To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content chan...To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.展开更多
Microwave processing has great potential for improving composite manufacturing such as reduction of curing time, energy requirements and operational costs. In this paper, the effects of microwave irradiation for resin...Microwave processing has great potential for improving composite manufacturing such as reduction of curing time, energy requirements and operational costs. In this paper, the effects of microwave irradiation for resin-curing of carbon fiber/epoxy resin composite that was composed of discontinuous carbon fibers of 130 μm or 3 mm were investigated. The mechanical properties of carbon fiber/epoxy resin composite cured by microwave irradiation for 20 min at 120°C were similar to ones of the sample prepared by conventional oven for 180 min at 120°C. Microwavecured carbon fiber/epoxy resin composite had higher glass transition temperature than the one prepared by conventional oven. The relation between curing time and flexural modulus indicated that the curing velocity of microwave-irradiated carbon fiber/epoxy resin composite was 9 times faster than the one prepared by conventional oven. Furthermore, activation energies for resincuring reaction on microwave and conventional-cured carbon fiber/epoxy resin composite were estimated. The resin-curing reaction in carbon fiber/epoxy resin composite was promoted by microwave irradiation.展开更多
The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber （CF） composites. To this end, a facile interracial strategy for fabricating flame-retardant carbon fibers...The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber （CF） composites. To this end, a facile interracial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes （PEC） consisting of chitosan （CH） and ammonium polyphosphate （APP） was developed, and its corresponding fire-retarded epoxy resin composites （EP/（PEC@CF）） without any other additional flame retardants were prepared. The decorated CFs were characterized by SEM- EDX, XPS and XRD, indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF. Thanks to the nitrogen- and phosphorous-containing PEC, the resulting composites exhibited excellent flame retardancy as the limiting oxygen index （LOI） increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt% PEC. EP/（PEC8.1@CF） also performed well in cone calorimetry with the decrease of peak-heat release rate （PHRR） and smoke production rate （SPR） by 50.0% and 30.4%, respectively, and the value of fire growth rate （FIGRA） was also reduced to 3.41 kW·m-2- s-1 from 4.84 kW· m-2· s-1, suggesting a considerably enhanced fire safety. Furthermore, SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char. In addition, the impact strength of the composite was improved, together with no obvious deterioration of flexural properties and glass transition temperature. Taking advantage of the features, the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.展开更多
Recycling of carbon fiber reinforced composites is important for sustainable development and the circular economy.Despite the use of dynamic chemistry,developing high-strength recyclable CFRPs remains a major challeng...Recycling of carbon fiber reinforced composites is important for sustainable development and the circular economy.Despite the use of dynamic chemistry,developing high-strength recyclable CFRPs remains a major challenge due to the mutual exclusivity between the dynamic and mechanical properties of materials.Here,we developed a high-strength recyclable epoxy resin(HREP)based on dynamic dithioacetal covalent adaptive network using diglycidyl ether bisphenol A(DGEBA),pentaerythritol tetra(3-mercapto-propionate)(PETMP),and vanillin epoxy resin(VEPR).At high temperatures,the exchange reaction of thermally activated dithioacetals accelerated the rearrangement of the network,giving it significant reprocessing ability.Moreover,HREP exhibited excellent solvent resistance due to the increased cross-linking density.Using this high-strength recyclable epoxy resin as the matrix and carbon fiber modified with hyperbranched ionic liquids(HBP-AMIM+PF6-)as the reinforcing agent,high performance CFRPs were successfully prepared.The tensile strength,interfacial shear strength(IFSS)and interlaminar shear strength(ILSS)of the optimized formulation(HREP20/CF-HBPPF6)were 1016.1,70.8 and 76.0 MPa,respectively.In addition,the CFRPs demonstrated excellent solvent and acid/alkali-resistance.The CFRPs could completely degrade within 24 h in DMSO at 140℃,and the recycled CF still maintained the same tensile strength and ILSS as the original after multiple degradation cycles.展开更多
In this study,two types of soluble thermoplastic resins were added to epoxy resin at a fixed weight ratio to prepare a three-phase cast body.The cast was then manufactured into hybrid nanofiber as interleaves for inte...In this study,two types of soluble thermoplastic resins were added to epoxy resin at a fixed weight ratio to prepare a three-phase cast body.The cast was then manufactured into hybrid nanofiber as interleaves for interlaminar toughening of carbon fiber/epoxy resin(CF/EP)composites using a co-solvent method.The results revealed that when the hybrid components reached 15 wt%,Polyethersulfone(PES)and polyaryletherketone cardo(PEK-C)exhibited the best synergistic toughening effect,and the fracture toughness increased by 99.8%and 39.8%,respectively,compared with the reference or the same proportion of the single PES toughened sample.We used PES/PEK-C hybrid nanofibers with an areal density of 19.2 g per square meter(gsm)as composite toughening layers.Apart from the lack of significant influence of PES nanofiber on CF/EP composites,the interlaminar fracture toughness of mode I and mode II layers increased by 88.3%and 46.9%,respectively,compared to the reference sample.Scanning Electron Microscopy of the fracture surface and cross-section micromorphology of the laminate displayed that the thermoplastic microspheres of different sizes contribute differently to crack resistance:PEK-C consumes more energy due to the debonding and extraction of microspheres and resin,whereas the presence of the PES phase can induce more plastic deformation and crack deflection.展开更多
基金Supported by Commission of Science Technology and Industry for National Defense of China(No.JPPT-115-477).
文摘To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.
文摘Microwave processing has great potential for improving composite manufacturing such as reduction of curing time, energy requirements and operational costs. In this paper, the effects of microwave irradiation for resin-curing of carbon fiber/epoxy resin composite that was composed of discontinuous carbon fibers of 130 μm or 3 mm were investigated. The mechanical properties of carbon fiber/epoxy resin composite cured by microwave irradiation for 20 min at 120°C were similar to ones of the sample prepared by conventional oven for 180 min at 120°C. Microwavecured carbon fiber/epoxy resin composite had higher glass transition temperature than the one prepared by conventional oven. The relation between curing time and flexural modulus indicated that the curing velocity of microwave-irradiated carbon fiber/epoxy resin composite was 9 times faster than the one prepared by conventional oven. Furthermore, activation energies for resincuring reaction on microwave and conventional-cured carbon fiber/epoxy resin composite were estimated. The resin-curing reaction in carbon fiber/epoxy resin composite was promoted by microwave irradiation.
基金Financial supports by the National Natural Science Foundation of China (Nos. 51773137 and 51721091)the Sichuan Province Youth Science and Technology Innovation Team (No. 2017TD0006)
文摘The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber （CF） composites. To this end, a facile interracial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes （PEC） consisting of chitosan （CH） and ammonium polyphosphate （APP） was developed, and its corresponding fire-retarded epoxy resin composites （EP/（PEC@CF）） without any other additional flame retardants were prepared. The decorated CFs were characterized by SEM- EDX, XPS and XRD, indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF. Thanks to the nitrogen- and phosphorous-containing PEC, the resulting composites exhibited excellent flame retardancy as the limiting oxygen index （LOI） increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt% PEC. EP/（PEC8.1@CF） also performed well in cone calorimetry with the decrease of peak-heat release rate （PHRR） and smoke production rate （SPR） by 50.0% and 30.4%, respectively, and the value of fire growth rate （FIGRA） was also reduced to 3.41 kW·m-2- s-1 from 4.84 kW· m-2· s-1, suggesting a considerably enhanced fire safety. Furthermore, SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char. In addition, the impact strength of the composite was improved, together with no obvious deterioration of flexural properties and glass transition temperature. Taking advantage of the features, the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.
基金financially supported by the National Natural Science Foundation of China(Nos.U23A2069 and 51403242)the Natural Science Foundation of Hubei Province(No.2024AFB800)+5 种基金the Fundamental Research Funds for the Central Universities,South-Central Minzu University(Nos.CZY23017 and CZD24001)the Innovation Group of National Ethnic Affairs Commission of China(No.MZR20006)the Fund for Academic Innovation Teams of South-Central Minzu University(No.XTZ24012)Scientific Research Platforms of South-Central Minzu University(No.PTZ24013)the Open Fund for Key Lab of Guangdong High Property and Functional Macromolecular Materials,China(No.20240007)State Key Laboratory of New Textile Materials and Advanced Processing Technologies(No.FZ20230012)。
文摘Recycling of carbon fiber reinforced composites is important for sustainable development and the circular economy.Despite the use of dynamic chemistry,developing high-strength recyclable CFRPs remains a major challenge due to the mutual exclusivity between the dynamic and mechanical properties of materials.Here,we developed a high-strength recyclable epoxy resin(HREP)based on dynamic dithioacetal covalent adaptive network using diglycidyl ether bisphenol A(DGEBA),pentaerythritol tetra(3-mercapto-propionate)(PETMP),and vanillin epoxy resin(VEPR).At high temperatures,the exchange reaction of thermally activated dithioacetals accelerated the rearrangement of the network,giving it significant reprocessing ability.Moreover,HREP exhibited excellent solvent resistance due to the increased cross-linking density.Using this high-strength recyclable epoxy resin as the matrix and carbon fiber modified with hyperbranched ionic liquids(HBP-AMIM+PF6-)as the reinforcing agent,high performance CFRPs were successfully prepared.The tensile strength,interfacial shear strength(IFSS)and interlaminar shear strength(ILSS)of the optimized formulation(HREP20/CF-HBPPF6)were 1016.1,70.8 and 76.0 MPa,respectively.In addition,the CFRPs demonstrated excellent solvent and acid/alkali-resistance.The CFRPs could completely degrade within 24 h in DMSO at 140℃,and the recycled CF still maintained the same tensile strength and ILSS as the original after multiple degradation cycles.
基金The project was funded by State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(no.KF2121)Science and Technology Tackle Key Project of Henan Province(no.212102210036)+1 种基金Science and Technology Tackle Key Project of Henan Province(no.212102210550)the Science and Technology Guidance Project of China National Textile and Apparel Council(no.2020061).
文摘In this study,two types of soluble thermoplastic resins were added to epoxy resin at a fixed weight ratio to prepare a three-phase cast body.The cast was then manufactured into hybrid nanofiber as interleaves for interlaminar toughening of carbon fiber/epoxy resin(CF/EP)composites using a co-solvent method.The results revealed that when the hybrid components reached 15 wt%,Polyethersulfone(PES)and polyaryletherketone cardo(PEK-C)exhibited the best synergistic toughening effect,and the fracture toughness increased by 99.8%and 39.8%,respectively,compared with the reference or the same proportion of the single PES toughened sample.We used PES/PEK-C hybrid nanofibers with an areal density of 19.2 g per square meter(gsm)as composite toughening layers.Apart from the lack of significant influence of PES nanofiber on CF/EP composites,the interlaminar fracture toughness of mode I and mode II layers increased by 88.3%and 46.9%,respectively,compared to the reference sample.Scanning Electron Microscopy of the fracture surface and cross-section micromorphology of the laminate displayed that the thermoplastic microspheres of different sizes contribute differently to crack resistance:PEK-C consumes more energy due to the debonding and extraction of microspheres and resin,whereas the presence of the PES phase can induce more plastic deformation and crack deflection.
