structures. SR decreases the crystallization temperature of EVA. EVA plays a significant role in reinforcing and increasing the viscosity of SR. For pure SR, the temperature range is -42~-28℃ when the loss factor is greater than 0.1. In contrast, for 100:40 (mass ratio) EVA/SR, the effective damping temperature range is -23~37℃ corresponding to the maximum loss factor of 0.18 in comparison of 0.125 for pure SR. This obviously widens the effective damping temperature range rendering the shock-absorbing and de-noising applications at higher temperature.
Ethylene vinyl acetate (EVA) with 18%(mass ratio) of vinyl acetate was blended with silicone rubber (SR) in the mixer, then the other rubber components were added in the roll-milling to prepare un-vulcanized EVA/SR rubber composites, then they were vulcanized to produce EVA/SR viscoelastic damping composites with wider effective temperature range. The effects of different contents of EVA on the mechanical properties, processability, damping characteristics and thermal properties of EVA/SR composites were studied by capillary rheometer, rubber processing analyzer (RPA), DMA and DSC. The results show that adding more EVA can significantly improve the hardness and modulus and tear strength of SR. Meanwhile, the tensile strength and elongation at break are still high remaining within the range of SR application requirements, and EVA/SR is sheared thinner. The compound exhibits distinct Payne effect in strain scanning by increasing its amplitude. The effects of EVA content and vulcanization can be analyzed by Kraus model. EVA micro-cluster is dispersed in chemically crosslink network SR together filled with silica forming multiple structures. SR decreases the crystallization temperature of EVA. EVA plays a significant role in reinforcing and increasing the viscosity of SR. For pure SR, the temperature range is -42~-28℃ when the loss factor is greater than 0.1. In contrast, for 100:40 (mass ratio) EVA/SR, the effective damping temperature range is -23~37℃ corresponding to the maximum loss factor of 0.18 in comparison of 0.125 for pure SR. This obviously widens the effective damping temperature range rendering the shock-absorbing and de-noising applications at higher temperature.
