2018 Vol. 35, No. 7
2018, 35(7): 1683-1690.
doi: 10.13801/j.cnki.fhclxb.20171120.003
Abstract:
The functionalized graphene oxide (TDI-GO) was prepared by grafting 2, 4-di-isocyanate(TDI) onto the surface of GO. Then a series of TDI-GO/thermoplastic polyurethane elastomer(TPU) composites with different TDI-GO contents were prepared by prepolymer method via in-situ polymerization. The structure of TDI-GO was characterized and the influences of the dosage of TDI-GO on the structure and properties of TDI-GO/TPU composites were studied by FTIR, XPS, DSC, TG, SEM, the Vicat softening temperature and the mechanical property tester. The results demonstrate that, TDI successfully graft onto GO; TDI-GO can decrease microphase separation of TPU, and improve the crystallinity of hard segment as a heterogeneous nucleation agent; comparing with the pristine TPU, TDI-GO/TPU composites have excellent thermal properties, when the mass fraction of TDI-GO is 0.5wt%, the 5% degradation temperature increases by 9℃, and the Vicat softening temperature raises by 18℃; the mechanical properties of TDI-GO/TPU composites enhance markedly, comparing with the pristine TPU, when the mass fraction of TDI-GO is 0.5wt%, the tensile strength increases almost 10 MPa, and the elongation at breaking increases about 32%.
The functionalized graphene oxide (TDI-GO) was prepared by grafting 2, 4-di-isocyanate(TDI) onto the surface of GO. Then a series of TDI-GO/thermoplastic polyurethane elastomer(TPU) composites with different TDI-GO contents were prepared by prepolymer method via in-situ polymerization. The structure of TDI-GO was characterized and the influences of the dosage of TDI-GO on the structure and properties of TDI-GO/TPU composites were studied by FTIR, XPS, DSC, TG, SEM, the Vicat softening temperature and the mechanical property tester. The results demonstrate that, TDI successfully graft onto GO; TDI-GO can decrease microphase separation of TPU, and improve the crystallinity of hard segment as a heterogeneous nucleation agent; comparing with the pristine TPU, TDI-GO/TPU composites have excellent thermal properties, when the mass fraction of TDI-GO is 0.5wt%, the 5% degradation temperature increases by 9℃, and the Vicat softening temperature raises by 18℃; the mechanical properties of TDI-GO/TPU composites enhance markedly, comparing with the pristine TPU, when the mass fraction of TDI-GO is 0.5wt%, the tensile strength increases almost 10 MPa, and the elongation at breaking increases about 32%.
2018, 35(7): 1691-1699.
doi: 10.13801/j.cnki.fhclxb.20171026.001
Abstract:
Five graphene oxide (GO) with different oxidation degrees were prepared by the modified Hummers method. The composition and structure evolution of prepared GO were studied by elemental analysis, X-ray photo-electron spectroscopy and FTIR spectroscopy. The disperse states of different GO in the epoxy hardener (isophorone diamine, IPDA) were observed by an optical microscope. The GO sample which showed the best dispersibility was used to modify carbon fiber/epoxy(CF/EP) composites. The results indicate that by increasing the quantity of oxidant and reaction time, the oxidation degrees of GO increase accordingly. At a low oxidation degree, the functional groups on GO surfaces mainly contain carboxyl, carbonyl and phenolic groups. As the oxidation degree increases, the ether, epoxy and aliphatic hydroxyl groups gradually become dominant on GO surfaces. The disperse state of GO in IPDA is closely associated with the oxidation degree of GO. Both GO with the low and high oxidation degrees show clear aggregation. In addition, the GO surfaces can be chemically functionalized by IPDA during the dispersing process. Compared with the control sample with the unmodified EP matrix, the CF-GO/EP composites show about 14%, 17% and 14% increases in flexural strength, interlaminar shear strength and mode Ⅱ critical strain energy release rate (GⅡC), respectively, when the GO(0.2wt%) is added which has the best dispersibility is incorporated in the EP matrix.
Five graphene oxide (GO) with different oxidation degrees were prepared by the modified Hummers method. The composition and structure evolution of prepared GO were studied by elemental analysis, X-ray photo-electron spectroscopy and FTIR spectroscopy. The disperse states of different GO in the epoxy hardener (isophorone diamine, IPDA) were observed by an optical microscope. The GO sample which showed the best dispersibility was used to modify carbon fiber/epoxy(CF/EP) composites. The results indicate that by increasing the quantity of oxidant and reaction time, the oxidation degrees of GO increase accordingly. At a low oxidation degree, the functional groups on GO surfaces mainly contain carboxyl, carbonyl and phenolic groups. As the oxidation degree increases, the ether, epoxy and aliphatic hydroxyl groups gradually become dominant on GO surfaces. The disperse state of GO in IPDA is closely associated with the oxidation degree of GO. Both GO with the low and high oxidation degrees show clear aggregation. In addition, the GO surfaces can be chemically functionalized by IPDA during the dispersing process. Compared with the control sample with the unmodified EP matrix, the CF-GO/EP composites show about 14%, 17% and 14% increases in flexural strength, interlaminar shear strength and mode Ⅱ critical strain energy release rate (GⅡC), respectively, when the GO(0.2wt%) is added which has the best dispersibility is incorporated in the EP matrix.
2018, 35(7): 1700-1708.
doi: 10.13801/j.cnki.fhclxb.20171114.005
Abstract:
The modified graphene/polyvinyl chloride (KH-GE/PVC) composites were prepared by melting mixing of polyvinyl chloride and modified graphene. The GE was modified with different contents of silane coupling agent γ-methacryloxy propyl trimethoxy silane(KH570), the changes of graphene structure before and after modification were characterized by FTIR, Raman, XRD, TEM and SEM. And the mechanical properties, electrical conductivity and stability of KH-GE/PVC composites were also investigated. The results show that the layer spacing of KH-GE composite is larger whenW(GE:KH570) mass ratio (the total amount is 100) is 1:2. With the increase of KH-GE content, the mechanical properties of KH-GE/PVC composites are significantly improved. When the content of KH-GE is 1.5wt%, the tensile strength and elongation at break of the composite are 23.98 MPa and 226.78%, respectively, which are 51.1% and 65.73% higher than the composite without KH-GE. Comparing with pure PVC, the corresponding 50% thermal weight loss(T50%) and 90% thermal weight loss(T90%) increase from 289.81℃ to 298.51℃ and 486.01℃ to 596.53℃ when the content of KH-GE is 1.5wt%. It indicates that the thermal stability of the films are improved and the conductivity of the composites are also enhanced.
The modified graphene/polyvinyl chloride (KH-GE/PVC) composites were prepared by melting mixing of polyvinyl chloride and modified graphene. The GE was modified with different contents of silane coupling agent γ-methacryloxy propyl trimethoxy silane(KH570), the changes of graphene structure before and after modification were characterized by FTIR, Raman, XRD, TEM and SEM. And the mechanical properties, electrical conductivity and stability of KH-GE/PVC composites were also investigated. The results show that the layer spacing of KH-GE composite is larger whenW(GE:KH570) mass ratio (the total amount is 100) is 1:2. With the increase of KH-GE content, the mechanical properties of KH-GE/PVC composites are significantly improved. When the content of KH-GE is 1.5wt%, the tensile strength and elongation at break of the composite are 23.98 MPa and 226.78%, respectively, which are 51.1% and 65.73% higher than the composite without KH-GE. Comparing with pure PVC, the corresponding 50% thermal weight loss(T50%) and 90% thermal weight loss(T90%) increase from 289.81℃ to 298.51℃ and 486.01℃ to 596.53℃ when the content of KH-GE is 1.5wt%. It indicates that the thermal stability of the films are improved and the conductivity of the composites are also enhanced.
2018, 35(7): 1709-1715.
doi: 10.13801/j.cnki.fhclxb.20171010.001
Abstract:
The purpose of the study is to design and prepare new conductive composites with both electrical and magnetic functions. The chopped carbon fiber (CF) with good conductivity and chopped Ni-plated CF (Ni-CF) with both magnetic and conductive properties were used as the functional body. The chopped glass fiber (GF) was used as the filler, the vinyl ester resin (VER) was used as the matrix, and the electromagnetic properties can be controlled. The effects of CF content on the volume resistivity of CF-GF/VER conductive composites were studied. The effects of Ni-CF length on the volume resistivity of (Ni-CF)-CF-GF/VER were also investigated. The effects of Ni-CF content on the volume resistivity of the composites were investigated. The volume resistivity and magnetic permeability, and the electromagnetic shielding performance of conductive composite material were preliminarily explored. The results show that the volume resistivity is adjustable from 0.35 to 36.48 Ω·cm, and the permeability is adjustable from 0.2 to 0.7. The CF and Ni-CF content and length will have a great influence on the electromagnetic properties of (Ni-CF)-CF-GF/VER conductive composites. The prepared (Ni-CF)-CF-GF/VER conductive composites are expected to be used in the field of electromagnetic shielding.
The purpose of the study is to design and prepare new conductive composites with both electrical and magnetic functions. The chopped carbon fiber (CF) with good conductivity and chopped Ni-plated CF (Ni-CF) with both magnetic and conductive properties were used as the functional body. The chopped glass fiber (GF) was used as the filler, the vinyl ester resin (VER) was used as the matrix, and the electromagnetic properties can be controlled. The effects of CF content on the volume resistivity of CF-GF/VER conductive composites were studied. The effects of Ni-CF length on the volume resistivity of (Ni-CF)-CF-GF/VER were also investigated. The effects of Ni-CF content on the volume resistivity of the composites were investigated. The volume resistivity and magnetic permeability, and the electromagnetic shielding performance of conductive composite material were preliminarily explored. The results show that the volume resistivity is adjustable from 0.35 to 36.48 Ω·cm, and the permeability is adjustable from 0.2 to 0.7. The CF and Ni-CF content and length will have a great influence on the electromagnetic properties of (Ni-CF)-CF-GF/VER conductive composites. The prepared (Ni-CF)-CF-GF/VER conductive composites are expected to be used in the field of electromagnetic shielding.
2018, 35(7): 1716-1724.
doi: 10.13801/j.cnki.fhclxb.20170911.002
Abstract:
Graphene oxide (GO) was prepared by modified Hummers method, and nano SiO2-GO was prepared by combining GO with nano SiO2, which modified by silane coupling agent γ-aminopropyltriethoxysilane(KH550). The nano SiO2-GO was characterized by FTIR, XRD, SEM and TEM. The nano SiO2-GO was added to the epoxy resin(EP) coating by mechanical mixing and ultrasonic dispersion.The physical properties and electrochemical properties of the coatings with different mass fraction of nano SiO2, GO and nano SiO2-GO composites were tested. The results show that compared with the pure EP coating, the hardness, adhesion and corrosion resistance of nano SiO2/EP, GO/EP and nano SiO2-GO/EP are obviously enhanced. The hardness of the coating with 2wt% nano SiO2-GO is 5 H, the adhesion grade reaches 1, and the protection efficiency is 99.33% after immersion 24 h. The results of 15 days immersion test show that the coating hardness of 1.5wt% nano SiO2-GO/EP reaches 5 H, the adhesion grade is 1, and the protection efficiency still remain at 97.12%.
Graphene oxide (GO) was prepared by modified Hummers method, and nano SiO2-GO was prepared by combining GO with nano SiO2, which modified by silane coupling agent γ-aminopropyltriethoxysilane(KH550). The nano SiO2-GO was characterized by FTIR, XRD, SEM and TEM. The nano SiO2-GO was added to the epoxy resin(EP) coating by mechanical mixing and ultrasonic dispersion.The physical properties and electrochemical properties of the coatings with different mass fraction of nano SiO2, GO and nano SiO2-GO composites were tested. The results show that compared with the pure EP coating, the hardness, adhesion and corrosion resistance of nano SiO2/EP, GO/EP and nano SiO2-GO/EP are obviously enhanced. The hardness of the coating with 2wt% nano SiO2-GO is 5 H, the adhesion grade reaches 1, and the protection efficiency is 99.33% after immersion 24 h. The results of 15 days immersion test show that the coating hardness of 1.5wt% nano SiO2-GO/EP reaches 5 H, the adhesion grade is 1, and the protection efficiency still remain at 97.12%.
2018, 35(7): 1725-1730.
doi: 10.13801/j.cnki.fhclxb.20171012.004
Abstract:
Oleic acid-capped nanocrystals (nano ZrO2) were fabricated via two-phase approach, modified and grafted onto polyamic acid (PAA). After the imidization of nano ZrO2/PAA, nano ZrO2/polyamide (PI) ultra-thin composite films were finally obtained. The nanocrystals and nano ZrO2/PI ultra-thin composite films were characterized by TEM, XRD, FTIR and SEM, and the dielectric properties of the nano ZrO2/PI ultra-thin composite films were also exploited. The results demonstrate the nano-size (about 5.0 nm) and mono-dispersity of ZrO2, the morphology and crystallinity of the nanocrystals are not negatively influenced by modification or grafting. The nanocrystals are homogenously dispersed in the bulk of PI. The dielectric properties of nano ZrO2/PI ultra-thin composite films are influenced by the mass fraction of nanocrystals and the filming condition (i.e., imidization temperature). With a PAA:ZrO2 mass ratio of 2:3 and aimidization temperature of 320℃, the dielectric constant exhibites the maximum, around twice that of pure PI thin films. Overall, nano ZrO2/PI ultra-thin composite film fabrication method (general nanocrystal preparation-modification-grafting-imidization) exhibites its efficiency, feasibility, flexibility and versatility. This method can be extended by evolving other nanoparticles with high dielectric constant, tailor the properties by tuning the content of nanoparticles and filming condition, and obtain high dielectric constant composite films with low cost and pollution.
Oleic acid-capped nanocrystals (nano ZrO2) were fabricated via two-phase approach, modified and grafted onto polyamic acid (PAA). After the imidization of nano ZrO2/PAA, nano ZrO2/polyamide (PI) ultra-thin composite films were finally obtained. The nanocrystals and nano ZrO2/PI ultra-thin composite films were characterized by TEM, XRD, FTIR and SEM, and the dielectric properties of the nano ZrO2/PI ultra-thin composite films were also exploited. The results demonstrate the nano-size (about 5.0 nm) and mono-dispersity of ZrO2, the morphology and crystallinity of the nanocrystals are not negatively influenced by modification or grafting. The nanocrystals are homogenously dispersed in the bulk of PI. The dielectric properties of nano ZrO2/PI ultra-thin composite films are influenced by the mass fraction of nanocrystals and the filming condition (i.e., imidization temperature). With a PAA:ZrO2 mass ratio of 2:3 and aimidization temperature of 320℃, the dielectric constant exhibites the maximum, around twice that of pure PI thin films. Overall, nano ZrO2/PI ultra-thin composite film fabrication method (general nanocrystal preparation-modification-grafting-imidization) exhibites its efficiency, feasibility, flexibility and versatility. This method can be extended by evolving other nanoparticles with high dielectric constant, tailor the properties by tuning the content of nanoparticles and filming condition, and obtain high dielectric constant composite films with low cost and pollution.
2018, 35(7): 1731-1737.
doi: 10.13801/j.cnki.fhclxb.20171026.002
Abstract:
A novel flame retardant containing P and N was successfully synthesized via the addition reaction between triglycidyl isocyanurate (TGIC), acrylic acid and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). A flame retardant composite material TGICA-DOPO/vinyl ester resin (VER) was prepared by applying it to VER. The structure of TGICA-DOPO is characterized by FTIR, 1H and 31P nuclear magnetic resonance (NMR). The flame retardancy and thermal properties of TGICA-DOPO/VER resin system were respectively investigated by limited oxygen index (LOI) measurement, TGA and DMA. The results show that the LOI value of the resin system containing 30wt% TGICA-DOPO is improved to 35. TGA results indicate that the char yields of VER casting containing 25wt% TGICA-DOPO under 800℃ is increased by 322%. The FTIR and SEM results indicate that TGICA-DOPO promotes the formation of continuous, compact and intumescent char layer which can reduce the efficiency of heat-and oxygen-exchange.
A novel flame retardant containing P and N was successfully synthesized via the addition reaction between triglycidyl isocyanurate (TGIC), acrylic acid and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). A flame retardant composite material TGICA-DOPO/vinyl ester resin (VER) was prepared by applying it to VER. The structure of TGICA-DOPO is characterized by FTIR, 1H and 31P nuclear magnetic resonance (NMR). The flame retardancy and thermal properties of TGICA-DOPO/VER resin system were respectively investigated by limited oxygen index (LOI) measurement, TGA and DMA. The results show that the LOI value of the resin system containing 30wt% TGICA-DOPO is improved to 35. TGA results indicate that the char yields of VER casting containing 25wt% TGICA-DOPO under 800℃ is increased by 322%. The FTIR and SEM results indicate that TGICA-DOPO promotes the formation of continuous, compact and intumescent char layer which can reduce the efficiency of heat-and oxygen-exchange.
2018, 35(7): 1738-1744.
doi: 10.13801/j.cnki.fhclxb.20180529.002
Abstract:
The anti-corrosive coating was prepared by graphite nanosheets (GNs), epoxy emulsion (EP emulsion) and its curing agent, and the anti-corrosive mechanism of the GNs/EP emulsion anti-corrosive coating with graphite was analyzed. The best GNs amount is 4% of epoxy resin in EP emulsion, as a result of the salt spray testing, with the breaking time is 240 h, and its corrosion under the scribe line or an area of damaged edge corroded for 200 h is smaller than the Fe2O3/EP coating. The anti-corrosive ability of the GNs/EP emulsion coating is enhanced by the improvement of the GNs distribution, as could be seen from the SEM images of the coating surface. GNs/EP emulsion coating film has the higher corrosion potential and smaller corrosion current listed in the Tafel testing, as the result of the dielectric constant increased by the miniature capacitor formed with epoxy and well distributed GNs, the electric charge storage ability is enhanced and the electron transfer ability is reduced by this. As a result, the anti-corrosive model of GNs/EP emulsion coating is formed employing the Nyquist diagrams and the SEM images of GNs/EP emulsion coating cross section. The function of the anti-corrosive GNs/EP emulsion coating is attribute by the physical function to defend the H2O and O2 employing the high chemical stability of GNs and the electrochemistry function to reduce the electron transfer ability by forming the miniature capacitor.
The anti-corrosive coating was prepared by graphite nanosheets (GNs), epoxy emulsion (EP emulsion) and its curing agent, and the anti-corrosive mechanism of the GNs/EP emulsion anti-corrosive coating with graphite was analyzed. The best GNs amount is 4% of epoxy resin in EP emulsion, as a result of the salt spray testing, with the breaking time is 240 h, and its corrosion under the scribe line or an area of damaged edge corroded for 200 h is smaller than the Fe2O3/EP coating. The anti-corrosive ability of the GNs/EP emulsion coating is enhanced by the improvement of the GNs distribution, as could be seen from the SEM images of the coating surface. GNs/EP emulsion coating film has the higher corrosion potential and smaller corrosion current listed in the Tafel testing, as the result of the dielectric constant increased by the miniature capacitor formed with epoxy and well distributed GNs, the electric charge storage ability is enhanced and the electron transfer ability is reduced by this. As a result, the anti-corrosive model of GNs/EP emulsion coating is formed employing the Nyquist diagrams and the SEM images of GNs/EP emulsion coating cross section. The function of the anti-corrosive GNs/EP emulsion coating is attribute by the physical function to defend the H2O and O2 employing the high chemical stability of GNs and the electrochemistry function to reduce the electron transfer ability by forming the miniature capacitor.
2018, 35(7): 1745-1753.
doi: 10.13801/j.cnki.fhclxb.20171114.010
Abstract:
The activated carbon (AC) was synthesized using cattail as a raw material and H3PO4 as an activator. Activated carbon supported Fe2O3 (AC-Fe2O3) composite was prepared by a dipping-roasting method. The obtained AC and AC-Fe2O3 were incorporated into the flexible polyvinyl chloride (PVC) to prepare AC/PVC and AC-Fe2O3/PVC, respectively. The thermal decomposition behavior of AC/PVC and AC-Fe2O3/PVC composites was investigated by thermal gravity analysis; the flame retardation of AC/PVC and AC-Fe2O3/PVC composites was studied by limiting oxygen index test (LOI), vertical burning test (UL-94) and cone calorimeter (CONE). The results show that AC/PVC and AC-Fe2O3/PVC composites can meet the requirement of V-0 grade in UL-94 test and LOI value is higher. Both the peak heat release rate and total smoke release for AC/PVC and AC-Fe2O3/PVC composites decrease significantly in comparison to neat PVC. The enhancement for AC/PVC and AC-Fe2O3/PVC composites in flame retardation mainly attributes to synergistic effect of AC and Fe2O3 in condensed phase. On one hand, it can be assigned to the physical barrier effect of the AC; on the other hand, during the earlier stage of combustion of PVC, Fe2O3 promotes the crosslinking carbonization reaction which can catalyze charring of PVC to form a more stable char layer, improving the char residual ratio and effectively suppressing combustion of PVC.
The activated carbon (AC) was synthesized using cattail as a raw material and H3PO4 as an activator. Activated carbon supported Fe2O3 (AC-Fe2O3) composite was prepared by a dipping-roasting method. The obtained AC and AC-Fe2O3 were incorporated into the flexible polyvinyl chloride (PVC) to prepare AC/PVC and AC-Fe2O3/PVC, respectively. The thermal decomposition behavior of AC/PVC and AC-Fe2O3/PVC composites was investigated by thermal gravity analysis; the flame retardation of AC/PVC and AC-Fe2O3/PVC composites was studied by limiting oxygen index test (LOI), vertical burning test (UL-94) and cone calorimeter (CONE). The results show that AC/PVC and AC-Fe2O3/PVC composites can meet the requirement of V-0 grade in UL-94 test and LOI value is higher. Both the peak heat release rate and total smoke release for AC/PVC and AC-Fe2O3/PVC composites decrease significantly in comparison to neat PVC. The enhancement for AC/PVC and AC-Fe2O3/PVC composites in flame retardation mainly attributes to synergistic effect of AC and Fe2O3 in condensed phase. On one hand, it can be assigned to the physical barrier effect of the AC; on the other hand, during the earlier stage of combustion of PVC, Fe2O3 promotes the crosslinking carbonization reaction which can catalyze charring of PVC to form a more stable char layer, improving the char residual ratio and effectively suppressing combustion of PVC.
2018, 35(7): 1754-1761.
doi: 10.13801/j.cnki.fhclxb.20170905.004
Abstract:
Microencapsulated Mg(OH)2 (M-Mg(OH)2) flame retardant with micro-sized Mg(OH)2 particles as the core and cross-linking polyurea as the shell, was synthesized by in-situ polymerization. The obtained M-Mg(OH)2 was incorporated into ethylene-vinyl acetate copolymer (EVA) and its flame retardant effect on EVA was studied. FTIR, SEM, thermal analysis and acid titration were used to investigate the properties of M-Mg(OH)2. Limiting oxygen index (LOI) and vertical burning test (UL-94 VBT) were employed to study the flame retardancy of M-Mg(OH)2/EVA composite and the effect of acid erosion on the flame retardancy of M-Mg(OH)2/EVA composite. It shows that the surface of Mg(OH)2 particles can be successfully encapsulated with cross-linking polyurea by in-situ polymerization and microencapsulated Mg(OH)2 can be obtained. Compared with the pure Mg(OH)2, the size of M-Mg(OH)2 is larger, its thermal stability increases and the water solubility of M-Mg(OH)2 decreases remarkably. The dispersion of M-Mg(OH)2 in EVA matrix is more even than that of the pure Mg(OH)2. The LOI of the M-Mg(OH)2/EVA composite is always slightly larger than that of its Mg(OH)2/EVA counterpart at identical loadings of flame retardant (FR). When the mass ratio of FR/EVA is less than 135:100, the VBT ratings of both composites are V-2. When the mass ratio of FR/EVA is between 135:100-150:100, the rating of the former is V-0, but the latter can only reach V-2 rating. When the mass ratio of FR/EVA surpasses 150:100, both composites can reach V-0 rating. In contrast with Mg(OH)2/EVA composite, the acid resistance of the M-Mg(OH)2/EVA composite increases substantially and it can be used in acid environment.
Microencapsulated Mg(OH)2 (M-Mg(OH)2) flame retardant with micro-sized Mg(OH)2 particles as the core and cross-linking polyurea as the shell, was synthesized by in-situ polymerization. The obtained M-Mg(OH)2 was incorporated into ethylene-vinyl acetate copolymer (EVA) and its flame retardant effect on EVA was studied. FTIR, SEM, thermal analysis and acid titration were used to investigate the properties of M-Mg(OH)2. Limiting oxygen index (LOI) and vertical burning test (UL-94 VBT) were employed to study the flame retardancy of M-Mg(OH)2/EVA composite and the effect of acid erosion on the flame retardancy of M-Mg(OH)2/EVA composite. It shows that the surface of Mg(OH)2 particles can be successfully encapsulated with cross-linking polyurea by in-situ polymerization and microencapsulated Mg(OH)2 can be obtained. Compared with the pure Mg(OH)2, the size of M-Mg(OH)2 is larger, its thermal stability increases and the water solubility of M-Mg(OH)2 decreases remarkably. The dispersion of M-Mg(OH)2 in EVA matrix is more even than that of the pure Mg(OH)2. The LOI of the M-Mg(OH)2/EVA composite is always slightly larger than that of its Mg(OH)2/EVA counterpart at identical loadings of flame retardant (FR). When the mass ratio of FR/EVA is less than 135:100, the VBT ratings of both composites are V-2. When the mass ratio of FR/EVA is between 135:100-150:100, the rating of the former is V-0, but the latter can only reach V-2 rating. When the mass ratio of FR/EVA surpasses 150:100, both composites can reach V-0 rating. In contrast with Mg(OH)2/EVA composite, the acid resistance of the M-Mg(OH)2/EVA composite increases substantially and it can be used in acid environment.
2018, 35(7): 1762-1768.
doi: 10.13801/j.cnki.fhclxb.20171114.009
Abstract:
A kind of novolac-based polytriazole (NPTA) resins was designed and synthesized from propargyl-functionalized novolac resin and diazides. The rheological properties, curing behavior and thermal properties of the novolac-based polytriazole resins were studied. The NPTA resins were also evaluated as the matrix for carbon fiber reinforced composites. The results reveal that the NPTA resins have good processiblity. The initial curing temperature is under 80℃, while the activation energy for the cross-linking is higher than the reported linear polytriazoles. The chain structures have little effect on the rheological properties, curing behavior and apparent activation energy of curing reaction of the NPTA resins. However, the thermal properties of the cured resins are greatly influenced by the structure of the crosslinked backbone. The glass transition temperature of the resins arrives at as high as 278℃. The flexural strengths of the T700 carbon fiber-reinforced NPTA composites (T700/NPTA) at ambient temperature reach the value higher than 1 590 MPa and their retention rates at 150℃ stand over 68.6%.
A kind of novolac-based polytriazole (NPTA) resins was designed and synthesized from propargyl-functionalized novolac resin and diazides. The rheological properties, curing behavior and thermal properties of the novolac-based polytriazole resins were studied. The NPTA resins were also evaluated as the matrix for carbon fiber reinforced composites. The results reveal that the NPTA resins have good processiblity. The initial curing temperature is under 80℃, while the activation energy for the cross-linking is higher than the reported linear polytriazoles. The chain structures have little effect on the rheological properties, curing behavior and apparent activation energy of curing reaction of the NPTA resins. However, the thermal properties of the cured resins are greatly influenced by the structure of the crosslinked backbone. The glass transition temperature of the resins arrives at as high as 278℃. The flexural strengths of the T700 carbon fiber-reinforced NPTA composites (T700/NPTA) at ambient temperature reach the value higher than 1 590 MPa and their retention rates at 150℃ stand over 68.6%.
2018, 35(7): 1769-1774.
doi: 10.13801/j.cnki.fhclxb.20171012.005
Abstract:
Versatile high-performance organo-montmorillonite (O-MMT)-nano TiO2/epoxy composite was successfully prepared by co-incorporating O-MMT and nano TiO2 into the epoxy matrix. XRD and TEM reveale that in O-MMT-nano TiO2/epoxy composites, montmorillonite (MMT) layers are highly exfoliated into nanoscale MMT mono-platelets by the strong interaction among O-MMT, nano TiO2 and epoxy, and the 2D MMT mono-platelets take an interlacing arrangement with the 0D nano TiO2 particles in the epoxy matrix. The mechanical tests, thermal analyses and test for dirt pickup resistance and stain removal show that the resulting O-MMT-nano TiO2/epoxy composite obtain considerable improvements over the pure epoxy in multiple properties. This study suggests that co-incorporation of proper, dimensionally different nanoscale particles into polymer matrices is a successful way for preparing versatile high-performance polymer composites.
Versatile high-performance organo-montmorillonite (O-MMT)-nano TiO2/epoxy composite was successfully prepared by co-incorporating O-MMT and nano TiO2 into the epoxy matrix. XRD and TEM reveale that in O-MMT-nano TiO2/epoxy composites, montmorillonite (MMT) layers are highly exfoliated into nanoscale MMT mono-platelets by the strong interaction among O-MMT, nano TiO2 and epoxy, and the 2D MMT mono-platelets take an interlacing arrangement with the 0D nano TiO2 particles in the epoxy matrix. The mechanical tests, thermal analyses and test for dirt pickup resistance and stain removal show that the resulting O-MMT-nano TiO2/epoxy composite obtain considerable improvements over the pure epoxy in multiple properties. This study suggests that co-incorporation of proper, dimensionally different nanoscale particles into polymer matrices is a successful way for preparing versatile high-performance polymer composites.
2018, 35(7): 1775-1782.
doi: 10.13801/j.cnki.fhclxb.20171114.001
Abstract:
Studies on characteristics of 9518 cyanate ester curing reaction were performed via differential scanning calorimetry (DSC) analysis, the curing process of stated resin was determined; Thermal stability, mechanical properties, fiber morphology and interface properties of T800 carbon fiber/9518 cyanate ester composites were analyzed via dynamic mechanical analysis (DMA) testing, mechanical property testing, metallography and SEM, respectively. The results show that, the curing reaction of 9518 cyanate ester has only one reaction exothermic peak, one of the reasonable curing processes for the resin is 130℃/0.5 h+160℃/0.5 h(pressure-enforcement and mold-closing)+200℃/2 h+230℃/2 h. The glass transition temperature of T800 carbon fiber/9518 cyanate ester composites is 255℃. In general, mechanical properties of T800 carbon/9518 cyanate ester composites at room temperature are 10% higher than that of T700 carbon fiber/9518 cyanate ester composites, wet mechanical properties conservation rate of stated composites at room temperature are more than 83%, and withhold more than 60% at 200℃.Cross-section of T800 carbon fiber appeares abnormal round shape and along the fiber has ditches on the surface, contributing a fine interface between T800 carbon fiber and 9518 cyanate ester resin.
Studies on characteristics of 9518 cyanate ester curing reaction were performed via differential scanning calorimetry (DSC) analysis, the curing process of stated resin was determined; Thermal stability, mechanical properties, fiber morphology and interface properties of T800 carbon fiber/9518 cyanate ester composites were analyzed via dynamic mechanical analysis (DMA) testing, mechanical property testing, metallography and SEM, respectively. The results show that, the curing reaction of 9518 cyanate ester has only one reaction exothermic peak, one of the reasonable curing processes for the resin is 130℃/0.5 h+160℃/0.5 h(pressure-enforcement and mold-closing)+200℃/2 h+230℃/2 h. The glass transition temperature of T800 carbon fiber/9518 cyanate ester composites is 255℃. In general, mechanical properties of T800 carbon/9518 cyanate ester composites at room temperature are 10% higher than that of T700 carbon fiber/9518 cyanate ester composites, wet mechanical properties conservation rate of stated composites at room temperature are more than 83%, and withhold more than 60% at 200℃.Cross-section of T800 carbon fiber appeares abnormal round shape and along the fiber has ditches on the surface, contributing a fine interface between T800 carbon fiber and 9518 cyanate ester resin.
2018, 35(7): 1783-1790.
doi: 10.13801/j.cnki.fhclxb.20171011.001
Abstract:
Wheat straw fiber/recycled polyethylene (WF/rPE) composites were preparaed with Shaanxi Guanzhong WF and rPE as the raw materials, using the method of extrusion and molding. The effects of maleate grafted polyethylene (MAPE), maleate grafted polyethylene wax(MAPE wax) and γ-aminopropyltriethoxysilane(KH550) and MAPE wax content on the mechanical properties, moisture absorption, thermal stability and interface performance of WF/rPE composites were studied; The chemical structure of WF and the tensile profile of WF/rPE composites were analyzed by FTIR and SEM. The results show that the mechanical properties of WF/rPE composites with MAPE wax are the best, when the content of WF and MAPE wax are 40wt% and 2wt%, the tensile strength and flexural strength of the WF/rPE composites reach a maximum of 15.0 MPa and 23.8 MPa; When the content of MAPE wax is over 2wt%, the mechanical properties and moisture absorption of WF/rPE composites decrease. The TG result shows that the addition of different interfacial modifiers has no significant influence on the thermal stability of WF/rPE composites; The FTIR analysis shows that the silane coupling agent KH550 can react with the hydroxyl group in WF. The SEM analysis shows that the addition of MAPE wax to the WF/rPE composites interface is better than the addition of MAPE and KH550 WF/rPE composites.
Wheat straw fiber/recycled polyethylene (WF/rPE) composites were preparaed with Shaanxi Guanzhong WF and rPE as the raw materials, using the method of extrusion and molding. The effects of maleate grafted polyethylene (MAPE), maleate grafted polyethylene wax(MAPE wax) and γ-aminopropyltriethoxysilane(KH550) and MAPE wax content on the mechanical properties, moisture absorption, thermal stability and interface performance of WF/rPE composites were studied; The chemical structure of WF and the tensile profile of WF/rPE composites were analyzed by FTIR and SEM. The results show that the mechanical properties of WF/rPE composites with MAPE wax are the best, when the content of WF and MAPE wax are 40wt% and 2wt%, the tensile strength and flexural strength of the WF/rPE composites reach a maximum of 15.0 MPa and 23.8 MPa; When the content of MAPE wax is over 2wt%, the mechanical properties and moisture absorption of WF/rPE composites decrease. The TG result shows that the addition of different interfacial modifiers has no significant influence on the thermal stability of WF/rPE composites; The FTIR analysis shows that the silane coupling agent KH550 can react with the hydroxyl group in WF. The SEM analysis shows that the addition of MAPE wax to the WF/rPE composites interface is better than the addition of MAPE and KH550 WF/rPE composites.
2018, 35(7): 1791-1799.
doi: 10.13801/j.cnki.fhclxb.20171027.001
Abstract:
The rice straw fiber and acrylonitrile-butadiene-styrene(ABS)were used for the raw materials. The acticarbon, Al2O3、SiO2 and silane coupling agent were used for modifiers, respectively. The modifier-straw fiber/ABS composites were prepared via mixing molding process. The reinforcing effect and its strengthening mechanism of several different modifiers were compared. The results show that the effect of silane coupling agent on the straw fiber/ABS composites is poor, and the strengthening of the acticarbon, Al2O3 and SiO2 on the composite is better than silane coupling agents, in which the enhancement effect of Al2O3 is the best. When the mass ratio(Al2O3:ABS) of Al2O3 is 5%, the tensile, flexural and impact strength reach the maximum values which is 27.719 MPa, 61.05 MPa and 26.53 kJ/m2; when the amount of inorganic addition is 5%(inorganic:ABS), the water resistance of composite adheres to:5% Al2O3 >5% acticarbon > 5% SiO2 > not added, which is in accordance with the gra-dient of mechanical properties of the modifier-straw fiber/ABS composites, the rheological properties of composite adhere to:5% acticarbon > 5% Al2O3 > 5% SiO2 > not added.
The rice straw fiber and acrylonitrile-butadiene-styrene(ABS)were used for the raw materials. The acticarbon, Al2O3、SiO2 and silane coupling agent were used for modifiers, respectively. The modifier-straw fiber/ABS composites were prepared via mixing molding process. The reinforcing effect and its strengthening mechanism of several different modifiers were compared. The results show that the effect of silane coupling agent on the straw fiber/ABS composites is poor, and the strengthening of the acticarbon, Al2O3 and SiO2 on the composite is better than silane coupling agents, in which the enhancement effect of Al2O3 is the best. When the mass ratio(Al2O3:ABS) of Al2O3 is 5%, the tensile, flexural and impact strength reach the maximum values which is 27.719 MPa, 61.05 MPa and 26.53 kJ/m2; when the amount of inorganic addition is 5%(inorganic:ABS), the water resistance of composite adheres to:5% Al2O3 >5% acticarbon > 5% SiO2 > not added, which is in accordance with the gra-dient of mechanical properties of the modifier-straw fiber/ABS composites, the rheological properties of composite adhere to:5% acticarbon > 5% Al2O3 > 5% SiO2 > not added.
2018, 35(7): 1800-1809.
doi: 10.13801/j.cnki.fhclxb.20171012.001
Abstract:
The tetrapod-shaped ZnO whisker/poly(butylene succinate) (T-ZnOW/PBS) composites were fabricated by melt-mixing method with PBS as the matrix and T-ZnOW as the filler. The structure of surface modification T-ZnOW was characterized by FTIR testing. The morphology of modification of T-ZnOW and T-ZnOW/PBS composites were available to observe by SEM testing. The crystallization properties of surface modification of T-ZnOW and T-ZnOW/PBS composites were availabled to discuss by XRD testing. The thermal stability of T-ZnOW/PBS composites was availabled to analysis by TG and DSC. The mechanical properties of T-ZnOW/PBS composites was availabled to study by tensile testing. The results show that among the three modifying agents including polyethylene glycol 2000 (PEG2000) (P), stearic acid (S) and silane coupling agent (KH560) (K), S performs the best. After S modification, the T-ZnOW (ST-ZnOW) surface has been loaded with organic groups. Not only the surface roughness of ST-ZnOW increases, but also interfacial adhesion with the pure PBS, which makes the thermal stability and mechanical properties of ST-ZnOW/PBS composites improved obviously. During the pyrolysis process, the temperatures at 10% mass loss (Td-10%) and the value of the pyrolysis temperature (Td-max) are increase by 37.7℃ and 35.3℃, respectively. The tensile strength, elongation at break, and elastic modulus are increase by 17.7%, 140.5%, and 95.4%, respectively, compared with the pure PBS.
The tetrapod-shaped ZnO whisker/poly(butylene succinate) (T-ZnOW/PBS) composites were fabricated by melt-mixing method with PBS as the matrix and T-ZnOW as the filler. The structure of surface modification T-ZnOW was characterized by FTIR testing. The morphology of modification of T-ZnOW and T-ZnOW/PBS composites were available to observe by SEM testing. The crystallization properties of surface modification of T-ZnOW and T-ZnOW/PBS composites were availabled to discuss by XRD testing. The thermal stability of T-ZnOW/PBS composites was availabled to analysis by TG and DSC. The mechanical properties of T-ZnOW/PBS composites was availabled to study by tensile testing. The results show that among the three modifying agents including polyethylene glycol 2000 (PEG2000) (P), stearic acid (S) and silane coupling agent (KH560) (K), S performs the best. After S modification, the T-ZnOW (ST-ZnOW) surface has been loaded with organic groups. Not only the surface roughness of ST-ZnOW increases, but also interfacial adhesion with the pure PBS, which makes the thermal stability and mechanical properties of ST-ZnOW/PBS composites improved obviously. During the pyrolysis process, the temperatures at 10% mass loss (Td-10%) and the value of the pyrolysis temperature (Td-max) are increase by 37.7℃ and 35.3℃, respectively. The tensile strength, elongation at break, and elastic modulus are increase by 17.7%, 140.5%, and 95.4%, respectively, compared with the pure PBS.
2018, 35(7): 1810-1815.
doi: 10.13801/j.cnki.fhclxb.20171130.002
Abstract:
By simulating geosynchronous orbit space γ ray irradiation environment, the high modulus carbon fiber and carbon fiber/cyanate ester composites were irradiated by 60Co-γ ray. The carbon fiber and carbon fiber/cyanate ester composites were analyzed and characterized by SEM and XRD before and after irradiation. The effects of irradiation on the mass loss rate, tensile strength and interlaminar shear strength were studied. The results show that the mass loss rates increase with the increase of γ ray dose and then tend to be gentle, but less than 1%; the tensile strength and interlaminar shear strength of carbon fiber/cyanate ester composites both increase firstly and then decrease with increasing dose, the maximum values occur at 5×105 rad with tensile strength of 1 803 MPa, tensile modulus of 243 GPa and interlaminar shear strength of 72 MPa.
By simulating geosynchronous orbit space γ ray irradiation environment, the high modulus carbon fiber and carbon fiber/cyanate ester composites were irradiated by 60Co-γ ray. The carbon fiber and carbon fiber/cyanate ester composites were analyzed and characterized by SEM and XRD before and after irradiation. The effects of irradiation on the mass loss rate, tensile strength and interlaminar shear strength were studied. The results show that the mass loss rates increase with the increase of γ ray dose and then tend to be gentle, but less than 1%; the tensile strength and interlaminar shear strength of carbon fiber/cyanate ester composites both increase firstly and then decrease with increasing dose, the maximum values occur at 5×105 rad with tensile strength of 1 803 MPa, tensile modulus of 243 GPa and interlaminar shear strength of 72 MPa.
2018, 35(7): 1816-1821.
doi: 10.13801/j.cnki.fhclxb.20171115.007
Abstract:
In order to enhance the industrial filter's filtration efficiency for fine particle, baghouse polyphenylene sulfide(PPS) needle filter as the base material, polyurethane hot melt film as the adhesive layer, tourmaline(TM) particles which have spontaneous polarization characteristic were homogeneous deposited on the material surface by the method of direct precipitation from water solution, TM particles/PPS needle composite filter with different TM purity, contents and particle sizes were prepared by heat treating. SEM was used to investigate the adsorption effect of TM for fine particles, the filter media testing platform was used to evaluate the filtration ability of composite filter. The results show that the filtration efficiency of TM particles/PPS needle composite filter for the submicron particle is improved obviously after adding TM, and the filtration efficiency improves with the increase of TM purity. When the TM purity is 87.16%, the efficiency of the composite filter for 0.3-1 μm particles increases ≥ 13.35%. TM particles/PPS needle composite filter with the optimal concentration of 5 mg·cm-2 has the highest quality factor(QF)which is used to comprehensive assess efficiency and pressure drop. The filtration efficiency increases with the TM size decrease, and the filtration efficiency of TM particles/PPS needle filter for 0.3-1 μm particles enhance ≥ 7.25% when the TM size is 18-38 μm. The filtration performance of TM particles/PPS needle composite filter enhances obviously than the traditional needle filter.
In order to enhance the industrial filter's filtration efficiency for fine particle, baghouse polyphenylene sulfide(PPS) needle filter as the base material, polyurethane hot melt film as the adhesive layer, tourmaline(TM) particles which have spontaneous polarization characteristic were homogeneous deposited on the material surface by the method of direct precipitation from water solution, TM particles/PPS needle composite filter with different TM purity, contents and particle sizes were prepared by heat treating. SEM was used to investigate the adsorption effect of TM for fine particles, the filter media testing platform was used to evaluate the filtration ability of composite filter. The results show that the filtration efficiency of TM particles/PPS needle composite filter for the submicron particle is improved obviously after adding TM, and the filtration efficiency improves with the increase of TM purity. When the TM purity is 87.16%, the efficiency of the composite filter for 0.3-1 μm particles increases ≥ 13.35%. TM particles/PPS needle composite filter with the optimal concentration of 5 mg·cm-2 has the highest quality factor(QF)which is used to comprehensive assess efficiency and pressure drop. The filtration efficiency increases with the TM size decrease, and the filtration efficiency of TM particles/PPS needle filter for 0.3-1 μm particles enhance ≥ 7.25% when the TM size is 18-38 μm. The filtration performance of TM particles/PPS needle composite filter enhances obviously than the traditional needle filter.
2018, 35(7): 1822-1831.
doi: 10.13801/j.cnki.fhclxb.20171114.006
Abstract:
Organic nano-montmorillonite/high density polyethylene (OMMT/HDPE) composites were prepared by multistage stretching extrusion and traditional extrusion process. The morphological structure and property of the two different OMMT/HDPE composites were comparatively studied by wide-angle X-ray diffraction (WAXD), TEM, DSC, small-angle X-ray scattering (SAXS) and so on. The results indicate that multistage stretching extrusion shows great effect on refining particle size of OMMT and promoting dispersion of OMMT in HDPE matrix. With increasing of the number of layer multiplying elements (LMEs), the dispersion of OMMT is gradually improved and the length-to-diameter ratio of OMMT aggregation is also increased, leading to the enhanced initial nucleation rate and crystallization rate of OMMT/HDPE composites, inducing the formation of oriented shish-kebab structures in OMMT/HDPE composites. Accordingly, the tensile strength of OMMT/HDPE composites prepared by multistage stretching extrusion is greatly enhanced. When the mass ratio of OMMT:HDPE is 1:100 and 5:100, the tensile strength of OMMT/HDPE composites prepared by multistage stretching extrusion increases about 50% and 356% compared to that of OMMT/HDPE composites prepared by traditional extrusion process.
Organic nano-montmorillonite/high density polyethylene (OMMT/HDPE) composites were prepared by multistage stretching extrusion and traditional extrusion process. The morphological structure and property of the two different OMMT/HDPE composites were comparatively studied by wide-angle X-ray diffraction (WAXD), TEM, DSC, small-angle X-ray scattering (SAXS) and so on. The results indicate that multistage stretching extrusion shows great effect on refining particle size of OMMT and promoting dispersion of OMMT in HDPE matrix. With increasing of the number of layer multiplying elements (LMEs), the dispersion of OMMT is gradually improved and the length-to-diameter ratio of OMMT aggregation is also increased, leading to the enhanced initial nucleation rate and crystallization rate of OMMT/HDPE composites, inducing the formation of oriented shish-kebab structures in OMMT/HDPE composites. Accordingly, the tensile strength of OMMT/HDPE composites prepared by multistage stretching extrusion is greatly enhanced. When the mass ratio of OMMT:HDPE is 1:100 and 5:100, the tensile strength of OMMT/HDPE composites prepared by multistage stretching extrusion increases about 50% and 356% compared to that of OMMT/HDPE composites prepared by traditional extrusion process.
2018, 35(7): 1832-1840.
doi: 10.13801/j.cnki.fhclxb.20171114.008
Abstract:
To understand the moisture absorption properties and its influence on composite, the adsorption energy of water molecules on the surface of nano MgO and SiO2 particles was calculated by Materials Studio simulation software. The relevant mechanisms of moisture absorption were discussed and the changes of the dielectric properties for dry and wet composite were studied. The simulation results show that water molecules are mainly absorbed by the oxygen atom on the surface of oxide. Because water molecules can penetrate into the amorphous SiO2 nanoparticles to form more adsorption so the nano SiO2 has a greater amount of moisture absorption. Due to nano MgO has larger water molecules absorption energy compared with nano SiO2, so the adsorbed water molecules in nano SiO2 are more difficult to be removed. The nano MgO/low-density polyethylene(LDPE) and nano SiO2/LDPE composites could absorb more water molecules than LDPE. The moisture absorption has a negative influence for the dielectric properties of composite. When MgO/LDPE and SiO2/LDPE composite get wet, the conductivity increases. The presence of water molecules may destroy the tight structure and charge characteristics of the original interface region, and weaken the ability of the composite to suppress the carrier migration. When the test temperature increases to above 60℃, the adsorbed water molecules in MgO/LDPE and SiO2/LDPE composite medium are basically removed, and the conductivity of composite recovers.
To understand the moisture absorption properties and its influence on composite, the adsorption energy of water molecules on the surface of nano MgO and SiO2 particles was calculated by Materials Studio simulation software. The relevant mechanisms of moisture absorption were discussed and the changes of the dielectric properties for dry and wet composite were studied. The simulation results show that water molecules are mainly absorbed by the oxygen atom on the surface of oxide. Because water molecules can penetrate into the amorphous SiO2 nanoparticles to form more adsorption so the nano SiO2 has a greater amount of moisture absorption. Due to nano MgO has larger water molecules absorption energy compared with nano SiO2, so the adsorbed water molecules in nano SiO2 are more difficult to be removed. The nano MgO/low-density polyethylene(LDPE) and nano SiO2/LDPE composites could absorb more water molecules than LDPE. The moisture absorption has a negative influence for the dielectric properties of composite. When MgO/LDPE and SiO2/LDPE composite get wet, the conductivity increases. The presence of water molecules may destroy the tight structure and charge characteristics of the original interface region, and weaken the ability of the composite to suppress the carrier migration. When the test temperature increases to above 60℃, the adsorbed water molecules in MgO/LDPE and SiO2/LDPE composite medium are basically removed, and the conductivity of composite recovers.
2018, 35(7): 1841-1849.
doi: 10.13801/j.cnki.fhclxb.20171018.003
Abstract:
Carbon nanotubes (CNTs) were respectively treated by mixed acid, epoxy resin (EP) and silane coupling agent. Montmorillonite (MMT) was modified by eighteen alkyl three methyl ammonium chloride. CNTs and organic montmorillonite (OMMT) were placed in EP cured by anhydride. Nano OMMT/EP, CNTs/EP and CNTs-OMMT/EP composites were prepared by method of solution blending. The impact strength of the three kinds of was tested by Charpy impact tester. The impact profile of the nano CNTs/EP, OMMT/EP and CNTs-OMMT/EP composites were observed by scanning electron microscopy. The experimental results show that when the mass fraction of OMMT is 4wt%, the impact strength of OMMT/EP composites is 16.7% higher than that of the pure EP. The interface between Si-CNTs and EP cured by anhydride is strong. When the mass fraction of Si-CNTs is 0.9wt%, the impact strength of Si-CNTs/EP composites is 84.0% higher than that of the pure EP. When the mass fraction of OMMT is 4wt% and the mass fraction of CNTs is 0.9wt%, the impact strength of Si-CNTs-OMMT/EP composites is 135.4% higher than that of the pure EP. CNTs and OMMT can synergistically enhance the toughness of EP.
Carbon nanotubes (CNTs) were respectively treated by mixed acid, epoxy resin (EP) and silane coupling agent. Montmorillonite (MMT) was modified by eighteen alkyl three methyl ammonium chloride. CNTs and organic montmorillonite (OMMT) were placed in EP cured by anhydride. Nano OMMT/EP, CNTs/EP and CNTs-OMMT/EP composites were prepared by method of solution blending. The impact strength of the three kinds of was tested by Charpy impact tester. The impact profile of the nano CNTs/EP, OMMT/EP and CNTs-OMMT/EP composites were observed by scanning electron microscopy. The experimental results show that when the mass fraction of OMMT is 4wt%, the impact strength of OMMT/EP composites is 16.7% higher than that of the pure EP. The interface between Si-CNTs and EP cured by anhydride is strong. When the mass fraction of Si-CNTs is 0.9wt%, the impact strength of Si-CNTs/EP composites is 84.0% higher than that of the pure EP. When the mass fraction of OMMT is 4wt% and the mass fraction of CNTs is 0.9wt%, the impact strength of Si-CNTs-OMMT/EP composites is 135.4% higher than that of the pure EP. CNTs and OMMT can synergistically enhance the toughness of EP.
2018, 35(7): 1850-1856.
doi: 10.13801/j.cnki.fhclxb.20171128.004
Abstract:
The short glass fiber/epoxy resin (GF/EP) composites with 0.5wt% GF were fabricated through casting method. The properties of GF/EP composites length 1 mm, 3 mm and 5 mm were studied, respectively. The mechanical properties and thermal properties of GF/EP composite and the tensile strength of the fiber tow with surface treatment of polyimide (PI) were investigated. Polyimides with reactive phenolic hydroxyl groups (PI1) and without (PI2) were prepared. The results show that tensile strength and strand integrity of the GF are improved. The tensile strength of GF treated with PI1 is increased from 517 MPa to 1 032 MPa and PI2 is increased to 986 MPa. GF/EP composites have the best mechanical properties when 3 mm GF treated with PI1, and tensile strength, tensile modulus, flexural strength and fracture toughness of PI1-GF/EP composites are increased by 23.62%, 34.03%, 28.74% and 13.04% respectively. The mechanical properties of GF/EP composites with treatment of PI2 are slightly improved. The tensile strength, tensile modulus, flexural strength and fracture toughness are increased by 15.87%, 23.70%, 14.11% and 4.05%, respectively. The glass transition temperature of PI2-GF/EP composite is significantly improved by treating GF with PI.
The short glass fiber/epoxy resin (GF/EP) composites with 0.5wt% GF were fabricated through casting method. The properties of GF/EP composites length 1 mm, 3 mm and 5 mm were studied, respectively. The mechanical properties and thermal properties of GF/EP composite and the tensile strength of the fiber tow with surface treatment of polyimide (PI) were investigated. Polyimides with reactive phenolic hydroxyl groups (PI1) and without (PI2) were prepared. The results show that tensile strength and strand integrity of the GF are improved. The tensile strength of GF treated with PI1 is increased from 517 MPa to 1 032 MPa and PI2 is increased to 986 MPa. GF/EP composites have the best mechanical properties when 3 mm GF treated with PI1, and tensile strength, tensile modulus, flexural strength and fracture toughness of PI1-GF/EP composites are increased by 23.62%, 34.03%, 28.74% and 13.04% respectively. The mechanical properties of GF/EP composites with treatment of PI2 are slightly improved. The tensile strength, tensile modulus, flexural strength and fracture toughness are increased by 15.87%, 23.70%, 14.11% and 4.05%, respectively. The glass transition temperature of PI2-GF/EP composite is significantly improved by treating GF with PI.
2018, 35(7): 1857-1863.
doi: 10.13801/j.cnki.fhclxb.20180402.003
Abstract:
In order to study the effect of interlayer hybrid type of unidirectional fiber on the mechanical properties and failure form of composites,the method of pultrusion process was adopted to prepare continuous unidirectional hybrid fiber reinforced epoxy composites with different interlaminar hybrid structure.The volume ratio of carbon fiber and glass fiber was 1:1 in the composites.The results show that the tensile strength of composites with interlaminar hybrid structure is between carbon fiber/epoxy composites and glass fiber/epoxy composites,and the tensile fracture mode is cleavage.The interlaminar shear strength of composites with interlaminar hybrid structure is better than carbon fiber/epoxy composites and glass fiber/epoxy composites,and the shear fracture mode is interlaminar fracture.
In order to study the effect of interlayer hybrid type of unidirectional fiber on the mechanical properties and failure form of composites,the method of pultrusion process was adopted to prepare continuous unidirectional hybrid fiber reinforced epoxy composites with different interlaminar hybrid structure.The volume ratio of carbon fiber and glass fiber was 1:1 in the composites.The results show that the tensile strength of composites with interlaminar hybrid structure is between carbon fiber/epoxy composites and glass fiber/epoxy composites,and the tensile fracture mode is cleavage.The interlaminar shear strength of composites with interlaminar hybrid structure is better than carbon fiber/epoxy composites and glass fiber/epoxy composites,and the shear fracture mode is interlaminar fracture.
2018, 35(7): 1864-1868.
doi: 10.13801/j.cnki.fhclxb.20170825.001
Abstract:
The effect of void distribution, size and shape on transverse tensile strength of unidirectional carbon fiber-reinforced epoxy resin composites with same void content was studied. SEM images of composites were processed using Matlab and the void radius distribution of composites was obtained. The void random algorithms were programmed by C++, including void random distribution algorithm, different void radius algorithm and different void shape algorithm. The representative volume element(RVE) of the composites microstructure was generated by Python. The effect of void distribution, size and shape on transverse tensile strength of unidirectional carbon fiber/epoxy resin composites was simulated by the finite element analysis. It is found that carbon fiber/epoxy resin with the same void content, the effect of void shape on transverse modulus is relatively large, and the void size and void shape affect the transverse tension strength largely.
The effect of void distribution, size and shape on transverse tensile strength of unidirectional carbon fiber-reinforced epoxy resin composites with same void content was studied. SEM images of composites were processed using Matlab and the void radius distribution of composites was obtained. The void random algorithms were programmed by C++, including void random distribution algorithm, different void radius algorithm and different void shape algorithm. The representative volume element(RVE) of the composites microstructure was generated by Python. The effect of void distribution, size and shape on transverse tensile strength of unidirectional carbon fiber/epoxy resin composites was simulated by the finite element analysis. It is found that carbon fiber/epoxy resin with the same void content, the effect of void shape on transverse modulus is relatively large, and the void size and void shape affect the transverse tension strength largely.
2018, 35(7): 1869-1877.
doi: 10.13801/j.cnki.fhclxb.20170905.001
Abstract:
The effect of prefabricated crack on the tear properties of plain weave fabric with 230 nylon yarns plain braided per square centimeter and composite thermoplastic polyurethane(Nylon-230T/TPU) was investigated by numerical simulation and tearing test. The effects of crack length, crack angle and crack location on the tear strength of the fabric skin were studied. The strain field of the fabric skin during tearing test process was measured by digital image correlation (DIC) technique. The variation of strain field during tearing process was obtained. The crack propagation process and path of prefabricated cracked Nylon-230T/TPU fabric skin were numerically simulated by using extended finite element method (XFEM), cohesive zone model (CZM) and virtual crack closure technique (VCCT). The validity of numerical simulation is verified by comparison with the experimental results. The results show that the tear strength of Nylon-230T/TPU fabric skin is closely related to the crack length, the crack angle and the crack location. The strain field distribution of Nylon-230T/TPU specimen is greatly affected by the presence of cracks. The numerical simulation results are well agreed with the experimental results.
The effect of prefabricated crack on the tear properties of plain weave fabric with 230 nylon yarns plain braided per square centimeter and composite thermoplastic polyurethane(Nylon-230T/TPU) was investigated by numerical simulation and tearing test. The effects of crack length, crack angle and crack location on the tear strength of the fabric skin were studied. The strain field of the fabric skin during tearing test process was measured by digital image correlation (DIC) technique. The variation of strain field during tearing process was obtained. The crack propagation process and path of prefabricated cracked Nylon-230T/TPU fabric skin were numerically simulated by using extended finite element method (XFEM), cohesive zone model (CZM) and virtual crack closure technique (VCCT). The validity of numerical simulation is verified by comparison with the experimental results. The results show that the tear strength of Nylon-230T/TPU fabric skin is closely related to the crack length, the crack angle and the crack location. The strain field distribution of Nylon-230T/TPU specimen is greatly affected by the presence of cracks. The numerical simulation results are well agreed with the experimental results.
2018, 35(7): 1878-1888.
doi: 10.13801/j.cnki.fhclxb.20180103.001
Abstract:
A novel three-dimensional composite damage model based on continuum damage mechanics (CDM) was developed to investigate low-velocity impact behavior of composite laminates. The maximum strain failure criterion was used to predict the initiation of fiber damage and the fiber damage revolution was evaluated by a bi-linear damage constitutive relation. A physically-based failure theory and three dimensional Puck criterion was employed to capture the onset of matrix damage and the damage evolution was determined by the effective strain on the fracture plane under the particular fracture angle. The in-situ strength of transverse tensile and in-plane shear depended on the assumption of fracture mechanics. The mesh dependency was alleviated effectively by introducing the characteristic length of element in the constitutive model of fiber and matrix damage. The interlaminar delamination damage was simulated by the cohesive element. Quadratic stress criterion and B-K power law was adopted to confirm the damage initiation and damage revolution for the interface element respectively. The impact damage and impact responses of composite laminates under four levels of impact energy were studied by experimental and numerical method. The agreement between the simulation results and experimental results about impact-force curves, delamination shape and size shows that the finite element analysis model can effectively predict the impact responses and impact damage.
A novel three-dimensional composite damage model based on continuum damage mechanics (CDM) was developed to investigate low-velocity impact behavior of composite laminates. The maximum strain failure criterion was used to predict the initiation of fiber damage and the fiber damage revolution was evaluated by a bi-linear damage constitutive relation. A physically-based failure theory and three dimensional Puck criterion was employed to capture the onset of matrix damage and the damage evolution was determined by the effective strain on the fracture plane under the particular fracture angle. The in-situ strength of transverse tensile and in-plane shear depended on the assumption of fracture mechanics. The mesh dependency was alleviated effectively by introducing the characteristic length of element in the constitutive model of fiber and matrix damage. The interlaminar delamination damage was simulated by the cohesive element. Quadratic stress criterion and B-K power law was adopted to confirm the damage initiation and damage revolution for the interface element respectively. The impact damage and impact responses of composite laminates under four levels of impact energy were studied by experimental and numerical method. The agreement between the simulation results and experimental results about impact-force curves, delamination shape and size shows that the finite element analysis model can effectively predict the impact responses and impact damage.
2018, 35(7): 1889-1896.
doi: 10.13801/j.cnki.fhclxb.20171108.004
Abstract:
Based on selective laser melting (SLM) method, Al matrix composites reinforced with various mass fraction of carbon nanotubes(CNTs, mass fractions were 0, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, respectively) were produced by changing scanning speed. The effect of CNTs content and laser scan speed on performance of Al matrix composites was investigated. The results show that the dispersion is better and most of CNTs adhere to the surface of Al powder in a single state when the CNTs content(mass fraction)is not more than 1.0wt%, while the number and size of CNTs agglomerations are enhanced when the CNTs content exceeds 1.0wt%. Under the same SLM process condition, the number of pores in CNTs/Al composite specimens at low CNTs content is less so that relative densities are high. At high CNTs content, porosity of CNTs/Al composite specimen increases and relative densities of specimens reduce. With the CNTs content rising, hardness of CNTs/Al composite specimen increases firstly and then decreases at scanning speed of 1 300 mm/s. The micro-hardness of CNTs/Al composite specimen at the CNTs content of 1.0wt% reaches the peak. Compared with aluminum alloy specimen, CNTs/Al composite specimen shows finer grain size. The hardness of CNTs/Al composite specimen that the CNTs content is exceeding 1.0wt% decreases due to lower relative density, though grain size demonstrates the fine tendency.
Based on selective laser melting (SLM) method, Al matrix composites reinforced with various mass fraction of carbon nanotubes(CNTs, mass fractions were 0, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, respectively) were produced by changing scanning speed. The effect of CNTs content and laser scan speed on performance of Al matrix composites was investigated. The results show that the dispersion is better and most of CNTs adhere to the surface of Al powder in a single state when the CNTs content(mass fraction)is not more than 1.0wt%, while the number and size of CNTs agglomerations are enhanced when the CNTs content exceeds 1.0wt%. Under the same SLM process condition, the number of pores in CNTs/Al composite specimens at low CNTs content is less so that relative densities are high. At high CNTs content, porosity of CNTs/Al composite specimen increases and relative densities of specimens reduce. With the CNTs content rising, hardness of CNTs/Al composite specimen increases firstly and then decreases at scanning speed of 1 300 mm/s. The micro-hardness of CNTs/Al composite specimen at the CNTs content of 1.0wt% reaches the peak. Compared with aluminum alloy specimen, CNTs/Al composite specimen shows finer grain size. The hardness of CNTs/Al composite specimen that the CNTs content is exceeding 1.0wt% decreases due to lower relative density, though grain size demonstrates the fine tendency.
2018, 35(7): 1897-1902.
doi: 10.13801/j.cnki.fhclxb.20170911.001
Abstract:
Using in situ adsorption method, the bacterial cellulose (BC) was soaked to curcumin in ethanol solutionin. Curcumin was adsorbed into BC to obtained BC/curcumin composite materials with different concentrations. SEM, FTIR, XRD and contact angle measurement instrument were used to test the characterization and performance of BC/curcumin composites. The results show that the curcumin could be introduced into BC materials by in situ adsorption method. As the concentration of curcumin increases, the amount of curcumin in the BC increases. The BC/curcumin composite samples in damp environment could prevent mildew. The BC/curcumin composites have good application prospect in packaging materials or tissue engineering materials.
Using in situ adsorption method, the bacterial cellulose (BC) was soaked to curcumin in ethanol solutionin. Curcumin was adsorbed into BC to obtained BC/curcumin composite materials with different concentrations. SEM, FTIR, XRD and contact angle measurement instrument were used to test the characterization and performance of BC/curcumin composites. The results show that the curcumin could be introduced into BC materials by in situ adsorption method. As the concentration of curcumin increases, the amount of curcumin in the BC increases. The BC/curcumin composite samples in damp environment could prevent mildew. The BC/curcumin composites have good application prospect in packaging materials or tissue engineering materials.
2018, 35(7): 1903-1911.
doi: 10.13801/j.cnki.fhclxb.20170911.003
Abstract:
Vanadium oxide (VOx, 1 ≤ x ≤ 2.5)-graphene oxide (GO) composite films were prepared by the combination of spin-coating of VOx sol-gel and spray-coating of GO dispersion.The physical morphologies, crystallinities, optical and electrical properties of the as-prepared films were systematically characterized by SEM, XRD, ellipsometry, UV-visible spectrometer, FTIR and high resistance meter. The results indicate that the resistivity of the composite film decreases from 108.78 Ω·cm for the pristine VOx film to 68.64 Ω·cm after GO addition, while the temperature coefficient of resistance(TCR) increases from -1.98%K-1 to -2.60%K-1. In addition, VOx-GO composite film exhibits a higher light absorption. These suggest that the GO addition can significantly improve the performance of VOx films as thermistor materials. The results present in this work not only provide valuable information for the exploration of novel VOx-based infrared thermistor materials, but also promote the development of uncooled infrared detectors.
Vanadium oxide (VOx, 1 ≤ x ≤ 2.5)-graphene oxide (GO) composite films were prepared by the combination of spin-coating of VOx sol-gel and spray-coating of GO dispersion.The physical morphologies, crystallinities, optical and electrical properties of the as-prepared films were systematically characterized by SEM, XRD, ellipsometry, UV-visible spectrometer, FTIR and high resistance meter. The results indicate that the resistivity of the composite film decreases from 108.78 Ω·cm for the pristine VOx film to 68.64 Ω·cm after GO addition, while the temperature coefficient of resistance(TCR) increases from -1.98%K-1 to -2.60%K-1. In addition, VOx-GO composite film exhibits a higher light absorption. These suggest that the GO addition can significantly improve the performance of VOx films as thermistor materials. The results present in this work not only provide valuable information for the exploration of novel VOx-based infrared thermistor materials, but also promote the development of uncooled infrared detectors.
2018, 35(7): 1912-1920.
doi: 10.13801/j.cnki.fhclxb.20171012.003
Abstract:
The planar anisotropic carbonyl iron (PACI) was firstly fabricated by mechanical ball milling. Then the carbon nanotubes(CNTs)/PACI composite was prepared by solution blending method. The complex permittivity and complex permeability of the samples between 2-18 GHz were measured through coaxial method. The effects of the CNTs doping content on the electromagnetic properties of CNTs/PACI composites were investigated. The results show that the CNTs/PACI composites have higher complex permittivity and attenuation constant compared with PACI.The complex permittivity and attenuation constant of the composites increase gradually with the increasing mass fraction of CNTs (WCNTs), while the microwave impedance decreases gradually. Doping CNTs can effectively improve the microwave absorption properties of CNTs/PACI composites. Through adjusting the thickness (d) and the CNTs doping content, the microwave absorption properties of the composites can be effectively controlled. When d=1.2 mm and WCNTs=2wt%, or d=1.6 mm and WCNTs=0.5wt%, the reflection loss (RL) of CNTs/PACI composite in Ku band (12-18 GHz) is below -10 dB. When d=2.0 mm, WCNTs=0.5wt% and 1wt%, the bandwidth corresponding to the RL of the composites below -10 dB is 5.28 GHz (8.24-13.52 GHz) and 5.04 GHz (7.52-12.56 GHz) respectively, which covering the entire X band (8-12 GHz).
The planar anisotropic carbonyl iron (PACI) was firstly fabricated by mechanical ball milling. Then the carbon nanotubes(CNTs)/PACI composite was prepared by solution blending method. The complex permittivity and complex permeability of the samples between 2-18 GHz were measured through coaxial method. The effects of the CNTs doping content on the electromagnetic properties of CNTs/PACI composites were investigated. The results show that the CNTs/PACI composites have higher complex permittivity and attenuation constant compared with PACI.The complex permittivity and attenuation constant of the composites increase gradually with the increasing mass fraction of CNTs (WCNTs), while the microwave impedance decreases gradually. Doping CNTs can effectively improve the microwave absorption properties of CNTs/PACI composites. Through adjusting the thickness (d) and the CNTs doping content, the microwave absorption properties of the composites can be effectively controlled. When d=1.2 mm and WCNTs=2wt%, or d=1.6 mm and WCNTs=0.5wt%, the reflection loss (RL) of CNTs/PACI composite in Ku band (12-18 GHz) is below -10 dB. When d=2.0 mm, WCNTs=0.5wt% and 1wt%, the bandwidth corresponding to the RL of the composites below -10 dB is 5.28 GHz (8.24-13.52 GHz) and 5.04 GHz (7.52-12.56 GHz) respectively, which covering the entire X band (8-12 GHz).
2018, 35(7): 1921-1929.
doi: 10.13801/j.cnki.fhclxb.20171018.002
Abstract:
Ni(OH)2-carbon nanotubes-reduced graphene oxide (Ni(OH)2-CNTs-RGO) ternary composites were synthesized by simple and practicable one-pot hydrothermal synthesis method. The influence of different reaction temperatures on properties of composite materials was researched. The microstructure and morphology of Ni(OH)2-CNTs-RGO composites were characterized by XRD, FTIR, Raman spectroscopy, X-ray photoelectron spectroscopy(XPS), SEM and TEM. The electrochemical characteristics of Ni(OH)2-CNTs-RGO electrode composites were tested by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and galvanostatic charge/discharge. The results show that the prepared Ni(OH)2-CNTs-RGO composite has large specific surface area and 3D network structure when the reaction temperature is 120℃. The synthesized Ni(OH)2-CNTs-RGO composite shows that hexagonal β-Ni(OH)2 nano sheets and CNTs are homogeneously dispersed and inserted into RGO sheets. The Ni(OH)2-CNTs-RGO electrode composite exhibits the discharge specific capacity up to 362.8 mAh/g at 0.2 C and 286.2 mAh/g at 5 C, which is still higher than the specific capacity of Ni(OH)2. The CNTs and RGO collaborative role effectively improves the conductivity of the electrode material and the utilization of active material. Finally, the rate performance of Ni(OH)2-CNTs-RGO composite is improved.
Ni(OH)2-carbon nanotubes-reduced graphene oxide (Ni(OH)2-CNTs-RGO) ternary composites were synthesized by simple and practicable one-pot hydrothermal synthesis method. The influence of different reaction temperatures on properties of composite materials was researched. The microstructure and morphology of Ni(OH)2-CNTs-RGO composites were characterized by XRD, FTIR, Raman spectroscopy, X-ray photoelectron spectroscopy(XPS), SEM and TEM. The electrochemical characteristics of Ni(OH)2-CNTs-RGO electrode composites were tested by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and galvanostatic charge/discharge. The results show that the prepared Ni(OH)2-CNTs-RGO composite has large specific surface area and 3D network structure when the reaction temperature is 120℃. The synthesized Ni(OH)2-CNTs-RGO composite shows that hexagonal β-Ni(OH)2 nano sheets and CNTs are homogeneously dispersed and inserted into RGO sheets. The Ni(OH)2-CNTs-RGO electrode composite exhibits the discharge specific capacity up to 362.8 mAh/g at 0.2 C and 286.2 mAh/g at 5 C, which is still higher than the specific capacity of Ni(OH)2. The CNTs and RGO collaborative role effectively improves the conductivity of the electrode material and the utilization of active material. Finally, the rate performance of Ni(OH)2-CNTs-RGO composite is improved.
2018, 35(7): 1930-1938.
doi: 10.13801/j.cnki.fhclxb.20171013.002
Abstract:
Microorganism growth can result in biofouling formation and equipment corrosion. In order to solve the biofouling and corrosion problems in recirculating cooling water system, nano ZnO was modified by the silence coupling agent γ-aminopropyltriethoxysilane(KH550). The modified nano ZnO and graphene oxide(GO) were compounded in the dimethylacetamide, and the nano ZnO-GO antibacterial composites were obtained. The waterborne polyurethane(PU) was modified by nano ZnO-GO to get nano ZnO-GO/PU coating composites. The characterizations and antibacterial properties of nano ZnO-GO and the antibacterial properties and physical properties of nano ZnO-GO/PU coating composites were tested and analyzed. The results show that nano ZnO is successfully supported on the surface of GO, and the purity of nano ZnO-GO is high. When the mass fraction of GO is 35wt% and the dosage of nano ZnO-GO is 160 mgL-1, the antibacterial rate of nano ZnO-GO is 97.16%. When the mass fraction of nano ZnO-GO is 2.33wt% in the coating, the antibacterial rate of nano ZnO-GO/PU composite coating is up to 90.29% and it has 4 H pencil hardness and 93.26% corrosion inhibition performance.
Microorganism growth can result in biofouling formation and equipment corrosion. In order to solve the biofouling and corrosion problems in recirculating cooling water system, nano ZnO was modified by the silence coupling agent γ-aminopropyltriethoxysilane(KH550). The modified nano ZnO and graphene oxide(GO) were compounded in the dimethylacetamide, and the nano ZnO-GO antibacterial composites were obtained. The waterborne polyurethane(PU) was modified by nano ZnO-GO to get nano ZnO-GO/PU coating composites. The characterizations and antibacterial properties of nano ZnO-GO and the antibacterial properties and physical properties of nano ZnO-GO/PU coating composites were tested and analyzed. The results show that nano ZnO is successfully supported on the surface of GO, and the purity of nano ZnO-GO is high. When the mass fraction of GO is 35wt% and the dosage of nano ZnO-GO is 160 mgL-1, the antibacterial rate of nano ZnO-GO is 97.16%. When the mass fraction of nano ZnO-GO is 2.33wt% in the coating, the antibacterial rate of nano ZnO-GO/PU composite coating is up to 90.29% and it has 4 H pencil hardness and 93.26% corrosion inhibition performance.
2018, 35(7): 1939-1951.
doi: 10.13801/j.cnki.fhclxb.20171016.001
Abstract:
Potassium nickel hexacyanoterrate/carboxymethyl konjac glucomannan gel microspheres (KNiFC/CKGM) biomass adsorbent was synthesized by the sol-gel method via composite with KNiFC, using CKGM as the substrate material, which was prepared by carboxymethylation modification of konjac glucomannan (KGM). The KNiFC/CKGM adsorbent was used to remove Cs+ in wastewater. Batch adsorption experiments such as pH value, contact time, initial Cs+ concentration, temperature and competing ions were investigated to analyze the adsorption properties of KNiFC/CKGM, and the adsorption process was studied by kinetic and thermodynamic analysis. The corresponding adsorption mechanisms were also analyzed by FTIR, SEM, EDX, XPS and XRD. Under the adsorption condition that the temperature is 298.15 K, the adsorption dosage is 1 gL-1, adsorption time is 18 h and initial Cs+ concentration is 20 mgL-1, the removal rate of the adsorbent material can reach 94.8%. The experimental results show that the adsorption data is well fitted with in line Freundlich isotherm model (R2=0.985) and pseudo-second-order kinetics model (R2=0.999). In the range of 288.15-328.15 K, there is a positive correlation between temperature and the Cs+ adsorption quantity. And the adsorption progress is a spontaneous endothermic reaction. The results of FTIR, SEM and XPS demonstrate that the KNiFC is loaded well on CKGM, and KNiFC/CKGM can keep the complete structure during adsorption experiments. EDX and XRD results show that adsorption of KNiFC/CKGM to Cs+ on adsorbents is mainly due to ion exchange between K+ and Cs+.
Potassium nickel hexacyanoterrate/carboxymethyl konjac glucomannan gel microspheres (KNiFC/CKGM) biomass adsorbent was synthesized by the sol-gel method via composite with KNiFC, using CKGM as the substrate material, which was prepared by carboxymethylation modification of konjac glucomannan (KGM). The KNiFC/CKGM adsorbent was used to remove Cs+ in wastewater. Batch adsorption experiments such as pH value, contact time, initial Cs+ concentration, temperature and competing ions were investigated to analyze the adsorption properties of KNiFC/CKGM, and the adsorption process was studied by kinetic and thermodynamic analysis. The corresponding adsorption mechanisms were also analyzed by FTIR, SEM, EDX, XPS and XRD. Under the adsorption condition that the temperature is 298.15 K, the adsorption dosage is 1 gL-1, adsorption time is 18 h and initial Cs+ concentration is 20 mgL-1, the removal rate of the adsorbent material can reach 94.8%. The experimental results show that the adsorption data is well fitted with in line Freundlich isotherm model (R2=0.985) and pseudo-second-order kinetics model (R2=0.999). In the range of 288.15-328.15 K, there is a positive correlation between temperature and the Cs+ adsorption quantity. And the adsorption progress is a spontaneous endothermic reaction. The results of FTIR, SEM and XPS demonstrate that the KNiFC is loaded well on CKGM, and KNiFC/CKGM can keep the complete structure during adsorption experiments. EDX and XRD results show that adsorption of KNiFC/CKGM to Cs+ on adsorbents is mainly due to ion exchange between K+ and Cs+.
2018, 35(7): 1952-1962.
doi: 10.13801/j.cnki.fhclxb.20170925.002
Abstract:
The effect of reactive elastomeric terpolymer (RET) on properties of matrix asphalt and styrene butadiene styrene block copolymer(SBS) modified asphalt was discussed by viscosity test and dynamic shear rheometer test. The surface topography characteristics of SBS modified asphalt and RET-SBS modified asphalt were analyzed by atomic force microscopy(AFM). Through wheel tracking test, bending test at low temperature, bending fatigue test and accelerated loaded test, the technical performance of RET modified asphalt mixture was evaluated. Finally, the fatigue properties of different RET modified asphalt mixture were analyzed by Weibull distribution under different failure probabilities. The results show that RET can significantly increase the viscosity and rutting resistance factor of asphalt, which obviously improves the rheological properties of asphalt at high temperature; RET-SBS modified asphalt can improve viscous component of asphalt; Compared with SBS modified asphalt, the surface roughness of RET-SBS modified asphalt increases significantly; RET has a significant effect on improving stability at high temperature; RET-SBS modified asphalt can improve crack resistance at low temperature, the fatigue properties and long-term stability at high temperature of asphalt mixtures.
The effect of reactive elastomeric terpolymer (RET) on properties of matrix asphalt and styrene butadiene styrene block copolymer(SBS) modified asphalt was discussed by viscosity test and dynamic shear rheometer test. The surface topography characteristics of SBS modified asphalt and RET-SBS modified asphalt were analyzed by atomic force microscopy(AFM). Through wheel tracking test, bending test at low temperature, bending fatigue test and accelerated loaded test, the technical performance of RET modified asphalt mixture was evaluated. Finally, the fatigue properties of different RET modified asphalt mixture were analyzed by Weibull distribution under different failure probabilities. The results show that RET can significantly increase the viscosity and rutting resistance factor of asphalt, which obviously improves the rheological properties of asphalt at high temperature; RET-SBS modified asphalt can improve viscous component of asphalt; Compared with SBS modified asphalt, the surface roughness of RET-SBS modified asphalt increases significantly; RET has a significant effect on improving stability at high temperature; RET-SBS modified asphalt can improve crack resistance at low temperature, the fatigue properties and long-term stability at high temperature of asphalt mixtures.
2018, 35(7): 1963-1974.
doi: 10.13801/j.cnki.fhclxb.20170821.003
Abstract:
In order to research the effect of polypropylene fibers on shear strength of dry joints in precast concrete segmental bridges, experiments were conducted to investigate the shear behavior of C40 regular concrete and C40 polypropylene fiber reinforced concrete. The main parameters for tests were joint types, key numbers, concrete types, amount of polypropylene fibers, and horizontal confining stress levels. The cracking loads, ultimate loads, and residual loads were recorded. The cracking pattern, failure mode and normalized shear stress-vertical slip curve relationship were investigated. It can be concluded that the utilization of polypropylene fibers can improve cracking loads, ultimate loads and the deformation capacity of dry joints specimens. The polypropylene fibers can prevent cracking, but the effect of different amount of polypropylene fibers on the shear behavior is not obvious.
In order to research the effect of polypropylene fibers on shear strength of dry joints in precast concrete segmental bridges, experiments were conducted to investigate the shear behavior of C40 regular concrete and C40 polypropylene fiber reinforced concrete. The main parameters for tests were joint types, key numbers, concrete types, amount of polypropylene fibers, and horizontal confining stress levels. The cracking loads, ultimate loads, and residual loads were recorded. The cracking pattern, failure mode and normalized shear stress-vertical slip curve relationship were investigated. It can be concluded that the utilization of polypropylene fibers can improve cracking loads, ultimate loads and the deformation capacity of dry joints specimens. The polypropylene fibers can prevent cracking, but the effect of different amount of polypropylene fibers on the shear behavior is not obvious.
2018, 35(7): 1975-1982.
doi: 10.13801/j.cnki.fhclxb.20170821.010
Abstract:
The constitutive equation of cement asphalt emulsified mastic (simplified as the composite mastic) was established based on Burgers model revised by fractional derivative. Combined with aging test and frequency scanning test of composite mastic of various mix proportions, the effects of aging time and mix proportion on the viscoelastic mechanical parameters of the composite mastic were analyzed. Study shows that with aging time increasing, both of the storage modulus and loss modulus of the composite mastic increase. The increase speed of the storage modulus and loss modulus are high during 0-8 h of aging, and then slow down after 8 h of aging. For the composite mastic at mass ratio of emulsified asphalt to cement (mA/mC) of 1.2 and 1.4, the phase angle decreases with the increase of aging time at different load frequencies. For the composite mastic at mA/mC of 1.0, the phase angle shows a rule of increasing first and then decreasing with the increase of aging time. With aging time increasing, the composite mastic tends to show mechanical properties like elastic materials. The Burgers model revised by fractional derivative can describe the viscoelastic dynamic mechanical behavior of the composite mastic after aging well, and the model parameters elastic modulus E1, viscosity η1 and fractional derivative r can describe change rules of the viscoelastic properties of the material in the case of aging well.
The constitutive equation of cement asphalt emulsified mastic (simplified as the composite mastic) was established based on Burgers model revised by fractional derivative. Combined with aging test and frequency scanning test of composite mastic of various mix proportions, the effects of aging time and mix proportion on the viscoelastic mechanical parameters of the composite mastic were analyzed. Study shows that with aging time increasing, both of the storage modulus and loss modulus of the composite mastic increase. The increase speed of the storage modulus and loss modulus are high during 0-8 h of aging, and then slow down after 8 h of aging. For the composite mastic at mass ratio of emulsified asphalt to cement (mA/mC) of 1.2 and 1.4, the phase angle decreases with the increase of aging time at different load frequencies. For the composite mastic at mA/mC of 1.0, the phase angle shows a rule of increasing first and then decreasing with the increase of aging time. With aging time increasing, the composite mastic tends to show mechanical properties like elastic materials. The Burgers model revised by fractional derivative can describe the viscoelastic dynamic mechanical behavior of the composite mastic after aging well, and the model parameters elastic modulus E1, viscosity η1 and fractional derivative r can describe change rules of the viscoelastic properties of the material in the case of aging well.
