2017 Vol. 34, No. 2
2017, 34(2): 231-239.
doi: 10.13801/j.cnki.fhclxb.20160513.001
Abstract:
TiO2@Fe3O4 magnetic nanoparticles with core-shell structure was prepared by sol-gel method,and then TiO2@Fe3O4/polypyrrole (PPy) magnetic ion exchange adsorption resin was prepared with PPy by chemical oxidation.The morphology and particle size of the samples were observed by TEM and SEM.The phase analysis was represented by XRD.The surface properties of the samples were represented by FTIR.VSM was used to determine the magnetic property.The absorbance could be represented by UV,and malachite green solution was used for the adsorption test.The results show that TiO2@Fe3O4/PPy composite nanoparticles which are superparamagnetic unchanged,agglomeration is obviously improved, the magnetic intensity is about 5.384 emu·g-1. When 0.05 g TiO2@Fe3O4/PPy adsorbent is used to adsort 25 mL 20 mg·L-1 malachite green solution (MG) at 298 K in the solution with pH=7,the saturated adsorption capacity of TiO2@Fe3O4/PPy adsorbent can reach up to 312.50 mg·g-1, and the removal rate of which can reach up to 99.1% within 30 min.Compared with the activated carbon,TiO2@Fe3O4/PPy magnetic ion exchange adsorption resin can undertake large area dynamic exchange and adsorption,which illustrates that its adsorption propertities are better than that of the activated carbon.
TiO2@Fe3O4 magnetic nanoparticles with core-shell structure was prepared by sol-gel method,and then TiO2@Fe3O4/polypyrrole (PPy) magnetic ion exchange adsorption resin was prepared with PPy by chemical oxidation.The morphology and particle size of the samples were observed by TEM and SEM.The phase analysis was represented by XRD.The surface properties of the samples were represented by FTIR.VSM was used to determine the magnetic property.The absorbance could be represented by UV,and malachite green solution was used for the adsorption test.The results show that TiO2@Fe3O4/PPy composite nanoparticles which are superparamagnetic unchanged,agglomeration is obviously improved, the magnetic intensity is about 5.384 emu·g-1. When 0.05 g TiO2@Fe3O4/PPy adsorbent is used to adsort 25 mL 20 mg·L-1 malachite green solution (MG) at 298 K in the solution with pH=7,the saturated adsorption capacity of TiO2@Fe3O4/PPy adsorbent can reach up to 312.50 mg·g-1, and the removal rate of which can reach up to 99.1% within 30 min.Compared with the activated carbon,TiO2@Fe3O4/PPy magnetic ion exchange adsorption resin can undertake large area dynamic exchange and adsorption,which illustrates that its adsorption propertities are better than that of the activated carbon.
2017, 34(2): 240-246.
doi: 10.13801/j.cnki.fhclxb.20160405.002
Abstract:
The fatigue property of T700/HT280 composite and HT280 resin in high temperature environment were studied via the stiffness reduction theory.The mass loss rate of composite and resin was measured.The chemical construction,interior damage and dynamic mechanical behavior were analyzed by FTIR,ultrasonic C-scanning and DMA.The results indicate that the mass loss rate T700/HT280 composite and HT280 resin increases rapidly at the initial aging stage and then increases slowly with further aging.After the long-term exposure to high temperature,thermal-oxidative aging can be seen in HT280 resin.The change of dynamic mechanical properties of HT280 resin is attributed to the post-curing and thermal aging,while for T700/HT280 composite,it is attributed to the synthetic action of the post-curing,thermal aging and interface debonding.The stiffness decline rate of treated composite is less than the original one.It indicates that the strengthening effect of post-curing and thermal aging is obvious after exposuring to high temperature.Therefore,a certain improvement in the fatigue-resistance of T700/HT280 composite can be obtained.
The fatigue property of T700/HT280 composite and HT280 resin in high temperature environment were studied via the stiffness reduction theory.The mass loss rate of composite and resin was measured.The chemical construction,interior damage and dynamic mechanical behavior were analyzed by FTIR,ultrasonic C-scanning and DMA.The results indicate that the mass loss rate T700/HT280 composite and HT280 resin increases rapidly at the initial aging stage and then increases slowly with further aging.After the long-term exposure to high temperature,thermal-oxidative aging can be seen in HT280 resin.The change of dynamic mechanical properties of HT280 resin is attributed to the post-curing and thermal aging,while for T700/HT280 composite,it is attributed to the synthetic action of the post-curing,thermal aging and interface debonding.The stiffness decline rate of treated composite is less than the original one.It indicates that the strengthening effect of post-curing and thermal aging is obvious after exposuring to high temperature.Therefore,a certain improvement in the fatigue-resistance of T700/HT280 composite can be obtained.
2017, 34(2): 247-255.
doi: 10.13801/j.cnki.fhclxb.20160511.001
Abstract:
By the reaction of epoxy ring and the amino group on the surface of amine functionalized multiwalled carbon nanotube (MWCNTs-NH2),monofunctional epoxy compound benzyl ether (EP 692) and twelve-fourteen alkyl ether (EPAGE) were grafted onto the surface of MWCNTs using ball milling techndogy,known as sizing treatment.As a result,the MWCNTs-692 and MWCNTs-AGE with different molecular structure of sizing were prepared.On this basis,1wt% of MWCNTs-NH2,MWCNTs-692 and MWCNTs-AGE were added into diaminodiphenylmethane (DDM) cured bisphenol a diglycidyl ether (DGEBA) system,respectively,and the effects of these MWCNTs on the viscosity-temperature relationships,cure kinetics,thermal-mechanical and flexural properties of the resulting epoxy composites were investigated.The results of FT-IR,TGA and XPS show that EP 692 and EP AGE can be successfully grafted onto the surface of MWCNTs via covalent bond.Comparing with MWCNTs-NH2,MWCNTs-AGE and MWCNTs-692 can effectively improve the dispersion states and compatibility of MWCNTs in epoxy resin,reduce the influence of nanoparticles on the viscosity and curing kinetics of epoxy resin.Moreover,these MWCNTs can improve the storage modulus and flexural properties of epoxy resin,especially for the MWCNTs-692 reinforced ones due to the existence of rigid functional groups.Comparing with the neat epoxy,the storage modulusof MWCNTs-692/epoxy composite increases by 30.6% after being added 1wt% MWCNTs-692,and the flexural strength and modulus of epoxy resin exhibit enhancement of 18.8% and 22.5%,respectively.
By the reaction of epoxy ring and the amino group on the surface of amine functionalized multiwalled carbon nanotube (MWCNTs-NH2),monofunctional epoxy compound benzyl ether (EP 692) and twelve-fourteen alkyl ether (EPAGE) were grafted onto the surface of MWCNTs using ball milling techndogy,known as sizing treatment.As a result,the MWCNTs-692 and MWCNTs-AGE with different molecular structure of sizing were prepared.On this basis,1wt% of MWCNTs-NH2,MWCNTs-692 and MWCNTs-AGE were added into diaminodiphenylmethane (DDM) cured bisphenol a diglycidyl ether (DGEBA) system,respectively,and the effects of these MWCNTs on the viscosity-temperature relationships,cure kinetics,thermal-mechanical and flexural properties of the resulting epoxy composites were investigated.The results of FT-IR,TGA and XPS show that EP 692 and EP AGE can be successfully grafted onto the surface of MWCNTs via covalent bond.Comparing with MWCNTs-NH2,MWCNTs-AGE and MWCNTs-692 can effectively improve the dispersion states and compatibility of MWCNTs in epoxy resin,reduce the influence of nanoparticles on the viscosity and curing kinetics of epoxy resin.Moreover,these MWCNTs can improve the storage modulus and flexural properties of epoxy resin,especially for the MWCNTs-692 reinforced ones due to the existence of rigid functional groups.Comparing with the neat epoxy,the storage modulusof MWCNTs-692/epoxy composite increases by 30.6% after being added 1wt% MWCNTs-692,and the flexural strength and modulus of epoxy resin exhibit enhancement of 18.8% and 22.5%,respectively.
2017, 34(2): 256-262.
doi: 10.13801/j.cnki.fhclxb.20160427.002
Abstract:
The nanometer calcium carbonate (Nano-CaCO3)/polylactic acid (PLA) composites was melt-compounded by twin-screw exturder with Nano-CaCO3 and PLA as raw materials,maleic anhydride grafted ethylene-octene copolymer (POE-g-MA) as compatibilizer.SEM,DSC,TG,capillary rheometer (CR) and universal testing machine were used to perform the interfacial compatibility,thermal properties,rheological properties and mechanical properties of Nano-CaCO3/PLA matrix composites,respectively.The results show that the aggregation phenomenon in the PLA matrix increases compared with pure PLA when the content of Nano-CaCO3 increases to 15wt%.The crystallinity,the maximum thermal decomposition temperature and the tensile strength of Nano-CaCO3/PLA composites decrease by 1.9%,15.5℃ and 28.2%,the flexural strength and elongation at break increase by 37.5% and 29.3%,respectively.And the interfacial compatibility of Nano-CaCO3/PLA composites with 4wt% POE-g-MA improves,the crystallinity and the tensile strength of sample decrease by 4.2% and 25.2%,the maximum thermal decomposition temperature,the flexural strength and elongation at break of sample increase by 5.8℃,25.3% and 174.4%,respectively.The shear viscosity of Nano-CaCO3/PLA composites increases due to thaddition of POE-g-MA.
The nanometer calcium carbonate (Nano-CaCO3)/polylactic acid (PLA) composites was melt-compounded by twin-screw exturder with Nano-CaCO3 and PLA as raw materials,maleic anhydride grafted ethylene-octene copolymer (POE-g-MA) as compatibilizer.SEM,DSC,TG,capillary rheometer (CR) and universal testing machine were used to perform the interfacial compatibility,thermal properties,rheological properties and mechanical properties of Nano-CaCO3/PLA matrix composites,respectively.The results show that the aggregation phenomenon in the PLA matrix increases compared with pure PLA when the content of Nano-CaCO3 increases to 15wt%.The crystallinity,the maximum thermal decomposition temperature and the tensile strength of Nano-CaCO3/PLA composites decrease by 1.9%,15.5℃ and 28.2%,the flexural strength and elongation at break increase by 37.5% and 29.3%,respectively.And the interfacial compatibility of Nano-CaCO3/PLA composites with 4wt% POE-g-MA improves,the crystallinity and the tensile strength of sample decrease by 4.2% and 25.2%,the maximum thermal decomposition temperature,the flexural strength and elongation at break of sample increase by 5.8℃,25.3% and 174.4%,respectively.The shear viscosity of Nano-CaCO3/PLA composites increases due to thaddition of POE-g-MA.
2017, 34(2): 263-269.
doi: 10.13801/j.cnki.fhclxb.20160328.002
Abstract:
Functionalized SiC particle-SiC whisker (SiCP-SiCW) hybrid fillers by γ-glycidoxypropyltrimethoxysilane (KH-560) were performed to fabricate the functionalized SiCP-SiCW/bismaleimide (SiCP-SiCW/BMI) thermal conductivity composites,BMI as the polymeric matrix and diallylbisphenol A (DABA) as a toughening agent,respectively.Effects of the shape,content,compound and surface functionalization of SiC fillers on the thermal conductivities,dielectric & mechanical properties and thermal stabilities of the functionalized SiCP-SiCW/BMI thermal conductivity composites were investigated.The results show that the functionalized SiCP-SiCW/BMI thermal conductivity composite with 40wt% functionalized SiCP-SiCW(1:3,mass ratio) hybrid fillers exhibits the best comprehensive performance,the corresponding thermally conductive coefficient λ of 1.125 W (m·K)-1,dielectric constant ε of 4.12,and 5wt% thermal mass loss temperature of 427℃.
Functionalized SiC particle-SiC whisker (SiCP-SiCW) hybrid fillers by γ-glycidoxypropyltrimethoxysilane (KH-560) were performed to fabricate the functionalized SiCP-SiCW/bismaleimide (SiCP-SiCW/BMI) thermal conductivity composites,BMI as the polymeric matrix and diallylbisphenol A (DABA) as a toughening agent,respectively.Effects of the shape,content,compound and surface functionalization of SiC fillers on the thermal conductivities,dielectric & mechanical properties and thermal stabilities of the functionalized SiCP-SiCW/BMI thermal conductivity composites were investigated.The results show that the functionalized SiCP-SiCW/BMI thermal conductivity composite with 40wt% functionalized SiCP-SiCW(1:3,mass ratio) hybrid fillers exhibits the best comprehensive performance,the corresponding thermally conductive coefficient λ of 1.125 W (m·K)-1,dielectric constant ε of 4.12,and 5wt% thermal mass loss temperature of 427℃.
2017, 34(2): 270-277.
doi: 10.13801/j.cnki.fhclxb.20160418.003
Abstract:
Direct currents (DC) ranged from 0.05 A·mm-2 to 0.2 A·mm-2 were subjected through carbon fiber/epoxy (CF/EP) unidirectional composites with a 1.5 h duration by the electro-thermal tester,meanwhile the tem-perature fields were measured on the surface of samples under different electro-thermal treatments.Changes in the longitudinal volume resistance and dielectric properties were analyzed respectively after electro-thermal treatments.In order to characterize the flexural property,the three-point flexure test was conducted before and after electro-thermal treatments.Preliminary experimental results show that temperature fields of all samples are rising rapidly with the duration before steady-state equilibrium.Treatments at less than 0.125 A·mm-2 lead to a uniform temperature field,and make the longitudinal volume resistance decrease and enhance dielectric properties.Treatments at more than 0.125 A·mm-2 come to a contrary result.The dielectric constant and loss tangent increase with the increment of test frequency,whereas the AC conductivity remains unchanged and then rises.The loss tangent affected mostly by electro-thermal treatments can be used as characteristic parameter of electro-thermal influence.The flexural property test demonstrates that treatments less than 0.125 A·mm-2 make flexural strength and modulus increase by 11.8% and 7.32% mostly,but they reduce by 8.26% and 6.52% maximally after treating more than 0.125 A·mm-2.
Direct currents (DC) ranged from 0.05 A·mm-2 to 0.2 A·mm-2 were subjected through carbon fiber/epoxy (CF/EP) unidirectional composites with a 1.5 h duration by the electro-thermal tester,meanwhile the tem-perature fields were measured on the surface of samples under different electro-thermal treatments.Changes in the longitudinal volume resistance and dielectric properties were analyzed respectively after electro-thermal treatments.In order to characterize the flexural property,the three-point flexure test was conducted before and after electro-thermal treatments.Preliminary experimental results show that temperature fields of all samples are rising rapidly with the duration before steady-state equilibrium.Treatments at less than 0.125 A·mm-2 lead to a uniform temperature field,and make the longitudinal volume resistance decrease and enhance dielectric properties.Treatments at more than 0.125 A·mm-2 come to a contrary result.The dielectric constant and loss tangent increase with the increment of test frequency,whereas the AC conductivity remains unchanged and then rises.The loss tangent affected mostly by electro-thermal treatments can be used as characteristic parameter of electro-thermal influence.The flexural property test demonstrates that treatments less than 0.125 A·mm-2 make flexural strength and modulus increase by 11.8% and 7.32% mostly,but they reduce by 8.26% and 6.52% maximally after treating more than 0.125 A·mm-2.
2017, 34(2): 278-283.
doi: 10.13801/j.cnki.fhclxb.20160523.010
Abstract:
Graphene oxide (GO) was prepared by a modified Hummers method,and then GO/furan resin composites were prepared through the solution blending and curing by increasing temperature step by step.The structure and morphology of the composites were characterized by FTIR,XRD and SEM.Meanwhile,the viscosity,glass transition temperature,thermal decomposition temperature,char yield and hardness were tested in detail.The results show that GO has good dispersibility in furan resin matrix and the interface between GO and furan resin of composites is quite compatible.Mechanical and thermal properties of GO/furan resin composites can be improved obviously.The glass transition temperature of the GO/furan resin composites with 0.3wt% of GO added increase by 36℃,and 5% mass loss temperature increased by 16℃ respectively compared with that of the pure furan resin.The char yield of GO/furan resin composites with 0.1wt% of GO added increase from 50.7% to 53.9% and the shore hardness increase from 90 to 97.
Graphene oxide (GO) was prepared by a modified Hummers method,and then GO/furan resin composites were prepared through the solution blending and curing by increasing temperature step by step.The structure and morphology of the composites were characterized by FTIR,XRD and SEM.Meanwhile,the viscosity,glass transition temperature,thermal decomposition temperature,char yield and hardness were tested in detail.The results show that GO has good dispersibility in furan resin matrix and the interface between GO and furan resin of composites is quite compatible.Mechanical and thermal properties of GO/furan resin composites can be improved obviously.The glass transition temperature of the GO/furan resin composites with 0.3wt% of GO added increase by 36℃,and 5% mass loss temperature increased by 16℃ respectively compared with that of the pure furan resin.The char yield of GO/furan resin composites with 0.1wt% of GO added increase from 50.7% to 53.9% and the shore hardness increase from 90 to 97.
2017, 34(2): 284-290.
doi: 10.13801/j.cnki.fhclxb.20160523.005
Abstract:
The microcapsules containing high temperature phase change paraffin (Phase change interval is 75-85℃) was prepared by in situ polymerization using melamine modified urea-formaldehyde resin as wall material.Morphology,thermal properties of paraffin urea-formaldehyde (Paraffin-UF) microcapsules were characterized and analyzed by DSC,SEM,the coefficient of thermal conductivity meter.The influence of the NaCl solution,melamine and graphene for microcapsules was analyzed.The results show that the NaCl addition can improve the microcapsule surface morphology,and the addition of melamine can improve the production of microcapsules.While adding 0.03wt% mass fraction of graphene at 80℃,the coefficient of thermal conductivity of microcapsules is increased by 55.56%,and its thermal stability is improved.
The microcapsules containing high temperature phase change paraffin (Phase change interval is 75-85℃) was prepared by in situ polymerization using melamine modified urea-formaldehyde resin as wall material.Morphology,thermal properties of paraffin urea-formaldehyde (Paraffin-UF) microcapsules were characterized and analyzed by DSC,SEM,the coefficient of thermal conductivity meter.The influence of the NaCl solution,melamine and graphene for microcapsules was analyzed.The results show that the NaCl addition can improve the microcapsule surface morphology,and the addition of melamine can improve the production of microcapsules.While adding 0.03wt% mass fraction of graphene at 80℃,the coefficient of thermal conductivity of microcapsules is increased by 55.56%,and its thermal stability is improved.
2017, 34(2): 291-297.
doi: 10.13801/j.cnki.fhclxb.20160411.005
Abstract:
Three types of plant fibers (hazelnut shell,coconut shell,and rice-husk) were separately added into polyvinyl chloride (PVC) as the fillers to prepare three types of husk's fibers/PVC composites through the extrusion molding process.The components of the plant fibers were analyzed and the mechanical property and water absorbency capability of the composites were tested.The FTIR spectra analysis and TG-DSC analysis was conducted on the husk's fibers/PVC composites.The section microstructures of the composites were observed by SEM.The results show that the rice-husk is the richest in cellulose,and rice-husk/PVC composite has the best binding interface and mechanical properties with bending strength at 69.79 MPa,which is 4.34% and 24.87% higher than that of the coconut shell/PVC and the hazelnut shell/PVC composites,respectively.The water absorption in 24 h of the comoposites are all below 1%,and the coconut shell/PVC composite has the lowest water absorption rate among them,which is 0.600 5% in 24h,while the hazelnut shell/PVC composite has the best heat stability.The mechanical property and water absorbency capability of husk's fibers/PVC composites are all up to GB/T 24137-2009 and GB/T 24508-2009,respectively.
Three types of plant fibers (hazelnut shell,coconut shell,and rice-husk) were separately added into polyvinyl chloride (PVC) as the fillers to prepare three types of husk's fibers/PVC composites through the extrusion molding process.The components of the plant fibers were analyzed and the mechanical property and water absorbency capability of the composites were tested.The FTIR spectra analysis and TG-DSC analysis was conducted on the husk's fibers/PVC composites.The section microstructures of the composites were observed by SEM.The results show that the rice-husk is the richest in cellulose,and rice-husk/PVC composite has the best binding interface and mechanical properties with bending strength at 69.79 MPa,which is 4.34% and 24.87% higher than that of the coconut shell/PVC and the hazelnut shell/PVC composites,respectively.The water absorption in 24 h of the comoposites are all below 1%,and the coconut shell/PVC composite has the lowest water absorption rate among them,which is 0.600 5% in 24h,while the hazelnut shell/PVC composite has the best heat stability.The mechanical property and water absorbency capability of husk's fibers/PVC composites are all up to GB/T 24137-2009 and GB/T 24508-2009,respectively.
2017, 34(2): 298-307.
doi: 10.13801/j.cnki.fhclxb.20160523.006
Abstract:
With using poly-(melamine-formaldehyde)(PMF) as the shell and Trimethylolpropane tris (3-mercaptopropionate)(TMPMP) as the core,TMPMP@PMF for epoxy based hardner was synthesized by in situ polymerization process.The influences of the content and type of emulsifier,the mass ratio between the core and the shell,reaction time and temperature,pH value on the properties and structural of obtained micro-encapsultes were studied.The results show that an optimal synthesis condition can be obtained with the content of 2wt% TMPMP and the mixing mass ratio of 2:1 between TMPMP to PMF.The obtained TMPMP@PMF encapsulates have stable morphology,closed shell structure and heat resistant performance.In addition the pressure-sensitive hardner of TMPMP@PMF/EP was prepared by mixing TMPMP@PMF and epoxy based hardener (EP).The results show that the microcapsules can be timely fractured under the action of external force,so EP also can be solidified in a short time at room temperature or even lower temperature (about 0℃),and the curing performance and the impact resistant performance of TMPMP@PMF/EP hardner can be effectively improved.
With using poly-(melamine-formaldehyde)(PMF) as the shell and Trimethylolpropane tris (3-mercaptopropionate)(TMPMP) as the core,TMPMP@PMF for epoxy based hardner was synthesized by in situ polymerization process.The influences of the content and type of emulsifier,the mass ratio between the core and the shell,reaction time and temperature,pH value on the properties and structural of obtained micro-encapsultes were studied.The results show that an optimal synthesis condition can be obtained with the content of 2wt% TMPMP and the mixing mass ratio of 2:1 between TMPMP to PMF.The obtained TMPMP@PMF encapsulates have stable morphology,closed shell structure and heat resistant performance.In addition the pressure-sensitive hardner of TMPMP@PMF/EP was prepared by mixing TMPMP@PMF and epoxy based hardener (EP).The results show that the microcapsules can be timely fractured under the action of external force,so EP also can be solidified in a short time at room temperature or even lower temperature (about 0℃),and the curing performance and the impact resistant performance of TMPMP@PMF/EP hardner can be effectively improved.
2017, 34(2): 308-313.
doi: 10.13801/j.cnki.fhclxb.20160418.005
Abstract:
This study focus on monitoring the surfacial temperature of carbon fiber/epoxy resin (CF/EP) composite under different electric current by electric-thermal damage test device,meanwhile deducing the resistivity variation law with temperature.The CF/EP specimens were dealed with moisture absorption treatment and the relationship between diffusion coefficients,saturated moisture absorption rate and electric current were obtained.The effects of current loading on moisture absorption behavior of CF/EP were analyzed by FTIR,flexural test and flexural fracture surface morphology.The results indicate that electric current make the equilibrium temperature increase and the resistivity decreases as the temperature increases.When current value 4 A (ρ=66.8 mA·mm-2) is applied to CF/EP specimens,the diffusion coefficient and saturated moisture absorption rate are lower than that of untreated samples.Opposite trend is shown when current value is 5 A (ρ=83.6 mA·mm-2) or 6 A (ρ=100.2 mA·mm-2).Low current intensity can optimize the interfacial performance and enhance flexural strength,while the high current intensity destroy interfacial property and decline flexural strength.When CF/EP specimens are exposed to the coupled electro-thermal and hygrothermal loadings,the flexural performance of samples decrease and flexural reduction is positively correlated with moisture absorption.
This study focus on monitoring the surfacial temperature of carbon fiber/epoxy resin (CF/EP) composite under different electric current by electric-thermal damage test device,meanwhile deducing the resistivity variation law with temperature.The CF/EP specimens were dealed with moisture absorption treatment and the relationship between diffusion coefficients,saturated moisture absorption rate and electric current were obtained.The effects of current loading on moisture absorption behavior of CF/EP were analyzed by FTIR,flexural test and flexural fracture surface morphology.The results indicate that electric current make the equilibrium temperature increase and the resistivity decreases as the temperature increases.When current value 4 A (ρ=66.8 mA·mm-2) is applied to CF/EP specimens,the diffusion coefficient and saturated moisture absorption rate are lower than that of untreated samples.Opposite trend is shown when current value is 5 A (ρ=83.6 mA·mm-2) or 6 A (ρ=100.2 mA·mm-2).Low current intensity can optimize the interfacial performance and enhance flexural strength,while the high current intensity destroy interfacial property and decline flexural strength.When CF/EP specimens are exposed to the coupled electro-thermal and hygrothermal loadings,the flexural performance of samples decrease and flexural reduction is positively correlated with moisture absorption.
2017, 34(2): 314-321.
doi: 10.13801/j.cnki.fhclxb.20160523.003
Abstract:
The surface of bamboo fibers was modified by using two sorts of methods including alkali treatment,alkali-silane treatment.Then unidirectional continuous bamboo fibers reinforced unsaturated polyester resin (BF/UP) composite was prepared by means of stitching-compression molding technology.The effects of different surface modification methods on the static and dynamic mechanical properties,water absorption were studied.SEM and FITR were used to describe the surface of treated fibers and the interface bonding condition in the BF/UP composite.The results show that the properties of the BF/UP composite after treating bamboo fiber using different modification methods all are improved.The performances of BF/UP composite are optimal with the treatment of 5wt% alkali-3wt% silane coupling agent.The BF/UP composite has the best comprehensive properties with the treatment of 5wt% alkali-3wt% silane coupling agent,whose tensile strength,flexural strength,flexural modulus and shear strength increase by 34.29%,15.95%,11.26% and 29.39% respectively.Compared with the untreated sample,the storage modulus of the BF/UP composite increases by 63.80%,the loss factor of BF/UP composite decreases,and the 24 h and 720 h water absorption of the BF/UP composite decrease by 55.35% and 27.32%.The results of SEM and FITR show that the impurity decrease and a layer of coupling agent film is attached on the surface of bamboo fiber,and there is a better interface adhesion occurs between the fiber and matrix after surface modification.
The surface of bamboo fibers was modified by using two sorts of methods including alkali treatment,alkali-silane treatment.Then unidirectional continuous bamboo fibers reinforced unsaturated polyester resin (BF/UP) composite was prepared by means of stitching-compression molding technology.The effects of different surface modification methods on the static and dynamic mechanical properties,water absorption were studied.SEM and FITR were used to describe the surface of treated fibers and the interface bonding condition in the BF/UP composite.The results show that the properties of the BF/UP composite after treating bamboo fiber using different modification methods all are improved.The performances of BF/UP composite are optimal with the treatment of 5wt% alkali-3wt% silane coupling agent.The BF/UP composite has the best comprehensive properties with the treatment of 5wt% alkali-3wt% silane coupling agent,whose tensile strength,flexural strength,flexural modulus and shear strength increase by 34.29%,15.95%,11.26% and 29.39% respectively.Compared with the untreated sample,the storage modulus of the BF/UP composite increases by 63.80%,the loss factor of BF/UP composite decreases,and the 24 h and 720 h water absorption of the BF/UP composite decrease by 55.35% and 27.32%.The results of SEM and FITR show that the impurity decrease and a layer of coupling agent film is attached on the surface of bamboo fiber,and there is a better interface adhesion occurs between the fiber and matrix after surface modification.
2017, 34(2): 322-328.
doi: 10.13801/j.cnki.fhclxb.20160413.003
Abstract:
Based on viscoelastic theory,the low temperature bending beam rheometer test (BBR) of asphalt with different mass fractions of poly phosphoric acid (PPA) modification (0.5wt%,1.0wt%,1.5wt%,1.0wt%) were carried out.The creep data from the low temperature BBR test was nonlinearyly fitted using the Burgers model,and low temperature performance index was determined using the four parameters of Burgers model (E1,η1 ,E2 and η2 Maxwell and Kelvin model of elastic modulus and viscosity coefficient),and so the low temperature performance of the PPA modified asphalt was analyzed.The results shows that the addition of PPA improves the viscosity and elasticity of asphalt,the relaxation time decreases in the asphalt,the stored energy reduces,the dissipation energy increases,and the stress relaxation ability is improved.At the same temperature,the PPA modified asphalt delays the time of asphalt into the creep stability period,but it was shortened with the temperature decreasing.The low temperature performance of asphalt improves with the addition of PPA,and the effect is better with more PPA contents.But the improvement degree reduces with the decrease of the temperature,and the differences between the effects of different mass fractions also become smaller.The PPA is suitable at the temperature above -24℃,while it is meaningless below -24℃.
Based on viscoelastic theory,the low temperature bending beam rheometer test (BBR) of asphalt with different mass fractions of poly phosphoric acid (PPA) modification (0.5wt%,1.0wt%,1.5wt%,1.0wt%) were carried out.The creep data from the low temperature BBR test was nonlinearyly fitted using the Burgers model,and low temperature performance index was determined using the four parameters of Burgers model (E1,η1 ,E2 and η2 Maxwell and Kelvin model of elastic modulus and viscosity coefficient),and so the low temperature performance of the PPA modified asphalt was analyzed.The results shows that the addition of PPA improves the viscosity and elasticity of asphalt,the relaxation time decreases in the asphalt,the stored energy reduces,the dissipation energy increases,and the stress relaxation ability is improved.At the same temperature,the PPA modified asphalt delays the time of asphalt into the creep stability period,but it was shortened with the temperature decreasing.The low temperature performance of asphalt improves with the addition of PPA,and the effect is better with more PPA contents.But the improvement degree reduces with the decrease of the temperature,and the differences between the effects of different mass fractions also become smaller.The PPA is suitable at the temperature above -24℃,while it is meaningless below -24℃.
2017, 34(2): 329-335.
doi: 10.13801/j.cnki.fhclxb.20160415.001
Abstract:
Based on the bending bean rheometer test (BBR) and DSC measurement of the glass transition temperature,the low temperature properties of asphalt with different dosage of poly phosphoric acid (PPA) and SBS-PPA were studied.The effect of PPA content on the performance of asphalt at low temperature was analyzed using the method of single factor variance.The phase structure characteristics of SBS-PPA composite modified asphalt were observed and analyzed by fluorescence microscope.The results shows that PPA addition can improve the low temperature performance of matrix asphalt and SBS modified asphalt,and with the increase of PPA content,low temperature anti-crack performance of bitumen is better.But with the decrease of temperature,the effect of low temperature improvement is gradually reduced.Effect degree of PPA on the properties of base asphalt at low temperature is different at different temperature.At the temperature of -18--12℃,PPA has significant effects on the low temperature performance of base asphalt.At the temperature of -30--24℃,PPA has no significant impact on the low temperature performance of base asphalt.While the effect of PPA on the low temperature performance of SBS-PPA modified asphalt at different temperatures is not significant.The low temperature anti-crack performance of SBS-PPA modified bitumen is better than that of PPA modified asphalt,and the addition of PPA can effectively promote the SBS to disperse into small particles and become more uniform distribution in the asphalt,so the storage stability and the space mesh structure of SBS modified asphalt can be improved effectively.
Based on the bending bean rheometer test (BBR) and DSC measurement of the glass transition temperature,the low temperature properties of asphalt with different dosage of poly phosphoric acid (PPA) and SBS-PPA were studied.The effect of PPA content on the performance of asphalt at low temperature was analyzed using the method of single factor variance.The phase structure characteristics of SBS-PPA composite modified asphalt were observed and analyzed by fluorescence microscope.The results shows that PPA addition can improve the low temperature performance of matrix asphalt and SBS modified asphalt,and with the increase of PPA content,low temperature anti-crack performance of bitumen is better.But with the decrease of temperature,the effect of low temperature improvement is gradually reduced.Effect degree of PPA on the properties of base asphalt at low temperature is different at different temperature.At the temperature of -18--12℃,PPA has significant effects on the low temperature performance of base asphalt.At the temperature of -30--24℃,PPA has no significant impact on the low temperature performance of base asphalt.While the effect of PPA on the low temperature performance of SBS-PPA modified asphalt at different temperatures is not significant.The low temperature anti-crack performance of SBS-PPA modified bitumen is better than that of PPA modified asphalt,and the addition of PPA can effectively promote the SBS to disperse into small particles and become more uniform distribution in the asphalt,so the storage stability and the space mesh structure of SBS modified asphalt can be improved effectively.
2017, 34(2): 336-344.
doi: 10.13801/j.cnki.fhclxb.20160407.003
Abstract:
A new type of coupling agent Azido-Benzimidazole (ABI) containing benzimidazole and azide groups was designed and prepared in this study.And ABI was added into the domestic aramid fiber Ⅲ(DAF-Ⅲ)/polytriazole (PTA) composites to reinforce their interfacial properties.The results of SEM,Attenuated Total internal Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and XPS show that ABI can bond with the fiber by intermolecular hydrogen;FTIR and DSC results indicate that the azide group in ABI can react with alkynyl in PTA and take part in the curing process synchronously.The mechanical performances of DAF-Ⅲ/PTA composite are improved greatly after ABI modification.The Inter Laminar Shear Strength (ILSS) and flexural strength increase by 62.0% and 43.7% respectively after 2.1wt% ABI treatment compared with those of untreated composites.
A new type of coupling agent Azido-Benzimidazole (ABI) containing benzimidazole and azide groups was designed and prepared in this study.And ABI was added into the domestic aramid fiber Ⅲ(DAF-Ⅲ)/polytriazole (PTA) composites to reinforce their interfacial properties.The results of SEM,Attenuated Total internal Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and XPS show that ABI can bond with the fiber by intermolecular hydrogen;FTIR and DSC results indicate that the azide group in ABI can react with alkynyl in PTA and take part in the curing process synchronously.The mechanical performances of DAF-Ⅲ/PTA composite are improved greatly after ABI modification.The Inter Laminar Shear Strength (ILSS) and flexural strength increase by 62.0% and 43.7% respectively after 2.1wt% ABI treatment compared with those of untreated composites.
2017, 34(2): 345-351.
doi: 10.13801/j.cnki.fhclxb.20160612.004
Abstract:
By the flexural test of fly ash cenospheres (FACs)/epoxy resin composites,the effect of cenospheres content,particle size and grading ratios on flexural properties of the cenospheres/epoxy resin composites were studied,and the flexural mechanism was analyzed through the flexural fracture morphology.The results show that the addition of cenospheres significantly affects the flexural strength of cenospheres/epoxy composites.With the increase of cenospheres content,the flexural strength of the composites increases first and then decreases and it reaches the maximum when the content of cenospheres is about 15wt%.With the decrease of particle size of the cenospheres,the flexural strength of cenospheres/epoxy composites increases.The smaller size of cenospheres is more benefical to improve the flexural strength of composites.So the flexural strength of composites filled with grading cenospheres is mainly affected by small particle content in grading cenospheres,and with the larger proportion of small size cenospheres,the higher flexural strength of cenospheres/epoxy resin composites can be obtained.
By the flexural test of fly ash cenospheres (FACs)/epoxy resin composites,the effect of cenospheres content,particle size and grading ratios on flexural properties of the cenospheres/epoxy resin composites were studied,and the flexural mechanism was analyzed through the flexural fracture morphology.The results show that the addition of cenospheres significantly affects the flexural strength of cenospheres/epoxy composites.With the increase of cenospheres content,the flexural strength of the composites increases first and then decreases and it reaches the maximum when the content of cenospheres is about 15wt%.With the decrease of particle size of the cenospheres,the flexural strength of cenospheres/epoxy composites increases.The smaller size of cenospheres is more benefical to improve the flexural strength of composites.So the flexural strength of composites filled with grading cenospheres is mainly affected by small particle content in grading cenospheres,and with the larger proportion of small size cenospheres,the higher flexural strength of cenospheres/epoxy resin composites can be obtained.
2017, 34(2): 352-357.
doi: 10.13801/j.cnki.fhclxb.20160530.002
Abstract:
The in-situ growth of carbon nanotubes (CNTs) on the carbon fiber can effectively avoid the uneven distribution of CNTs and exploit the advantages of carbon fiber and carbon nanotubes to the full,which play an important role in enhancing the interfaceproperties of the carbon fiber reinforcedpolymer (CF/EP).The surface of carbon fiber were modified and loaded with catalysts,and then the multy-walled carbon nanotubes (CNTs) were in-situ solid phase grown on the surface of carbon fiber with the assistance of thiophene.The carbon fiber obtained by this method can not only avoid the entanglement and uneven distribution of the CNTs in CNTs-CF/EP,but also enhance the interlaminar properties of CNTs-CF/EP due to the carbon source of synthesized CNTs mainly from the treated carbon fiber with the high surface bonding strength between the carbon fiber and the CNTs.The effects of the catalyst concentrations on the morphologies of growth CNTs and the performances of carbon fiber were investigated by SEM,XRD,FT-IR and other measurements.The results show that the synthesized CNTs can uniformly distribute and firmly bond on the surface of carbon fiber with the proper catalyst concentration of 0.2 mol·L-1.The mechanical properties of the carbon fiber decrease a little.
The in-situ growth of carbon nanotubes (CNTs) on the carbon fiber can effectively avoid the uneven distribution of CNTs and exploit the advantages of carbon fiber and carbon nanotubes to the full,which play an important role in enhancing the interfaceproperties of the carbon fiber reinforcedpolymer (CF/EP).The surface of carbon fiber were modified and loaded with catalysts,and then the multy-walled carbon nanotubes (CNTs) were in-situ solid phase grown on the surface of carbon fiber with the assistance of thiophene.The carbon fiber obtained by this method can not only avoid the entanglement and uneven distribution of the CNTs in CNTs-CF/EP,but also enhance the interlaminar properties of CNTs-CF/EP due to the carbon source of synthesized CNTs mainly from the treated carbon fiber with the high surface bonding strength between the carbon fiber and the CNTs.The effects of the catalyst concentrations on the morphologies of growth CNTs and the performances of carbon fiber were investigated by SEM,XRD,FT-IR and other measurements.The results show that the synthesized CNTs can uniformly distribute and firmly bond on the surface of carbon fiber with the proper catalyst concentration of 0.2 mol·L-1.The mechanical properties of the carbon fiber decrease a little.
2017, 34(2): 358-363.
doi: 10.13801/j.cnki.fhclxb.20160413.001
Abstract:
The binary model was used to simplify the simulation of short fiber reinforced syntactic foams (SFRSF).The randomness of fiber distribution in the space was considered,and the fiber and the matrix were separately divided by different element types without considering the mesh matching.Then the improved embedded element technique (EET) was used to couple the fiber and the matrix.A link element was introduced to simulate the interface and the force transfer mechanism between the fiber and the matrix.Then,a finite element numerical model was established to reflect the mesostructure of the material.Based on the numerical simulation,the influence of the length and content of fiber as well as the content and the wall thickness of hollow particle on the Young's modulus of the SFRSF was studied.The results show that a good agreement can be achieved between the numerical predictions and experimental observations.The increase of the content the length of carbon fibers and the wall thickness of syntactic foam can effectively improve Young's modulus of SFRSF.
The binary model was used to simplify the simulation of short fiber reinforced syntactic foams (SFRSF).The randomness of fiber distribution in the space was considered,and the fiber and the matrix were separately divided by different element types without considering the mesh matching.Then the improved embedded element technique (EET) was used to couple the fiber and the matrix.A link element was introduced to simulate the interface and the force transfer mechanism between the fiber and the matrix.Then,a finite element numerical model was established to reflect the mesostructure of the material.Based on the numerical simulation,the influence of the length and content of fiber as well as the content and the wall thickness of hollow particle on the Young's modulus of the SFRSF was studied.The results show that a good agreement can be achieved between the numerical predictions and experimental observations.The increase of the content the length of carbon fibers and the wall thickness of syntactic foam can effectively improve Young's modulus of SFRSF.
2017, 34(2): 364-373.
doi: 10.13801/j.cnki.fhclxb.20160413.004
Abstract:
This study established 3D finite element analysis models of composite laminates containing SMA wires of different angles and different distance intervals by combing ABAQUS software platform and VC++6.0 program designing.The SMA piecewise linear model derived from Brinson constitutive model to describe the SMA superelasticity and the 3D HASHIN failure criterion to predict intralaminar damage of composite laminates were compiled as ABAQUS/VUMAT subroutines.Interlaminar damage was modeled with cohesive element.Numerical simulation method of the low-velocity impact damage behaviour of composite laminates containing SMA wires and compression-after-impact was proposed.This study compared the damage behaviour of laminates with and without SMA wires,as well as ordinary metal wires at different impact energy.Compression-after-impact (CAI) simulation results indicate that the CAI strength of laminates containing SMA wires with volume friction of 25% and diameter of 0.5 mm,is increased by 5.78% compared with laminates not containing SMA wires,and by 4.69% compared with laminates containing ordinary metal wires at impact energy of 16 J.Furthermore,computation results of SMA wires volume friction and diameter value effecting on the impact behaviour show that laminates' anti-impact ability becomes stronger when volume friction increases.When volume friction keeps constant,the enhancing effect on the laminates' anti-impact ability with SMA wires of smaller diameter (0.3 mm) is better than that with larger diameter (0.6 mm).
This study established 3D finite element analysis models of composite laminates containing SMA wires of different angles and different distance intervals by combing ABAQUS software platform and VC++6.0 program designing.The SMA piecewise linear model derived from Brinson constitutive model to describe the SMA superelasticity and the 3D HASHIN failure criterion to predict intralaminar damage of composite laminates were compiled as ABAQUS/VUMAT subroutines.Interlaminar damage was modeled with cohesive element.Numerical simulation method of the low-velocity impact damage behaviour of composite laminates containing SMA wires and compression-after-impact was proposed.This study compared the damage behaviour of laminates with and without SMA wires,as well as ordinary metal wires at different impact energy.Compression-after-impact (CAI) simulation results indicate that the CAI strength of laminates containing SMA wires with volume friction of 25% and diameter of 0.5 mm,is increased by 5.78% compared with laminates not containing SMA wires,and by 4.69% compared with laminates containing ordinary metal wires at impact energy of 16 J.Furthermore,computation results of SMA wires volume friction and diameter value effecting on the impact behaviour show that laminates' anti-impact ability becomes stronger when volume friction increases.When volume friction keeps constant,the enhancing effect on the laminates' anti-impact ability with SMA wires of smaller diameter (0.3 mm) is better than that with larger diameter (0.6 mm).
2017, 34(2): 374-380.
doi: 10.13801/j.cnki.fhclxb.20160427.001
Abstract:
The collapsible tube semi-sheet with the different plies composite "Ω" figuration part was manufactured by the method of vacuum-oven cured using carbon fibre reinforced plastics (CFRP,T300/5228) composite as ultra-thin unidirectional prepreg with 0.04mm ply thickness,and was analyzed by ANSYS software of finite element analysis.The effects of ply mode and the deviation of orientation angle on deformation were studied.Four ply mode parts were manufactured,and the deformation measurements are consistent with the numerical simulation analysis results.The ply mode of less effect on the deformation was obtained.The research show that ±45°plies affecte on deformation more than that of 0°ply,and 90°plies addition can control ply orientation deformation,which can partly control collapsible tube semi-sheet deformation.The CFRP composite collapsible tube semi-sheet deformation can be controlled to a certain extent by stacking sequence design.
The collapsible tube semi-sheet with the different plies composite "Ω" figuration part was manufactured by the method of vacuum-oven cured using carbon fibre reinforced plastics (CFRP,T300/5228) composite as ultra-thin unidirectional prepreg with 0.04mm ply thickness,and was analyzed by ANSYS software of finite element analysis.The effects of ply mode and the deviation of orientation angle on deformation were studied.Four ply mode parts were manufactured,and the deformation measurements are consistent with the numerical simulation analysis results.The ply mode of less effect on the deformation was obtained.The research show that ±45°plies affecte on deformation more than that of 0°ply,and 90°plies addition can control ply orientation deformation,which can partly control collapsible tube semi-sheet deformation.The CFRP composite collapsible tube semi-sheet deformation can be controlled to a certain extent by stacking sequence design.
2017, 34(2): 381-388.
doi: 10.13801/j.cnki.fhclxb.20160606.004
Abstract:
The experimental investigation on mechanical properties of the multi axial glass fiber reinforced epoxy vinyl ester resin (GF/EVE) and glass fiber reinforced unsaturated polyester (GF/UP) resin composite material were carried out.And the bending strength,interlaminar shear strength and modulus of the specimens were analyzed.The results show that,in the same layer design and process,the bending strength and impact toughness of GF/EVE resin are superior to GF/UP resin.[0,90]6 specimen impact energy absorption performance is superior to the other five layer mode.And basing on SEM and micro ultrasonic C-scan imaging detection,the mechanism of the composites interface debonding mechanism and damage evolution behavior were elucidated.
The experimental investigation on mechanical properties of the multi axial glass fiber reinforced epoxy vinyl ester resin (GF/EVE) and glass fiber reinforced unsaturated polyester (GF/UP) resin composite material were carried out.And the bending strength,interlaminar shear strength and modulus of the specimens were analyzed.The results show that,in the same layer design and process,the bending strength and impact toughness of GF/EVE resin are superior to GF/UP resin.[0,90]6 specimen impact energy absorption performance is superior to the other five layer mode.And basing on SEM and micro ultrasonic C-scan imaging detection,the mechanism of the composites interface debonding mechanism and damage evolution behavior were elucidated.
2017, 34(2): 389-399.
doi: 10.13801/j.cnki.fhclxb.20160523.001
Abstract:
A new modeling method was introduced to solve the subsurface stress field of composites under Hertzian contact loads based on the equivalent inclusion method.The comparisons between the computation results solved by the present method and the finite element method demonstrated the effectiveness and advantage of the new method.The parametric study was carried out to investigate the influences of depth,shape,material property,volume fraction and relative location of reinforcements with different shapes on the stress field of the matrix.The analysis results reveal that the maximum von Mises stress is altered due to the changes in the depth,radius and material properties of the reinforcements for the double-reinforcement model,and the volume fraction and relative position of distributed reinforcements have significant influences on the stress field of the matrix.The rolling contact fatigue (RCF) life experiments of titanium-based composites were conducted,the corresponding results verify the capability of the proposed method on solving the contact performance of composites.
A new modeling method was introduced to solve the subsurface stress field of composites under Hertzian contact loads based on the equivalent inclusion method.The comparisons between the computation results solved by the present method and the finite element method demonstrated the effectiveness and advantage of the new method.The parametric study was carried out to investigate the influences of depth,shape,material property,volume fraction and relative location of reinforcements with different shapes on the stress field of the matrix.The analysis results reveal that the maximum von Mises stress is altered due to the changes in the depth,radius and material properties of the reinforcements for the double-reinforcement model,and the volume fraction and relative position of distributed reinforcements have significant influences on the stress field of the matrix.The rolling contact fatigue (RCF) life experiments of titanium-based composites were conducted,the corresponding results verify the capability of the proposed method on solving the contact performance of composites.
2017, 34(2): 400-405.
doi: 10.13801/j.cnki.fhclxb.20160606.002
Abstract:
The dynamic tensile properties of 2D C/SiC composites were investigated by means of Split Hopkinson Tensile Bar (SHTB) and ultra high-speed camera.Based on its macro mechanic behavior,the failure process of the specimen under dynamic tensile loading was analyzed.The experimental results indicate that the stress-strain curve is obviously non-linear,and examination of the failure process of the specimen helps define the four phases of crack propagation,namely,the damage accumulation phase,crack initiation phase,yield failure phase and crack fast spreading phase.
The dynamic tensile properties of 2D C/SiC composites were investigated by means of Split Hopkinson Tensile Bar (SHTB) and ultra high-speed camera.Based on its macro mechanic behavior,the failure process of the specimen under dynamic tensile loading was analyzed.The experimental results indicate that the stress-strain curve is obviously non-linear,and examination of the failure process of the specimen helps define the four phases of crack propagation,namely,the damage accumulation phase,crack initiation phase,yield failure phase and crack fast spreading phase.
2017, 34(2): 406-413.
doi: 10.13801/j.cnki.fhclxb.20160523.012
Abstract:
With plastering gypsum as basis material,decanoic acid-palmitic acid-SiO2 phase change and humidity storage composites were mixed with plastering gypsum to prepare decanoic acid-palmitic acid-SiO2/gypsum phase change and humidity storage composites.Basic performance,humidity storage humidity controlling performance,phase change temperature controlling performance and durability performance of decanoic acid-palmitic acid-SiO2/gypsum phase change and humidity storage composites were tested and analyzed.Structural composition and microstructure of gypsum phase change and humidity storage composites were analyzed by FTIR and SEM.The results show that decanoic acid-palmitic acid-SiO2 phase change and humidity storage composites with mass content of 40wt% can provide the best performance and good durability performance of decanoic acid-palmitic acid-SiO2/gypsum phase change and humidity storage composites.The standard diffusion degree of water consumption is 0.69,initial setting time is 37 min,final setting time is 51 min,bulk density is 916.67 kg·m-3,tensile connection strength is 0.08 MPa and compressive strength is 1.76 MPa.Equilibrium moisture content is 0.0620-0.0849 g·g-1 in relative humidity 40%-65%.Cooling time from 30℃ to 15℃ is 610 s with clear phase change platform.After the cycling test,the moisture absorption performance decline is 6.44%-9.45%,phase change and temperature controlling performance decline is 7.2%.
With plastering gypsum as basis material,decanoic acid-palmitic acid-SiO2 phase change and humidity storage composites were mixed with plastering gypsum to prepare decanoic acid-palmitic acid-SiO2/gypsum phase change and humidity storage composites.Basic performance,humidity storage humidity controlling performance,phase change temperature controlling performance and durability performance of decanoic acid-palmitic acid-SiO2/gypsum phase change and humidity storage composites were tested and analyzed.Structural composition and microstructure of gypsum phase change and humidity storage composites were analyzed by FTIR and SEM.The results show that decanoic acid-palmitic acid-SiO2 phase change and humidity storage composites with mass content of 40wt% can provide the best performance and good durability performance of decanoic acid-palmitic acid-SiO2/gypsum phase change and humidity storage composites.The standard diffusion degree of water consumption is 0.69,initial setting time is 37 min,final setting time is 51 min,bulk density is 916.67 kg·m-3,tensile connection strength is 0.08 MPa and compressive strength is 1.76 MPa.Equilibrium moisture content is 0.0620-0.0849 g·g-1 in relative humidity 40%-65%.Cooling time from 30℃ to 15℃ is 610 s with clear phase change platform.After the cycling test,the moisture absorption performance decline is 6.44%-9.45%,phase change and temperature controlling performance decline is 7.2%.
2017, 34(2): 414-422.
doi: 10.13801/j.cnki.fhclxb.20160418.001
Abstract:
A series of mesoporous SiO2/expanded graphite (EG) composites were directly synthesized via a facile one-step hydrothermal method in aqueous solutions that contain templates,aluminum salts,expanded graphite and siliceous source.The weak acid environment of reaction solutions were self-generated by the aluminum salts.The effects of the added amount of aluminum salt in the reaction system on the structures and properties of the obtained composites were carefully investigated.The structures and morphologies of the composites were characterized by XRD,N2 physisorption and SEM techniques.Methylene blue (MB) was used as a probe pollutant molecule to systematically evaluate the adsorption properties of the composites.The results show that all mesoporous SiO2/expanded graphite composites have large surface areas and high pore volumes,and they can be prepared by using aluminum salts in a wide range of rAl/Si=0.25-2.0(pH=3.1-2.3).It is further observed that multi-layered mesoporous SiO2 membranes are grown onto the carbon flakes of expanded graphite in SiO2/EG composites.Those SiO2/EG composites synthesized with rAl/Si of 0.25,0.5 and 1.0 have well-ordered mesoporous while those synthesized with rAl/Si of 1.5 and 2.0 have less-ordered mesoporous.Mesoporous SiO2/EG composite adsorption capacity in 52-55 mg·g-1,and the adsorption behavior is mainly in accordance with the Langmuir equation and pseudo-second-order kinetic model.
A series of mesoporous SiO2/expanded graphite (EG) composites were directly synthesized via a facile one-step hydrothermal method in aqueous solutions that contain templates,aluminum salts,expanded graphite and siliceous source.The weak acid environment of reaction solutions were self-generated by the aluminum salts.The effects of the added amount of aluminum salt in the reaction system on the structures and properties of the obtained composites were carefully investigated.The structures and morphologies of the composites were characterized by XRD,N2 physisorption and SEM techniques.Methylene blue (MB) was used as a probe pollutant molecule to systematically evaluate the adsorption properties of the composites.The results show that all mesoporous SiO2/expanded graphite composites have large surface areas and high pore volumes,and they can be prepared by using aluminum salts in a wide range of rAl/Si=0.25-2.0(pH=3.1-2.3).It is further observed that multi-layered mesoporous SiO2 membranes are grown onto the carbon flakes of expanded graphite in SiO2/EG composites.Those SiO2/EG composites synthesized with rAl/Si of 0.25,0.5 and 1.0 have well-ordered mesoporous while those synthesized with rAl/Si of 1.5 and 2.0 have less-ordered mesoporous.Mesoporous SiO2/EG composite adsorption capacity in 52-55 mg·g-1,and the adsorption behavior is mainly in accordance with the Langmuir equation and pseudo-second-order kinetic model.
2017, 34(2): 423-429.
doi: 10.13801/j.cnki.fhclxb.20160420.001
Abstract:
In order to obtain supercapacitor materials with high specific capacitance and good cycle life,The 3D-Fiberbased graphene (3D G) was prepared with a two-step carbonation by watermeon flesh as carbon source.At last CeO2-MnO/3D G composite was prepared with the Hydrothermal method.The results show thatthe 3D G exhibits an excellent BET-surface area of 332 m2·g-1 due to the good spatial structure.CeO2-MnO/3D G composite are featured with a 3D conductive network structure,and metal oxide particles between the graphene sheets grow evenly,with about 10 nm in diameter.The electrochemical testing results show that the CeO2-MnO/3D G composite exhibit an excellent capacitance of 308.5 F·g-1 with the current density of 1 A·g-1,MnO:CeO2=4:1 and composite load at 80% in 0.5 mol·L-1 Na2SO4 solution.Meanwhile,the CeO2-MnO/3D G composite also show outstanding cycling stability with 95.5% of the capacitance retention after 1000 cycles of charge/discharge.The high electrochemical properties of the CeO2-MnO/3D G composite is mainly attributed to the synergy of two metal oxide composite load with graphene.
In order to obtain supercapacitor materials with high specific capacitance and good cycle life,The 3D-Fiberbased graphene (3D G) was prepared with a two-step carbonation by watermeon flesh as carbon source.At last CeO2-MnO/3D G composite was prepared with the Hydrothermal method.The results show thatthe 3D G exhibits an excellent BET-surface area of 332 m2·g-1 due to the good spatial structure.CeO2-MnO/3D G composite are featured with a 3D conductive network structure,and metal oxide particles between the graphene sheets grow evenly,with about 10 nm in diameter.The electrochemical testing results show that the CeO2-MnO/3D G composite exhibit an excellent capacitance of 308.5 F·g-1 with the current density of 1 A·g-1,MnO:CeO2=4:1 and composite load at 80% in 0.5 mol·L-1 Na2SO4 solution.Meanwhile,the CeO2-MnO/3D G composite also show outstanding cycling stability with 95.5% of the capacitance retention after 1000 cycles of charge/discharge.The high electrochemical properties of the CeO2-MnO/3D G composite is mainly attributed to the synergy of two metal oxide composite load with graphene.
2017, 34(2): 430-437.
doi: 10.13801/j.cnki.fhclxb.20160606.001
Abstract:
Experiments and finite element analysis were carried out for the problem of open hole sensitivity of 3D carbon/carbon composite material plates.Finite element models of the representative volume element (RVE),the intact plate and open-hole plates of 3D carbon/carbon composite were established.Transition method between macro level stress and meso level stress was given and numerical simulation on the tensile failure of the intact plate and open-hole plates was implemented based on this method.By uniaxial tensile tests of 3D carbon/carbon composite intact plates and open-hole plates,good agreement between numerical results and experiments was observed.In addition,the influence of width to diameter ratio (WTDR) on the tensile strength was analyzed.The results show that the tensile strength of open-hole plate decreases by 11.5% comparing with that of intact plate when the WTDR reaches 6.It can be considered that the open hole makes little influence on the tensile strength of plates if the WTDR is not less than 6.And the result of the investigation provides insight into the design of carbon/carbon composite open-hole plate.
Experiments and finite element analysis were carried out for the problem of open hole sensitivity of 3D carbon/carbon composite material plates.Finite element models of the representative volume element (RVE),the intact plate and open-hole plates of 3D carbon/carbon composite were established.Transition method between macro level stress and meso level stress was given and numerical simulation on the tensile failure of the intact plate and open-hole plates was implemented based on this method.By uniaxial tensile tests of 3D carbon/carbon composite intact plates and open-hole plates,good agreement between numerical results and experiments was observed.In addition,the influence of width to diameter ratio (WTDR) on the tensile strength was analyzed.The results show that the tensile strength of open-hole plate decreases by 11.5% comparing with that of intact plate when the WTDR reaches 6.It can be considered that the open hole makes little influence on the tensile strength of plates if the WTDR is not less than 6.And the result of the investigation provides insight into the design of carbon/carbon composite open-hole plate.
2017, 34(2): 438-445.
doi: 10.13801/j.cnki.fhclxb.20160413.002
Abstract:
This study conducted comprehensive experimental and modeling investigations on compressive properties of polyurethane grout materials with the density of 0.08-0.5 g·cm-3.SEM and uniaxial compression tests were applied to specimens with varied density.Parameters obtained from SEM images were employed to predict compressive strength.It is found that foams in higher density specimens are spheres owning less contact area,which ensures the system stability based on the minimum energy principle.While majority foams in lower density specimen are polyhedrons and their contact area is larger.The uniaxial compression can be divided into elastic (strain less than 5%),yield (strain from 5% to 50%) and densification (strain higher than 50%) stages.In elastic stage,strain of higher density specimen develops faster with normalized stress,while the corresponding stress at yield stage can be viewed as compressive strength and develops with density,and in densification stage higher density specimens are characterized with brittle failure.Gibson-Ashby model based on geometric parameters of foams obtained from SEM image can be used to predict the compressive strength,and materials with varied density characterized with different strength can be applied in infrastructure maintenance.
This study conducted comprehensive experimental and modeling investigations on compressive properties of polyurethane grout materials with the density of 0.08-0.5 g·cm-3.SEM and uniaxial compression tests were applied to specimens with varied density.Parameters obtained from SEM images were employed to predict compressive strength.It is found that foams in higher density specimens are spheres owning less contact area,which ensures the system stability based on the minimum energy principle.While majority foams in lower density specimen are polyhedrons and their contact area is larger.The uniaxial compression can be divided into elastic (strain less than 5%),yield (strain from 5% to 50%) and densification (strain higher than 50%) stages.In elastic stage,strain of higher density specimen develops faster with normalized stress,while the corresponding stress at yield stage can be viewed as compressive strength and develops with density,and in densification stage higher density specimens are characterized with brittle failure.Gibson-Ashby model based on geometric parameters of foams obtained from SEM image can be used to predict the compressive strength,and materials with varied density characterized with different strength can be applied in infrastructure maintenance.
2017, 34(2): 446-455.
doi: 10.13801/j.cnki.fhclxb.20160406.001
Abstract:
In order to investigate the size effect and the sensibility of strain rate of the jute yarns,the quasi-static tests were conducted by utilizing a C43 electromechanical universal test system and dynamic tests were performed by utilizing a CEAST 9340 drop-weight impact system.The correlations between mechanical parameters (Young's modulus,tensile strength,ultimate strain and toughness) and experimental conditions (gauge lengths and strain rates) were obtained through the tests.The samples with six different gauge lengths (25,50,100,150,200 and 300 mm) were tested at the strain rate of 1/600 s-1 in the quasi-static tests,and the samples with the gauge length of 25 mm were tested over four different strain rates (40,80,120 and 160 s-1) in the dynamic tests in which the strain rate was a variable.The experimental results show that Young's modulus increases initially,and then tends to be stable when the gauge length is larger than 100 mm,while tensile strength,ultimate strain and toughness decrease with increasing the gauge length.As the strain rate increases,Young's modulus and tensile strength increase,while ultimate strain decreases initially and then maintains constant,and toughness decreases initially but then increases.Due to the large scatter in the material properties of plant yarns,Weibull distribution was used to fit the experimental data,by which the distribution of tensile strength of the jute yarns under different experimental conditions (gauge length and strain rate) were obtained.
In order to investigate the size effect and the sensibility of strain rate of the jute yarns,the quasi-static tests were conducted by utilizing a C43 electromechanical universal test system and dynamic tests were performed by utilizing a CEAST 9340 drop-weight impact system.The correlations between mechanical parameters (Young's modulus,tensile strength,ultimate strain and toughness) and experimental conditions (gauge lengths and strain rates) were obtained through the tests.The samples with six different gauge lengths (25,50,100,150,200 and 300 mm) were tested at the strain rate of 1/600 s-1 in the quasi-static tests,and the samples with the gauge length of 25 mm were tested over four different strain rates (40,80,120 and 160 s-1) in the dynamic tests in which the strain rate was a variable.The experimental results show that Young's modulus increases initially,and then tends to be stable when the gauge length is larger than 100 mm,while tensile strength,ultimate strain and toughness decrease with increasing the gauge length.As the strain rate increases,Young's modulus and tensile strength increase,while ultimate strain decreases initially and then maintains constant,and toughness decreases initially but then increases.Due to the large scatter in the material properties of plant yarns,Weibull distribution was used to fit the experimental data,by which the distribution of tensile strength of the jute yarns under different experimental conditions (gauge length and strain rate) were obtained.
2017, 34(2): 456-462.
doi: 10.13801/j.cnki.fhclxb.20160616.003
Abstract:
An imaging method,which combines the MUSIC (Multiple Signal Classification) algorithm and linear sensor array,was proposed and used for monitoring the composite structure damage.This method utilized the array signal processing method based on MUSIC algorithm,which performed the eigenvalue decomposition of the covariance matrix of array signal and then calculated the spatial spectrum by direction scanning to realize damage imaging.The method has an advantage of arranging the linear sensor array easily.The experiment on the aircraft oil tank,which was made of carbon fibers with a variable thickness,was established.Experimental results show that the proposed method can realize damage imaging on aircraft composite structures accurately,and the damage localization error is less than 2 cm.
An imaging method,which combines the MUSIC (Multiple Signal Classification) algorithm and linear sensor array,was proposed and used for monitoring the composite structure damage.This method utilized the array signal processing method based on MUSIC algorithm,which performed the eigenvalue decomposition of the covariance matrix of array signal and then calculated the spatial spectrum by direction scanning to realize damage imaging.The method has an advantage of arranging the linear sensor array easily.The experiment on the aircraft oil tank,which was made of carbon fibers with a variable thickness,was established.Experimental results show that the proposed method can realize damage imaging on aircraft composite structures accurately,and the damage localization error is less than 2 cm.
2017, 34(2): 463-470.
doi: 10.13801/j.cnki.fhclxb.20160425.001
Abstract:
The influence of mass loss,dynamic elastic modulus and mechanical properties of concrete in different solutions (Water,3.5wt% NaCl,Aircraft Deicing fluid) were studied through accelerated cyclic freeze-thaw tests,whose damage degree to concrete was also compared.The relationship between relative dynamic elastic modulus and relative residual compressive strength/relative residual flexural strength was analyzed.Meanwhile,the attenuation equation was also established on account of relative dynamic elastic modulus.The study shows that the freeze-thaw damage to the concrete in 3.5wt% NaCl solution is much worse than in the water,but its damage can be restrained in the Aircraft Deicing fluid.With the increase of the freeze-thaw testing times,the compressive strength,flexural strength and relative dynamic elastic modulus of concrete decrease.The loss ratio of the compressive strength and the flexural strength in different solutions ranges in a descendant sequence is from 3.5wt% NaCl solution to water and then to Aircraft Deicing fluid.The relative residual strength can be evaluated by the relative dynamic elastic modulus due to its good relativity to the relative residual compressive strength and relative residual flexural strength.
The influence of mass loss,dynamic elastic modulus and mechanical properties of concrete in different solutions (Water,3.5wt% NaCl,Aircraft Deicing fluid) were studied through accelerated cyclic freeze-thaw tests,whose damage degree to concrete was also compared.The relationship between relative dynamic elastic modulus and relative residual compressive strength/relative residual flexural strength was analyzed.Meanwhile,the attenuation equation was also established on account of relative dynamic elastic modulus.The study shows that the freeze-thaw damage to the concrete in 3.5wt% NaCl solution is much worse than in the water,but its damage can be restrained in the Aircraft Deicing fluid.With the increase of the freeze-thaw testing times,the compressive strength,flexural strength and relative dynamic elastic modulus of concrete decrease.The loss ratio of the compressive strength and the flexural strength in different solutions ranges in a descendant sequence is from 3.5wt% NaCl solution to water and then to Aircraft Deicing fluid.The relative residual strength can be evaluated by the relative dynamic elastic modulus due to its good relativity to the relative residual compressive strength and relative residual flexural strength.
