Carbon-fiber-reinforced plastics(CFRP)with improved mechanical properties based on modified epoxy binders were investigated in this study.By adding 15 parts by weight(p.b.w.)of copolymer of polysulfone with cardo phth...Carbon-fiber-reinforced plastics(CFRP)with improved mechanical properties based on modified epoxy binders were investigated in this study.By adding 15 parts by weight(p.b.w.)of copolymer of polysulfone with cardo phthalide group(PSFP-70C)to the epoxyanhydride binder,the flexural strength of the epoxy polymer was increased by 60%,the CFRP based on it by 57%,the flexural modulus of the epoxy polymer was increased by 83%,and the composite by 96%.The adhesion strength of the binder to carbon fiber reached a high level at 10 p.b.w.of thermoplastic modifier and increased by 65%compared to the unmodified binder.Scanning electron microscopy(SEM)was used to determine that in epoxyanhydride systems with a polysulfone content of 5–15 p.b.w.,the structure belongs to the"matrix dispersion"type and with a content of 20 p.b.w.to the"interpenetrating phase"type.A heterogeneous structure was also observed using dynamic mechanical analysis.展开更多
A simultaneous boost in toughness and fire safety of epoxy(EP)is achieved through solvent-free one-step neutralization of phytic acid with 1,8-diaminooctane to yield a multifunctional bio-based curing agent,PA-DAO.Whe...A simultaneous boost in toughness and fire safety of epoxy(EP)is achieved through solvent-free one-step neutralization of phytic acid with 1,8-diaminooctane to yield a multifunctional bio-based curing agent,PA-DAO.When used as the sole hardener,5 wt%PA-DAO increased the tensile,flexural,and impact strengths by 165%,81%,and 455%,respectively,over the parent amine system,whereas the tensile and flexural toughness increased by 1387% and 775%,respectively.At 25 wt% loading,the resin attained a UL-94 V-0 rating and a limiting oxygen index of 28.1%,accompanied by a 71% reduction in the peak heat-release rate and a 53%suppression of total smoke production.This facile,green protocol provides scalable access to ultra-tough,intrinsically flame-retardant epoxy networks without external plasticizers or additives.展开更多
This study presents a framework involving statistical modeling and machine learning to accurately predict and optimize the mechanical and damping properties of hybrid granite-epoxy(G-E)composites reinforced with cast ...This study presents a framework involving statistical modeling and machine learning to accurately predict and optimize the mechanical and damping properties of hybrid granite-epoxy(G-E)composites reinforced with cast iron(CI)filler particles.Hybrid G-E composite with added cast iron(CI)filler particles enhances stiffness,strength,and vibration damping,offering enhanced performance for vibration-sensitive engineering applications.Unlike conventional approaches,this work simultaneously employs Artificial Neural Networks(ANN)for highaccuracy property prediction and Response Surface Methodology(RSM)for in-depth analysis of factor interactions and optimization.A total of 24 experimental test data sets of varying input factors(granite weight%,epoxy weight%,and CI filler weight%)were utilized to train and test the prediction models using an ANN approach and further analyze the interaction effects using RSM.Mechanical properties,including tensile,compressive,and flexural strength,elastic modulus,density and damping properties measured under various testing conditions,were set as output parameters for prediction.This study analyzed and optimized the performance of the ANN model using Bayesian Regularization and Levenberg-Marquardt algorithms to identify the best performing number of neurons in the hidden layer for achieving the highest prediction accuracy.The proposed ANN framework achieved an exceptional average determination coefficient(R2)exceeding 99%,with Bayesian Regularization demonstrating remarkable stability in the 22-neuron range and minimal variation across all properties.RSM and ANN form a powerful framework for predicting and optimizing hybrid G-E composite properties,enabling efficient design for vibration-critical applications with reduced experimental effort and performance optimization.展开更多
Amid the escalating plastic pollution issue, the development of biodegradable and recyclable polymeric materials has become a focus within the scientific community. Chain extenders, which are an important class of com...Amid the escalating plastic pollution issue, the development of biodegradable and recyclable polymeric materials has become a focus within the scientific community. Chain extenders, which are an important class of compounds, facilitate the elongation of polymer chains through reactive functional groups, thereby enhancing the performance of the materials. Epoxy-based chain extenders, due to their cost-effectiveness, low toxicity, high reaction efficiency, and effective reactivity with hydroxyl and carboxyl groups, have emerged as a promising class of chain extenders. This manuscript comprehensively elaborates on the varieties, structural characteristics, and performance of chain extenders, the challenges they face, and the methods for their modification. Special emphasis is placed on the application of epoxy-based chain extenders in biodegradable polymers, such as polylactic acid (PLA), and their subsequent influence on the structural and performance properties of these materials.展开更多
The synergy between corrosion protection and wear resistance is an effective strategy for the development of multifunctional coating to withstand complex working conditions.This study reports an epoxy resin coating fi...The synergy between corrosion protection and wear resistance is an effective strategy for the development of multifunctional coating to withstand complex working conditions.This study reports an epoxy resin coating filled with benzotriazole loaded metal-organic frameworks(BTA-MOFs)functionalized graphene oxide nanoribbons(GONR)that exhibit active anti-corrosion,act as a barrier to corrosive ion,and enhance wear resistance.The GONR@BTA-MOFs composite is synthesized through chemically etching multi-walled carbon nanotubes and subsequent electrostatic self-assembly corrosion inhibitors loaded MOFs onto the GONR.The composite demonstrates improved compatibility with epoxy resins compared to carbon nanotubes.The anti-corrosion performance of the composite coating is investigated using electrochemical impedance spectroscopy.After immersing in a 3.5 wt.%NaCl solution for 25 d,the alternating current impedance of the composite coating is three orders of magnitude higher than that of pure epoxy resin.Simultaneously,the controlled release of the corrosion inhibitor retards the deterioration of the coating after localized damage occurrence,which functions as active corrosion protection.The GONR@BTA-MOFs/EP composite coating exhibits the highest corrosion potential of-0.188 V and the lowest corrosion current of 3.162×10^(−9)A cm^(−2)in the Tafel test.Tribological studies reveal a reduction in the friction coefficient from 0.62 to 0.08 after incorporating GONR@BTA-MOFs in the coating,with the wear volume being seven times lower than that of pure epoxy resin.The excellent lubrication effect of the nanomaterials reduces the coefficient of friction of the coating,thereby improving the abrasion resistance of the coating.The synergy between the self-lubrication of the two-dimensional layered fillers and the corrosion resistance of the smart inhibitor containers suggests a promising strategy for enhancing the performance of epoxy resins under complex working conditions.展开更多
Polyethylene glycol(PEG)with different chains was used to modify epoxy asphalt.Molecular models of PEG⁃modified epoxy asphalt were developed using molecu⁃lar simulations(MS).The thermodynamic and mechanical properties...Polyethylene glycol(PEG)with different chains was used to modify epoxy asphalt.Molecular models of PEG⁃modified epoxy asphalt were developed using molecu⁃lar simulations(MS).The thermodynamic and mechanical properties of PEG⁃modified epoxy asphalt were analyzed,and its toughening mechanisms were explored.A method based on the Dijkstra algorithm was proposed to evaluate ep⁃oxy asphalt crosslinked networks.The results show that the introduction of PEG chains into epoxy asphalt can lower the glass transition temperature and enhance its toughness be⁃cause of the extended length of the PEG chains,which can in⁃crease the free volume and improve the mobility of the epoxy resin in the epoxy asphalt.The crosslinked network quantita⁃tive evaluation method based on the Dijkstra algorithm can ef⁃fectively evaluate the distribution of epoxy asphalt crosslink⁃ing bonds,providing further explanation of the toughening mechanism of PEG⁃modified epoxy asphalt.The feasibility of designing and screening epoxy asphalt materials by MS is verified,and a guide for toughening mechanism research of epoxy asphalt at the molecular level is provided.展开更多
Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are kn...Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are known for their unique compact structure;they are not only lightweight but also strong.In this study,an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches.The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other,forming an effective mechanical interlocking structure.These structures bring owl feathers excellent mechanical properties.Inspired by the natural structure of owl feathers,a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber(CF)fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers.To evaluate the effect of the fine feather structure on the mechanical properties of CFRP,a mechanical property study on CFRP with and without the fine feather imitation structure were conducted.The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly.Specifically,the tensile strength of the composites increased by 6.42%and 13.06%and the flexural strength increased by 8.02%and 16.87%in the 0°and 90°sample directions,respectively.These results provide a new design idea for the improvement of the mechanical properties of the CFRP,promoting the application of CFRP in engineering fields,such as automotive transportation,rail transit,aerospace,and construction.展开更多
The pavement performance of epoxy resin modified asphalt mixtures was investigated by the Marshall test, the indirect tensile test, the rutting test, the three-pointed bending test and the composite beam fatigue test....The pavement performance of epoxy resin modified asphalt mixtures was investigated by the Marshall test, the indirect tensile test, the rutting test, the three-pointed bending test and the composite beam fatigue test. In comparison with the performance of epoxy resin modified asphalt mixtures, the performance of stone matrix asphalt mixtures （SMA10） was also investigated. The rutting test and composite beam fatigue test results show that the epoxy resin modified asphalt mixtures can improve permanent deformation and fatigue characteristics. They also show lower temperature susceptibility and greater resistance to moisture damage compared to the SMA10. Findings from the research indicate that the epoxy resin modified asphalt mixture provides an optional material for the pavement of long-span steel bridges in China due to profound performance and economic advantages.展开更多
Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and ...Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and controlled stress flexural fatigue test are used to study the performance of asphalt mixtures modified by epoxy resin including high-temperature stability, low-temperature cracking-resistance, and fatigue cracking-resistance, which are served to evaluate the modification effect of epoxy resin of different contents. With the addition of epoxy resin, all the three performances are improved greatly. However, when the amount of epoxy resin added is over a certain value, the modification effect will be stable with no extra benefit detected. Finally, in terms of the properties of the three respects, 20%, 30%, 30% are given separately as the proposal adding contents.展开更多
Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological beh...Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.展开更多
Graphene oxide (GO) reduced by Stachys lavandulifolia extract (SLE) was produced and characterised. The anti-corrosion behaviour of epoxy coatings containing GO and rGO nanosheets was investigated. FESEM-EDS, FT-IR, a...Graphene oxide (GO) reduced by Stachys lavandulifolia extract (SLE) was produced and characterised. The anti-corrosion behaviour of epoxy coatings containing GO and rGO nanosheets was investigated. FESEM-EDS, FT-IR, and Raman spectroscopy were used to examine the microstructure and chemical composition of the nanosheets and epoxy coatings. EIS experiment was used to explore the corrosion behaviour of the coatings. The O/C ratio for GO and rGO-SLE was found to be 2.5 and 4.5, indicating a decrease in the carbon content after the reduction of GO, confirming the adsorption of SLE onto the GO nanosheets. The successful reduction of GO in the presence of SLE particles was confirmed by disappearing the C=O peak and a significant decrease in the C-O-C bond intensity. The epoxy/rGO- SLE coatings exhibited the highest double-layer thickness and excellent corrosion resistance compared to neat epoxy and epoxy/GO coatings, emphasizing the significant role of rGO in enhancing the protective performance of epoxy coatings. The highest values for total charge transfer and film resistances and the inhibition efficiency were observed to be 6529 Ω·cm^(2) and 90%, respectively, for the epoxy/rGO-SLE coated steel plate. It was also found that the epoxy/0.15 wt.% rGO-SLE coating demonstrates the best corrosion resistance performance.展开更多
The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0....The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0.05 g/cm3) of the composite produced is lower than that of wood used in this field. The material has low porosity (9.8%) and is less absorbent (12.61%) than wood. The result of the thermal conductivity test by the hot plane method shows that this composite can contribute to the internal thermal insulation (an example of thermal conductivity is 0.32W/m.K) of floating boats. The mechanical tests of compression (young modulus is 22.86 GPa), resilience (1.238 J/Cm2) and hardness (233.04 BH30-2.5/187.5-15s) show that this composite is much harder and more absorbent than many wood and bio-composite materials used in the construction of pleasure boats. The abrasion test (0.005349) shows that this composite could well resist friction with the beach.展开更多
The self-healing properties of dual-component epoxy microcapsules are evaluated when incorporated into an epoxy coating.The performance of the coating was assessed under immersion in a saline solution,simulating seawa...The self-healing properties of dual-component epoxy microcapsules are evaluated when incorporated into an epoxy coating.The performance of the coating was assessed under immersion in a saline solution,simulating seawater conditions.Initially,synthesized microcapsules are incorporated into the epoxy coating.Then,the self-healing capabilities of the coating are studied under immersion using scanning vibrating electrode technique(SVET),open circuit potential(OCP),electrochemical impedance spectroscopy(EIS)and immersion corrosion test on coated samples with intentionally created artificial defects.The last three tests were conducted in a 3.5%NaCl solution.The adhesion of the coating is also studied by pull-off adhesion test.SVET analyses reveal lower ionic current densities in coated samples containing microcapsules during 24 h of immersion.EIS results demonstrate self-healing at the defect site for up to 12 h of immersion.After this time,the corrosion protection diminishes with prolonged immersion in the saline solution.Despite this,the coating with the microcapsules exhibits decrease in the corrosion process compared to the coating without the microcapsules.These results are consistent and complement the outcomes of the immersion tests conducted over 360 and 1056 h,which indicate that coated samples without microcapsules exhibit double the corroded areas around the scribes compared to coated samples containing the microcapsules.These findings offer a promising outlook for applying this coating on offshore carbon steel structures under immersion aiming for a longer lifetime with less maintenance intervention.展开更多
Effective antifouling coatings are critical for protecting marine infrastructure from biofouling and environmental degradation;however,achieving long-term antifouling performance along with environmental stability rem...Effective antifouling coatings are critical for protecting marine infrastructure from biofouling and environmental degradation;however,achieving long-term antifouling performance along with environmental stability remains a major challenge.In this study,a multifunctional bio-based epoxy coating is developed by integrating a dual-action antifouling system.Cinnamic acid(CA),which is known for its antibacterial and UV-shielding properties,was chemically grafted into ethylene glycol diglycidyl ether(EGDE)to provide intrinsic antifouling and anti-UV functions.Simultaneously,the KH560-modified silica aerogel was incorporated to create a dense hydrophobic surface that repels microorganism adhesion.The resulting coating exhibited a superhydrophobic contact angle of 154.3°,an ultralow surface energy,and exceptional resistance to protein and algal adhesion.Additionally,it achieves 99%bactericidal efficiency against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)while maintaining high transparency and ease of processing.These results highlight a promising strategy for designing durable and ecofriendly antifouling coatings suitable for demanding marine environments.展开更多
Epoxy resin is widely used in electronic packaging due to its exceptional performance,particularly the low-temperature curable thiol/epoxy system,which effectively minimizes thermal damage to sensitive electronic comp...Epoxy resin is widely used in electronic packaging due to its exceptional performance,particularly the low-temperature curable thiol/epoxy system,which effectively minimizes thermal damage to sensitive electronic components.However,the majority of commercial thiol curing agents contain hydrolysable ester bonds and lack rigid structures,which induces most of thiol/epoxy systems still suffering from unsatisfactory heat resistance and hygrothermal resistance,significantly hindering their application in electronic packaging.In this study,we synthesized a tetrafunctional thiol compound,bis[3-(3-sulfanylpropyl)-4-(3-sulfanylpropoxy)phenyl]sulfone(TMBPS)with rigid and ester-free structures to replace traditional commercial thiol curing agents,pentaerythritol tetra(3-mercaptopropionate)(PETMP).Compared to the PETMP/epoxy system,the TMBPS/epoxy system exhibited superior comprehensive properties.The rigid structures of bisphenol S-type tetrathiol enhanced the heat resistance and mechanical properties of TMBPS/epoxy resin cured products,outperforming those of PETMP/epoxy resin cured products.Notably,the glass transition temperature of TMBPS/epoxy resin cured products was 74.2℃which was 11.8°C higher than that of PETMP cured products.Moreover,the ester-free structure in TMBPS contributed to its enhanced resistance to chemicals and hygrothermal conditions.After undergoing 1000 h of hightemperature and high-humidity aging,the tensile strength and adhesion strength of TMBPS-cured products were 73.33 MPa and 3.39 MPa,respectively exceeding 100%and 40%of their initial values,while PETMP-cured products exhibited a complete loss of both tensile strength and adhesion strength.This study provides a strategy for obtaining thermosetting polymers that can be cured at low temperatures and exhibit excellent comprehensive properties.展开更多
The demand for energy-efficient and environmental-friendly power grid construction has made the exploitation of bio-based electrical epoxy resins with excellent properties increasingly important.This work developed th...The demand for energy-efficient and environmental-friendly power grid construction has made the exploitation of bio-based electrical epoxy resins with excellent properties increasingly important.This work developed the bio-based electrotechnical epoxy resins based on magnolol.High-performance epoxy resin(DGEMT)with a double crosslinked points and its composites(Al_(2)O_(3)/DGEMT)were obtained taking advantages of the two bifunctional groups(allyl and phenolic hydroxyl groups)of magnolol.Benefitting from the distinctive structure of DGEMT,the Al_(2)O_(3)/DGEMT composites exhibited the advantages of intrinsically high thermal conductivity,high insulation,and low dielectric loss.The AC breakdown strength and thermal conductivity of Al_(2)O_(3)/DGEMT composites were 35.5 kV/mm and 1.19 W·m-1·K-1,respectively,which were 15.6%and 52.6%higher than those of petroleum-based composites(Al_(2)O_(3)/DGEBA).And its dielectric loss tanδ=0.0046 was 20.7%lower than that of Al_(2)O_(3)/DGEBA.Furthermore,the mechanical,thermal and processing properties of Al_(2)O_(3)/DGEMT are fully comparable to those of Al_(2)O_(3)/DGEBA.This work confirms the feasibility of manufacturing environmentally friendly power equipment using bio-based epoxy resins,which has excellent engineering applications.展开更多
In gas-insulated lines,basin-insulators can accumulate charge under non-uniform electric fields,distorting the field distribution and potentially causing surface flashover,which threatens the stability of power system...In gas-insulated lines,basin-insulators can accumulate charge under non-uniform electric fields,distorting the field distribution and potentially causing surface flashover,which threatens the stability of power systems.In this study,Atmospheric Pressure Plasma Jet(APPJ)technology was used to deposit TiO_(2) on the surface of alumina/epoxy(Al_(2)O_(3)/EP)composites.The impact of deposition of TiO_(2) layer on the surface morphology and chemical composition of Al_(2)O_(3)/EP was studied using testing methods such as Scanning Electron Microscope,X-ray photoelectron spectroscopy,Fourier Transform Infrared Spectrometer,and Energy Dispersive Spectrometer.It was found that APPJ creates a dense,rough Ti-O layer on the Al_(2)O_(3)/EP surface,which bonds tightly with the substrate.The efficacy of APPJ was found to depend on processing time,with optimal results observed at 3 min,DC and AC flashover voltages increased by 29.6% and 15.7%,respectively.TiO_(2)layer enhances the conductivity of the resin and shallows trap levels.Through the synergistic effects of various factors,surface charges are efficiently dissipated and evenly distributed.This study not only reveals the physicochemical process of TiO_(2)deposition via APPJ but also integrates surface characteristics with electrical performance.The findings offer a new strategy to enhance surface flashover voltage and ensure equipment safety.展开更多
Carbon fiber-reinforced composites(CFRCs)have a wide range of applications in the aerospace,automotive,and energy sectors.A higher specific strength-to-weight ratio is desired in high-performance applications.The fail...Carbon fiber-reinforced composites(CFRCs)have a wide range of applications in the aerospace,automotive,and energy sectors.A higher specific strength-to-weight ratio is desired in high-performance applications.The failure mechanism of CFRCs involves multiscale phenomena,such as failure that can occur at the matrix,fibers,interface,layers,lamina,and laminates.When an impactor hits the CFRCs,the design involves analyzing each of these stages to prevent failure and optimize the properties of CFRCs under various loading conditions.A numerical model was employed to predict the fracture toughness of CFRCs with varying weight fractions and orientations.Finite Element Analysis(FEA)was conducted at the fiber level on a micrometer scale for the CFRCs against an impact loading.Epoxy composite samples at the coupon level were prepared using the hand layup technique with carbon fibers laid at three different angles,i.e.,longitudinal,transverse,and angular orientations.Samples with five different weight percentages of carbon fibers were prepared and investigated.An Izod impact tester was used to fracture the samples and characterize the energy absorption.The fractured surfaces were observed with a scanning electron microscope(SEM).The numerical and experimental results show that crack propagation is inhibited at higher loading fractions at an angular orientation by creating obstacles for the crack to propagate and arresting the dislocation motion.The fractography analysis through a scanning electron microscope exhibits how the angular orientations of the fibers are reoriented after fracture to prevent further crack propagation.展开更多
The introduction of dynamic covalent bonds into the structure of epoxy resins can improve the degradation performance of the materials.But to a certain extent,it will affect the insulating properties of the resin,and ...The introduction of dynamic covalent bonds into the structure of epoxy resins can improve the degradation performance of the materials.But to a certain extent,it will affect the insulating properties of the resin,and how to balance the insulating properties and degradation performance has become an urgent problem.In this paper,the effects of different catalysts on the thermal-force-electrical properties of sorbitolbased resins were systematically investigated based on the dynamic ester bonding to construct the resin crosslinking network,and the biobased sorbitol glycidyl ether was used as the resin matrix.The experiments show that the resin system catalyzed by triethanolamine(TEOA)exhibits excellent comprehensive performance,which combines good thermal stability and mechanical properties with excellent electrical properties(breakdown field strength of 44.21 k V/mm and dielectric loss factor of 0.29%).In addition,chemical degradation tests were conducted on the resin systems with different catalysts,and the experiments showed that the produced resins could be degraded in benzyl alcohol and exhibited good degradation performance.This study provides a theoretical basis and technical path for the development of new bio-based electrical insulating materials with both high insulation and degradation properties,which is conducive to the popularization and application of bio-based resins in the field of electrical equipment.展开更多
The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades(EWTBs).Herein,we proposed a selective degradation strategy for di...The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades(EWTBs).Herein,we proposed a selective degradation strategy for direct recycling and high-value recovery of epoxy resins by introducing degradable Schiff base groups into the molecular structure and utilizing the resulting oligomers as curing agents.To realize this strategy,a series of Schiff base compounds were synthesized using bio-based vanillin and diamines and subsequently functionalized with epichlorohydrin to yield bio-based epoxy resins.The cured epoxy resins demonstrated remarkable improvements in the mechanical properties of diglycidyl ether of bisphenol-A(DGEBA),with an increases of 44.49%in the tensile strength of 38.55%,bending strength,and impact strength of 71.20%.The introduction of dynamic Schiff base bonds enabled the selective degradation of the vanillin-2,2-bis[4-(4-aminophenoxy)phenyl]propane-based epoxy resin(VBEP)/DGEBA copolymer,producing 84.20% oligomers that can be directly recycled and reused.Replacing 30 wt% of the curing agent with the oligomer increased the tensile strength of the cured sample to 75.40 MPa,surpassing that of the cured DGEBA.Under simulated acid rain and seawater exposure,the copolymer exhibited a service life of 27 years at 40℃,significantly exceeding the currently reported service life of 20 years.This study presents a sustainable strategy for the direct recycling and high-value reuse of epoxy resin,offering a promising solution for EWTBs.展开更多
基金financially supported by the Ministry of Science and Higher Education of the Russian Federation。
文摘Carbon-fiber-reinforced plastics(CFRP)with improved mechanical properties based on modified epoxy binders were investigated in this study.By adding 15 parts by weight(p.b.w.)of copolymer of polysulfone with cardo phthalide group(PSFP-70C)to the epoxyanhydride binder,the flexural strength of the epoxy polymer was increased by 60%,the CFRP based on it by 57%,the flexural modulus of the epoxy polymer was increased by 83%,and the composite by 96%.The adhesion strength of the binder to carbon fiber reached a high level at 10 p.b.w.of thermoplastic modifier and increased by 65%compared to the unmodified binder.Scanning electron microscopy(SEM)was used to determine that in epoxyanhydride systems with a polysulfone content of 5–15 p.b.w.,the structure belongs to the"matrix dispersion"type and with a content of 20 p.b.w.to the"interpenetrating phase"type.A heterogeneous structure was also observed using dynamic mechanical analysis.
基金financially supported by Zhejiang Provincial"Leading Force"and"Leading Bird"R&D Key Project(No.2022C03128)Basic Public Welfare Research Plan of Zhejiang Province(No.LY21C160003)+1 种基金National Natural Science Foundation(No.51991355)Zhejiang A&F University Scientific Research Start-up Fund(No.2023LFR134)。
文摘A simultaneous boost in toughness and fire safety of epoxy(EP)is achieved through solvent-free one-step neutralization of phytic acid with 1,8-diaminooctane to yield a multifunctional bio-based curing agent,PA-DAO.When used as the sole hardener,5 wt%PA-DAO increased the tensile,flexural,and impact strengths by 165%,81%,and 455%,respectively,over the parent amine system,whereas the tensile and flexural toughness increased by 1387% and 775%,respectively.At 25 wt% loading,the resin attained a UL-94 V-0 rating and a limiting oxygen index of 28.1%,accompanied by a 71% reduction in the peak heat-release rate and a 53%suppression of total smoke production.This facile,green protocol provides scalable access to ultra-tough,intrinsically flame-retardant epoxy networks without external plasticizers or additives.
文摘This study presents a framework involving statistical modeling and machine learning to accurately predict and optimize the mechanical and damping properties of hybrid granite-epoxy(G-E)composites reinforced with cast iron(CI)filler particles.Hybrid G-E composite with added cast iron(CI)filler particles enhances stiffness,strength,and vibration damping,offering enhanced performance for vibration-sensitive engineering applications.Unlike conventional approaches,this work simultaneously employs Artificial Neural Networks(ANN)for highaccuracy property prediction and Response Surface Methodology(RSM)for in-depth analysis of factor interactions and optimization.A total of 24 experimental test data sets of varying input factors(granite weight%,epoxy weight%,and CI filler weight%)were utilized to train and test the prediction models using an ANN approach and further analyze the interaction effects using RSM.Mechanical properties,including tensile,compressive,and flexural strength,elastic modulus,density and damping properties measured under various testing conditions,were set as output parameters for prediction.This study analyzed and optimized the performance of the ANN model using Bayesian Regularization and Levenberg-Marquardt algorithms to identify the best performing number of neurons in the hidden layer for achieving the highest prediction accuracy.The proposed ANN framework achieved an exceptional average determination coefficient(R2)exceeding 99%,with Bayesian Regularization demonstrating remarkable stability in the 22-neuron range and minimal variation across all properties.RSM and ANN form a powerful framework for predicting and optimizing hybrid G-E composite properties,enabling efficient design for vibration-critical applications with reduced experimental effort and performance optimization.
文摘Amid the escalating plastic pollution issue, the development of biodegradable and recyclable polymeric materials has become a focus within the scientific community. Chain extenders, which are an important class of compounds, facilitate the elongation of polymer chains through reactive functional groups, thereby enhancing the performance of the materials. Epoxy-based chain extenders, due to their cost-effectiveness, low toxicity, high reaction efficiency, and effective reactivity with hydroxyl and carboxyl groups, have emerged as a promising class of chain extenders. This manuscript comprehensively elaborates on the varieties, structural characteristics, and performance of chain extenders, the challenges they face, and the methods for their modification. Special emphasis is placed on the application of epoxy-based chain extenders in biodegradable polymers, such as polylactic acid (PLA), and their subsequent influence on the structural and performance properties of these materials.
基金supported by the National Natural Science Foundation of China(No.52475216)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515240030)+2 种基金the Natural Science Foundation of Shaanxi Province(No.2024RSCXTD-62)the Research Fund of the State Key Laboratory of Solidification Processing(NPU)(No.2022-QZ-04)We would like to thank the Analytical&Testing Center of Northwestern Polytechnical University and the Shaanxi Materials Analysis and Research Center.
文摘The synergy between corrosion protection and wear resistance is an effective strategy for the development of multifunctional coating to withstand complex working conditions.This study reports an epoxy resin coating filled with benzotriazole loaded metal-organic frameworks(BTA-MOFs)functionalized graphene oxide nanoribbons(GONR)that exhibit active anti-corrosion,act as a barrier to corrosive ion,and enhance wear resistance.The GONR@BTA-MOFs composite is synthesized through chemically etching multi-walled carbon nanotubes and subsequent electrostatic self-assembly corrosion inhibitors loaded MOFs onto the GONR.The composite demonstrates improved compatibility with epoxy resins compared to carbon nanotubes.The anti-corrosion performance of the composite coating is investigated using electrochemical impedance spectroscopy.After immersing in a 3.5 wt.%NaCl solution for 25 d,the alternating current impedance of the composite coating is three orders of magnitude higher than that of pure epoxy resin.Simultaneously,the controlled release of the corrosion inhibitor retards the deterioration of the coating after localized damage occurrence,which functions as active corrosion protection.The GONR@BTA-MOFs/EP composite coating exhibits the highest corrosion potential of-0.188 V and the lowest corrosion current of 3.162×10^(−9)A cm^(−2)in the Tafel test.Tribological studies reveal a reduction in the friction coefficient from 0.62 to 0.08 after incorporating GONR@BTA-MOFs in the coating,with the wear volume being seven times lower than that of pure epoxy resin.The excellent lubrication effect of the nanomaterials reduces the coefficient of friction of the coating,thereby improving the abrasion resistance of the coating.The synergy between the self-lubrication of the two-dimensional layered fillers and the corrosion resistance of the smart inhibitor containers suggests a promising strategy for enhancing the performance of epoxy resins under complex working conditions.
基金The Major Science and Technology Project of Nan⁃jing(No.202209012)the Postgraduate Research and Practice Innova⁃tion Program of Jiangsu Province(No.KYCX22⁃0277).
文摘Polyethylene glycol(PEG)with different chains was used to modify epoxy asphalt.Molecular models of PEG⁃modified epoxy asphalt were developed using molecu⁃lar simulations(MS).The thermodynamic and mechanical properties of PEG⁃modified epoxy asphalt were analyzed,and its toughening mechanisms were explored.A method based on the Dijkstra algorithm was proposed to evaluate ep⁃oxy asphalt crosslinked networks.The results show that the introduction of PEG chains into epoxy asphalt can lower the glass transition temperature and enhance its toughness be⁃cause of the extended length of the PEG chains,which can in⁃crease the free volume and improve the mobility of the epoxy resin in the epoxy asphalt.The crosslinked network quantita⁃tive evaluation method based on the Dijkstra algorithm can ef⁃fectively evaluate the distribution of epoxy asphalt crosslink⁃ing bonds,providing further explanation of the toughening mechanism of PEG⁃modified epoxy asphalt.The feasibility of designing and screening epoxy asphalt materials by MS is verified,and a guide for toughening mechanism research of epoxy asphalt at the molecular level is provided.
基金supported by the Science and Technology Development Program of Jilin Province(No.20240101122JC)and(No.20240101143JC)the Key Scientific and Technological Research and Development Projects of Jilin Provincial Science and Technology Department(Grant Number 20230201108GX)。
文摘Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are known for their unique compact structure;they are not only lightweight but also strong.In this study,an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches.The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other,forming an effective mechanical interlocking structure.These structures bring owl feathers excellent mechanical properties.Inspired by the natural structure of owl feathers,a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber(CF)fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers.To evaluate the effect of the fine feather structure on the mechanical properties of CFRP,a mechanical property study on CFRP with and without the fine feather imitation structure were conducted.The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly.Specifically,the tensile strength of the composites increased by 6.42%and 13.06%and the flexural strength increased by 8.02%and 16.87%in the 0°and 90°sample directions,respectively.These results provide a new design idea for the improvement of the mechanical properties of the CFRP,promoting the application of CFRP in engineering fields,such as automotive transportation,rail transit,aerospace,and construction.
基金The National Natural Science Foundation of China(No50578038)the PhDPrograms Foundation of Ministry of Education of China (No20050286008)
文摘The pavement performance of epoxy resin modified asphalt mixtures was investigated by the Marshall test, the indirect tensile test, the rutting test, the three-pointed bending test and the composite beam fatigue test. In comparison with the performance of epoxy resin modified asphalt mixtures, the performance of stone matrix asphalt mixtures （SMA10） was also investigated. The rutting test and composite beam fatigue test results show that the epoxy resin modified asphalt mixtures can improve permanent deformation and fatigue characteristics. They also show lower temperature susceptibility and greater resistance to moisture damage compared to the SMA10. Findings from the research indicate that the epoxy resin modified asphalt mixture provides an optional material for the pavement of long-span steel bridges in China due to profound performance and economic advantages.
文摘Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and controlled stress flexural fatigue test are used to study the performance of asphalt mixtures modified by epoxy resin including high-temperature stability, low-temperature cracking-resistance, and fatigue cracking-resistance, which are served to evaluate the modification effect of epoxy resin of different contents. With the addition of epoxy resin, all the three performances are improved greatly. However, when the amount of epoxy resin added is over a certain value, the modification effect will be stable with no extra benefit detected. Finally, in terms of the properties of the three respects, 20%, 30%, 30% are given separately as the proposal adding contents.
基金the Puncak RM for the project under the grant 6733204-13069 to carry out the experiments。
文摘Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.
文摘Graphene oxide (GO) reduced by Stachys lavandulifolia extract (SLE) was produced and characterised. The anti-corrosion behaviour of epoxy coatings containing GO and rGO nanosheets was investigated. FESEM-EDS, FT-IR, and Raman spectroscopy were used to examine the microstructure and chemical composition of the nanosheets and epoxy coatings. EIS experiment was used to explore the corrosion behaviour of the coatings. The O/C ratio for GO and rGO-SLE was found to be 2.5 and 4.5, indicating a decrease in the carbon content after the reduction of GO, confirming the adsorption of SLE onto the GO nanosheets. The successful reduction of GO in the presence of SLE particles was confirmed by disappearing the C=O peak and a significant decrease in the C-O-C bond intensity. The epoxy/rGO- SLE coatings exhibited the highest double-layer thickness and excellent corrosion resistance compared to neat epoxy and epoxy/GO coatings, emphasizing the significant role of rGO in enhancing the protective performance of epoxy coatings. The highest values for total charge transfer and film resistances and the inhibition efficiency were observed to be 6529 Ω·cm^(2) and 90%, respectively, for the epoxy/rGO-SLE coated steel plate. It was also found that the epoxy/0.15 wt.% rGO-SLE coating demonstrates the best corrosion resistance performance.
文摘The mechanical, physical and thermal characterization of a composite made from woven raffia fiber vinifiera molded in epoxy resin intended for shipbuilding shows that the density (0.5 g/cm3 with a relative error of 0.05 g/cm3) of the composite produced is lower than that of wood used in this field. The material has low porosity (9.8%) and is less absorbent (12.61%) than wood. The result of the thermal conductivity test by the hot plane method shows that this composite can contribute to the internal thermal insulation (an example of thermal conductivity is 0.32W/m.K) of floating boats. The mechanical tests of compression (young modulus is 22.86 GPa), resilience (1.238 J/Cm2) and hardness (233.04 BH30-2.5/187.5-15s) show that this composite is much harder and more absorbent than many wood and bio-composite materials used in the construction of pleasure boats. The abrasion test (0.005349) shows that this composite could well resist friction with the beach.
基金supported by CAPES scholarship-Brazil Coordination for the Improvement of Higher Education Personnel(No.88887.507764/2020-00)]by CNPq-Brazil National Council of Technological and Scientific Development(No.308564/2023-5).
文摘The self-healing properties of dual-component epoxy microcapsules are evaluated when incorporated into an epoxy coating.The performance of the coating was assessed under immersion in a saline solution,simulating seawater conditions.Initially,synthesized microcapsules are incorporated into the epoxy coating.Then,the self-healing capabilities of the coating are studied under immersion using scanning vibrating electrode technique(SVET),open circuit potential(OCP),electrochemical impedance spectroscopy(EIS)and immersion corrosion test on coated samples with intentionally created artificial defects.The last three tests were conducted in a 3.5%NaCl solution.The adhesion of the coating is also studied by pull-off adhesion test.SVET analyses reveal lower ionic current densities in coated samples containing microcapsules during 24 h of immersion.EIS results demonstrate self-healing at the defect site for up to 12 h of immersion.After this time,the corrosion protection diminishes with prolonged immersion in the saline solution.Despite this,the coating with the microcapsules exhibits decrease in the corrosion process compared to the coating without the microcapsules.These results are consistent and complement the outcomes of the immersion tests conducted over 360 and 1056 h,which indicate that coated samples without microcapsules exhibit double the corroded areas around the scribes compared to coated samples containing the microcapsules.These findings offer a promising outlook for applying this coating on offshore carbon steel structures under immersion aiming for a longer lifetime with less maintenance intervention.
基金financially supported by the National Natural Science Foundation of China(Nos.U23A20589 and E52307038)China Postdoctoral Science Foundation(No.2023M743622)+3 种基金Zhejiang Provincial Natural Science Foundation of China(No.LQ23E030006)Ningbo 2025 Key Scientific Research Programs(Nos.2022Z111,2022Z160,and 2022Z198)Natural Science Foundation of Ningbo City(Nos.2022J302 and 2024J122)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2021R01005)。
文摘Effective antifouling coatings are critical for protecting marine infrastructure from biofouling and environmental degradation;however,achieving long-term antifouling performance along with environmental stability remains a major challenge.In this study,a multifunctional bio-based epoxy coating is developed by integrating a dual-action antifouling system.Cinnamic acid(CA),which is known for its antibacterial and UV-shielding properties,was chemically grafted into ethylene glycol diglycidyl ether(EGDE)to provide intrinsic antifouling and anti-UV functions.Simultaneously,the KH560-modified silica aerogel was incorporated to create a dense hydrophobic surface that repels microorganism adhesion.The resulting coating exhibited a superhydrophobic contact angle of 154.3°,an ultralow surface energy,and exceptional resistance to protein and algal adhesion.Additionally,it achieves 99%bactericidal efficiency against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)while maintaining high transparency and ease of processing.These results highlight a promising strategy for designing durable and ecofriendly antifouling coatings suitable for demanding marine environments.
基金the support of the Science and Technology Commission of Shanghai Municipality(STCSM,No.20dz1203600)the Experimental Center of Materials Science and Engineering in Tongji University。
文摘Epoxy resin is widely used in electronic packaging due to its exceptional performance,particularly the low-temperature curable thiol/epoxy system,which effectively minimizes thermal damage to sensitive electronic components.However,the majority of commercial thiol curing agents contain hydrolysable ester bonds and lack rigid structures,which induces most of thiol/epoxy systems still suffering from unsatisfactory heat resistance and hygrothermal resistance,significantly hindering their application in electronic packaging.In this study,we synthesized a tetrafunctional thiol compound,bis[3-(3-sulfanylpropyl)-4-(3-sulfanylpropoxy)phenyl]sulfone(TMBPS)with rigid and ester-free structures to replace traditional commercial thiol curing agents,pentaerythritol tetra(3-mercaptopropionate)(PETMP).Compared to the PETMP/epoxy system,the TMBPS/epoxy system exhibited superior comprehensive properties.The rigid structures of bisphenol S-type tetrathiol enhanced the heat resistance and mechanical properties of TMBPS/epoxy resin cured products,outperforming those of PETMP/epoxy resin cured products.Notably,the glass transition temperature of TMBPS/epoxy resin cured products was 74.2℃which was 11.8°C higher than that of PETMP cured products.Moreover,the ester-free structure in TMBPS contributed to its enhanced resistance to chemicals and hygrothermal conditions.After undergoing 1000 h of hightemperature and high-humidity aging,the tensile strength and adhesion strength of TMBPS-cured products were 73.33 MPa and 3.39 MPa,respectively exceeding 100%and 40%of their initial values,while PETMP-cured products exhibited a complete loss of both tensile strength and adhesion strength.This study provides a strategy for obtaining thermosetting polymers that can be cured at low temperatures and exhibit excellent comprehensive properties.
基金supported by the China Postdoctoral Science Foundation(No.2023M743622)Natural Science Foundation of Ningbo City(No.2024J109)+2 种基金National Natural Science Foundation of China(Nos.E52307038 and U23A20589)Ningbo 2025 Key Scientific Research Programs(Nos.2022Z111,2022Z160 and 2022Z198)the Leading Innovativeand Entrepreneur Team Introduction Program of Zhejiang(No.2021R01005).
文摘The demand for energy-efficient and environmental-friendly power grid construction has made the exploitation of bio-based electrical epoxy resins with excellent properties increasingly important.This work developed the bio-based electrotechnical epoxy resins based on magnolol.High-performance epoxy resin(DGEMT)with a double crosslinked points and its composites(Al_(2)O_(3)/DGEMT)were obtained taking advantages of the two bifunctional groups(allyl and phenolic hydroxyl groups)of magnolol.Benefitting from the distinctive structure of DGEMT,the Al_(2)O_(3)/DGEMT composites exhibited the advantages of intrinsically high thermal conductivity,high insulation,and low dielectric loss.The AC breakdown strength and thermal conductivity of Al_(2)O_(3)/DGEMT composites were 35.5 kV/mm and 1.19 W·m-1·K-1,respectively,which were 15.6%and 52.6%higher than those of petroleum-based composites(Al_(2)O_(3)/DGEBA).And its dielectric loss tanδ=0.0046 was 20.7%lower than that of Al_(2)O_(3)/DGEBA.Furthermore,the mechanical,thermal and processing properties of Al_(2)O_(3)/DGEMT are fully comparable to those of Al_(2)O_(3)/DGEBA.This work confirms the feasibility of manufacturing environmentally friendly power equipment using bio-based epoxy resins,which has excellent engineering applications.
基金National Natural Science Foundation of China(Nos.52007065 and 52277147)the Fundamental Research Funds for the Central Universities(No.2022MS071)。
文摘In gas-insulated lines,basin-insulators can accumulate charge under non-uniform electric fields,distorting the field distribution and potentially causing surface flashover,which threatens the stability of power systems.In this study,Atmospheric Pressure Plasma Jet(APPJ)technology was used to deposit TiO_(2) on the surface of alumina/epoxy(Al_(2)O_(3)/EP)composites.The impact of deposition of TiO_(2) layer on the surface morphology and chemical composition of Al_(2)O_(3)/EP was studied using testing methods such as Scanning Electron Microscope,X-ray photoelectron spectroscopy,Fourier Transform Infrared Spectrometer,and Energy Dispersive Spectrometer.It was found that APPJ creates a dense,rough Ti-O layer on the Al_(2)O_(3)/EP surface,which bonds tightly with the substrate.The efficacy of APPJ was found to depend on processing time,with optimal results observed at 3 min,DC and AC flashover voltages increased by 29.6% and 15.7%,respectively.TiO_(2)layer enhances the conductivity of the resin and shallows trap levels.Through the synergistic effects of various factors,surface charges are efficiently dissipated and evenly distributed.This study not only reveals the physicochemical process of TiO_(2)deposition via APPJ but also integrates surface characteristics with electrical performance.The findings offer a new strategy to enhance surface flashover voltage and ensure equipment safety.
基金supported by the University of Texas(UT)system STARs grant,Semester Undergraduate Research Experience(SURE)program at the College of Engineering at the University of Texas Permian Basin(UTPB)EM-STEP(Engineering Minority Student Engagement Project)at UTPB College of Engineering,funded by Department of Education.
文摘Carbon fiber-reinforced composites(CFRCs)have a wide range of applications in the aerospace,automotive,and energy sectors.A higher specific strength-to-weight ratio is desired in high-performance applications.The failure mechanism of CFRCs involves multiscale phenomena,such as failure that can occur at the matrix,fibers,interface,layers,lamina,and laminates.When an impactor hits the CFRCs,the design involves analyzing each of these stages to prevent failure and optimize the properties of CFRCs under various loading conditions.A numerical model was employed to predict the fracture toughness of CFRCs with varying weight fractions and orientations.Finite Element Analysis(FEA)was conducted at the fiber level on a micrometer scale for the CFRCs against an impact loading.Epoxy composite samples at the coupon level were prepared using the hand layup technique with carbon fibers laid at three different angles,i.e.,longitudinal,transverse,and angular orientations.Samples with five different weight percentages of carbon fibers were prepared and investigated.An Izod impact tester was used to fracture the samples and characterize the energy absorption.The fractured surfaces were observed with a scanning electron microscope(SEM).The numerical and experimental results show that crack propagation is inhibited at higher loading fractions at an angular orientation by creating obstacles for the crack to propagate and arresting the dislocation motion.The fractography analysis through a scanning electron microscope exhibits how the angular orientations of the fibers are reoriented after fracture to prevent further crack propagation.
基金financially supported by the National Natural Science Foundation of China(No.52377025)。
文摘The introduction of dynamic covalent bonds into the structure of epoxy resins can improve the degradation performance of the materials.But to a certain extent,it will affect the insulating properties of the resin,and how to balance the insulating properties and degradation performance has become an urgent problem.In this paper,the effects of different catalysts on the thermal-force-electrical properties of sorbitolbased resins were systematically investigated based on the dynamic ester bonding to construct the resin crosslinking network,and the biobased sorbitol glycidyl ether was used as the resin matrix.The experiments show that the resin system catalyzed by triethanolamine(TEOA)exhibits excellent comprehensive performance,which combines good thermal stability and mechanical properties with excellent electrical properties(breakdown field strength of 44.21 k V/mm and dielectric loss factor of 0.29%).In addition,chemical degradation tests were conducted on the resin systems with different catalysts,and the experiments showed that the produced resins could be degraded in benzyl alcohol and exhibited good degradation performance.This study provides a theoretical basis and technical path for the development of new bio-based electrical insulating materials with both high insulation and degradation properties,which is conducive to the popularization and application of bio-based resins in the field of electrical equipment.
基金financially supported by the National Natural Science Foundation of China(No.U23A20691)Innovation Group of National Ethnic Affairs Commission of China(No.MZR20006)+2 种基金Fund for Academic Innovation Teams of SouthCentral Minzu University(No.XTZ24012)Fundamental Research Fund for the Central Universities of South-Central Minzu University(Nos.CZD24001 and CZQ25012)Scientific Research Fund of South-Central Minzu University(No.YZY25007)。
文摘The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades(EWTBs).Herein,we proposed a selective degradation strategy for direct recycling and high-value recovery of epoxy resins by introducing degradable Schiff base groups into the molecular structure and utilizing the resulting oligomers as curing agents.To realize this strategy,a series of Schiff base compounds were synthesized using bio-based vanillin and diamines and subsequently functionalized with epichlorohydrin to yield bio-based epoxy resins.The cured epoxy resins demonstrated remarkable improvements in the mechanical properties of diglycidyl ether of bisphenol-A(DGEBA),with an increases of 44.49%in the tensile strength of 38.55%,bending strength,and impact strength of 71.20%.The introduction of dynamic Schiff base bonds enabled the selective degradation of the vanillin-2,2-bis[4-(4-aminophenoxy)phenyl]propane-based epoxy resin(VBEP)/DGEBA copolymer,producing 84.20% oligomers that can be directly recycled and reused.Replacing 30 wt% of the curing agent with the oligomer increased the tensile strength of the cured sample to 75.40 MPa,surpassing that of the cured DGEBA.Under simulated acid rain and seawater exposure,the copolymer exhibited a service life of 27 years at 40℃,significantly exceeding the currently reported service life of 20 years.This study presents a sustainable strategy for the direct recycling and high-value reuse of epoxy resin,offering a promising solution for EWTBs.
