2017 Vol. 34, No. 12
2017, 34(12): 2643-2652.
doi: 10.13801/j.cnki.fhclxb.20170327.003
Abstract:
The functionalized graphene(FG-PEI)was prepared from graphite by oxidizing, modifying with poly(ethylene imine) (PEI) and reducing with hydrazine hydrate.The FG-PEI was mixed with UV waterborne polyurethane(WPU) to prepare FG-PEI/WPU composite coating adhesive to modify WPU. The structure of the FG-PEI was characterized by FTIR, XRD, Raman, XPS, SEM, TEM, the dispersibility of the FG-PEI was investigated, the influences of the dosage of FG-PEI on electrical conductivity, and the thermal stability and the mechanical properties of FG-PEI/WPU film were also studied. The results show that FG can be dispersed well in dimethyl formamide and WPU. With the increase of the dosage of FG-PEI, the electrical resistivity of the film decreases and the tensile strength of the film increases, and elongation at break of the film decreases. The thermal stability of WPU is improved after being modified by FG-PEI. The study results show that the modification WPU with FG-PEI can improve the electrical conductivity and water resistance of the film, thus the film has good performance.
The functionalized graphene(FG-PEI)was prepared from graphite by oxidizing, modifying with poly(ethylene imine) (PEI) and reducing with hydrazine hydrate.The FG-PEI was mixed with UV waterborne polyurethane(WPU) to prepare FG-PEI/WPU composite coating adhesive to modify WPU. The structure of the FG-PEI was characterized by FTIR, XRD, Raman, XPS, SEM, TEM, the dispersibility of the FG-PEI was investigated, the influences of the dosage of FG-PEI on electrical conductivity, and the thermal stability and the mechanical properties of FG-PEI/WPU film were also studied. The results show that FG can be dispersed well in dimethyl formamide and WPU. With the increase of the dosage of FG-PEI, the electrical resistivity of the film decreases and the tensile strength of the film increases, and elongation at break of the film decreases. The thermal stability of WPU is improved after being modified by FG-PEI. The study results show that the modification WPU with FG-PEI can improve the electrical conductivity and water resistance of the film, thus the film has good performance.
2017, 34(12): 2653-2660.
doi: 10.13801/j.cnki.fhclxb.20170323.002
Abstract:
The CNT sheet prepregs were fabricated by cyano resin solution impregnating continuous carbon nanotube (CNT) sheet, which was prepared by floating catalyst chemical vapor deposition grown (FCCVD) method. A well aligned CNT sheet composite was fabricated by subsequent hot-stretching treatment and hot pressing process. The effects of hot-stretching temperature and resin solution concentration on the tensile properties of the CNT prepregs were analyzed and the hot-stretching process was optimized. The effect of curing cycle on the tensile properties of CNT sheet reinforced cyano resin matrix composite was studied. Through analyzing the wetting characteristics, CNT alignment and interlaminar shear strength, the strengthen mechanisms of CNT sheet reinforced cyano resin matrix composites were revealed. The results indicate that the CNT sheet prepreg hot stretching process is more beneficial for getting highly aligned CNTs within the CNT sheet reinforced cyano resin matrix composite than the traditional CNT sheet stretching process. The temperature and resin solution concentration are the key factors to prepare high property cyano resin impregnated CNT film, which has high CNT orientation and low porosity. Through changing the curing cycle, the extent of reaction of cyano resin and the tensile properties of the CNT sheet/cyano resin composite are improved. The tensile strength and modulus of the CNT sheet/cyano resin composite reach up to 2 748 MPa and 302 GPa after postprocessing. Benefited from the superior wetting property, the high interlaminar shear strength and the high alignment degree of CNTs, the CNT sheet/cyano resin composite shows high tensile properties, due to efficient load bearing inside the CNT network.
The CNT sheet prepregs were fabricated by cyano resin solution impregnating continuous carbon nanotube (CNT) sheet, which was prepared by floating catalyst chemical vapor deposition grown (FCCVD) method. A well aligned CNT sheet composite was fabricated by subsequent hot-stretching treatment and hot pressing process. The effects of hot-stretching temperature and resin solution concentration on the tensile properties of the CNT prepregs were analyzed and the hot-stretching process was optimized. The effect of curing cycle on the tensile properties of CNT sheet reinforced cyano resin matrix composite was studied. Through analyzing the wetting characteristics, CNT alignment and interlaminar shear strength, the strengthen mechanisms of CNT sheet reinforced cyano resin matrix composites were revealed. The results indicate that the CNT sheet prepreg hot stretching process is more beneficial for getting highly aligned CNTs within the CNT sheet reinforced cyano resin matrix composite than the traditional CNT sheet stretching process. The temperature and resin solution concentration are the key factors to prepare high property cyano resin impregnated CNT film, which has high CNT orientation and low porosity. Through changing the curing cycle, the extent of reaction of cyano resin and the tensile properties of the CNT sheet/cyano resin composite are improved. The tensile strength and modulus of the CNT sheet/cyano resin composite reach up to 2 748 MPa and 302 GPa after postprocessing. Benefited from the superior wetting property, the high interlaminar shear strength and the high alignment degree of CNTs, the CNT sheet/cyano resin composite shows high tensile properties, due to efficient load bearing inside the CNT network.
2017, 34(12): 2661-2667.
doi: 10.13801/j.cnki.fhclxb.20170314.004
Abstract:
To improve the mechanical and thermal properties of polypropylene (PP) matrix composites, ultrafine bamboo-char (UFBC) was introduced into PP by twin-screw extrusion and injection moulding. Effects of different mass fractions of UFBC on the properties of the resulting UFBC/PP composites were investigated. A combination of SEM, DSC, mechanical test and moisture absorption test was performed to provide a comprehensive analysis of the structure and properties of UFBC/PP composites. Uniform dispersion of UFBC in the PP matrix and good interaction via physical interfacial interlocks were observed with SEM. The addition of UFBC has remarkable impact on mechanical properties of the composites. Tensile strength and bending strength increase with the increase of UFBC contents, and reach maximum values of 26 MPa and 54 MPa, respectively when 30% mass fraction of UFBCaddition is used, which increase by 9% and 18% comparing with those of PP.The moisture resistance of UFBC/PP composites is still excellent, and the moisture absorption is less than 0.1%.DSC analysis illustrates that melting temperature increases by 3.1℃ when mass fraction of UFBC is 40%, and the crystallization temperature increases by 10.8℃ when the mass fraction of UFBC is 50%. The crystallization and fabricability of composites are improved with the addition of UFBC.
To improve the mechanical and thermal properties of polypropylene (PP) matrix composites, ultrafine bamboo-char (UFBC) was introduced into PP by twin-screw extrusion and injection moulding. Effects of different mass fractions of UFBC on the properties of the resulting UFBC/PP composites were investigated. A combination of SEM, DSC, mechanical test and moisture absorption test was performed to provide a comprehensive analysis of the structure and properties of UFBC/PP composites. Uniform dispersion of UFBC in the PP matrix and good interaction via physical interfacial interlocks were observed with SEM. The addition of UFBC has remarkable impact on mechanical properties of the composites. Tensile strength and bending strength increase with the increase of UFBC contents, and reach maximum values of 26 MPa and 54 MPa, respectively when 30% mass fraction of UFBCaddition is used, which increase by 9% and 18% comparing with those of PP.The moisture resistance of UFBC/PP composites is still excellent, and the moisture absorption is less than 0.1%.DSC analysis illustrates that melting temperature increases by 3.1℃ when mass fraction of UFBC is 40%, and the crystallization temperature increases by 10.8℃ when the mass fraction of UFBC is 50%. The crystallization and fabricability of composites are improved with the addition of UFBC.
2017, 34(12): 2668-2673.
doi: 10.13801/j.cnki.fhclxb.20170310.002
Abstract:
A series of sulfadiazine Ag(SD-Ag)/polyvinyl alcohol(PVA)hydrogel composites were preparated by e-Beam irradiation combining with freeze-thawing. The influence of preparation process of polyvinyl alcohol (PVA) hydrogel on its properties was investigated. The tensile strength, elongation at break, water absorption, gel content, morphologies of the surfaces and their relationships with the mass fraction of PVA and preparation process were characterized using tensile testing machine, SEM and FT-IR.The mechanical tests show that the tensile strength of PVA hydrogel increases with the mass fraction of PVA(5%-15%). When the mass fraction of PVA is 15%, and the irradiation doses is 25 kGy, the tensile strength of PVA hydrogel is 0.023 MPa, 0.048 MPa, 0.028 MPa and the water absorption is 95%, 45%, 63%, by e-Beam irradiation alone, freeze-thawing after irradiation and irradiation after freeze-thawing, respectively, which indicate that e-Beam irradiation combining with freeze-thawing increases the tensile strength and decreses the water absorption of the PVA hydrogel. The antibacterial activity of SD-Ag/PVA hydrogel was investigated after adding SD-Ag into the PVA hydrogel. The zones of inhibition show that the antibacterial activities can be enhanced with the mass fraction of SD-Ag increasing and that the composites have higher antibacterial activity towards Gram-negative bacteria (E. coli) than Gram-positive bacteria (S.aureus).
A series of sulfadiazine Ag(SD-Ag)/polyvinyl alcohol(PVA)hydrogel composites were preparated by e-Beam irradiation combining with freeze-thawing. The influence of preparation process of polyvinyl alcohol (PVA) hydrogel on its properties was investigated. The tensile strength, elongation at break, water absorption, gel content, morphologies of the surfaces and their relationships with the mass fraction of PVA and preparation process were characterized using tensile testing machine, SEM and FT-IR.The mechanical tests show that the tensile strength of PVA hydrogel increases with the mass fraction of PVA(5%-15%). When the mass fraction of PVA is 15%, and the irradiation doses is 25 kGy, the tensile strength of PVA hydrogel is 0.023 MPa, 0.048 MPa, 0.028 MPa and the water absorption is 95%, 45%, 63%, by e-Beam irradiation alone, freeze-thawing after irradiation and irradiation after freeze-thawing, respectively, which indicate that e-Beam irradiation combining with freeze-thawing increases the tensile strength and decreses the water absorption of the PVA hydrogel. The antibacterial activity of SD-Ag/PVA hydrogel was investigated after adding SD-Ag into the PVA hydrogel. The zones of inhibition show that the antibacterial activities can be enhanced with the mass fraction of SD-Ag increasing and that the composites have higher antibacterial activity towards Gram-negative bacteria (E. coli) than Gram-positive bacteria (S.aureus).
2017, 34(12): 2674-2680.
doi: 10.13801/j.cnki.fhclxb.20170320.001
Abstract:
The flame retardantcy polyethylene (PE) matrix composites were prepared by twin-screw extruder, with hydromagnesite (HM) and Mg(OH)2 as the flame retardants. The flame retardant properties and mechanism of HM-Mg(OH)2/PE flame retardant composites were investigated by limited oxygen index (LOI), vertical buring test (UL-94), cone calorimetric test (CCT) and universal tensile test. The thermal decomposition behavior of HM-Mg(OH)2/PE flame retardant composites was studied by thermogravimetric analysis (TGA). The results show that, the flame retardant in appropriate proportions of HM and Mg(OH)2 decomposes in the combustion temperature range which leads to a better flame retardantcy. In the premise of the same LOI and tensile strength, the cost of PE composite with synergistic flame retardant decreases significantly compared with Mg(OH)2 as flame retardant alone. The ineffective even negative decomposition of HM reduces in the synergistic flame retardant, and the inhibitory effect on the decomposition by the PE matrix with HM under high temperature is retained, at the same time, a relatively stable scaly protective layer forms in the combustion region surface, in adition, the total lost mass of synergistic flame composite is higher. With those variety of factors, the flame retardancy effect of the synergistic flame composite is higher. The HM-Mg(OH2)/PE flame retardant composites pass the UL-94 V-0 rating with LOI value of 28%, and the tensile strength reaches 28.8 MPa when the mass ratio of HM to Mg(OH)2 is 1:2 with 60wt% loading.
The flame retardantcy polyethylene (PE) matrix composites were prepared by twin-screw extruder, with hydromagnesite (HM) and Mg(OH)2 as the flame retardants. The flame retardant properties and mechanism of HM-Mg(OH)2/PE flame retardant composites were investigated by limited oxygen index (LOI), vertical buring test (UL-94), cone calorimetric test (CCT) and universal tensile test. The thermal decomposition behavior of HM-Mg(OH)2/PE flame retardant composites was studied by thermogravimetric analysis (TGA). The results show that, the flame retardant in appropriate proportions of HM and Mg(OH)2 decomposes in the combustion temperature range which leads to a better flame retardantcy. In the premise of the same LOI and tensile strength, the cost of PE composite with synergistic flame retardant decreases significantly compared with Mg(OH)2 as flame retardant alone. The ineffective even negative decomposition of HM reduces in the synergistic flame retardant, and the inhibitory effect on the decomposition by the PE matrix with HM under high temperature is retained, at the same time, a relatively stable scaly protective layer forms in the combustion region surface, in adition, the total lost mass of synergistic flame composite is higher. With those variety of factors, the flame retardancy effect of the synergistic flame composite is higher. The HM-Mg(OH2)/PE flame retardant composites pass the UL-94 V-0 rating with LOI value of 28%, and the tensile strength reaches 28.8 MPa when the mass ratio of HM to Mg(OH)2 is 1:2 with 60wt% loading.
2017, 34(12): 2681-2688.
doi: 10.13801/j.cnki.fhclxb.20170401.001
Abstract:
With the enzymatic hydrolysis lignin (EHL) as the raw materials, and the phenol-sulfuric acid method was used to modify EHL. Under alkaline conditions, the lignin-epoxy resin (L-EP) was synthesized by phenolated lignin (PL) reacted with epichlorohydrin (ECH). The structure of EHL and its modification and the synthetic resin were analyzed by FT-IR. The effects of single factor reaction conditions on the process of phenolation were discussed. The results indicate that the effect of modification is the best under the condition of 3.0 h, 95℃ and 4 mL/g H2SO4 (2 mol/L), and the content of phenolic hydroxyl group reaches 4.632 mmol/g, which increases by 42% compared with EHL. The effects of different L-EP adding amount on the mechanical properties and thermal properties of L-EP/epoxy E-51 composites were investigated. The results show that the tensile strength of L-EP/epoxy E-51 composites is the best when the amount of L-EP is 5%, which increases by 26% compared with that of the pure E-51 epoxy resin. With the increase in the amount of L-EP, the thermal stability of L-EP/E-51 composites is enhanced. The non-isothermal method was used to analyze the curing kinetics of epoxy E-51 and L-EP/E-51 composites. The results reveal that L-EP has a certain effect on the curing of L-EP/epoxy resin composites.
With the enzymatic hydrolysis lignin (EHL) as the raw materials, and the phenol-sulfuric acid method was used to modify EHL. Under alkaline conditions, the lignin-epoxy resin (L-EP) was synthesized by phenolated lignin (PL) reacted with epichlorohydrin (ECH). The structure of EHL and its modification and the synthetic resin were analyzed by FT-IR. The effects of single factor reaction conditions on the process of phenolation were discussed. The results indicate that the effect of modification is the best under the condition of 3.0 h, 95℃ and 4 mL/g H2SO4 (2 mol/L), and the content of phenolic hydroxyl group reaches 4.632 mmol/g, which increases by 42% compared with EHL. The effects of different L-EP adding amount on the mechanical properties and thermal properties of L-EP/epoxy E-51 composites were investigated. The results show that the tensile strength of L-EP/epoxy E-51 composites is the best when the amount of L-EP is 5%, which increases by 26% compared with that of the pure E-51 epoxy resin. With the increase in the amount of L-EP, the thermal stability of L-EP/E-51 composites is enhanced. The non-isothermal method was used to analyze the curing kinetics of epoxy E-51 and L-EP/E-51 composites. The results reveal that L-EP has a certain effect on the curing of L-EP/epoxy resin composites.
2017, 34(12): 2689-2694.
doi: 10.13801/j.cnki.fhclxb.20170322.003
Abstract:
Halloysite nanotubes (HNTs)/Polyvinyl alcohol (PVA)-Starch composite films were prepared by solution casting method. And the structure and properties of HNTs/PVA-Starch composite films were investigated. The results show that with the increase of HNTs content, the mechanical properties, thermal stability, water resistance and ultraviolet-shielding property of HNTs/PVA-Starch composite membranes are improved. When the mass ratio of HNTs to PVA-Starch is 10%, the mechanical properties the composites are the best and the tensile strength increases by 22%. The morphological observations suggest that HNTs can be uniformly dispersed with a single tubular distribution and have good interfacial bonding in the HNTs/PVA-Starch composites. Dynamic mechanical analysis (DMA) shows that the addition of HNTs has little effect on the glass transition temperature of the HNTs/PVA-Starch composite film, while the storage modulus of the composite film increases and the mechanical loss decreases. The light transmittance test result shows that HNTs have little effect on the transparency of the HNTs/PVA-Starch composite film, while in the UV region (200-400 nm), the transmittance decreases with the increase of the amount of HNTs.
Halloysite nanotubes (HNTs)/Polyvinyl alcohol (PVA)-Starch composite films were prepared by solution casting method. And the structure and properties of HNTs/PVA-Starch composite films were investigated. The results show that with the increase of HNTs content, the mechanical properties, thermal stability, water resistance and ultraviolet-shielding property of HNTs/PVA-Starch composite membranes are improved. When the mass ratio of HNTs to PVA-Starch is 10%, the mechanical properties the composites are the best and the tensile strength increases by 22%. The morphological observations suggest that HNTs can be uniformly dispersed with a single tubular distribution and have good interfacial bonding in the HNTs/PVA-Starch composites. Dynamic mechanical analysis (DMA) shows that the addition of HNTs has little effect on the glass transition temperature of the HNTs/PVA-Starch composite film, while the storage modulus of the composite film increases and the mechanical loss decreases. The light transmittance test result shows that HNTs have little effect on the transparency of the HNTs/PVA-Starch composite film, while in the UV region (200-400 nm), the transmittance decreases with the increase of the amount of HNTs.
2017, 34(12): 2695-2701.
doi: 10.13801/j.cnki.fhclxb.20170321.002
Abstract:
The TiO2-linear low density polyethylene (LLDPE)-g-maleic anhydride (MA)/low density polyethylene (LDPE) film with photocatalytic degradation property was prepared by blending LLDPE-g-MA. The SEM, XRD and FT-IR were employed to characterize the properties of the prepared TiO2-(LLDPE-g-MA)/LDPE samples. The prepared TiO2-(LLDPE-g-MA)/LDPE film possesses higher elongation which could be attributed to the promoted the interphase force between the nanoTiO2 and LDPE. The SEM images demonstrate that the agglomeration of nanoTiO2 is obviously reduced. Therefore, the nanoTiO2 with higher dispersibility performs higher photocatalytic degradation efficiency and causes higher mass loss of TiO2-(LLDPE-g-MA)/LDPE film.
The TiO2-linear low density polyethylene (LLDPE)-g-maleic anhydride (MA)/low density polyethylene (LDPE) film with photocatalytic degradation property was prepared by blending LLDPE-g-MA. The SEM, XRD and FT-IR were employed to characterize the properties of the prepared TiO2-(LLDPE-g-MA)/LDPE samples. The prepared TiO2-(LLDPE-g-MA)/LDPE film possesses higher elongation which could be attributed to the promoted the interphase force between the nanoTiO2 and LDPE. The SEM images demonstrate that the agglomeration of nanoTiO2 is obviously reduced. Therefore, the nanoTiO2 with higher dispersibility performs higher photocatalytic degradation efficiency and causes higher mass loss of TiO2-(LLDPE-g-MA)/LDPE film.
2017, 34(12): 2702-2707.
doi: 10.13801/j.cnki.fhclxb.20170321.003
Abstract:
The coupling agent modified graphene oxide (GO) was added into phenolic resin to prepare basalt fabric reinforced phenolic composites. The influence of graphene oxide mass fraction on the mechanical and impact properties of basalt fabric reinforced phenolic composites was investigated. The results show that the addition of GO increases the flexural strength, modulus and interlaminar strength (ILSS) of the basalt fabric reinforced phenolic composites. The maximum flexural strength and modulus are obtained at the GO mass fraction of 2wt%, which is increased by nearly 39% and 25%, respectively. The maximu mimpact load and damage absorbed energy increase by 40% and 60%, respectively, after adding 1wt% GO.
The coupling agent modified graphene oxide (GO) was added into phenolic resin to prepare basalt fabric reinforced phenolic composites. The influence of graphene oxide mass fraction on the mechanical and impact properties of basalt fabric reinforced phenolic composites was investigated. The results show that the addition of GO increases the flexural strength, modulus and interlaminar strength (ILSS) of the basalt fabric reinforced phenolic composites. The maximum flexural strength and modulus are obtained at the GO mass fraction of 2wt%, which is increased by nearly 39% and 25%, respectively. The maximu mimpact load and damage absorbed energy increase by 40% and 60%, respectively, after adding 1wt% GO.
2017, 34(12): 2708-2714.
doi: 10.13801/j.cnki.fhclxb.20170329.001
Abstract:
The glass fiber, basalt fiber and carbon fiber surface were modified by laser, and three kinds of fiber/epoxy resin composites were prepared. The surface morphology and the mechanical properties of three kinds of fiber as well as the mechanical properties and the fracture morphology of three kinds of fiber/epoxy resin composites were characterized by SEM and universal testing machine. The effects of surface modification on the mechanical properties of the composites were studied. The results show that the laser surface modification of fibers can enhance the mechanical properties of carbon fiber/epoxy resin composite to the highest, in which the maximum tensile strength increases by 77.06% and the impact strength increases by 31.25%, while the improvement for basalt fiber/epoxy resin composites take the second place, however, the mechanical properties of glass fiber composites decrease. So the carbon fiber and basalt fiber are suitable for the surface modification by laser.
The glass fiber, basalt fiber and carbon fiber surface were modified by laser, and three kinds of fiber/epoxy resin composites were prepared. The surface morphology and the mechanical properties of three kinds of fiber as well as the mechanical properties and the fracture morphology of three kinds of fiber/epoxy resin composites were characterized by SEM and universal testing machine. The effects of surface modification on the mechanical properties of the composites were studied. The results show that the laser surface modification of fibers can enhance the mechanical properties of carbon fiber/epoxy resin composite to the highest, in which the maximum tensile strength increases by 77.06% and the impact strength increases by 31.25%, while the improvement for basalt fiber/epoxy resin composites take the second place, however, the mechanical properties of glass fiber composites decrease. So the carbon fiber and basalt fiber are suitable for the surface modification by laser.
2017, 34(12): 2715-2721.
doi: 10.13801/j.cnki.fhclxb.20170320.004
Abstract:
Montmorillonite containing Ca2+ (Ca-MMT) and montmorillonite modified with organic group (Na-MMT) were used in flame retardant ethylene vinyl acetate copolymer (EVA) with Al(OH)3, respectively. The effect of Ca-MMT was investigated on mechanical, thermal and flammability properties of Al(OH)3/EVA composites, compared with Na-MMT. MMT-Al(OH)3/EVA composites were processed by melt blending in a twin-screw extrude. XRD and TEM show that MMT achieves exfoliation in MMT-Al(OH)3/EVA composites and the exfoliated layer of Ca-MMT is relatively smaller than Na-MMT. Ca-MMT-Al(OH)3/EVA shows better tensile strength and thermal stability than Na-MMT-Al(OH)3/EVA. In Cone calorimeter test, Ca-MMT-Al(OH)3/EVA also performs better than Na-MMT-Al(OH)3/EVA with lower heat release. Moreover, the condensed phase of Ca-MMT-Al(OH)3/EVA exhibits higher thermal insulation through lower and flatter back-temperature curves of CONE, corresponding to the compact and intact residue char surface after CONE. All the evidences indicate that the exfoliation of Ca-MMT in Al(OH)3/EVA is conducive to barrier effect of flame retardancy and calcium ions of Ca-MMT can promote the charring of Al(OH)3/EVA. Finally, fire performance indexes (FPI) of MMT-Al(OH)3/EVA composites were calculated with the ratio of time to ignition (TTI) and heat-release peak value. The FPI data verify that the loading of Ca-MMT remarkably contributes to the increase of FPI, thus fire risk of Ca-MMT-Al(OH)3/EVA is significantly decreased.
Montmorillonite containing Ca2+ (Ca-MMT) and montmorillonite modified with organic group (Na-MMT) were used in flame retardant ethylene vinyl acetate copolymer (EVA) with Al(OH)3, respectively. The effect of Ca-MMT was investigated on mechanical, thermal and flammability properties of Al(OH)3/EVA composites, compared with Na-MMT. MMT-Al(OH)3/EVA composites were processed by melt blending in a twin-screw extrude. XRD and TEM show that MMT achieves exfoliation in MMT-Al(OH)3/EVA composites and the exfoliated layer of Ca-MMT is relatively smaller than Na-MMT. Ca-MMT-Al(OH)3/EVA shows better tensile strength and thermal stability than Na-MMT-Al(OH)3/EVA. In Cone calorimeter test, Ca-MMT-Al(OH)3/EVA also performs better than Na-MMT-Al(OH)3/EVA with lower heat release. Moreover, the condensed phase of Ca-MMT-Al(OH)3/EVA exhibits higher thermal insulation through lower and flatter back-temperature curves of CONE, corresponding to the compact and intact residue char surface after CONE. All the evidences indicate that the exfoliation of Ca-MMT in Al(OH)3/EVA is conducive to barrier effect of flame retardancy and calcium ions of Ca-MMT can promote the charring of Al(OH)3/EVA. Finally, fire performance indexes (FPI) of MMT-Al(OH)3/EVA composites were calculated with the ratio of time to ignition (TTI) and heat-release peak value. The FPI data verify that the loading of Ca-MMT remarkably contributes to the increase of FPI, thus fire risk of Ca-MMT-Al(OH)3/EVA is significantly decreased.
2017, 34(12): 2722-2733.
doi: 10.13801/j.cnki.fhclxb.20170301.002
Abstract:
In order to study the influence of structure parameters on process-induced distortions of V-shaped composite parts, a series of experiments were performed to analysis the effect of structure parameters including part thickness, part radius, part angle and lay-up. Based on the shear-lag theory and bending theory, an analytical model considering the effect of structure parameters was developed to predict the spring-in of V-shaped composite parts and the influence mechanism of different structure parameters on spring-in with the model was analyzed. The results show that spring-in decreases with the increase of the thickness and the maximum variation of spring-in angle is about 30% when thickness is between 1 mm and 3 mm. There is a proportion relationship whose value is about 0.014 between spring-in angles and part angle. The differences of spring-in angles which result from different radius are less than 5%. The test pieces with quasi-isotropic lay-up exhibit the biggest spring-in angles. The spring-in angles of 0° lay-up pieces decrease by 23.5% and 90° pieces almost have no spring-in. Analysis results show that the influence of thickness on spring-in should consider its effect on bending stiffness and shear deformation; Mechanical properties and Poisson's effect differences caused by lay-up are the main reasons for spring-in diversity; The maximum distortions of flange is 0.20°which has greatly influences on spring-in. The comparison between simulation results and experiment verifies the accuracy of analytical model.
In order to study the influence of structure parameters on process-induced distortions of V-shaped composite parts, a series of experiments were performed to analysis the effect of structure parameters including part thickness, part radius, part angle and lay-up. Based on the shear-lag theory and bending theory, an analytical model considering the effect of structure parameters was developed to predict the spring-in of V-shaped composite parts and the influence mechanism of different structure parameters on spring-in with the model was analyzed. The results show that spring-in decreases with the increase of the thickness and the maximum variation of spring-in angle is about 30% when thickness is between 1 mm and 3 mm. There is a proportion relationship whose value is about 0.014 between spring-in angles and part angle. The differences of spring-in angles which result from different radius are less than 5%. The test pieces with quasi-isotropic lay-up exhibit the biggest spring-in angles. The spring-in angles of 0° lay-up pieces decrease by 23.5% and 90° pieces almost have no spring-in. Analysis results show that the influence of thickness on spring-in should consider its effect on bending stiffness and shear deformation; Mechanical properties and Poisson's effect differences caused by lay-up are the main reasons for spring-in diversity; The maximum distortions of flange is 0.20°which has greatly influences on spring-in. The comparison between simulation results and experiment verifies the accuracy of analytical model.
2017, 34(12): 2734-2740.
doi: 10.13801/j.cnki.fhclxb.20170706.004
Abstract:
The thermo-physical property experiments had been done for the 3D 4-directional braided composites with different braiding parameters in thermal environment. The changing rule and distribution characteristics of the thermo-physical properties for the 3D 4-directional braided composites were obtained. The effects of temperature and braiding angle on the coefficients of thermal expansion (CTE), the coefficients of thermal conduction (CTC), the specific heat(SH) and the thermal diffusivities(TD) were investigated at the same time, by which some important conclusions were drawn. These results can provide an experimental basis for the numerical analysis on the thermo-physical properties and the further studies on the thermo-mechanical coupling behaviors of 3D braided composites.
The thermo-physical property experiments had been done for the 3D 4-directional braided composites with different braiding parameters in thermal environment. The changing rule and distribution characteristics of the thermo-physical properties for the 3D 4-directional braided composites were obtained. The effects of temperature and braiding angle on the coefficients of thermal expansion (CTE), the coefficients of thermal conduction (CTC), the specific heat(SH) and the thermal diffusivities(TD) were investigated at the same time, by which some important conclusions were drawn. These results can provide an experimental basis for the numerical analysis on the thermo-physical properties and the further studies on the thermo-mechanical coupling behaviors of 3D braided composites.
2017, 34(12): 2741-2746.
doi: 10.13801/j.cnki.fhclxb.20170307.004
Abstract:
The thermostamping process of carbon fiber reinforced thermoplastic resin composites (CFRTP) involves large deformation, anisotropy and multi-field coupling phenomenon. In order to characterize these mechanical behaviors of CFRTP, a lamination model combining thermoplastic resin and carbon woven fabric was established based on continuum mechanics and finite element method. Compared with the hyperelastic model of woven fabric, the proposed lamination model can simulate the condition of wrinkling visually at different forming temperatures, blank holder force and fiber orientation and optimize these process parameters in the thermostamping process. The proposed model is simple, useful and easy for material parameter determination. It provides a theoretical foundation for the numerical simulation and processing optimization of CFRTP forming.
The thermostamping process of carbon fiber reinforced thermoplastic resin composites (CFRTP) involves large deformation, anisotropy and multi-field coupling phenomenon. In order to characterize these mechanical behaviors of CFRTP, a lamination model combining thermoplastic resin and carbon woven fabric was established based on continuum mechanics and finite element method. Compared with the hyperelastic model of woven fabric, the proposed lamination model can simulate the condition of wrinkling visually at different forming temperatures, blank holder force and fiber orientation and optimize these process parameters in the thermostamping process. The proposed model is simple, useful and easy for material parameter determination. It provides a theoretical foundation for the numerical simulation and processing optimization of CFRTP forming.
2017, 34(12): 2747-2755.
doi: 10.13801/j.cnki.fhclxb.20170308.001
Abstract:
In order to effectively simulate the time-dependent, nonlinear and multiphysics response of the new type of multi-functional smart materials-metal core piezoelectric and piezomagnetic fiber reinforced polymer matrix composite (MPPF/PMC), an incremental micromechanics model was developed based on the variational asymptotic method. Firstly, the incremental constitutive equations of polymer, piezoelectric/piezomagnetic materials and metal materials were derived respectively, and a unified constitutive equation was established. Considering the time-dependent and nonlinear characteristics of composites, an incremental procedure in conjunction with an instantaneous tangential electro-magneto-mechanical matrix of composites was established. The fluctuate functions of field variables were solved by minimizing the approximate energy functional and realized by finite element method, resulting in a micromechanics model as close as possible to the physical and engineering authenticity. The numerical example of aluminum core piezoelectric (BaTiO3) and piezomagnetic (CoFe2O4) polymer matrix shows that this constructed model can be used to simulate the effective response of MPPF/PMCs under different physical fields and can accurately capture the stress mutation phenomenon between the fiber and the matrix.
In order to effectively simulate the time-dependent, nonlinear and multiphysics response of the new type of multi-functional smart materials-metal core piezoelectric and piezomagnetic fiber reinforced polymer matrix composite (MPPF/PMC), an incremental micromechanics model was developed based on the variational asymptotic method. Firstly, the incremental constitutive equations of polymer, piezoelectric/piezomagnetic materials and metal materials were derived respectively, and a unified constitutive equation was established. Considering the time-dependent and nonlinear characteristics of composites, an incremental procedure in conjunction with an instantaneous tangential electro-magneto-mechanical matrix of composites was established. The fluctuate functions of field variables were solved by minimizing the approximate energy functional and realized by finite element method, resulting in a micromechanics model as close as possible to the physical and engineering authenticity. The numerical example of aluminum core piezoelectric (BaTiO3) and piezomagnetic (CoFe2O4) polymer matrix shows that this constructed model can be used to simulate the effective response of MPPF/PMCs under different physical fields and can accurately capture the stress mutation phenomenon between the fiber and the matrix.
2017, 34(12): 2756-2761.
doi: 10.13801/j.cnki.fhclxb.20170302.002
Abstract:
In order to study the strain rate sensitivity of laminate composites with brick-and-mortar microstructure, the mechanical properties of nacre were tested by nanoindentation test system. Continuous stiffness measurement (CSM) technique was adopted to obtain hardness and elastic modulus values under different strain rates. Scanning electron microscope (SEM) was used to observe the microstructure of nacre in different directions. The effects of indentation depths and strain rates on the mechanical properties of nacre both in the surface and the cross-section were investigated. Results show that, under the same loading condition, elastic modulus in the surface is lower than that in the cross-section, but hardness is higher, and under constant strain rate, elastic modulus and hardness of nacre are increased with the increase of indentation, and when indentation reaches 750 nm, the elastic modulus stays unchanged with indentation increasing, while when indentation is a constant, the hardness, elastic modulus and elastic recovery increase with the increase of strain rate.
In order to study the strain rate sensitivity of laminate composites with brick-and-mortar microstructure, the mechanical properties of nacre were tested by nanoindentation test system. Continuous stiffness measurement (CSM) technique was adopted to obtain hardness and elastic modulus values under different strain rates. Scanning electron microscope (SEM) was used to observe the microstructure of nacre in different directions. The effects of indentation depths and strain rates on the mechanical properties of nacre both in the surface and the cross-section were investigated. Results show that, under the same loading condition, elastic modulus in the surface is lower than that in the cross-section, but hardness is higher, and under constant strain rate, elastic modulus and hardness of nacre are increased with the increase of indentation, and when indentation reaches 750 nm, the elastic modulus stays unchanged with indentation increasing, while when indentation is a constant, the hardness, elastic modulus and elastic recovery increase with the increase of strain rate.
2017, 34(12): 2762-2769.
doi: 10.13801/j.cnki.fhclxb.20170307.005
Abstract:
The multi-bolt countersunk single-lap joint of SLM aluminum plate and CFRP composite laminate under tensional load was analyzed via numerical simulation and experiment. Damage initiation and progression in the structure were present in 3D FEM based on the progressive damage analysis (PDA), and the bolt load distributions as well as the failure loads and modes were compared with the physical test. With the consideration of fracture stain to stress triaxiality curve approximated by the author, it is found that there is only 1.9% difference of the failure loads between FEM and test, when both Ductile damage and Hashin criteria are introduced through UMAT. Besides, the failure modes are both pulling out illustrated in FEA and experiment. Consequently, the method assessed in this study has enough accuracy to satisfy the application requirement for such an engineering problem. The progressive damage process of both SLM aluminum plate and CFRP laminate were investigated with the validated FEM and the effect on the failure mode of the joint was studied with different stiffness of SLM aluminum plates. When the thickness of SLM aluminum plate increases to 4 mm, the pulling-out failure mode of the joints transfers from SLM aluminum plate to the CFRP composite laminate.
The multi-bolt countersunk single-lap joint of SLM aluminum plate and CFRP composite laminate under tensional load was analyzed via numerical simulation and experiment. Damage initiation and progression in the structure were present in 3D FEM based on the progressive damage analysis (PDA), and the bolt load distributions as well as the failure loads and modes were compared with the physical test. With the consideration of fracture stain to stress triaxiality curve approximated by the author, it is found that there is only 1.9% difference of the failure loads between FEM and test, when both Ductile damage and Hashin criteria are introduced through UMAT. Besides, the failure modes are both pulling out illustrated in FEA and experiment. Consequently, the method assessed in this study has enough accuracy to satisfy the application requirement for such an engineering problem. The progressive damage process of both SLM aluminum plate and CFRP laminate were investigated with the validated FEM and the effect on the failure mode of the joint was studied with different stiffness of SLM aluminum plates. When the thickness of SLM aluminum plate increases to 4 mm, the pulling-out failure mode of the joints transfers from SLM aluminum plate to the CFRP composite laminate.
2017, 34(12): 2770-2777.
doi: 10.13801/j.cnki.fhclxb.20170314.002
Abstract:
Ordered Ag nanowires(AgNW)@Au nanoparticles(AuNP) hybrid nanowires were synthesized on bare Si substrate using AgNW-water solution and HAuCl4-ethanol solution by three-phase-interface method and galvanic displacement reaction. Field emission SEM (FESEM) and high resolution TEM (HRTEM) were employed to analyze the influence of HAuCl4-ethanol concentration and reaction time of galvanic displacement reaction on the morphology of the hybrid nanowires. Fluorescence spectra and laser-Raman spectra were carried out to analyze the influence of various ordered AgNW@AuNP hybrid nanowires on the fluorescence properties of conjugated polymer poly(3-hexylthiophene) (P3HT). The results show that the AuNP particle sizes of ordered AgNW@AuNP hybrid nanowires increase when the reaction time or the concentration of HAuCl4-ethanol solution increases. The fluorescence properties of P3HT films are improved on various ordered AgNW@AuNP hybrid nanowires compared with those on bare silicon substrate, but the fluorescence intensity of P3HT films on the ordered hybrid nanowires decreases as the galvanic displacement process.
Ordered Ag nanowires(AgNW)@Au nanoparticles(AuNP) hybrid nanowires were synthesized on bare Si substrate using AgNW-water solution and HAuCl4-ethanol solution by three-phase-interface method and galvanic displacement reaction. Field emission SEM (FESEM) and high resolution TEM (HRTEM) were employed to analyze the influence of HAuCl4-ethanol concentration and reaction time of galvanic displacement reaction on the morphology of the hybrid nanowires. Fluorescence spectra and laser-Raman spectra were carried out to analyze the influence of various ordered AgNW@AuNP hybrid nanowires on the fluorescence properties of conjugated polymer poly(3-hexylthiophene) (P3HT). The results show that the AuNP particle sizes of ordered AgNW@AuNP hybrid nanowires increase when the reaction time or the concentration of HAuCl4-ethanol solution increases. The fluorescence properties of P3HT films are improved on various ordered AgNW@AuNP hybrid nanowires compared with those on bare silicon substrate, but the fluorescence intensity of P3HT films on the ordered hybrid nanowires decreases as the galvanic displacement process.
2017, 34(12): 2778-2784.
doi: 10.13801/j.cnki.fhclxb.20170310.001
Abstract:
The CF/Al2O3-20% Ni metal-ceramic composites with 0%, 5%, 10% and 15% volume fraction of carbon fiber (CF) were prepared by sol-gel method and hot-pressing sintering. The phase composition,surface and fracture morphology were analyzed by XRD, SEM and EDS. The effect of CF content on CF/Al2O3-20% Ni hardness, bending strength, fracture toughness was studied. The fracture morphology of composites was analyzed by SEM and its mechanism was discussed. The results show that CF/Al2O3-20% Ni composites with well dispersed CF and evenly distributed Ni particles was obtained, and can prevent the loss CF in the sintering process at high temperature by the formation of α-Al2O3 protective film layer on the CF surface. With the increase of volume fraction of CF, The hardness of the CF/Al2O3-20% Ni composites reduce, and its bending strength and fracture toughness first increase and then decrease. When the CF volume fraction is 10%, the bending strength and fracture toughness reach the maximum values, which increase by 79% and 134%, respectively, compared with the composites without CF. The addition of CF improves the strength and toughness of the CF/Al2O3-20% Ni composites. The toughening mechanism of CF/Al2O3-20% Ni is CF pull out, bridge and disbonding.
The CF/Al2O3-20% Ni metal-ceramic composites with 0%, 5%, 10% and 15% volume fraction of carbon fiber (CF) were prepared by sol-gel method and hot-pressing sintering. The phase composition,surface and fracture morphology were analyzed by XRD, SEM and EDS. The effect of CF content on CF/Al2O3-20% Ni hardness, bending strength, fracture toughness was studied. The fracture morphology of composites was analyzed by SEM and its mechanism was discussed. The results show that CF/Al2O3-20% Ni composites with well dispersed CF and evenly distributed Ni particles was obtained, and can prevent the loss CF in the sintering process at high temperature by the formation of α-Al2O3 protective film layer on the CF surface. With the increase of volume fraction of CF, The hardness of the CF/Al2O3-20% Ni composites reduce, and its bending strength and fracture toughness first increase and then decrease. When the CF volume fraction is 10%, the bending strength and fracture toughness reach the maximum values, which increase by 79% and 134%, respectively, compared with the composites without CF. The addition of CF improves the strength and toughness of the CF/Al2O3-20% Ni composites. The toughening mechanism of CF/Al2O3-20% Ni is CF pull out, bridge and disbonding.
2017, 34(12): 2785-2793.
doi: 10.13801/j.cnki.fhclxb.20170310.004
Abstract:
Arginine-glycine-aspartic (RGD) peptide was grafted to the surface of apatite-wollastonite (AW) via plasma-aided treatment. The bioactivity of the RGD-AW was investigated by SEM and EDS after immersing in simulated body fluid (SBF). The results show that modifying AW with RGD peptide enhance the HA deposition and in vitro mineralization properties, and the HA shows warm-like appearance. In order to survey the in vitro and in vivo biocompatibility of RGD-AW, MG-63 osteoblast-like cells were employed to co-culture with these two materials and animal test was carried out to evaluate the bone regenerative properties of RGD-AW materials. The fluorescence microscope result shows that RGD-AW improves the cell adhesion and spreading compared with AW. The histological evaluation of RGD-AW shows that the bone regeneration and remodeling process are significantly enhanced compared with the original AW after 2 weeks, 4 weeks and 8 weeks implantation, respectively. And the hematopoietic function reconstruction which is along with the structure remodeling is only observed on RGD-AW composite after 8 weeks implantation.
Arginine-glycine-aspartic (RGD) peptide was grafted to the surface of apatite-wollastonite (AW) via plasma-aided treatment. The bioactivity of the RGD-AW was investigated by SEM and EDS after immersing in simulated body fluid (SBF). The results show that modifying AW with RGD peptide enhance the HA deposition and in vitro mineralization properties, and the HA shows warm-like appearance. In order to survey the in vitro and in vivo biocompatibility of RGD-AW, MG-63 osteoblast-like cells were employed to co-culture with these two materials and animal test was carried out to evaluate the bone regenerative properties of RGD-AW materials. The fluorescence microscope result shows that RGD-AW improves the cell adhesion and spreading compared with AW. The histological evaluation of RGD-AW shows that the bone regeneration and remodeling process are significantly enhanced compared with the original AW after 2 weeks, 4 weeks and 8 weeks implantation, respectively. And the hematopoietic function reconstruction which is along with the structure remodeling is only observed on RGD-AW composite after 8 weeks implantation.
2017, 34(12): 2794-2799.
doi: 10.13801/j.cnki.fhclxb.20170320.007
Abstract:
The thermal-mechanical coupling buckling behavior of simply supported porous functionally graded beams was studied by classical Euler beam theory and high-order sinusoidal shear deformation theory. The correlation between material properties and temperature was considered, and the material properties of the porous functional graded beams were described by modified Voight mixture rule with porosity. The iterative algorithm was used to solve the critical thermal-mechanical coupling buckling temperature of the porous functionally graded beams under uniform, linear and nonlinear temperature rise (considering the heat conduction effect). And the influence of the parameters such as gradient distribution index, porosity and slenderness ratio on the critical buckling temperature were discussed. By comparing the results of ABAQUS and the literature, the theory is proved to be reliable, and the high-order sinusoidal shear deformation theory can obtain more accurate results than the classical Euler beam theory. The results show that in the analysis of the thermal buckling of functionally graded materials, the temperature dependence of material properties must be taken into account. Otherwise, the critical buckling temperature may be over-estimated by 10%-30%. As the porosity of the material increases, the equivalent elastic modulus of the functionally graded material will decrease, namely the structural stiffness will be weakened, while the critical buckling temperature of the structure will increase greatly.
The thermal-mechanical coupling buckling behavior of simply supported porous functionally graded beams was studied by classical Euler beam theory and high-order sinusoidal shear deformation theory. The correlation between material properties and temperature was considered, and the material properties of the porous functional graded beams were described by modified Voight mixture rule with porosity. The iterative algorithm was used to solve the critical thermal-mechanical coupling buckling temperature of the porous functionally graded beams under uniform, linear and nonlinear temperature rise (considering the heat conduction effect). And the influence of the parameters such as gradient distribution index, porosity and slenderness ratio on the critical buckling temperature were discussed. By comparing the results of ABAQUS and the literature, the theory is proved to be reliable, and the high-order sinusoidal shear deformation theory can obtain more accurate results than the classical Euler beam theory. The results show that in the analysis of the thermal buckling of functionally graded materials, the temperature dependence of material properties must be taken into account. Otherwise, the critical buckling temperature may be over-estimated by 10%-30%. As the porosity of the material increases, the equivalent elastic modulus of the functionally graded material will decrease, namely the structural stiffness will be weakened, while the critical buckling temperature of the structure will increase greatly.
2017, 34(12): 2800-2809.
doi: 10.13801/j.cnki.fhclxb.20170310.003
Abstract:
The ceramifiable ethylene propylene diene monomer(EPDM) composites with different fiber contents were prepared by taking EPDM as the matrix, kaolin and talc as the functional fillers, aluminum hydroxide as the flame retardant, and the chopped polyimide(PI) fiber as the reinforcement. The effects of chopped polyimide fibers on the tensile properties, thermal stability and microstructure of ceramifiable PI fiber-Kaolin-Talc-Al(OH)3/EPDM (PKTA/EPDM)composites were investigated, and the ceramicization mechanism of chopped polyimide fiber reinforced composites was analyzed. The results show that the tensile strength of the composites decreases with the increasing of the content of chopped polyimide fibers. When the chopped PI fibers are less than 10:100 (mass ratio to EPDM), the mechanical properties of the composites are good. The ceramifiable PKTA/EPDM composites can be ceramicized after pyrolysis at 800-1 100℃. The addition of 4:100-8:100 (mass ratio to EPDM) chopped polyimide fibers can effectively keep the shape stability of the composites after pyrolysis at 800-1 100℃, and the bending strength of the ceramic products is between 6-18 MPa. The results of thermal analysis show that the thermal stability of the composites can be improved by adding the chopped polyimide fibers. The results of thermal analysis and SEM analysis indicate that the pyrolysis and carbonization of the chopped PI fibers in the char layer form the structure of fiber-reinforced char layer. The PI fiber reinforced structure contributes to obtaining the well-shaped ceramic products in the pyrolysis of the PKTA/EPDM composites.
The ceramifiable ethylene propylene diene monomer(EPDM) composites with different fiber contents were prepared by taking EPDM as the matrix, kaolin and talc as the functional fillers, aluminum hydroxide as the flame retardant, and the chopped polyimide(PI) fiber as the reinforcement. The effects of chopped polyimide fibers on the tensile properties, thermal stability and microstructure of ceramifiable PI fiber-Kaolin-Talc-Al(OH)3/EPDM (PKTA/EPDM)composites were investigated, and the ceramicization mechanism of chopped polyimide fiber reinforced composites was analyzed. The results show that the tensile strength of the composites decreases with the increasing of the content of chopped polyimide fibers. When the chopped PI fibers are less than 10:100 (mass ratio to EPDM), the mechanical properties of the composites are good. The ceramifiable PKTA/EPDM composites can be ceramicized after pyrolysis at 800-1 100℃. The addition of 4:100-8:100 (mass ratio to EPDM) chopped polyimide fibers can effectively keep the shape stability of the composites after pyrolysis at 800-1 100℃, and the bending strength of the ceramic products is between 6-18 MPa. The results of thermal analysis show that the thermal stability of the composites can be improved by adding the chopped polyimide fibers. The results of thermal analysis and SEM analysis indicate that the pyrolysis and carbonization of the chopped PI fibers in the char layer form the structure of fiber-reinforced char layer. The PI fiber reinforced structure contributes to obtaining the well-shaped ceramic products in the pyrolysis of the PKTA/EPDM composites.
2017, 34(12): 2810-2818.
doi: 10.13801/j.cnki.fhclxb.20170314.001
Abstract:
Due to theosteoinduction of the bone morphogenetic protein-2 (BMP-2) and stabilization of bovine serum albumin (BSA), three types of new biological mat was fabricated, namely silk fibroin (SF)/poly (L-lactide-co-caprolactone)(PLCL) mat loaded with BMP-2 and BSA by coaxial electrospinning (BMP-2-BSA@SF/PLCL, Mat A), SF/PLCL mat loaded with BMP-2 and BSA by blend electrospinning (BMP-2-BSA-SF/PLCL, Mat B), non-loaded SF/PLCL mat (SF/PLCL, Mat C). The results of apparent characteristics show all the fibrous mats present homogeneous network structure, and the core-shell structure is formed only in Mat A. The physicochemical properties results show contact angle and mechanical properties of Mat A, Mat B and Mat C increase in turn. Although each group has good biocompatibility and barrier function, Mat A which has the ability of sustained drugrelease can stimulate growth and osteogenic differentiation of cells more effectively. The BMP-2-BSA@SF/PLCL fibrous mat can meet the requirements of guided bone regeneration (GBR) and will be used as the ideal carrier for bone defect repair.
Due to theosteoinduction of the bone morphogenetic protein-2 (BMP-2) and stabilization of bovine serum albumin (BSA), three types of new biological mat was fabricated, namely silk fibroin (SF)/poly (L-lactide-co-caprolactone)(PLCL) mat loaded with BMP-2 and BSA by coaxial electrospinning (BMP-2-BSA@SF/PLCL, Mat A), SF/PLCL mat loaded with BMP-2 and BSA by blend electrospinning (BMP-2-BSA-SF/PLCL, Mat B), non-loaded SF/PLCL mat (SF/PLCL, Mat C). The results of apparent characteristics show all the fibrous mats present homogeneous network structure, and the core-shell structure is formed only in Mat A. The physicochemical properties results show contact angle and mechanical properties of Mat A, Mat B and Mat C increase in turn. Although each group has good biocompatibility and barrier function, Mat A which has the ability of sustained drugrelease can stimulate growth and osteogenic differentiation of cells more effectively. The BMP-2-BSA@SF/PLCL fibrous mat can meet the requirements of guided bone regeneration (GBR) and will be used as the ideal carrier for bone defect repair.
2017, 34(12): 2819-2825.
doi: 10.13801/j.cnki.fhclxb.20170320.002
Abstract:
A magnesium phytic acid/hydroxyapatite composite coating was rapidly prepared on AZ31 Mg alloy substrate by microwave assisted method. The surface morphology and composition, as well as the corrosion resistance, were characterized by FESEM, EDS, XRD and electrochemical tests. The influence of pH value of phytic acid solution on the microstructure and corrosion resistance of the magnesium phytic acid/hydroxyapatite coatings was investigated. The biodegradation and biomineralization behavior of Mg alloy and its coatings in simulated body fluid (SBF) were evaluated via immersion tests. The results show that when the pH value of phytic acid solution is 5.0, the magnesium phytic acid/hydroxyapatite composite coating is uniform and crack-free, with a good interface bonding to the substrate. The electrochemical measurements in SBF reveal that magnesium phytic acid/hydroxyapatite coating with pH=5.0 exhibits the best corrosion resistance compared with those with other pH values. The magnesium phytic acid/hydroxyapatite composite coating can induce apatite deposition and effectively improve the corrosion resistance of Mg alloy in SBF.
A magnesium phytic acid/hydroxyapatite composite coating was rapidly prepared on AZ31 Mg alloy substrate by microwave assisted method. The surface morphology and composition, as well as the corrosion resistance, were characterized by FESEM, EDS, XRD and electrochemical tests. The influence of pH value of phytic acid solution on the microstructure and corrosion resistance of the magnesium phytic acid/hydroxyapatite coatings was investigated. The biodegradation and biomineralization behavior of Mg alloy and its coatings in simulated body fluid (SBF) were evaluated via immersion tests. The results show that when the pH value of phytic acid solution is 5.0, the magnesium phytic acid/hydroxyapatite composite coating is uniform and crack-free, with a good interface bonding to the substrate. The electrochemical measurements in SBF reveal that magnesium phytic acid/hydroxyapatite coating with pH=5.0 exhibits the best corrosion resistance compared with those with other pH values. The magnesium phytic acid/hydroxyapatite composite coating can induce apatite deposition and effectively improve the corrosion resistance of Mg alloy in SBF.
2017, 34(12): 2826-2833.
doi: 10.13801/j.cnki.fhclxb.20170303.003
Abstract:
Fe3O4/aspergillus Niger were prepared by adding culturing media nanoparticles in Fe3O4, then the static adsorption experiment was carried out, Through a static test, different experimental parameters such as solution pH, temperature, dosing, adsorption time and initial concentration were examined to investigate their effects on adsorption of U(Ⅵ) by Fe3O4/Aspergillus niger. The results show that pH value can be the important factor for affecting U(Ⅵ). When solution pH=4, 25℃, dosing quantity 1 g/L, U(Ⅵ) of the initial concentration is 10 mg/L, the adsorption rate is as high as 98.89%, adsorption process is verging to be balanced after 15 h. The prepared composites were characterized by SEM, EDS and FTIR. SEM-EDS show that part of the hyphae surface was coated with tiny particles and the structure is the grid. FTIR spectra demonstrate that -OH, -C═O and -CONH interact with U(Ⅵ).
Fe3O4/aspergillus Niger were prepared by adding culturing media nanoparticles in Fe3O4, then the static adsorption experiment was carried out, Through a static test, different experimental parameters such as solution pH, temperature, dosing, adsorption time and initial concentration were examined to investigate their effects on adsorption of U(Ⅵ) by Fe3O4/Aspergillus niger. The results show that pH value can be the important factor for affecting U(Ⅵ). When solution pH=4, 25℃, dosing quantity 1 g/L, U(Ⅵ) of the initial concentration is 10 mg/L, the adsorption rate is as high as 98.89%, adsorption process is verging to be balanced after 15 h. The prepared composites were characterized by SEM, EDS and FTIR. SEM-EDS show that part of the hyphae surface was coated with tiny particles and the structure is the grid. FTIR spectra demonstrate that -OH, -C═O and -CONH interact with U(Ⅵ).
2017, 34(12): 2834-2840.
doi: 10.13801/j.cnki.fhclxb.20170314.003
Abstract:
As (V) ion adsorbent was prepared by using diatomite as matrix, MnCl2 and NaOH as the complex modifiers. The effect of adsorbent dosage on the removal rate of As(V) was studied. The samples of the adsorbent before and after the modification were analyzed by SEM, IR, XRD and XPS. The results show that the removal rate of As(V) increases from 44.9% to 93.9% with the increase of MnCl2-NaOH/diatomite adsorbent. After modification, the diatom matrix is not changed, and the average pore size of MnCl2-NaOH/diatomite adsorbent increases and the specific surface area increases by nearly seven times. After the diatom modification, the active hydroxyl peak disappears, and the new Mn-O-Si absorption peak appears on the surface. XRD data show that Mn-O-Si phase is newly formed. The surface of Mn gets electrons, through oxidation and diatom surface formation of MnO2 composite grafting. The adsorption of As(V) ions on the adsorbent results in the formation of Mn3 (AsO4) (OH)4. As in the adsorption process, As gets electrons, Mn losses electrons, while O and Si surface electrons shift to As. Adsorption on the surface of MnCl2-NaOH/diatomite adsorbent is coordination adsorption, charge adsorption, and so on.
As (V) ion adsorbent was prepared by using diatomite as matrix, MnCl2 and NaOH as the complex modifiers. The effect of adsorbent dosage on the removal rate of As(V) was studied. The samples of the adsorbent before and after the modification were analyzed by SEM, IR, XRD and XPS. The results show that the removal rate of As(V) increases from 44.9% to 93.9% with the increase of MnCl2-NaOH/diatomite adsorbent. After modification, the diatom matrix is not changed, and the average pore size of MnCl2-NaOH/diatomite adsorbent increases and the specific surface area increases by nearly seven times. After the diatom modification, the active hydroxyl peak disappears, and the new Mn-O-Si absorption peak appears on the surface. XRD data show that Mn-O-Si phase is newly formed. The surface of Mn gets electrons, through oxidation and diatom surface formation of MnO2 composite grafting. The adsorption of As(V) ions on the adsorbent results in the formation of Mn3 (AsO4) (OH)4. As in the adsorption process, As gets electrons, Mn losses electrons, while O and Si surface electrons shift to As. Adsorption on the surface of MnCl2-NaOH/diatomite adsorbent is coordination adsorption, charge adsorption, and so on.
2017, 34(12): 2841-2845.
doi: 10.13801/j.cnki.fhclxb.20170313.002
Abstract:
Carbon nanotubes were modified by non covalent bond with trimethyl-1-propanaminium iodide (FC-134) which was a water soluble cationic surfactant. The modified carbon nanotubes/natural rubber composites were prepared with the liquid phase method. The effect of the modified carbon nanotubes on the properties of the composites was studied. The results show that the modified carbon nanotubes are stable in water. Payne effect shows that the interaction between carbon nanotubes is weakened, and the carbon nanotubes-rubber interaction is enhanced. And the carbon nanotubes are uniformly dispersed in the composites as the result of rubber processing analyzer (RPA). When compared to the pristine carbon nanotubes/natural rubber latex composites, the tear strength and tensile strength are increased by 65% and 29%, respectively.
Carbon nanotubes were modified by non covalent bond with trimethyl-1-propanaminium iodide (FC-134) which was a water soluble cationic surfactant. The modified carbon nanotubes/natural rubber composites were prepared with the liquid phase method. The effect of the modified carbon nanotubes on the properties of the composites was studied. The results show that the modified carbon nanotubes are stable in water. Payne effect shows that the interaction between carbon nanotubes is weakened, and the carbon nanotubes-rubber interaction is enhanced. And the carbon nanotubes are uniformly dispersed in the composites as the result of rubber processing analyzer (RPA). When compared to the pristine carbon nanotubes/natural rubber latex composites, the tear strength and tensile strength are increased by 65% and 29%, respectively.
2017, 34(12): 2846-2855.
doi: 10.13801/j.cnki.fhclxb.20170320.003
Abstract:
An amino-functionalized Fe3O4-ion imprinted poly(methyl methacrylate (MMA)-3-(2-amino-ethylamino)-2-hydroxypropyl methacrylate (HPMA)-divinylbenzene(DVB)) magnetic composite (Fe3O4@ion imprinted poly(ⅡP) (MMA-HPMA-DVB)) was synthesized via ultrasonic assisted suspension polymerization with nickel(Ⅱ) as ion imprinting template. The Fe3O4@ⅡP(MMA-HPMA-DVB) was characterized by EA, XRD, FTIR, TEM, TG and VSM. The application for its adsorption properties on Ni(Ⅱ) from water was investigated. The results show that the Fe3O4@ⅡP(MMA-HPMA-DVB) has an average size of 100 nm, with the saturation magnetization intensity of 43.8 emu/g. The carbonyl group of the co-monomer methyl methacrylate (MMA) can connect with the hydroxyl group at the surface of the nano-Fe3O4 via hydrogen bonds, which would be favorable to the formation and stabilization of the coreashell structure of the Fe3O4@ⅡP(MMA-HPMA-DVB). The adsorption capacities were investigated by adsorbing the Ni(Ⅱ) from aqueous solutions, which demonstrate an excellent adsorption capacity with the maximum adsorption capacity (qm,c at 500 mg/g, qm,e at 478 mg/g) much higher than that of amino-functionalized nano-Fe3O4-none-ion imprinted polymer magnetic material (Fe3O4@NIP(MMA-HPMA-DVB) (qm,c at 90.9 mg/g, qm,e at 83.8 mg/g). The isothermal adsorption curve mainly obeys the Langmuir mode. The adsorption kinetic studies show that the adsorption processes reach the equilibrium within 5 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 Ni(Ⅱ), with imprinting factor (α) at 1.9, and selectivity factor (β) more than 7.7 for several kinds of common co-existing ions, respectively. The Fe3O4@ⅡP(MMA-HPMA-DVB) is an ideal candidate for adsorption and recycle Ni(Ⅱ) from aqueous solution.
An amino-functionalized Fe3O4-ion imprinted poly(methyl methacrylate (MMA)-3-(2-amino-ethylamino)-2-hydroxypropyl methacrylate (HPMA)-divinylbenzene(DVB)) magnetic composite (Fe3O4@ion imprinted poly(ⅡP) (MMA-HPMA-DVB)) was synthesized via ultrasonic assisted suspension polymerization with nickel(Ⅱ) as ion imprinting template. The Fe3O4@ⅡP(MMA-HPMA-DVB) was characterized by EA, XRD, FTIR, TEM, TG and VSM. The application for its adsorption properties on Ni(Ⅱ) from water was investigated. The results show that the Fe3O4@ⅡP(MMA-HPMA-DVB) has an average size of 100 nm, with the saturation magnetization intensity of 43.8 emu/g. The carbonyl group of the co-monomer methyl methacrylate (MMA) can connect with the hydroxyl group at the surface of the nano-Fe3O4 via hydrogen bonds, which would be favorable to the formation and stabilization of the coreashell structure of the Fe3O4@ⅡP(MMA-HPMA-DVB). The adsorption capacities were investigated by adsorbing the Ni(Ⅱ) from aqueous solutions, which demonstrate an excellent adsorption capacity with the maximum adsorption capacity (qm,c at 500 mg/g, qm,e at 478 mg/g) much higher than that of amino-functionalized nano-Fe3O4-none-ion imprinted polymer magnetic material (Fe3O4@NIP(MMA-HPMA-DVB) (qm,c at 90.9 mg/g, qm,e at 83.8 mg/g). The isothermal adsorption curve mainly obeys the Langmuir mode. The adsorption kinetic studies show that the adsorption processes reach the equilibrium within 5 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 Ni(Ⅱ), with imprinting factor (α) at 1.9, and selectivity factor (β) more than 7.7 for several kinds of common co-existing ions, respectively. The Fe3O4@ⅡP(MMA-HPMA-DVB) is an ideal candidate for adsorption and recycle Ni(Ⅱ) from aqueous solution.
2017, 34(12): 2856-2865.
doi: 10.13801/j.cnki.fhclxb.20170407.001
Abstract:
In order to further reveal the mechanism of chloride erosion to cement matrix composite materials under dry-wet cycling, the resistance to chloride erosion of two kinds of water to cement ratio of cement concrete, mortar and paste specimens under dry-wet cycling were studied. It is found that dry-wet cycling can promote the intrusion speed of chloride ions and increase its invasion depth and concentration. With the increase of water to cement ratio, the above effect of dry-wet cycling gets more obvious. Furthermore, the incorporation of slag can increase the resistance to chloride erosion of cement matrix composite materials and reduce the invasive effect of dry-wet cycling. Meanwhile, the corresponding micro-structural changes before and after chloride erosion under dry-wet cycling show that Friedel's salt is obvious on the surface of paste samples of cement matrix composite materials and adding slag significantly increases the formation of Friedel's salt in the sample.
In order to further reveal the mechanism of chloride erosion to cement matrix composite materials under dry-wet cycling, the resistance to chloride erosion of two kinds of water to cement ratio of cement concrete, mortar and paste specimens under dry-wet cycling were studied. It is found that dry-wet cycling can promote the intrusion speed of chloride ions and increase its invasion depth and concentration. With the increase of water to cement ratio, the above effect of dry-wet cycling gets more obvious. Furthermore, the incorporation of slag can increase the resistance to chloride erosion of cement matrix composite materials and reduce the invasive effect of dry-wet cycling. Meanwhile, the corresponding micro-structural changes before and after chloride erosion under dry-wet cycling show that Friedel's salt is obvious on the surface of paste samples of cement matrix composite materials and adding slag significantly increases the formation of Friedel's salt in the sample.
2017, 34(12): 2866-2873.
doi: 10.13801/j.cnki.fhclxb.20170321.001
Abstract:
The equivalent elasticity modulus, equivalent yield strain and equivalent plate stress of V-type folded core could be got using surrogate models. Based on the surrogate model, a homogenized equivalent model of V-type folded core under static/quasi-static compression was set up. The calculation results show that the mechanical properties of the original structure are simulated well by the homogenized equivalent model, and the computing cost is greatly reduced. The equivalent model in this paper provides an efficient way to calculate or optimize the property of folded core applied in structures, especially in anti-crash and energy absorbing structures.
The equivalent elasticity modulus, equivalent yield strain and equivalent plate stress of V-type folded core could be got using surrogate models. Based on the surrogate model, a homogenized equivalent model of V-type folded core under static/quasi-static compression was set up. The calculation results show that the mechanical properties of the original structure are simulated well by the homogenized equivalent model, and the computing cost is greatly reduced. The equivalent model in this paper provides an efficient way to calculate or optimize the property of folded core applied in structures, especially in anti-crash and energy absorbing structures.
2017, 34(12): 2874-2881.
doi: 10.13801/j.cnki.fhclxb.20170314.005
Abstract:
The hybrid sandwich structure consistes of tooth-plate-glass-fiber facesheets and a foam core. Tooth plate was connected with foam core through tooth nails. Tooth-plate-glass-fiber hybrid sandwich beams were made by vacuum assisted resin transfer molding. Compared with the normal sandwich structures, the failure mode and flexural performance with different spans and core densities were investigated by three-point bending tests. Meanwhile, the influence of the tooth plate on the interfacial property was also studied. The test results show that in the case of foam core density of 35 kg/m3、80 kg/m3 and 150 kg/m3, the ultimate bending strength increases by 168%, 211% and 258%, respectively, compared with the normal sandwich beams and the interfacial shear strength are 0.09 MPa、0.21 MPa and 0.45 MPa in turn. With the change of core density and span, the structures mainly occur two kinds of failure modes, which are core shear and core indentation. The tooth plate suppresses shear failure effectively. In addition, the analytical model used to predict the ultimate bearing capacity of specimen was proposed. The calculated results are in good accordance with the experimented results.
The hybrid sandwich structure consistes of tooth-plate-glass-fiber facesheets and a foam core. Tooth plate was connected with foam core through tooth nails. Tooth-plate-glass-fiber hybrid sandwich beams were made by vacuum assisted resin transfer molding. Compared with the normal sandwich structures, the failure mode and flexural performance with different spans and core densities were investigated by three-point bending tests. Meanwhile, the influence of the tooth plate on the interfacial property was also studied. The test results show that in the case of foam core density of 35 kg/m3、80 kg/m3 and 150 kg/m3, the ultimate bending strength increases by 168%, 211% and 258%, respectively, compared with the normal sandwich beams and the interfacial shear strength are 0.09 MPa、0.21 MPa and 0.45 MPa in turn. With the change of core density and span, the structures mainly occur two kinds of failure modes, which are core shear and core indentation. The tooth plate suppresses shear failure effectively. In addition, the analytical model used to predict the ultimate bearing capacity of specimen was proposed. The calculated results are in good accordance with the experimented results.
2017, 34(12): 2882-2889.
doi: 10.13801/j.cnki.fhclxb.20170320.005
Abstract:
A prediction model of starch matrix foam composites by radial basis function artificial neural network (RBF ANN) based on chaotic self-adaptive particle swarm optimization algorithm with population entropy diversity and convergence divergence strategy was established. The input variables of this model included ethylene-vinyl acetate (EVA)/starch mass ratio, glycerin content and NaHCO3 content, and the output variables were tensile strength and rebound rate. The results show that the proposed model has a good performance. The root mean square error of prediction and correlation coefficient are 0.0160 and 0.9890, respectively. The prediction results show that the tensile strength of starch matrix foam composites reduces slowly with the increase of glycerin content, and it reduces firstly and then increases with the increase of NaHCO3 content. The rebound rate increases with the increase of glycerin content, and it increases firstly and then decreases with the increase of NaHCO3 content in the starch matrix composites.
A prediction model of starch matrix foam composites by radial basis function artificial neural network (RBF ANN) based on chaotic self-adaptive particle swarm optimization algorithm with population entropy diversity and convergence divergence strategy was established. The input variables of this model included ethylene-vinyl acetate (EVA)/starch mass ratio, glycerin content and NaHCO3 content, and the output variables were tensile strength and rebound rate. The results show that the proposed model has a good performance. The root mean square error of prediction and correlation coefficient are 0.0160 and 0.9890, respectively. The prediction results show that the tensile strength of starch matrix foam composites reduces slowly with the increase of glycerin content, and it reduces firstly and then increases with the increase of NaHCO3 content. The rebound rate increases with the increase of glycerin content, and it increases firstly and then decreases with the increase of NaHCO3 content in the starch matrix composites.
2017, 34(12): 2890-2901.
doi: 10.13801/j.cnki.fhclxb.20170412.002
Abstract:
Based on the work conducted by Sørensen etc., a method for determining interfacial traction-separation law with dilatancy was presented to investigate interfacial cracking processes of composites. The tangential traction-separation law was derived via a pre-defined shear dilation function and the normal traction-separation law while the interface was in tension. On the contrary, the tangential traction was decomposed into bond strength and friction strength while the interface was in compression. The friction strength is related to the normal pressure and the damage process on the cohesive interface. The results of the method explain why the tangential traction-separation law of Sørensen model is not continuous and violates the consistently coupled rule. In order to facilitate numerical simulation, expressions of interface stiffness matrix applying to three dimensional finite element models were also presented. Then a particular shear dilation function was adopted and the normal traction-separation law was assumed as multilinear form and exponential form, respectively. The corresponding tangential traction-separation law was derived applying the method presented in this paper to those functions. Finally, two examples of engineering application were given. These numerical simulation results are in good agreement with the experimental data.
Based on the work conducted by Sørensen etc., a method for determining interfacial traction-separation law with dilatancy was presented to investigate interfacial cracking processes of composites. The tangential traction-separation law was derived via a pre-defined shear dilation function and the normal traction-separation law while the interface was in tension. On the contrary, the tangential traction was decomposed into bond strength and friction strength while the interface was in compression. The friction strength is related to the normal pressure and the damage process on the cohesive interface. The results of the method explain why the tangential traction-separation law of Sørensen model is not continuous and violates the consistently coupled rule. In order to facilitate numerical simulation, expressions of interface stiffness matrix applying to three dimensional finite element models were also presented. Then a particular shear dilation function was adopted and the normal traction-separation law was assumed as multilinear form and exponential form, respectively. The corresponding tangential traction-separation law was derived applying the method presented in this paper to those functions. Finally, two examples of engineering application were given. These numerical simulation results are in good agreement with the experimental data.
