2016 Vol. 33, No. 9
2016, 33(9): 1859-1867.
doi: 10.13801/j.cnki.fhclxb.20151203.001
Abstract:
In order to investigate the effects of waterborne polyaniline/versatate-fluoro-acrylate (PANI/VFAc) composite coating on anticorrosion performance of Q235 steel, VFAc emulsion was synthesized firstly by using versatate (Veova 10) and dodecafluoroheptyl methacrylate (DFMA) as the functional monomers, and after mixed with PANI emulsion, it was applied to the surface of Q235 steel to prepare PANI/VFAc composite coatings. Then, the structure of VFAc was characterized by TEM and FTIR, the surface performance of composite coatings was evaluated by XPS and contact angle (CA), and the influences of different modified acrylate emulsions on the anticorrosion performances of the composite coatings were investigated by electrochemical method. The results show that the water contact angle of PANI/VFAc composite coating is 97.56°, the grade of wet adhesion is 0, which means the coating shows preferable hydrophobicity. The corrosion current density is 8.72×10-8 A·cm-2, and the electrochemical impedance reaches 106 Ω·cm2. The conclusions obtained show that PANI/VFAc composite coating has preferable anticorrosion performance for Q235 steel.
In order to investigate the effects of waterborne polyaniline/versatate-fluoro-acrylate (PANI/VFAc) composite coating on anticorrosion performance of Q235 steel, VFAc emulsion was synthesized firstly by using versatate (Veova 10) and dodecafluoroheptyl methacrylate (DFMA) as the functional monomers, and after mixed with PANI emulsion, it was applied to the surface of Q235 steel to prepare PANI/VFAc composite coatings. Then, the structure of VFAc was characterized by TEM and FTIR, the surface performance of composite coatings was evaluated by XPS and contact angle (CA), and the influences of different modified acrylate emulsions on the anticorrosion performances of the composite coatings were investigated by electrochemical method. The results show that the water contact angle of PANI/VFAc composite coating is 97.56°, the grade of wet adhesion is 0, which means the coating shows preferable hydrophobicity. The corrosion current density is 8.72×10-8 A·cm-2, and the electrochemical impedance reaches 106 Ω·cm2. The conclusions obtained show that PANI/VFAc composite coating has preferable anticorrosion performance for Q235 steel.
2016, 33(9): 1868-1878.
doi: 10.13801/j.cnki.fhclxb.20151117.003
Abstract:
In order to investigate high performance protective coatings for electric power fittings, nano-graphite/polyurethane composite paintings with different nano-graphite contents were prepared firstly using hydroxyl acrylic resin and isocynate as main film-forming substances as well as nano-graphite as fillers. Then, the nano-graphite/polyurethane composite paintings were applied on electric hot dip galvanized steel, and nano-graphite/polyurethane composite coatings were obtained after solid drying. Finally, the mechanical properties and abrasion resistance of nano-graphite/polyurethane composite coatings were tested, and the anti-corrosion performances of nano-graphite/polyurethane composite coatings were investigated using simulated acid rain tests, neutral salt spray tests and electrochemical impedance spectroscopy (EIS). The results show that the adhesion between coating and hot dip galvanized steel is improved after adding nano-graphite, the abrasion resistance of nano-graphite/polyurethane composite coating whose nano-graphite content is 2.0wt% is improved by 92% comparing with the blank coating without adding nano-graphite, and the distribution of nano-graphite in the coating is relatively uniform, which shows good anti-corrosion performance. The conclusions obtained show that the addition of nano-graphite with suitable amount in coatings can enhance the abrasion resistance and anti-corrosion performances of coatings, thus the coatings can be used for surface protection of electric power fittings.
In order to investigate high performance protective coatings for electric power fittings, nano-graphite/polyurethane composite paintings with different nano-graphite contents were prepared firstly using hydroxyl acrylic resin and isocynate as main film-forming substances as well as nano-graphite as fillers. Then, the nano-graphite/polyurethane composite paintings were applied on electric hot dip galvanized steel, and nano-graphite/polyurethane composite coatings were obtained after solid drying. Finally, the mechanical properties and abrasion resistance of nano-graphite/polyurethane composite coatings were tested, and the anti-corrosion performances of nano-graphite/polyurethane composite coatings were investigated using simulated acid rain tests, neutral salt spray tests and electrochemical impedance spectroscopy (EIS). The results show that the adhesion between coating and hot dip galvanized steel is improved after adding nano-graphite, the abrasion resistance of nano-graphite/polyurethane composite coating whose nano-graphite content is 2.0wt% is improved by 92% comparing with the blank coating without adding nano-graphite, and the distribution of nano-graphite in the coating is relatively uniform, which shows good anti-corrosion performance. The conclusions obtained show that the addition of nano-graphite with suitable amount in coatings can enhance the abrasion resistance and anti-corrosion performances of coatings, thus the coatings can be used for surface protection of electric power fittings.
2016, 33(9): 1879-1885.
doi: 10.13801/j.cnki.fhclxb.20151110.001
Abstract:
In order to investigate the reinforcement and modification effects of graphite oxide (GO) on blending rubber, GO was synthesized by modified Hummers method, and GO/natural rubber (NR)-nitrile-butadiene rubber (NBR) composites were fabricated by latex co-coagulation technology firstly. Then, SEM, FTIR, XRD, swelling tests and mechanical property tests were employed to characterize the morphologies, structures and mechanical properties of GO, NR-NBR vulcanized rubber and GO/NR-NBR composites. The results show that the GO obtained contains a large amount of oxygen-containing functional groups, the oxidation effect is good; GO is homogeneously dispersed in rubber matrix, and the roughness of stretching section for GO/NR-NBR composites improves obviously. The apparent cross-linking density of the composites increases for the filling of GO. The mechanical properties of GO/NR-NBR composites improve with GO content increasing. When GO content is 3.0wt%, the tensile strength, tensile stress at 100% and Shore A hardness of GO/NR-NBR composites increase by 53.3%, 67.3% and 10.5%, respectively, and the elongation at break decreases by 9.6%.
In order to investigate the reinforcement and modification effects of graphite oxide (GO) on blending rubber, GO was synthesized by modified Hummers method, and GO/natural rubber (NR)-nitrile-butadiene rubber (NBR) composites were fabricated by latex co-coagulation technology firstly. Then, SEM, FTIR, XRD, swelling tests and mechanical property tests were employed to characterize the morphologies, structures and mechanical properties of GO, NR-NBR vulcanized rubber and GO/NR-NBR composites. The results show that the GO obtained contains a large amount of oxygen-containing functional groups, the oxidation effect is good; GO is homogeneously dispersed in rubber matrix, and the roughness of stretching section for GO/NR-NBR composites improves obviously. The apparent cross-linking density of the composites increases for the filling of GO. The mechanical properties of GO/NR-NBR composites improve with GO content increasing. When GO content is 3.0wt%, the tensile strength, tensile stress at 100% and Shore A hardness of GO/NR-NBR composites increase by 53.3%, 67.3% and 10.5%, respectively, and the elongation at break decreases by 9.6%.
2016, 33(9): 1886-1898.
doi: 10.13801/j.cnki.fhclxb.20151124.003
Abstract:
In order to improve the tribological performances of polytetrafluoroethylene (PTFE), PTFE matrix composites filled with mullite and carbon fiber were prepared by processes such as mechanical blending, heat pre-compression and sintering etc., and the microscopic structures, mechanical properties and thermal properties of PTFE matrix composites were characterized by FTIR, XRD, universal material testing machine, Rockwell hard meter, DSC and thermomechanical analyzer respectively. Then, the friction coefficients and wear rates of the composites were measured by MRH-3 high speed ring-on-block wear tester, and a self-designed sand slurry wear apparatus with silicone oil was used to detect the sand slurry wear resistance of the composites at different temperatures. Finally, the morphologies of friction surfaces for the composites were investigated by 3D measurement laser microscope, and the friction and wear mechanisms were analyzed. The results show that mullite and carbon fiber play a role of filling and toughening in PTFE system, and the elastic modulus of 20wt% mullite-10wt% carbon fiber/PTFE composite is enhanced from 364 MPa to 874 MPa. The dry friction coefficient of 20wt% mullite-10wt% carbon fiber/PTFE composite is higher, while its wear rate decreases by more than three orders compared with pure PTFE, and the composite maintains relatively good friction coefficient and wear rate under water friction condition, the friction coefficient is 0.157 and the wear rate is 7.40 × 10-6 mm3·N-1·m-1. Further, 20wt% mullite-10wt% carbon fiber/PTFE composite also shows favorable sand slurry wear resistant even at relatively high temperature. The conclusions obtained suggest that the tribological performances of PTFE matrix composites obtained by modification improve significantly, and the composites can be applied to the eccentric wear of the sucker-rod pumping well.
In order to improve the tribological performances of polytetrafluoroethylene (PTFE), PTFE matrix composites filled with mullite and carbon fiber were prepared by processes such as mechanical blending, heat pre-compression and sintering etc., and the microscopic structures, mechanical properties and thermal properties of PTFE matrix composites were characterized by FTIR, XRD, universal material testing machine, Rockwell hard meter, DSC and thermomechanical analyzer respectively. Then, the friction coefficients and wear rates of the composites were measured by MRH-3 high speed ring-on-block wear tester, and a self-designed sand slurry wear apparatus with silicone oil was used to detect the sand slurry wear resistance of the composites at different temperatures. Finally, the morphologies of friction surfaces for the composites were investigated by 3D measurement laser microscope, and the friction and wear mechanisms were analyzed. The results show that mullite and carbon fiber play a role of filling and toughening in PTFE system, and the elastic modulus of 20wt% mullite-10wt% carbon fiber/PTFE composite is enhanced from 364 MPa to 874 MPa. The dry friction coefficient of 20wt% mullite-10wt% carbon fiber/PTFE composite is higher, while its wear rate decreases by more than three orders compared with pure PTFE, and the composite maintains relatively good friction coefficient and wear rate under water friction condition, the friction coefficient is 0.157 and the wear rate is 7.40 × 10-6 mm3·N-1·m-1. Further, 20wt% mullite-10wt% carbon fiber/PTFE composite also shows favorable sand slurry wear resistant even at relatively high temperature. The conclusions obtained suggest that the tribological performances of PTFE matrix composites obtained by modification improve significantly, and the composites can be applied to the eccentric wear of the sucker-rod pumping well.
2016, 33(9): 1899-1904.
doi: 10.13801/j.cnki.fhclxb.20151029.002
Abstract:
In order to prepare the composites of grafted polyethylene and SiO2, and endow it with new special properties, low-density polyethylene graft polystyrene (LDPE-g-PS) was prepared by pre-irradiation and suspension graft technique firstly, and PS modified nano-SiO2 (PS@nano-SiO2) were prepared by surface grafting. Then, PS@nano-SiO2/LDPE-g-PS composites were prepared by melt blend of LDPE-g-PS and PS@nano-SiO2. Finally, the structures and properties of the materials were investigated by FTIR, SEM, DSC and electronic tensile machine etc. The results indicate that the PS has been grafted onto LDPE and nano-SiO2 respectively. In PS@nano-SiO2/LDPE-g-PS composites, SiO2 reaches nano-scale dispersion in LDPE-g-PS, and forms unique fibrous network structure. The impact strength of 2wt% PS@nano-SiO2/LDPE-g-PS composite improves by 99.3% comparing with that of LDPE-g-PS. Comparing with LDPE-g-PS, crystallization temperature of PS@nano-SiO2/LDPE-g-PS composite increases, and the breakdown field strength is 1.4 times higher than that of LDPE. The conclusions obtained show that the properties of PS@nano-SiO2/LDPE-g-PS composites are better.
In order to prepare the composites of grafted polyethylene and SiO2, and endow it with new special properties, low-density polyethylene graft polystyrene (LDPE-g-PS) was prepared by pre-irradiation and suspension graft technique firstly, and PS modified nano-SiO2 (PS@nano-SiO2) were prepared by surface grafting. Then, PS@nano-SiO2/LDPE-g-PS composites were prepared by melt blend of LDPE-g-PS and PS@nano-SiO2. Finally, the structures and properties of the materials were investigated by FTIR, SEM, DSC and electronic tensile machine etc. The results indicate that the PS has been grafted onto LDPE and nano-SiO2 respectively. In PS@nano-SiO2/LDPE-g-PS composites, SiO2 reaches nano-scale dispersion in LDPE-g-PS, and forms unique fibrous network structure. The impact strength of 2wt% PS@nano-SiO2/LDPE-g-PS composite improves by 99.3% comparing with that of LDPE-g-PS. Comparing with LDPE-g-PS, crystallization temperature of PS@nano-SiO2/LDPE-g-PS composite increases, and the breakdown field strength is 1.4 times higher than that of LDPE. The conclusions obtained show that the properties of PS@nano-SiO2/LDPE-g-PS composites are better.
2016, 33(9): 1905-1914.
doi: 10.13801/j.cnki.fhclxb.20151102.002
Abstract:
The surface properties and crystalline structure of three kinds of domestic high-modulus carbon fibers (CCM40J, CCM40, CCM46J) and an imported high-modulus carbon fiber (Toray M40JB) were investigated by SEM, metallographic microscope, AFM, XPS and XRD. The micro interface and multifilament mechanical properties of high-modulus carbon fiber and epoxy resin were studied. The results show that all the surfaces of high-modulus carbon fiber have obvious grooves, but the differences of surface roughness are not obvious. Their cross-section shapes include circle, cashew, ellipse and so on. Their surface elements mainly contains four elements of C, O, N, Si, and both O/C ratio and the content of active carbon atoms of M40JB are higher than that of domestic high-modulus carbon fibers. Following the sequence of M40JB, CCM40J, CCM40, CCM46J, the size of graphite microcrystalline becomes larger, and the degree of graphitization increases. The degree of orientation of M40JB is the smallest, and the degree of orientation of CCM46J is the largest, while the degrees of orientation of CCM40J and CCM40 are similar. The order of surface energy from large to small is M40JB > CCM40 > CCM46J > CCM40J, and their dynamic contact angles with resin system E51-DDS of epoxy resin E51, curing agent 4,4'- diamino diphenyl sulfone (DDS) and resin system AG80-DDS of 4,4'- diamino diphenyl methane epoxy resin (AG80), curing agent DDS at 80 ℃ rang from 35° to 50°, indicating good wettability. The interface shear strength (IFSS) of CCM46J with E51-DDS is the largest, and the interface shear strength of M40JB with AG80-DDS is the largest. The tensile strength and tensile modulus of three kinds of domestic high-modulus carbon fiber multifilaments are all larger than those of M40JB, where the tensile strength of CCM40J is the largest, and the tensile modulus of CCM46J is the largest. The proportion of the compression strength of high-modulus carbon fiber multifilaments with its tensile strength is from 44% to 53%, and the compression strength of CCM46J multifilament is the largest.
The surface properties and crystalline structure of three kinds of domestic high-modulus carbon fibers (CCM40J, CCM40, CCM46J) and an imported high-modulus carbon fiber (Toray M40JB) were investigated by SEM, metallographic microscope, AFM, XPS and XRD. The micro interface and multifilament mechanical properties of high-modulus carbon fiber and epoxy resin were studied. The results show that all the surfaces of high-modulus carbon fiber have obvious grooves, but the differences of surface roughness are not obvious. Their cross-section shapes include circle, cashew, ellipse and so on. Their surface elements mainly contains four elements of C, O, N, Si, and both O/C ratio and the content of active carbon atoms of M40JB are higher than that of domestic high-modulus carbon fibers. Following the sequence of M40JB, CCM40J, CCM40, CCM46J, the size of graphite microcrystalline becomes larger, and the degree of graphitization increases. The degree of orientation of M40JB is the smallest, and the degree of orientation of CCM46J is the largest, while the degrees of orientation of CCM40J and CCM40 are similar. The order of surface energy from large to small is M40JB > CCM40 > CCM46J > CCM40J, and their dynamic contact angles with resin system E51-DDS of epoxy resin E51, curing agent 4,4'- diamino diphenyl sulfone (DDS) and resin system AG80-DDS of 4,4'- diamino diphenyl methane epoxy resin (AG80), curing agent DDS at 80 ℃ rang from 35° to 50°, indicating good wettability. The interface shear strength (IFSS) of CCM46J with E51-DDS is the largest, and the interface shear strength of M40JB with AG80-DDS is the largest. The tensile strength and tensile modulus of three kinds of domestic high-modulus carbon fiber multifilaments are all larger than those of M40JB, where the tensile strength of CCM40J is the largest, and the tensile modulus of CCM46J is the largest. The proportion of the compression strength of high-modulus carbon fiber multifilaments with its tensile strength is from 44% to 53%, and the compression strength of CCM46J multifilament is the largest.
2016, 33(9): 1915-1921.
doi: 10.13801/j.cnki.fhclxb.20151123.003
Abstract:
The microcellular epoxy resin was prepared by the solid-state batch foaming technique with supercritical CO2 as a physical-blowing agent. The preparation processes of microcellular epoxy resin were studied by SEM and DSC, mechanical properties and dielectric properties of the epoxy resin before and after foaming were analyzed. The results show that when the pre-curing degree of epoxy resin sheets is 75%-85%, the gas concentration will reach 5.11%-5.43%, the gas saturation time will be 48 h, and the cells are closely packed and the size is uniform. With the improvement of foaming temperature and extension of foaming time, the average cell diameter of the microcellular epoxy resin will gradually enlarge and the cell density will decrease. When the pre-curing degree of epoxy resin sheets reaches 75%, the foaming temperature is 120 ℃ and the foaming time is 10 s, the average cell diameter of microcellular epoxy resin will be 10.6 μm and cell density will be 1.03×109 cells/cm3. And the cells are uniform and compact spheres or polygons structure. Compared with materials without foaming, the elongation at break and impact strength of the microcellular epoxy resin increase by 43% and 39% respectively. The dielectric constant and the dielectric loss decreases by 42% and 50% respectively.
The microcellular epoxy resin was prepared by the solid-state batch foaming technique with supercritical CO2 as a physical-blowing agent. The preparation processes of microcellular epoxy resin were studied by SEM and DSC, mechanical properties and dielectric properties of the epoxy resin before and after foaming were analyzed. The results show that when the pre-curing degree of epoxy resin sheets is 75%-85%, the gas concentration will reach 5.11%-5.43%, the gas saturation time will be 48 h, and the cells are closely packed and the size is uniform. With the improvement of foaming temperature and extension of foaming time, the average cell diameter of the microcellular epoxy resin will gradually enlarge and the cell density will decrease. When the pre-curing degree of epoxy resin sheets reaches 75%, the foaming temperature is 120 ℃ and the foaming time is 10 s, the average cell diameter of microcellular epoxy resin will be 10.6 μm and cell density will be 1.03×109 cells/cm3. And the cells are uniform and compact spheres or polygons structure. Compared with materials without foaming, the elongation at break and impact strength of the microcellular epoxy resin increase by 43% and 39% respectively. The dielectric constant and the dielectric loss decreases by 42% and 50% respectively.
2016, 33(9): 1922-1930.
doi: 10.13801/j.cnki.fhclxb.20151112.003
Abstract:
The high performance carbon fiber (CF) can be recycled from CF/epoxy resin (CF/EP) composites by supercritical n-butanol under the action of KOH. Influences of reaction temperature and reaction time on degradation rate of EP in CF/EP composites were analyzed, and mechanical properties of the recycled CF reinforced polypropylene (PP) composites were investigated. Catalytic degradation process of the EP curing system in supercritical n-butanol was investigated based on analysis for components of degradation liquid phase products, and the degradation kinetics model was established. The catalytic degradation kinetics equation was proposed based on the calculation of the kinetics parameters. The results indicate that reaction temperature and reaction time show obvious positive correlation to degradation rate of EP. In comparison with the original CF reinforced PP composites, the tensile strength of the recycled CF reinforced PP composites decreases by 9.2%, the bending strength decreases by 20.9%, the bending modulus decreases by 10.9%, and the impact strength decreases by 7.4%. Degradation reactions of CF/EP composites are mainly the scission of linear chains such as C—C, —O—, etc. and the scission of C—N at the cross-linked segment in the molecule segment of EP curing system, and catalytic degradation reaction order of CF/EP composites is 2, reaction activation energy is 165.2 kJ·mol-1, pre-exponential factor is 3.62×1013 min-1, and the established kinetics equation can solve the problem that the reaction temperature and reaction time can not be estimated.
The high performance carbon fiber (CF) can be recycled from CF/epoxy resin (CF/EP) composites by supercritical n-butanol under the action of KOH. Influences of reaction temperature and reaction time on degradation rate of EP in CF/EP composites were analyzed, and mechanical properties of the recycled CF reinforced polypropylene (PP) composites were investigated. Catalytic degradation process of the EP curing system in supercritical n-butanol was investigated based on analysis for components of degradation liquid phase products, and the degradation kinetics model was established. The catalytic degradation kinetics equation was proposed based on the calculation of the kinetics parameters. The results indicate that reaction temperature and reaction time show obvious positive correlation to degradation rate of EP. In comparison with the original CF reinforced PP composites, the tensile strength of the recycled CF reinforced PP composites decreases by 9.2%, the bending strength decreases by 20.9%, the bending modulus decreases by 10.9%, and the impact strength decreases by 7.4%. Degradation reactions of CF/EP composites are mainly the scission of linear chains such as C—C, —O—, etc. and the scission of C—N at the cross-linked segment in the molecule segment of EP curing system, and catalytic degradation reaction order of CF/EP composites is 2, reaction activation energy is 165.2 kJ·mol-1, pre-exponential factor is 3.62×1013 min-1, and the established kinetics equation can solve the problem that the reaction temperature and reaction time can not be estimated.
2016, 33(9): 1931-1938.
doi: 10.13801/j.cnki.fhclxb.20151208.001
Abstract:
One-pot in situ approach had been employed to prepare Cu-Al layered double hydroxides (CuAl-LDHs). Through controlling the mass ratio (0.82-3.28) of sodium aluminate/ammonium polyphosphate (NaAlO2/APP), CuAl-LDHs-APP was prepared. XRD, FTIR, SEM and TG were utilized to characterize the prepared CuAl-LDHs and CuAl-LDHs-APP. The fire retardancy and mechanical properties of CuAl-LDHs/polypropylene (PP) and CuAl-LDHs-APP/PP composites were evaluated by limiting oxygen index (LOI), vertical burning (UL-94) test , as well as flexural and tensile tests. SEM observation indicates that the structure of LDHs is sheet-like, with the mass ratio of NaAlO2 and APP decreasing, the particle size of CuAl-LDHs-APP reduces accordingly, when the mass ratio of NaAlO2 and APP is 0.82, particle size of CuAl-LDHs-APP reaches about 20 nm, with specific surface area of 183.5 m2/g. TG analysis shows that CuAl-LDHs-APP has preferable thermostability at high temperature. When 20% mass fraction of CuAl-LDHs and CuAl-LDHs-APP is added in PP, the surface of LDHs/PP composites is covered with char. When the mass ratio of NaAlO2 and APP is no more than 1.64, the addition of CuAl-LDHs-APP can suppress the melting drop phenomenon caused by PP combustion. CuAl-LDHs-APP/PP composite has superior flame retardant and mechanical properties compared with CuAl-LDHs/PP composite. Decreases of mechanical properties of CuAl-LDHs-APP/PP composite such as flexural strength and tensile strength etc. are not obvious compared with PP materials.
One-pot in situ approach had been employed to prepare Cu-Al layered double hydroxides (CuAl-LDHs). Through controlling the mass ratio (0.82-3.28) of sodium aluminate/ammonium polyphosphate (NaAlO2/APP), CuAl-LDHs-APP was prepared. XRD, FTIR, SEM and TG were utilized to characterize the prepared CuAl-LDHs and CuAl-LDHs-APP. The fire retardancy and mechanical properties of CuAl-LDHs/polypropylene (PP) and CuAl-LDHs-APP/PP composites were evaluated by limiting oxygen index (LOI), vertical burning (UL-94) test , as well as flexural and tensile tests. SEM observation indicates that the structure of LDHs is sheet-like, with the mass ratio of NaAlO2 and APP decreasing, the particle size of CuAl-LDHs-APP reduces accordingly, when the mass ratio of NaAlO2 and APP is 0.82, particle size of CuAl-LDHs-APP reaches about 20 nm, with specific surface area of 183.5 m2/g. TG analysis shows that CuAl-LDHs-APP has preferable thermostability at high temperature. When 20% mass fraction of CuAl-LDHs and CuAl-LDHs-APP is added in PP, the surface of LDHs/PP composites is covered with char. When the mass ratio of NaAlO2 and APP is no more than 1.64, the addition of CuAl-LDHs-APP can suppress the melting drop phenomenon caused by PP combustion. CuAl-LDHs-APP/PP composite has superior flame retardant and mechanical properties compared with CuAl-LDHs/PP composite. Decreases of mechanical properties of CuAl-LDHs-APP/PP composite such as flexural strength and tensile strength etc. are not obvious compared with PP materials.
2016, 33(9): 1939-1946.
doi: 10.13801/j.cnki.fhclxb.20151112.002
Abstract:
The CaCl2/epoxy resin (E51)/polyamide 6 (PA6) composites with different mass fractions of CaCl2 were prepared by melting co-extrusion. The crystallization behavior and mechanical properties of CaCl2/E51/PA6 composites were studied by DSC, rheometer, FTIR and electronic tensile testing machine et al. The confined mechanism was also investigated. The mechanical property results show that with increases of mass fraction of CaCl2, the tensile strength of CaCl2/E51/PA6 composites increases firstly and decrease finally. When mass fraction of CaCl2 is 3%, the tensile strength of composites reaches maximum 82.67 MPa, which is 1.366 times of the tensile strength of pure PA6 (60.5 MPa). The crystallization behavior results show that increase of mass fraction of CaCl2 decrease the temperature of nucleation, the growth temperature of crystal, the melt temperature and glass transition temperature of CaCl2/E51 PA6 composites. The density of nucleation and the rate of nucleation also decrease gradually, the crystallization decreases and the degree of crystallinity changes from original 25.22% to 9.90%.
The CaCl2/epoxy resin (E51)/polyamide 6 (PA6) composites with different mass fractions of CaCl2 were prepared by melting co-extrusion. The crystallization behavior and mechanical properties of CaCl2/E51/PA6 composites were studied by DSC, rheometer, FTIR and electronic tensile testing machine et al. The confined mechanism was also investigated. The mechanical property results show that with increases of mass fraction of CaCl2, the tensile strength of CaCl2/E51/PA6 composites increases firstly and decrease finally. When mass fraction of CaCl2 is 3%, the tensile strength of composites reaches maximum 82.67 MPa, which is 1.366 times of the tensile strength of pure PA6 (60.5 MPa). The crystallization behavior results show that increase of mass fraction of CaCl2 decrease the temperature of nucleation, the growth temperature of crystal, the melt temperature and glass transition temperature of CaCl2/E51 PA6 composites. The density of nucleation and the rate of nucleation also decrease gradually, the crystallization decreases and the degree of crystallinity changes from original 25.22% to 9.90%.
2016, 33(9): 1947-1955.
doi: 10.13801/j.cnki.fhclxb.20151117.002
Abstract:
Hectorite/LiCl/nylon 6(PA6) composites were prepared through melting extrusion process, the effects of mass fraction of hectorite on structure and properties of LiCl/PA6 composites were studied. The effect of complexation reaction on the dispersion of hectorite in the matrix was also discussed. DSC and XRD research indicate that addition of hectorite is advantageous to the crystal of composites, but the crystallinity is less than that of LiCl/PA6 composites. When the mass fraction of hectorite is 5%, the crystallinity of hectorite/LiCl/PA6 composites is the largest. Meanwhile, the tensile strength and bending strength of the composites reach the maximum values of 99.17 MPa and 154.17 MPa, respectively. TEM shows that when the mass fraction of hectorite is 5%, the dispersion of hectorite in the matrix was mainly intercalated dispersion and partly exfoliated morphology. In addition, dynamic Han curves show that the viscous response dominates in hectorite/LiCl/PA6 composites. As the agglomeration of hectorite and different relaxation state of different phases for inorganic clay and organic phase, Cole-Cole curves display a phenomenon of severe smearing when the mass fraction of hectorite is greater than 5%. Hectorite/LiCl/PA6 composites not only keep the characteristics of the low melting point and show excellent mechanical properties. Hence, hectorite shows obvious enhancement effect.
Hectorite/LiCl/nylon 6(PA6) composites were prepared through melting extrusion process, the effects of mass fraction of hectorite on structure and properties of LiCl/PA6 composites were studied. The effect of complexation reaction on the dispersion of hectorite in the matrix was also discussed. DSC and XRD research indicate that addition of hectorite is advantageous to the crystal of composites, but the crystallinity is less than that of LiCl/PA6 composites. When the mass fraction of hectorite is 5%, the crystallinity of hectorite/LiCl/PA6 composites is the largest. Meanwhile, the tensile strength and bending strength of the composites reach the maximum values of 99.17 MPa and 154.17 MPa, respectively. TEM shows that when the mass fraction of hectorite is 5%, the dispersion of hectorite in the matrix was mainly intercalated dispersion and partly exfoliated morphology. In addition, dynamic Han curves show that the viscous response dominates in hectorite/LiCl/PA6 composites. As the agglomeration of hectorite and different relaxation state of different phases for inorganic clay and organic phase, Cole-Cole curves display a phenomenon of severe smearing when the mass fraction of hectorite is greater than 5%. Hectorite/LiCl/PA6 composites not only keep the characteristics of the low melting point and show excellent mechanical properties. Hence, hectorite shows obvious enhancement effect.
2016, 33(9): 1956-1963.
doi: 10.13801/j.cnki.fhclxb.20151209.001
Abstract:
In order to research the method of toughening bismaleimide and its effects on properties, nano-SiO2 was modified by supercritical ethanol (SCE-SiO2), and its surface activity of SCE-SiO2 were improved, 4,4'-diamino diphenyl methane bismaleimide (MBMI), 3,3'- diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE) were used to synthesize MBAE(MBMI-BBA-BBE) composite matrix, SCE-SiO2/PES-MBAE multi-phase composite was prepared from adding SCE-SiO2 and polyether sulfone (PES) into MBAE matrix by in-situ polymerization method and sol-gel method. SEM was used to observe the fracture morphology of SCE-SiO2/PES-MBAE composites. The analysis result of FTIR shows that the absorption peak of Si—OH at 3 434 cm-1 disappeares and the absorption peaks of —OH between ethanol molecules (3 310 cm-1), —CH3 and —CH2— (2 984 cm-1)appeares, this indicates the nano particle is coated with ethanol molecule in some form and surface properties improve. PES exists in the matrix as dispersed phase in the form of "honeycomb", the fracture modes transform from brittle fracture to ductile fracture. SCE-SiO2 and PES have the toughing effect to the material, the toughing effect of PES are extremely obvious, and there are synergistic between them. When the content of SCE-SiO2 is 2wt%, PES content is 4wt%, the impact strength and the bending strength of multi-phase composites are 15.02 kJ/m2 and 130.47 MPa, enhance 57.3% and 35.8% than that of MBAE matrix, respectively. The dielectric property test shows that the dielectric constant and dielectric loss of SCE-SiO2/PES-MBAE composites show a little increase while SCE-SiO2 and PES exist, but the synergistic reaction between them can reduce the negative impacts of PES.
In order to research the method of toughening bismaleimide and its effects on properties, nano-SiO2 was modified by supercritical ethanol (SCE-SiO2), and its surface activity of SCE-SiO2 were improved, 4,4'-diamino diphenyl methane bismaleimide (MBMI), 3,3'- diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE) were used to synthesize MBAE(MBMI-BBA-BBE) composite matrix, SCE-SiO2/PES-MBAE multi-phase composite was prepared from adding SCE-SiO2 and polyether sulfone (PES) into MBAE matrix by in-situ polymerization method and sol-gel method. SEM was used to observe the fracture morphology of SCE-SiO2/PES-MBAE composites. The analysis result of FTIR shows that the absorption peak of Si—OH at 3 434 cm-1 disappeares and the absorption peaks of —OH between ethanol molecules (3 310 cm-1), —CH3 and —CH2— (2 984 cm-1)appeares, this indicates the nano particle is coated with ethanol molecule in some form and surface properties improve. PES exists in the matrix as dispersed phase in the form of "honeycomb", the fracture modes transform from brittle fracture to ductile fracture. SCE-SiO2 and PES have the toughing effect to the material, the toughing effect of PES are extremely obvious, and there are synergistic between them. When the content of SCE-SiO2 is 2wt%, PES content is 4wt%, the impact strength and the bending strength of multi-phase composites are 15.02 kJ/m2 and 130.47 MPa, enhance 57.3% and 35.8% than that of MBAE matrix, respectively. The dielectric property test shows that the dielectric constant and dielectric loss of SCE-SiO2/PES-MBAE composites show a little increase while SCE-SiO2 and PES exist, but the synergistic reaction between them can reduce the negative impacts of PES.
2016, 33(9): 1964-1972.
doi: 10.13801/j.cnki.fhclxb.20151216.001
Abstract:
With the aim of enhancing the toughness of epoxy based conductive ink, we adopted a vinylchoride-vinylacetate-dicarboxylic acid terpolymer (E15/45M) to toughen epoxy resin E51. Flexible conductive ink was prepared with 2-ethyl-4-methylimidazole (2E4MI) as curing agent and Cu@Ag powder as conductive filler. The results indicate that the volume resistivity of conductive ink decreases with the conductive filler content increasing. It also finds that the volume resistivity of conductive ink decreases firstly and then increases, as the content of 2E4MI increases. The optimal mass ratio of 2E4MI to E51 is 1:5, and with further investigation, the best curing temperature and time of conductive ink are 105 ℃ and 2.5 h, respectively. E15/45M can not only enhance the flexibility of conductive ink, but also decreases the volume resistivity. With increasing the content of E15/45M, the glass transition temperature of E15/45M/E51-2E4MI glue film decreases from 91.5 ℃ to 58.0 ℃, and the volume resistivity of conductive ink decreases from 27.5×10-4 Ω·cm to 9.50×10-4 Ω·cm. When mass ratio of E51-2E4MI to E15/45M is 50:50, the volume resistivity of the conductive ink with conductive filler content of 70wt% reaches 9.57×10-4 Ω·cm, the adhesion grade is zero, and the resistance variation is less than 80% after folding repeatedly for 20 cycles. Therefore, toughening epoxy resin with E15/45M can improve both the flexibility and the conductivity of conductive ink.
With the aim of enhancing the toughness of epoxy based conductive ink, we adopted a vinylchoride-vinylacetate-dicarboxylic acid terpolymer (E15/45M) to toughen epoxy resin E51. Flexible conductive ink was prepared with 2-ethyl-4-methylimidazole (2E4MI) as curing agent and Cu@Ag powder as conductive filler. The results indicate that the volume resistivity of conductive ink decreases with the conductive filler content increasing. It also finds that the volume resistivity of conductive ink decreases firstly and then increases, as the content of 2E4MI increases. The optimal mass ratio of 2E4MI to E51 is 1:5, and with further investigation, the best curing temperature and time of conductive ink are 105 ℃ and 2.5 h, respectively. E15/45M can not only enhance the flexibility of conductive ink, but also decreases the volume resistivity. With increasing the content of E15/45M, the glass transition temperature of E15/45M/E51-2E4MI glue film decreases from 91.5 ℃ to 58.0 ℃, and the volume resistivity of conductive ink decreases from 27.5×10-4 Ω·cm to 9.50×10-4 Ω·cm. When mass ratio of E51-2E4MI to E15/45M is 50:50, the volume resistivity of the conductive ink with conductive filler content of 70wt% reaches 9.57×10-4 Ω·cm, the adhesion grade is zero, and the resistance variation is less than 80% after folding repeatedly for 20 cycles. Therefore, toughening epoxy resin with E15/45M can improve both the flexibility and the conductivity of conductive ink.
2016, 33(9): 1973-1980.
doi: 10.13801/j.cnki.fhclxb.20151201.002
Abstract:
Thermoset polyimide resins with molecular weight of 1 500, 2 500, 3 500, 5 000 g/mol were synthesized firstly by asymmetric dianhydride 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA), diamines and 4-phenylacetylene anhydride (4-PEPA) as the endcapping agent. Then, the relation between molecular weight and curing reaction process, aggregation structure, heat resistance, rheology property and toughness property, and its mechanism were investigated by characterisation and analyses methods such as FTIR, XRD, DSC, DMA, TGA, rheometer and so on. The results indicate that with the increase of molecular weight, glass transition temperature of resin decreases from 370 ℃ to 344 ℃, the lowest melt viscosity increases from 15.5 Pa·s to 37 090.0 Pa·s and impact strength also increases from 25.93 kJ/m2 to 45.04 kJ/m2.The glass transition temperature and processability of the thermoset polyimides will reduce by increasing its molecular weight, but toughness will increase.
Thermoset polyimide resins with molecular weight of 1 500, 2 500, 3 500, 5 000 g/mol were synthesized firstly by asymmetric dianhydride 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA), diamines and 4-phenylacetylene anhydride (4-PEPA) as the endcapping agent. Then, the relation between molecular weight and curing reaction process, aggregation structure, heat resistance, rheology property and toughness property, and its mechanism were investigated by characterisation and analyses methods such as FTIR, XRD, DSC, DMA, TGA, rheometer and so on. The results indicate that with the increase of molecular weight, glass transition temperature of resin decreases from 370 ℃ to 344 ℃, the lowest melt viscosity increases from 15.5 Pa·s to 37 090.0 Pa·s and impact strength also increases from 25.93 kJ/m2 to 45.04 kJ/m2.The glass transition temperature and processability of the thermoset polyimides will reduce by increasing its molecular weight, but toughness will increase.
2016, 33(9): 1981-1988.
doi: 10.13801/j.cnki.fhclxb.20160102.001
Abstract:
Based on the classical lamination theory (CLT), a multi-parameter analytic model was developed to quantitatively investigate influence of out-of-plane waviness defect on the elastic properties (i.e. elastic modulus, shear modulus and Poisson's ratios) of composite laminates with waviness. The results show that out-of-plane waviness has strong effects on the major elastic modulus, Z-direction elastic modulus, shear modulus in X-Z plane, and in-plane Poisson's ratio. The negative in-plane Poisson's ratio occurs in a particular range of the waviness ratio and wavy region for the example of carbon fiber/epoxy resin material system. The present approach provides a useful reference to evaluate the effects of out-of-plane waviness on elastic properties of composite laminates.
Based on the classical lamination theory (CLT), a multi-parameter analytic model was developed to quantitatively investigate influence of out-of-plane waviness defect on the elastic properties (i.e. elastic modulus, shear modulus and Poisson's ratios) of composite laminates with waviness. The results show that out-of-plane waviness has strong effects on the major elastic modulus, Z-direction elastic modulus, shear modulus in X-Z plane, and in-plane Poisson's ratio. The negative in-plane Poisson's ratio occurs in a particular range of the waviness ratio and wavy region for the example of carbon fiber/epoxy resin material system. The present approach provides a useful reference to evaluate the effects of out-of-plane waviness on elastic properties of composite laminates.
2016, 33(9): 1989-1998.
doi: 10.13801/j.cnki.fhclxb.20151106.004
Abstract:
Considering the effect on material interfacial mechanical properties caused by friction which appears on the debonding interface under compression stress, a damage-friction combination interface constitutive model was proposed. Then a user material subroutine VUMAT involved this constitutive model was developed and implemented in finite element software ABAQUS. In conjunction with the damage-friction interface combination constitutive model, a meso finite element model of 3D four-directional braided composites based on the periodic unit-cell was established. In the unit-cell model, the interface element was introduced in the yarn/matrix and yarn/yarn interfaces. The initiation and propagation of interface damage under typical loads were simulated, and the mechanisms of interface stress transfer and interface failure were revealed. The effect rule of interface properties on macro- and micro- mechanical properties of composites were studied, which provides a reference for optimizing design and control of the interface performance of 3D four-directional braided composites.
Considering the effect on material interfacial mechanical properties caused by friction which appears on the debonding interface under compression stress, a damage-friction combination interface constitutive model was proposed. Then a user material subroutine VUMAT involved this constitutive model was developed and implemented in finite element software ABAQUS. In conjunction with the damage-friction interface combination constitutive model, a meso finite element model of 3D four-directional braided composites based on the periodic unit-cell was established. In the unit-cell model, the interface element was introduced in the yarn/matrix and yarn/yarn interfaces. The initiation and propagation of interface damage under typical loads were simulated, and the mechanisms of interface stress transfer and interface failure were revealed. The effect rule of interface properties on macro- and micro- mechanical properties of composites were studied, which provides a reference for optimizing design and control of the interface performance of 3D four-directional braided composites.
2016, 33(9): 1999-2005.
doi: 10.13801/j.cnki.fhclxb.20151126.003
Abstract:
The polytetrafluoroethylene (PTFE) composite filled with glass fiber (GF) and halloysite (HNTs) were prepared by cold forming and sintering. The effects of the filler type and its matching on the interface, frictional property, linear expansion coefficient and mechanical property of PTFE composites were investigated. The results indicate that filling with HNTs suitably not only increases the friction property of GF/PTFE composites, but also causes the wear, thermal expansion and mechanical properties to increase. The wear rate of the HNTs-GF/PTFE ternary composite filled with 2.0% HNTs is reduced by 32.7% in comparison with GF/PTFE composite. The linear expansion coefficient (CTE) of this HNTs-GF/PTFE composite is reduced by almost 2 orders of magnitude compared with that of pure PTFE during high temperature. The elongation at break, tensile strength and bend strength of HNTs-GF/PTFE are improved by 40.0%, 2.3% and 7.1%, respectively.
The polytetrafluoroethylene (PTFE) composite filled with glass fiber (GF) and halloysite (HNTs) were prepared by cold forming and sintering. The effects of the filler type and its matching on the interface, frictional property, linear expansion coefficient and mechanical property of PTFE composites were investigated. The results indicate that filling with HNTs suitably not only increases the friction property of GF/PTFE composites, but also causes the wear, thermal expansion and mechanical properties to increase. The wear rate of the HNTs-GF/PTFE ternary composite filled with 2.0% HNTs is reduced by 32.7% in comparison with GF/PTFE composite. The linear expansion coefficient (CTE) of this HNTs-GF/PTFE composite is reduced by almost 2 orders of magnitude compared with that of pure PTFE during high temperature. The elongation at break, tensile strength and bend strength of HNTs-GF/PTFE are improved by 40.0%, 2.3% and 7.1%, respectively.
2016, 33(9): 2006-2012.
doi: 10.13801/j.cnki.fhclxb.20151208.002
Abstract:
Combined effect of sodium 2,2'-methylene-bis-(4, 6-di-tert-butyphenyl) phosphate (NA-11) and sodium bicycle[2, 2, 1]-heptane-2, 3-dicarboxylate (NA-CA) on mechanical properties and crystallization behaviors of isotactic polypropylene (iPP) were investigated. The nucleating agents and iPP were blended using a twin-screw extruder to prepare NA-11/NA-CA/iPP composites. The mechanical properties, crystallization behaviors and microstructure were characterized by universal material testing machine, XRD, DSC and polarized optical microscopy (PLM). The results show that NA-11 and NA-CA nucleating agents combined can improve the tensile properties and the flexural properties of iPP. The combined nucleating agent induces the formation of α phase iPP. The crystallization peak temperature increases by 20.3 ℃ and the crystallinity increases by 8.8% when 0.4wt% 1:1 combined nucleating agents are added into iPP. PLM show that the combined nucleating agents make the spherulite size of iPP decrease obviously. NA-11 and NA-CA combined nucleating agents show good nucleating efficiency and two nucleating agents show synergistic effects on improving crystallization behaviors and mechanical properties of iPP.
Combined effect of sodium 2,2'-methylene-bis-(4, 6-di-tert-butyphenyl) phosphate (NA-11) and sodium bicycle[2, 2, 1]-heptane-2, 3-dicarboxylate (NA-CA) on mechanical properties and crystallization behaviors of isotactic polypropylene (iPP) were investigated. The nucleating agents and iPP were blended using a twin-screw extruder to prepare NA-11/NA-CA/iPP composites. The mechanical properties, crystallization behaviors and microstructure were characterized by universal material testing machine, XRD, DSC and polarized optical microscopy (PLM). The results show that NA-11 and NA-CA nucleating agents combined can improve the tensile properties and the flexural properties of iPP. The combined nucleating agent induces the formation of α phase iPP. The crystallization peak temperature increases by 20.3 ℃ and the crystallinity increases by 8.8% when 0.4wt% 1:1 combined nucleating agents are added into iPP. PLM show that the combined nucleating agents make the spherulite size of iPP decrease obviously. NA-11 and NA-CA combined nucleating agents show good nucleating efficiency and two nucleating agents show synergistic effects on improving crystallization behaviors and mechanical properties of iPP.
2016, 33(9): 2013-2021.
doi: 10.13801/j.cnki.fhclxb.20151211.003
Abstract:
Extracted active ingredients(SBGE)from natural plant Scutellaria baicalensis Georgi (SBG) and compounded with biodegradable material poly (butylene succinate) (PBS). In order to improve the compatibility between them, two PBS modified products were synthesized: PBS—OH and PBS—COOH. The interfacial interactions of the SBGE/PBS composites were discussed, and the effects of SBGE on the performances of PBS materials were studied. The results show that the introduction of the —OH and —COOH improve the compatibility between the matrix and hydrophilic extracts which reinforce the hydrogen bonds between each other and enhance the interfacial bond strength. The addition of SBGE has almost no impact on the crystalline of PBS. Thermal properties of 1% SBGE/PBS, 3% SBGE/PBS—OH and 1% SBGE/PBS—COOH are the best, and higher than the matrix itself; mechanical properties of 7% SBGE/PBS, 3% SBGE/PBS—OH and 1% SBGE/PBS—COOH are better than others; and the change of antibacterial properties all further indicate the existences of the interaction. The comprehensive properties of the SBGE/PBS—OH and SBGE/PBS—COOH are superior to SBGE/PBS.
Extracted active ingredients(SBGE)from natural plant Scutellaria baicalensis Georgi (SBG) and compounded with biodegradable material poly (butylene succinate) (PBS). In order to improve the compatibility between them, two PBS modified products were synthesized: PBS—OH and PBS—COOH. The interfacial interactions of the SBGE/PBS composites were discussed, and the effects of SBGE on the performances of PBS materials were studied. The results show that the introduction of the —OH and —COOH improve the compatibility between the matrix and hydrophilic extracts which reinforce the hydrogen bonds between each other and enhance the interfacial bond strength. The addition of SBGE has almost no impact on the crystalline of PBS. Thermal properties of 1% SBGE/PBS, 3% SBGE/PBS—OH and 1% SBGE/PBS—COOH are the best, and higher than the matrix itself; mechanical properties of 7% SBGE/PBS, 3% SBGE/PBS—OH and 1% SBGE/PBS—COOH are better than others; and the change of antibacterial properties all further indicate the existences of the interaction. The comprehensive properties of the SBGE/PBS—OH and SBGE/PBS—COOH are superior to SBGE/PBS.
2016, 33(9): 2022-2029.
doi: 10.13801/j.cnki.fhclxb.20151109.002
Abstract:
With poplar wood flour as filling material, polyvinyl chloride (PVC) as matrix materials, by adding bamboo charcoal and chitosan, bamboo charcoal and chitosan modified wood powder/PVC wood-plastic composites were prepared by extrusion molding. The surface micro morphology of the composites was observed by SEM. The thermostability and the functional group variation of the composites were analyzed by comprehensive thermal analyzer and FTIR, respectively. And the mechanical properties of the wood flour/PVC wood-plastic composites were also measured. The results show that the compound of bamboo charcoal and chitosan could effectively improve the interface reaction and interface compatibility between wood flour and PVC and increase the mechanical properties of the composites. The tensile strength, impact strength, flexural strength and flexural modulus of the composites added bamboo charcoal and chitosan increase 14.6%, 28.8%, 11.1% and 4.85% compared with those of wood flour/PVC composites, respectively, and the micro interface defect of the composites was less. Bamboo charcoal could enhance the thermostability of the composites. The compound of bamboo charcoal and chitosan could increase the amount of hydroxyl, amidogen and methylene groups in the composites, and decrease the adhesive strength of carbon-chlorine bond, which will reinforce the interface bonding force between wood flour and PVC of composites.
With poplar wood flour as filling material, polyvinyl chloride (PVC) as matrix materials, by adding bamboo charcoal and chitosan, bamboo charcoal and chitosan modified wood powder/PVC wood-plastic composites were prepared by extrusion molding. The surface micro morphology of the composites was observed by SEM. The thermostability and the functional group variation of the composites were analyzed by comprehensive thermal analyzer and FTIR, respectively. And the mechanical properties of the wood flour/PVC wood-plastic composites were also measured. The results show that the compound of bamboo charcoal and chitosan could effectively improve the interface reaction and interface compatibility between wood flour and PVC and increase the mechanical properties of the composites. The tensile strength, impact strength, flexural strength and flexural modulus of the composites added bamboo charcoal and chitosan increase 14.6%, 28.8%, 11.1% and 4.85% compared with those of wood flour/PVC composites, respectively, and the micro interface defect of the composites was less. Bamboo charcoal could enhance the thermostability of the composites. The compound of bamboo charcoal and chitosan could increase the amount of hydroxyl, amidogen and methylene groups in the composites, and decrease the adhesive strength of carbon-chlorine bond, which will reinforce the interface bonding force between wood flour and PVC of composites.
2016, 33(9): 2030-2037.
doi: 10.13801/j.cnki.fhclxb.20151223.005
Abstract:
A new kind of high damping viscoelastic material which can co-cure with glass fiber/BA9913 epoxy resin prepreg in low-temperature was investigated by the orthogonal test. After the high damping material was dissolved in tetrahydrofuran (THF)dissolvant to form viscoelastic material solution. The double-side brush coating process was developed to make the glass fiber/BA9913 epoxy resin composites into prepreg with damping membrane. According to the design layer, the embedded low-temperature co-curing high damping composite specimens were manufactured on the basis of autoclave curing process. The modal tests and interlaminar shear tests were used to verify the validity of the processing technology and viscoelastic material ingredient presented in this paper. The first order modal loss factor of specimen is up to 7.2%. The conclusions lay the foundation for the wide application of embedded low-temperature co-curing high damping composites.
A new kind of high damping viscoelastic material which can co-cure with glass fiber/BA9913 epoxy resin prepreg in low-temperature was investigated by the orthogonal test. After the high damping material was dissolved in tetrahydrofuran (THF)dissolvant to form viscoelastic material solution. The double-side brush coating process was developed to make the glass fiber/BA9913 epoxy resin composites into prepreg with damping membrane. According to the design layer, the embedded low-temperature co-curing high damping composite specimens were manufactured on the basis of autoclave curing process. The modal tests and interlaminar shear tests were used to verify the validity of the processing technology and viscoelastic material ingredient presented in this paper. The first order modal loss factor of specimen is up to 7.2%. The conclusions lay the foundation for the wide application of embedded low-temperature co-curing high damping composites.
2016, 33(9): 2038-2044.
doi: 10.13801/j.cnki.fhclxb.20151109.003
Abstract:
The poly(ε-caprolactone) (PCL) and chitosan (CS) as excellent biodegradable polymers were blended in glacial acetic acid solution, and then the CS/PCL composite membranes were prepared by casting method with different CS:PCL mass ratios of 0:100, 5:95, 10:90, 15:85, 20: 80, 100:0. The micromorphology and structure characteristics were detected by the XRD, FTIR, 1HNMR, SEM and AFM. The results show that PCL and CS have good compatibility, and strong hydrogen bonds form between molecules and new chemical bonds between PCL end carboxyl and CS side chain hydroxyl, which makes the structure of CS/PCL composite membranes stable. The blend ratio of CS/PCL composite membranes has a great influence on the structure characteristics and micromorphology. The crystallinity and porosity of CS/PCL(10:90)composite membranes are 29.97% and 85.61% respectively, and it shows prevented leakage surface and internal connected porous microstructure. All the results initially identifies 10:90 as the best blend ratio between CS and PCL. The micromorphology and structure analysis of CS/PCL composite membranes with different blend ratios provide an important theoretical basis for their development and application.
The poly(ε-caprolactone) (PCL) and chitosan (CS) as excellent biodegradable polymers were blended in glacial acetic acid solution, and then the CS/PCL composite membranes were prepared by casting method with different CS:PCL mass ratios of 0:100, 5:95, 10:90, 15:85, 20: 80, 100:0. The micromorphology and structure characteristics were detected by the XRD, FTIR, 1HNMR, SEM and AFM. The results show that PCL and CS have good compatibility, and strong hydrogen bonds form between molecules and new chemical bonds between PCL end carboxyl and CS side chain hydroxyl, which makes the structure of CS/PCL composite membranes stable. The blend ratio of CS/PCL composite membranes has a great influence on the structure characteristics and micromorphology. The crystallinity and porosity of CS/PCL(10:90)composite membranes are 29.97% and 85.61% respectively, and it shows prevented leakage surface and internal connected porous microstructure. All the results initially identifies 10:90 as the best blend ratio between CS and PCL. The micromorphology and structure analysis of CS/PCL composite membranes with different blend ratios provide an important theoretical basis for their development and application.
2016, 33(9): 2045-2053.
doi: 10.13801/j.cnki.fhclxb.20151117.001
Abstract:
Using three different length chain alkyl quaternary ammonium cationic surfactants which are dodecyl trimethyl ammonium bromide (DTAB) , tetradecyl trimethyl ammonium bromide (TTAB) and cetrimonium bromide(CTAB) to modify the fly ash floating beads (FAFB).The polyaniline @organic modified fly ash floating beads (PAn@OFAFB) composites were obtained by emulsion polymerization using modified products and aniline(An). The structure characterization and electrorheological property of composites were analyzed by chemical element analysis, FTIR, XRD, SEM, TGA, four point probe technique , LCR dielectric spectrometer and rotational viscometer. The results show that the longer the carbon chain length of modified agents, the better modification effect, and the surface of FAFB modified with CTAB obtains the maximum adsorption amount, surface adsorption ratio is 1.91wt%, the PAn and OFAFB compound better and FAFB surface is surrounded by more PAn. The highest conductivity is 0.06 S·cm-1 which obtained by polyaniline @ cetrimonium bromide modified fly ash floating beads (PAn@FAFB-CTAB).The electrorheological effect of electrorheological fluid with PAn@FAFB-CTAB as dispersed phase is better than PAn-dodecylbenzene sulfonic acid (PAn-DBSA) and the breakdown capacity increases by 0.5 kV/mm compared with pure PAn. The suspension stability of composites can be improved by making FAFB as the carrier of PAn.The thermal stability of composites is enhanced significantly owing to the introduction of FAFB-CTAB, and the relative amount of PAn coated is 28.07wt%.
Using three different length chain alkyl quaternary ammonium cationic surfactants which are dodecyl trimethyl ammonium bromide (DTAB) , tetradecyl trimethyl ammonium bromide (TTAB) and cetrimonium bromide(CTAB) to modify the fly ash floating beads (FAFB).The polyaniline @organic modified fly ash floating beads (PAn@OFAFB) composites were obtained by emulsion polymerization using modified products and aniline(An). The structure characterization and electrorheological property of composites were analyzed by chemical element analysis, FTIR, XRD, SEM, TGA, four point probe technique , LCR dielectric spectrometer and rotational viscometer. The results show that the longer the carbon chain length of modified agents, the better modification effect, and the surface of FAFB modified with CTAB obtains the maximum adsorption amount, surface adsorption ratio is 1.91wt%, the PAn and OFAFB compound better and FAFB surface is surrounded by more PAn. The highest conductivity is 0.06 S·cm-1 which obtained by polyaniline @ cetrimonium bromide modified fly ash floating beads (PAn@FAFB-CTAB).The electrorheological effect of electrorheological fluid with PAn@FAFB-CTAB as dispersed phase is better than PAn-dodecylbenzene sulfonic acid (PAn-DBSA) and the breakdown capacity increases by 0.5 kV/mm compared with pure PAn. The suspension stability of composites can be improved by making FAFB as the carrier of PAn.The thermal stability of composites is enhanced significantly owing to the introduction of FAFB-CTAB, and the relative amount of PAn coated is 28.07wt%.
2016, 33(9): 2054-2060.
doi: 10.13801/j.cnki.fhclxb.20151118.001
Abstract:
Graphene oxide (GO) was modified by silane coupling agent 3-triethoxysilyl-1-propanamine(KH-550) and hydrazine hydrate with chemical grafting technology, and functionalized graphene (FG) was prepared. Light-emitting diode (LED) packaged FG/phenyl-silicone rubber composites were synthesized by blending FG and phenyl-silicone rubber through hydrogenated silane method under the effect of platinum catalyst. Effects of modified FG structure, variation of surface functional group and amount on mechanical properties and optical properties of FG/phenyl-silicone rubber composites were studied. Microscopic morphology and thermal stability of FG/phenyl-silicone rubber composites were analyzed. The results show that special functional group are attached on surface of FG modified by KH-550, which will improve the dispersion in phenyl-silicone rubber. Transmittance of FG/phenyl-silicone rubber composites can reach more than 85% by introducing 0.010 0wt% FG in phenyl-silicone rubber, ultraviolet aging resistance properties and mechanical properties were significantly improved. Thermal decomposition temperature of FG/phenyl-silicone rubber composites is 690 ℃, GO/phenyl-silicone rubber composites is 623 ℃, and pure phenyl-silicone rubber is 491 ℃. Heat release of FG/phenyl-silicone rubber composites is lower than that of pure phenyl-silicone rubber. By introducing 0.010 0wt% modified FG in phenyl-silicone rubber, the thermal decomposition temperature of materials will increase by 200 ℃ and heat release decreases which will meet the thermal stability requirements of functional LED composite packaging materials.
Graphene oxide (GO) was modified by silane coupling agent 3-triethoxysilyl-1-propanamine(KH-550) and hydrazine hydrate with chemical grafting technology, and functionalized graphene (FG) was prepared. Light-emitting diode (LED) packaged FG/phenyl-silicone rubber composites were synthesized by blending FG and phenyl-silicone rubber through hydrogenated silane method under the effect of platinum catalyst. Effects of modified FG structure, variation of surface functional group and amount on mechanical properties and optical properties of FG/phenyl-silicone rubber composites were studied. Microscopic morphology and thermal stability of FG/phenyl-silicone rubber composites were analyzed. The results show that special functional group are attached on surface of FG modified by KH-550, which will improve the dispersion in phenyl-silicone rubber. Transmittance of FG/phenyl-silicone rubber composites can reach more than 85% by introducing 0.010 0wt% FG in phenyl-silicone rubber, ultraviolet aging resistance properties and mechanical properties were significantly improved. Thermal decomposition temperature of FG/phenyl-silicone rubber composites is 690 ℃, GO/phenyl-silicone rubber composites is 623 ℃, and pure phenyl-silicone rubber is 491 ℃. Heat release of FG/phenyl-silicone rubber composites is lower than that of pure phenyl-silicone rubber. By introducing 0.010 0wt% modified FG in phenyl-silicone rubber, the thermal decomposition temperature of materials will increase by 200 ℃ and heat release decreases which will meet the thermal stability requirements of functional LED composite packaging materials.
2016, 33(9): 2061-2066.
doi: 10.13801/j.cnki.fhclxb.20151113.001
Abstract:
In order to obtain wollastonite filled β-polypropylene (W/β-PP) composites with high toughness, calcium pimelate-supported wollasonite (β-W) was used to fill polypropylene (PP). The β-nucleating effect of β-W in W/β-PP composites was investigated, and mechanical properties of wollastonite and β-W filled PP composites were compared. The results show that wollastonite filled polypropylene (W/PP) composites mainly form α-crystal, while β-W has strong β-nucleating effect for PP crystallization. The notched impact strength of W/PP composites is lower than that of β-polypropylene (β-PP), and the synergistic effect of toughening between wollastonite and β-crystal results in higher notched impact strength of W/β-PP composites compare with β-PP. The notched impact strength of W/β-PP composites increase firstly and then decrease with the increase of the β-W content and reaches to the maximum at the mass fraction of 5%. In addition, the reinforcement of wollastonite enhances the stiffness of β-PP.
In order to obtain wollastonite filled β-polypropylene (W/β-PP) composites with high toughness, calcium pimelate-supported wollasonite (β-W) was used to fill polypropylene (PP). The β-nucleating effect of β-W in W/β-PP composites was investigated, and mechanical properties of wollastonite and β-W filled PP composites were compared. The results show that wollastonite filled polypropylene (W/PP) composites mainly form α-crystal, while β-W has strong β-nucleating effect for PP crystallization. The notched impact strength of W/PP composites is lower than that of β-polypropylene (β-PP), and the synergistic effect of toughening between wollastonite and β-crystal results in higher notched impact strength of W/β-PP composites compare with β-PP. The notched impact strength of W/β-PP composites increase firstly and then decrease with the increase of the β-W content and reaches to the maximum at the mass fraction of 5%. In addition, the reinforcement of wollastonite enhances the stiffness of β-PP.
2016, 33(9): 2067-2073.
doi: 10.13801/j.cnki.fhclxb.20151112.004
Abstract:
Ni/Al and (Ni+La2O3)/Al composites were fabricated by adding micron Ni powder and (Ni+La2O3) mixed powder to the Al matrix with means of the friction stir processing. The microstructures and phase composition of the composite zone were analyzed by SEM, EDS and XRD. Mechanical properties of Ni/Al and (Ni+La2O3)/Al composites were tested by tensile test at room temperature. Results show that Ni/Al composites are mainly composed of Al, Al3Ni and agglomerates of Ni powder, the size of agglomerates of Ni powder is very coarse and the morphology is core-shell structure. The core is composed of agglomerated Ni, the shell is composed of the reinforced phase layer of Al3Ni; La2O3 reinforces Al-Ni in-situ reaction to produce more reinforced phase; La2O3 reduces the agglomeration of Ni powder by retarding the mutual adsorption and aggregated behavior of Ni powder; The tensile strength of (Ni+La2O3)/Al composites can reach 186 MPa. Compared with the Al matrix(tensile strength is 72 MPa), the FSPed Al(tensile strength is 90 MPa) and Ni/Al composites(tensile strength is 144 MPa), the tensile strength of (Ni+La2O3)/Al composites has increased by 158%, 107% and 29% respectively.
Ni/Al and (Ni+La2O3)/Al composites were fabricated by adding micron Ni powder and (Ni+La2O3) mixed powder to the Al matrix with means of the friction stir processing. The microstructures and phase composition of the composite zone were analyzed by SEM, EDS and XRD. Mechanical properties of Ni/Al and (Ni+La2O3)/Al composites were tested by tensile test at room temperature. Results show that Ni/Al composites are mainly composed of Al, Al3Ni and agglomerates of Ni powder, the size of agglomerates of Ni powder is very coarse and the morphology is core-shell structure. The core is composed of agglomerated Ni, the shell is composed of the reinforced phase layer of Al3Ni; La2O3 reinforces Al-Ni in-situ reaction to produce more reinforced phase; La2O3 reduces the agglomeration of Ni powder by retarding the mutual adsorption and aggregated behavior of Ni powder; The tensile strength of (Ni+La2O3)/Al composites can reach 186 MPa. Compared with the Al matrix(tensile strength is 72 MPa), the FSPed Al(tensile strength is 90 MPa) and Ni/Al composites(tensile strength is 144 MPa), the tensile strength of (Ni+La2O3)/Al composites has increased by 158%, 107% and 29% respectively.
2016, 33(9): 2074-2081.
doi: 10.13801/j.cnki.fhclxb.20151112.005
Abstract:
Mo2C coating was fabricated throughout the low-density carbon/carbon (C/C) preform from inside by a molten salt method, and then C/C-Cu composite was obtained by pressureless infiltration. The structure and tribological property with electric current of C/C-Cu composite were studied. The results show that molten Cu infiltrates into the Mo2C-modified C/C preform spontaneously and retains interpenetrating network structure with the C/C preform. The Mo2C coating presents good interfacial bonding with Cu and PyC, and pyrolytic carbon(PyC) near the Mo2C coating presents an order degree improvement as a result of catalytic and stress graphitization in process of generating Mo2C. With the increase of load, the friction coefficient of C/C-Cu composite decreases, the volume wear rate increases, while the mass loss of counter part decreases gradually. The worn surface under higher load is coated by a more continuous friction film, while roughness of the worn film increases due to adhesion wear. The material experiences oxidation wear during the wear process, and the content of oxygen on wear surface increases with the increase of load.
Mo2C coating was fabricated throughout the low-density carbon/carbon (C/C) preform from inside by a molten salt method, and then C/C-Cu composite was obtained by pressureless infiltration. The structure and tribological property with electric current of C/C-Cu composite were studied. The results show that molten Cu infiltrates into the Mo2C-modified C/C preform spontaneously and retains interpenetrating network structure with the C/C preform. The Mo2C coating presents good interfacial bonding with Cu and PyC, and pyrolytic carbon(PyC) near the Mo2C coating presents an order degree improvement as a result of catalytic and stress graphitization in process of generating Mo2C. With the increase of load, the friction coefficient of C/C-Cu composite decreases, the volume wear rate increases, while the mass loss of counter part decreases gradually. The worn surface under higher load is coated by a more continuous friction film, while roughness of the worn film increases due to adhesion wear. The material experiences oxidation wear during the wear process, and the content of oxygen on wear surface increases with the increase of load.
2016, 33(9): 2082-2087.
doi: 10.13801/j.cnki.fhclxb.20151216.002
Abstract:
Two step anodic oxidation method was firstly used to prepare freestanding porous silicon. Then ZnO nanocrystal layer was deposited in the freestanding porous silicon using vacuum filtration method and hydro-thermal synthesis approach was used for further growth of ZnO nanocrystals finally. The morphology, element and luminescence properties of the samples were characterized by scanning electron microscope, X-ray energy dispersive spectrum analysis and photoluminence spectrum analysis. The results show that ZnO nanoparticles exist in the freestanding porous silicon and porous silicon/ZnO composites form successfully. Moreover, the electrochemical tests of the composites as a supercapacitor electrode was conducted by cyclic voltamerty, impendance spectrum and galvanostatic charge/discharge tests. The composites have good supercapacitor property. The specific capacitances can reach 15.7 F/g, with an increase of 120 times compared with the freestanding porous silicon.
Two step anodic oxidation method was firstly used to prepare freestanding porous silicon. Then ZnO nanocrystal layer was deposited in the freestanding porous silicon using vacuum filtration method and hydro-thermal synthesis approach was used for further growth of ZnO nanocrystals finally. The morphology, element and luminescence properties of the samples were characterized by scanning electron microscope, X-ray energy dispersive spectrum analysis and photoluminence spectrum analysis. The results show that ZnO nanoparticles exist in the freestanding porous silicon and porous silicon/ZnO composites form successfully. Moreover, the electrochemical tests of the composites as a supercapacitor electrode was conducted by cyclic voltamerty, impendance spectrum and galvanostatic charge/discharge tests. The composites have good supercapacitor property. The specific capacitances can reach 15.7 F/g, with an increase of 120 times compared with the freestanding porous silicon.
2016, 33(9): 2088-2093.
doi: 10.13801/j.cnki.fhclxb.20160328.003
Abstract:
Si-B-N fibers were prepared by melt-spinning, curing and pyrolysis under high temperature of a precursor polyborosilazane(PBSZ) under NH3 atmosphere, then the fibers were heated up to ultra-high temperature under purity N2. The ultra-high temperature resistance property of the fibers was researched by elemental analysis, FTIR, XRD, SEM, mechanical properties analysis and wave-guide methods. The results show that the weight of Si-B-N fibers lose little annealed at 1 500 ℃, the fibers can remain amorphous up to 1 700 ℃ in inert atmospheres, and a mixture of Si3N4 and BN crystalline phases are observed upon heating to 1 850 ℃; average tensile strength and average elastic modulus of Si-B-N fibers are 1.72 GPa and 196 GPa at room temperature respectively, and they are 1.86 GPa and 205 GPa annealed at 1 500 ℃, respectively. So the fibers exhibit excellent ultra-high temperature resistance property. In addition, the Si-B-N fibers show good dielectric properties according to the measurement by a wave-guide method, average dielectric constant and dielectric loss tangent of the Si-B-N fibers annealed at 1 400 ℃ are about 3.68 and 0.001 1 in 8-12 GHz, respectively.
Si-B-N fibers were prepared by melt-spinning, curing and pyrolysis under high temperature of a precursor polyborosilazane(PBSZ) under NH3 atmosphere, then the fibers were heated up to ultra-high temperature under purity N2. The ultra-high temperature resistance property of the fibers was researched by elemental analysis, FTIR, XRD, SEM, mechanical properties analysis and wave-guide methods. The results show that the weight of Si-B-N fibers lose little annealed at 1 500 ℃, the fibers can remain amorphous up to 1 700 ℃ in inert atmospheres, and a mixture of Si3N4 and BN crystalline phases are observed upon heating to 1 850 ℃; average tensile strength and average elastic modulus of Si-B-N fibers are 1.72 GPa and 196 GPa at room temperature respectively, and they are 1.86 GPa and 205 GPa annealed at 1 500 ℃, respectively. So the fibers exhibit excellent ultra-high temperature resistance property. In addition, the Si-B-N fibers show good dielectric properties according to the measurement by a wave-guide method, average dielectric constant and dielectric loss tangent of the Si-B-N fibers annealed at 1 400 ℃ are about 3.68 and 0.001 1 in 8-12 GHz, respectively.
2016, 33(9): 2094-2103.
doi: 10.13801/j.cnki.fhclxb.20151028.002
Abstract:
Polyaspartic acid(PASP)/lignocellulose (LNC) hydrogels were synthesized through aqueous polymerization method; the effects of pretreatment time, pretreatment temperature, KMnO4 concentration, glutaraldehyde amount, PASP amount, reaction time and reaction temperature on adsorption property of PASP/LNC hydrogels for Pb2+, Cd2+ were evaluated; the maximum adsorption capacity of PASP/LNC hydrogels was calculated by Langmuir adsorption isotherm; HNO3 was used to perform desorption and regeneration experiments of PASP/LNC hydrogels; the structure of the hydrogels was characterized by SEM and FTIR. The adsorption result shows that when the pretreatment time is 15 min, the pretreatment temperature is 50 ℃, the KMnO4 concentration is 0.06 mol·L-1, the glutaraldehyde amount is 1.00 g, the PASP amount is 11 g, the reaction time is 3.5 h and the reaction temperature is 70 ℃, the equilibrium adsorption capality for Pb2+, Cd2+ could reach 980.39 mg·g-1, 813.01 mg·g-1. The adsorption/desorption cycling experiment indicates that the adsorption capality of PASP/LNC hydrogels is ideal after four cycles of adsorption/desorption, so PASP/LNC hydrogels are confirmed as a adsorbent for recycling. The characterization results show that the surface of PASP/LNC hydrogels has gap of varying sizes, polycondensation reaction is developed between —COOH of PASP and O—H of LNC, which forms hydrogels of three-dimensional network structure.
Polyaspartic acid(PASP)/lignocellulose (LNC) hydrogels were synthesized through aqueous polymerization method; the effects of pretreatment time, pretreatment temperature, KMnO4 concentration, glutaraldehyde amount, PASP amount, reaction time and reaction temperature on adsorption property of PASP/LNC hydrogels for Pb2+, Cd2+ were evaluated; the maximum adsorption capacity of PASP/LNC hydrogels was calculated by Langmuir adsorption isotherm; HNO3 was used to perform desorption and regeneration experiments of PASP/LNC hydrogels; the structure of the hydrogels was characterized by SEM and FTIR. The adsorption result shows that when the pretreatment time is 15 min, the pretreatment temperature is 50 ℃, the KMnO4 concentration is 0.06 mol·L-1, the glutaraldehyde amount is 1.00 g, the PASP amount is 11 g, the reaction time is 3.5 h and the reaction temperature is 70 ℃, the equilibrium adsorption capality for Pb2+, Cd2+ could reach 980.39 mg·g-1, 813.01 mg·g-1. The adsorption/desorption cycling experiment indicates that the adsorption capality of PASP/LNC hydrogels is ideal after four cycles of adsorption/desorption, so PASP/LNC hydrogels are confirmed as a adsorbent for recycling. The characterization results show that the surface of PASP/LNC hydrogels has gap of varying sizes, polycondensation reaction is developed between —COOH of PASP and O—H of LNC, which forms hydrogels of three-dimensional network structure.
2016, 33(9): 2104-2114.
doi: 10.13801/j.cnki.fhclxb.20151105.001
Abstract:
In order to obtain the effect laws of circular hole on the impact resistance of glass fiber reinforced aluminum (GLARE) laminates, the drop weight low velocity impact tests on GLARE laminates without hole and with a circular hole were performed with impact energy of 40 J, and the impact load, deflection, and energy-time curves were obtained. The commercial finite element software ABAQUS/Explicit finite element amalysis software was employed to simulate the tests and predict the effect of circular hole diameter on the impact resistance of GLARE laminates. The results show that the damage patterns of fiber layers in GLARE laminates are mainly delamination damage and fiber fracture under low velocity impact. The impact peak load of laminates increases with increasing distance between the edge of circular hole and impacted center, while the peak deflection decreases. The comparison between numerical simulation results and test results verifies the rationality of the model. With the increase of circular hole diameter, the impact resistance of GLARE laminates decreases gradually.
In order to obtain the effect laws of circular hole on the impact resistance of glass fiber reinforced aluminum (GLARE) laminates, the drop weight low velocity impact tests on GLARE laminates without hole and with a circular hole were performed with impact energy of 40 J, and the impact load, deflection, and energy-time curves were obtained. The commercial finite element software ABAQUS/Explicit finite element amalysis software was employed to simulate the tests and predict the effect of circular hole diameter on the impact resistance of GLARE laminates. The results show that the damage patterns of fiber layers in GLARE laminates are mainly delamination damage and fiber fracture under low velocity impact. The impact peak load of laminates increases with increasing distance between the edge of circular hole and impacted center, while the peak deflection decreases. The comparison between numerical simulation results and test results verifies the rationality of the model. With the increase of circular hole diameter, the impact resistance of GLARE laminates decreases gradually.
2016, 33(9): 2115-2122.
doi: 10.13801/j.cnki.fhclxb.20151106.002
Abstract:
In order to investigate the mechanical properties of nanofiber-reinforced closed-cell foams, the micro-geometry structures of closed-cell foams were simulated by Voronoi random foam model, and nanofiber was distributed in cell walls of foams randomly, fiber nodes and matrix nodes were coupled by the improved automatic search coupling (ASC) technology, thus the numerical model which can reflect the micro-structures of nanofiber-reinforced closed-cell foams was established. On the basis, the influence rules of random level of foam model, relative density as well as aspect ratio and mass fraction of nanofiber on elastic modulus and yield strength of nanofiber-reinforced closed-cell foams were investigated further. The results show that the elastic modulus and yield strength of nanofiber-reinforced closed-cell foams obtained by the numerical model established agree well with the experimental values. The increase for random degree of foam model will enhance the elastic modulus and yield strength of composite foams, while after the random degree reaches 0.450, the elastic modulus and yield strength of the materials change little. When the relative density changing in the range of 0.05-0.30, the elastic modulus and yield strength of composite foams almost increase linearly with the increase of relative density. The elastic modulus and yield strength of the materials can also be enhanced by increase the aspect ratio and mass fraction of nanofiber, while the strengthening effect of fiber aspect ratio gradually weakens after fiber aspect ratio achieves 500. The conclusions obtained have significance for the preparation of nanofiber-reinforced closed-cell foams.
In order to investigate the mechanical properties of nanofiber-reinforced closed-cell foams, the micro-geometry structures of closed-cell foams were simulated by Voronoi random foam model, and nanofiber was distributed in cell walls of foams randomly, fiber nodes and matrix nodes were coupled by the improved automatic search coupling (ASC) technology, thus the numerical model which can reflect the micro-structures of nanofiber-reinforced closed-cell foams was established. On the basis, the influence rules of random level of foam model, relative density as well as aspect ratio and mass fraction of nanofiber on elastic modulus and yield strength of nanofiber-reinforced closed-cell foams were investigated further. The results show that the elastic modulus and yield strength of nanofiber-reinforced closed-cell foams obtained by the numerical model established agree well with the experimental values. The increase for random degree of foam model will enhance the elastic modulus and yield strength of composite foams, while after the random degree reaches 0.450, the elastic modulus and yield strength of the materials change little. When the relative density changing in the range of 0.05-0.30, the elastic modulus and yield strength of composite foams almost increase linearly with the increase of relative density. The elastic modulus and yield strength of the materials can also be enhanced by increase the aspect ratio and mass fraction of nanofiber, while the strengthening effect of fiber aspect ratio gradually weakens after fiber aspect ratio achieves 500. The conclusions obtained have significance for the preparation of nanofiber-reinforced closed-cell foams.
2016, 33(9): 2123-2131.
doi: 10.13801/j.cnki.fhclxb.20160112.007
Abstract:
In order to analyze the influences of freeze-thaw cycle on the crack resistance of styrene-butadiene-styrene (SBS) and crumb rubber (CR) modified asphalt mixtures, semicircle specimen flexural tensile tests were performed on salt solution freeze-thaw cycled and water solution freeze-thaw cycled modified asphalt mixtures firstly. At the same time, speckle images for the surfaces of specimens during the loading processes were processed using digital speckle correlation technique (DSCT), and the information of displacement field and strain field for the surfaces of the specimens changing with the load was extracted. Then, the crack resistance of asphalt mixtures was determined by analyzing the deformation field information and the results were compared with the fracture toughness test results. The results show that the horizontal strain is more suitable for the characteristic investigation on crack resistance of asphalt mixture. Both of the crack resistances for SBS and CR modified asphalt mixtures are degraded at some degree after freeze-thaw cycle, and the influence of salt solution freeze-thaw cycle on the crack resistance of asphalt mixture is greater than that of water solution freeze-thaw cycle according to horizontal strain-time curves. Compared with SBS modified asphalt mixture, the crack resistance of CR modified asphalt mixture is better. The conclusions obtained show that the analysis results of DSCT are consistent with the analysis results of fracture toughness tests, and indicates that it is feasible to evaluate the crack resistance of asphalt mixture adopting DSCT.
In order to analyze the influences of freeze-thaw cycle on the crack resistance of styrene-butadiene-styrene (SBS) and crumb rubber (CR) modified asphalt mixtures, semicircle specimen flexural tensile tests were performed on salt solution freeze-thaw cycled and water solution freeze-thaw cycled modified asphalt mixtures firstly. At the same time, speckle images for the surfaces of specimens during the loading processes were processed using digital speckle correlation technique (DSCT), and the information of displacement field and strain field for the surfaces of the specimens changing with the load was extracted. Then, the crack resistance of asphalt mixtures was determined by analyzing the deformation field information and the results were compared with the fracture toughness test results. The results show that the horizontal strain is more suitable for the characteristic investigation on crack resistance of asphalt mixture. Both of the crack resistances for SBS and CR modified asphalt mixtures are degraded at some degree after freeze-thaw cycle, and the influence of salt solution freeze-thaw cycle on the crack resistance of asphalt mixture is greater than that of water solution freeze-thaw cycle according to horizontal strain-time curves. Compared with SBS modified asphalt mixture, the crack resistance of CR modified asphalt mixture is better. The conclusions obtained show that the analysis results of DSCT are consistent with the analysis results of fracture toughness tests, and indicates that it is feasible to evaluate the crack resistance of asphalt mixture adopting DSCT.
2016, 33(9): 2132-2140.
doi: 10.13801/j.cnki.fhclxb.20151124.001
Abstract:
In order to improve the photocatalytic activity of TiO2, the poly-2-aminobenzene sulfonic acid modified TiO2 (P2ABSA/TiO2) nano particles were synthesized via the in situ oxidative polymerization method. The prepared nano particles were characterized by TEM, EDS, XRD, UV-Vis DRS and Photocurrent Test. The methylene blue was used as simulated pollutants, the synthesis conditions of nano materials were optimized, the influences of initial pH value and P2ABSA/TiO2 concentration on photocatalytic effect were investigated, the contributions of reactive oxidation species were determined by using trap experiment in photocatalytic process. The results show that the optimum synthesis conditions of P2ABSA/TiO2 nano particles are P2ABSA, TiO2 and oxidant amount of substance ratio 2:1:2, HCl concentration 1.2 mol/L. There is a P2ABSA film on the surface of TiO2. The modification of P2ABSA does not impact on the phase and grain size of TiO2. P2ABSA/TiO2 nano particles enhance the response to visible light and photocurrent density (from 18.3 μA/cm2 to 28.7 μA/cm2). The photocatalytic degradation rate of methylene blue increases from 92.0% to 99.0%, with initial pH value increasing from 3.93 to 11.36, the optimum concentration of P2ABSA/TiO2 nano particles is 1.5 g/L. The contribution order of reactive oxidation species in photocatalytic process is ·OH > h+ > ·O2-, the photosensitization effect of P2ABSA to TiO2 is a key reason for enhancing photocatalytic activity of P2ABSA/TiO2 nano particles.
In order to improve the photocatalytic activity of TiO2, the poly-2-aminobenzene sulfonic acid modified TiO2 (P2ABSA/TiO2) nano particles were synthesized via the in situ oxidative polymerization method. The prepared nano particles were characterized by TEM, EDS, XRD, UV-Vis DRS and Photocurrent Test. The methylene blue was used as simulated pollutants, the synthesis conditions of nano materials were optimized, the influences of initial pH value and P2ABSA/TiO2 concentration on photocatalytic effect were investigated, the contributions of reactive oxidation species were determined by using trap experiment in photocatalytic process. The results show that the optimum synthesis conditions of P2ABSA/TiO2 nano particles are P2ABSA, TiO2 and oxidant amount of substance ratio 2:1:2, HCl concentration 1.2 mol/L. There is a P2ABSA film on the surface of TiO2. The modification of P2ABSA does not impact on the phase and grain size of TiO2. P2ABSA/TiO2 nano particles enhance the response to visible light and photocurrent density (from 18.3 μA/cm2 to 28.7 μA/cm2). The photocatalytic degradation rate of methylene blue increases from 92.0% to 99.0%, with initial pH value increasing from 3.93 to 11.36, the optimum concentration of P2ABSA/TiO2 nano particles is 1.5 g/L. The contribution order of reactive oxidation species in photocatalytic process is ·OH > h+ > ·O2-, the photosensitization effect of P2ABSA to TiO2 is a key reason for enhancing photocatalytic activity of P2ABSA/TiO2 nano particles.
