Among various architectures of polymers,end-group-free rings have attracted growing interests due to their distinct physicochemical performances over the linear counterparts which are exemplified by reduced hydrodynam...Among various architectures of polymers,end-group-free rings have attracted growing interests due to their distinct physicochemical performances over the linear counterparts which are exemplified by reduced hydrodynamic size and slower degradation.It is key to develop facile methods to large-scale synthesis of polymer rings with tunable compositions and microstructures.Recent progresses in large-scale synthesis of polymer rings against single-chain dynamic nanoparticles,and the example applications in synchronous enhancing toughness and strength of polymer nanocomposites are summarized.Once there is the breakthrough in rational design and effective large-scale synthesis of polymer rings and their functional derivatives,a family of cyclic functional hybrids would be available,thus providing a new paradigm in developing polymer science and engineering.展开更多
Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with ...Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.展开更多
A gradient structure was introduced into a metal laminated target plate,and the anti-penetration simulation of the gradient structure was compared with that of a uniform-layer-thickness target plate by finite element ...A gradient structure was introduced into a metal laminated target plate,and the anti-penetration simulation of the gradient structure was compared with that of a uniform-layer-thickness target plate by finite element simulation.The analysis was verified by an impact experiment.Results show that the high-level thickness and appropriate percentage of Ti alloy at the upper side of the gradient structure provide greater impact resistance against the bullet,which increases the warhead breakage and enhances the anti-penetration performance.In addition,during the impact process,the stress is transmitted and reflected in the form of waves in each layer of the target plate,and the interaction between the compression and tension waves causes non-synergistic deformation of the target plate and leads to delamination.The gradient target plate takes penetration resistance a step further through the higher energy absorption rate and more consumption of the bullet kinetic energy.This research provides a theoretical basis for the application of gradient structures in metallic laminated armor.展开更多
KIT-5/Beta composite supports were synthesized using an in situ self-assembly hydrothermal method,and NiW/KIT-5/Beta catalysts were prepared by impregnation.A series of characterization techniques were utilized to eva...KIT-5/Beta composite supports were synthesized using an in situ self-assembly hydrothermal method,and NiW/KIT-5/Beta catalysts were prepared by impregnation.A series of characterization techniques were utilized to evaluate the influence of varying hydrothermal synthesis temperatures on the physicochemical properties of both the KIT-5/Beta supports and the resulting catalysts.The catalytic performances of catalysts were evaluated under reaction conditions of 320℃,4 MPa H_(2)pressure,and a weight hourly space velocity(WHSV)of 4.8 h^(-1)for hydrodenitrogenation(HDN)of quinoline.The results indicated that the specific surface area and pore structure of the materials could be effectively regulated by adjusting the hydrothermal synthesis temperature,which in turn influenced the number of active sites on the catalyst.The NiW/KB-125 catalyst,synthesized at 125℃,presented the highest quinoline HDN efficiency(96.8%),which can be attributed to its favorable pore channel structure,greater Brønsted acid number,higher degree of metal sulfidation(80.12%)and appropriate metal-support interaction(MSI).展开更多
Carbon fiber-reinforced carbon aerogel(C/CA)composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities.The preparation of anti-oxidation coatin...Carbon fiber-reinforced carbon aerogel(C/CA)composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities.The preparation of anti-oxidation coatings on C/CA to address its susceptibility to oxidation is a feasible approach to promote its application in oxidative environments.However,the currently reported coatings on C/CA mainly focus on improving the ablation performance and coating preparation process typically necessitating high-temperature heat treatment.This procedure can increase its thermal conductivity and reduce its thermal insulation ability.In this study,a series of ceramic-resin coatings were fabricated on C/CA through a simple slurry brushing-drying approach at room temperature.The effects of phenolic resin content on the coating structure,residual stress,thermal shock,and oxidation behaviors were investigated.Due to the adhesive properties and curing-induced shrinkage,the PR-7.5 coating(containing 7.5%(in mass)phenolic resin in the slurry)exhibits bonding strength close to fracture strength of the substrate and residual compressive stress of 0.853 GPa,which is beneficial for resisting thermal shock cracking.However,excessive resin content(PR-10.0 containing 10.0%(in mass)phenolic resin in the slurry)induces tensile stress due to uneven curing shrinkage,thereby leading to thermal shock cracking.Meanwhile,oxidation tests reveal significantly reduced weight losses for PR-7.5(17.46%at 800℃/100 min,8.15%at 1000℃/120 min,3.15%at 1200℃/120 min)versus uncoated C/CA’s 44.60%loss at 800℃/20 min.This work provides a brand-new and simple approach to improving the anti-oxidation performance of C/CA and expands its application in mild oxidative environments.展开更多
The poor electrical conductivity of metal-organic frameworks(MOFs)limits their electrocatalytic performance in the oxygen evolution reaction(OER).In this study,a Py@Co-MOF composite material based on pyrene(Py)molecul...The poor electrical conductivity of metal-organic frameworks(MOFs)limits their electrocatalytic performance in the oxygen evolution reaction(OER).In this study,a Py@Co-MOF composite material based on pyrene(Py)molecules and{[Co2(BINDI)(DMA)_(2)]·DMA}_(n)(Co-MOF,H4BINDI=N,N'-bis(5-isophthalic acid)naphthalenediimide,DMA=N,N-dimethylacetamide)was synthesized via a one-pot method,leveragingπ-πinteractions between pyrene and Co-MOF to modulate electrical conductivity.Results demonstrate that the Py@Co-MOF catalyst exhibited significantly enhanced OER performance compared to pure Co-MOF or pyrene-based electrodes,achieving an overpotential of 246 mV at a current density of 10 mA·cm^(-2) along with excellent stability.Density functional theory(DFT)calculations reveal that the formation of O*in the second step is the rate-determining step(RDS)during the OER process on Co-MOF,with an energy barrier of 0.85 eV due to the weak adsorption affinity of the OH*intermediate for Co sites.CCDC:2419276.展开更多
A comparative analysis was performed on poly(lactic acid)(PLA),poly(caprolactone)(PCL),basalt fiber(BF)composites produced using two distinct approaches:direct blending and masterbatching.The limitations of PLA-BF com...A comparative analysis was performed on poly(lactic acid)(PLA),poly(caprolactone)(PCL),basalt fiber(BF)composites produced using two distinct approaches:direct blending and masterbatching.The limitations of PLA-BF composites with regard to distribution and adhesion are well-documented,as are chemical treatment methods(addition of compatibilisers,surface treatments,silanization).This work aimed to study an industrially relevant potential solution of utilising a PCL-BF masterbatch,prepared as a 50/50 wt.%blend using planetary roller extrusion(PEX)to both improve the distribution and homogeneity of the fibers as well as provide a secondary adhesion site to facilitate improved mechanical properties of the final PLA-PCL-BF composite.The resultant materials were injection moulded to prepare ISO standard test specimens and tested on the basis of their physical properties via tensile testing,impact strength testing,flexural analysis,Fourier transforminfrared spectroscopy and water absorption capability.The results displayed that the incorporation of PCL and BF led to an increase in ductility of the composite materials,allowing for improvements in the inherent brittleness of virgin PLA.Major increases in the impact strength were achieved with the utilisation of a 25% PCL/BF masterbatch,allowing for a greater than 50%increase.As an overall observation,the use of a masterbatching process,opposed to direct blending of the constituent materials allows for a greater consistency of composite to be achieved at the expense of increased gains.展开更多
A new,cost-effective porous polymer composite was developed by reinforcing polypropylene(PP)with cenosphere particles.This study investigates how the composite’s dielectric properties are affected by their porosity.D...A new,cost-effective porous polymer composite was developed by reinforcing polypropylene(PP)with cenosphere particles.This study investigates how the composite’s dielectric properties are affected by their porosity.Dielectric constant(ε′)measurements were taken over a range of frequencies at roomtemperature.A theoreticalmodel was developed to explain the electrical conductivity of the porous PP/cenosphere composites.The study thoroughly examined how the inclusion of cenosphere particles influenced key electrical parameters,including dielectric constant,dissipation factor(tanδ),DC(direct current)conductivity,and AC(alternating current)conductivity.The results revealed that increasing the cenosphere content caused a decrease in the dielectric constant,while the dissipation factor increased.The developed porous PP/cenosphere composite exhibits a unique balance of low dielectric constant,lightweight structure making it suitable for several practical applications.Its low dielectric constant and reduced DC conductivity make it an excellent candidate for electronic packaging,insulating layers,and high-frequency components,where minimal energy loss and signal interference are required.The lightweight nature of the cenosphere-reinforced structure also suggests potential use in aerospace and automotive industries for lightweight insulation panels or structural components.Furthermore,its cost-effectiveness and tunable porosity could enable applications in microwave substrates,radar-absorbing materials,and energy-efficient building materials where dielectric control and weight reduction are critical.Additionally,DC conductivity was found to decline with higher cenosphere concentrations.The theoretical model was in good agreement with the experimental data.展开更多
Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the...Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.展开更多
To exploit the combined strengthening effects of nanotwins and carbon nanotubes(CNTs)in Cu matrix composites,the nanotwins with a width ranging from 3 to 30 nm were incorporated into the CNTs-reinforced Cu matrix comp...To exploit the combined strengthening effects of nanotwins and carbon nanotubes(CNTs)in Cu matrix composites,the nanotwins with a width ranging from 3 to 30 nm were incorporated into the CNTs-reinforced Cu matrix composites using cryogenic rolling and optimizing the initial particle size of the raw Cu powders.The formation of nanotwins in the Cu matrix composite reinforced by only 0.2 wt.%CNTs is accompanied by the increased dislocation density and refined Cu grain size,resulting in much better strength−ductility synergy than the referenced composite without significant nanotwins formation.The analysis of strengthening and toughening mechanisms demonstrates that the strength increment mainly derives from grain refinement strengthening,dislocation strengthening,and nanotwin strengthening.The strength increment from the contribution of the nanotwins accounts for 19.9%of the overall strength increment for the composite.Meanwhile,the retention of good tensile ductility can be reasonably explained by the increased dislocation accommodation ability due to the formed nanotwins and the decreased induced dislocation proliferation.展开更多
This study evaluates the stabilizing effect of lignin, extracted from Eucalyptus globulus, on an energetic composite of nitrated cellulose carbamate (NCC) plasticized with diethylene glycol dinitrate (DEGDN), compared...This study evaluates the stabilizing effect of lignin, extracted from Eucalyptus globulus, on an energetic composite of nitrated cellulose carbamate (NCC) plasticized with diethylene glycol dinitrate (DEGDN), compared to conventional stabilizers 2-nitrodiphenylamine (2-NDPA) and 1,3-dimethyl-1,3-diphenylurea (C-II). FTIR analysis confirms lignin's capacity to scavenge nitroxyl radicals formed during thermolysis of nitrocarbamate and nitrate ester bonds, thereby inhibiting decomposition. Moreover, the incorporation of C-II, 2-NDPA, and lignin significantly raised the peak temperature of the main thermolysis, as confirmed by DSC and TGA, indicating a progressive stability enhancement in the order: NCC/DEGDN < NCC/DEGDN/C-II < NCC/DEGDN/lignin < NCC/DEGDN/2-NDPA. Additionally, the effect of each stabilizer on the decomposition pathway was characterized by TGA-FTIR. The findings show that stabilizer type significantly affects the intensity of gaseous products released during decomposition without altering their nature. Notably, NH2 groups formed during NCC degradation play a key role in nitrogen conversion, particularly by reducing toxic NO emissions.展开更多
The ablation behavior of ZrC-coated C/C composites is a complex coupling process involving thermal,mechanical,chemical interactions,formation and propagation of cracks.In the present study,we propose a peridynamic(PD)...The ablation behavior of ZrC-coated C/C composites is a complex coupling process involving thermal,mechanical,chemical interactions,formation and propagation of cracks.In the present study,we propose a peridynamic(PD)thermo-mechanical-oxidation-diffusion coupled model to describe such a phenomenon comprehensively.Firstly,motion and heat transfer equations are formulated,incorporating growth strain governed by the Clarke model.The oxidation rate of the material is evaluated using diffusion equilibrium and oxidation equations.In addition,the effects of oxidation on different materials are considered,such as growth strain in ZrC materials and material consumption caused by oxidation of C/C composites.To characterize the material failure caused by mechanical and chemical reactions in ablation,a porosity criterion is proposed and its effect on diffusion is considered.The reliability and accuracy of the proposed PD model are validated by analyzing the oxidation process of C/C composites and ZrC and comparing with experimental results.Further,the model effectively captured the crack propagation and oxidation of ZrC-coated C/C composites in an oxyacetylene environment.展开更多
There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with h...There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.展开更多
The curing behavior of composites significantly influences their performance,making it crucial to understand the curing process.This study experimentally measured specific heat capacity,thermal conductivity,glass tran...The curing behavior of composites significantly influences their performance,making it crucial to understand the curing process.This study experimentally measured specific heat capacity,thermal conductivity,glass transition temperature,coefficient of thermal expansion,and cure shrinkage of materials.A simulation model of its curing deformation was established and validated against strain data obtained from fiber Bragg grating experiments.The effects of thickness,heating rate,and cooling rate on the curing temperature field and residual stress field during the molding of thick-section composite plates were analyzed.展开更多
The increasing power density of chips poses a significant challenge in the form of material aging for aluminumfilled polydimethylsiloxane(Al/PDMS)composites,which are widely used in thermal interface materials.Despite...The increasing power density of chips poses a significant challenge in the form of material aging for aluminumfilled polydimethylsiloxane(Al/PDMS)composites,which are widely used in thermal interface materials.Despite the growing importance of this issue,the specific mechanisms behind the interfacial aging process remain elusive,hindering a comprehensive grasp of the aging dynamics in these composites.In our research,we have developed an in-situ Raman aging monitoring system that leverages the non-contact and high-resolution capabilities of Raman spectroscopy to study the interface aging process.Our findings indicate a notable decrease in the intensity of the Raman peak as further cross-linking of the molecules during aging,with the most pronounced decline occurring at the interface between aluminum and PDMS.This insight could potentially elucidate why the interface in composite materials is frequently the site of failure during aging.Our study offers a versatile methodology for investigating the interfacial aging of polymer composites,contributing to a broader understanding of the interface behavior in composite materials at the molecular level.展开更多
The demand for extended electric vehicle(EV)range necessitates advanced lightweighting strategies.This study introduces a materials genome approach,augmented by machine learning(ML),for optimizing lightweight composit...The demand for extended electric vehicle(EV)range necessitates advanced lightweighting strategies.This study introduces a materials genome approach,augmented by machine learning(ML),for optimizing lightweight composite designs for EVs.A comprehensive materials genome database was developed,encompassing composites based on carbon,glass,and natural fibers.This database systematically records critical parameters such as mechanical properties,density,cost,and environmental impact.Machine learning models,including Random Forest,Support Vector Machines,and Artificial Neural Networks,were employed to construct a predictive system for material performance.Subsequent material composition optimization was performed using amulti-objective genetic algorithm.Experimental validation demonstrated that an optimized carbon fiber/bio-based resin composite achieved a 45%weight reduction compared to conventional steel,while maintaining equivalent structural strength.The predictive accuracy of the models reached 94.2%.A cost-benefit analysis indicated that despite a 15%increase in material cost,the overall vehicle energy consumption decreased by 12%,leading to an 18%total cost saving over a five-year operational lifecycle,under a representative mid-size battery electric vehicle(BEV)operational scenario.展开更多
The complex interactions and conflicting performance demands in multi-component composites pose significant challenges for achieving balanced multi-property optimization through conventional trial-and-error approaches...The complex interactions and conflicting performance demands in multi-component composites pose significant challenges for achieving balanced multi-property optimization through conventional trial-and-error approaches.Machine learning(ML)offers a promising solution,markedly improving materials discovery efficiency.However,the high dimensionality of feature spaces in such systems has long impeded effective ML-driven feature representation and inverse design.To overcome this,we present an Intelligent Screening System(ISS)framework to accelerate the discovery of optimal formulations balancing four key properties in 15-component PTFE-based copper-clad laminate composites(PTFE-CCLCs).ISS adopts modular descriptors based on the physical information of component volume fractions,thereby simplifying the feature representation.By leveraging the inverse prediction capability of ML models and constructing a performance-driven virtual candidate database,ISS significantly reduced the computational complexity associated with high-dimensional spaces.Experimental validation confirmed that ISSoptimized formulations exhibited superior synergy,notably resolving the trade-off between thermal conductivity and peel strength,and outperform many commercial counterparts.Despite limited data and inherent process variability,ISS achieved an average prediction accuracy of 76.5%,with thermal conductivity predictions exceeding 90%,demonstrating robust reliability.This work provides an innovative,efficient strategy for multifunctional optimization and accelerated discovery in ultra-complex composite systems,highlighting the integration of ML and advanced materials design.展开更多
Biochar and zero-valent iron are promising materials for the removal of trichloroethylene(TCE)from groundwater,but further research is still required on the synergistic mechanism and hydraulic performance in the perme...Biochar and zero-valent iron are promising materials for the removal of trichloroethylene(TCE)from groundwater,but further research is still required on the synergistic mechanism and hydraulic performance in the permeable reactive barriers(PRBs)with biochar-iron composites.In this work,biochar-iron composites were synthesized by two different methods,and subjected to the microscopic analysis,batch experiments and the PRB’s model tests.The results indicated that the removal rates of TCE on biochar-iron composites reached above 90%,and the optimal removal conditions were the initial pH of 6.0 and a biochar/iron mass ratio of 5:1.The removal of TCE on biochar-iron composites followed the pseudo-second-order and Freundlich models,and the maximum adsorption capacity of TCE was 25.95 mg/g.The adsorption of biochar and dechlorination of nZVI dominated the removal of TCE.Biochar significantly enhanced the dechlorination of TCE on nZVI through modifying the electrochemical characteristics to lower its corrosion potential of nZVI,promote direct electron transfer,and improve electronic transfer capability.M-5BC-1nZVI exhibited excellent hydraulic performance for maintaining an adequate permeability coefficient(10^(−6)to 10^(−5)m/s).展开更多
Biomass structural materials can effectively address the issues of high energy consumption and environmental degradation brought by traditional engineering structural materials.However,natural structural materials oft...Biomass structural materials can effectively address the issues of high energy consumption and environmental degradation brought by traditional engineering structural materials.However,natural structural materials often suffer from drawbacks such as low mechanical performance and flammability.Therefore,this study has developed an ultra-strong fire-resistant bamboo composite(UFBC).Natural bamboo(NB)was used as the raw material.After delignification treatment,bamboo fibers are grafted with epoxy groups through in-situ chemical bonding.Subsequently,polymer chains underwent in-situ chemical cross-linking within the bamboo fiber framework,combined with reinforcement from nano silica,resulting in strengthened cell walls.In addition,the softened and expanded cell walls can facilitate the deposition of phosphate and borate salt on the cell walls,forming an N-P-B flame-retardant system within the system.The tensile strength(463 MPa vs NB 112 MPa)and flexural strength(655 MPa vs NB 157 MPa)of UFBC increased fourfold,with a Limiting Oxygen Index(LOI)of 54.4%.Compared to similar bamboo-based composite materials,UFBC exhibits superior environmental friendliness and sustainability throughout its lifecycle,with all 18 environmental factors being optimized(up to a 92%reduction).This study provides an important reference for the application of high-performance biomass structural materials in construction and industry.展开更多
Petroleum-based polycyclic aromatic hydrocarbons(PAHs),as by-products of petroleum,offer the advantages of abundant availability and high carbon content,making them ideal high-quality raw materials for the fabrication...Petroleum-based polycyclic aromatic hydrocarbons(PAHs),as by-products of petroleum,offer the advantages of abundant availability and high carbon content,making them ideal high-quality raw materials for the fabrication of carbon anode materials in lithium batteries(LIBs).This study presents a novel,dual-purpose strategy to fabricate hollow core–shell silicon-carbon composites(Si@Void@Cx)via the in-situ catalytic polycondensation of Fluid Catalytic Cracking(FCC)slurry.Unlike traditional synthesis routes employing metallic Lewis acids(e.g.,AlCl_(3),FeCl_(3)),silicon tetrachloride(SiCl_(4))was used as a cleaner,bifunctional catalyst that avoids metallic contamination while facilitating the precise polymerization of the carbon matrix.This approach not only circumvents the integration of heteroatoms via the catalyst,but also simplifies the process flow,reduces energy consumption,and contributes to a greener,sustainable technology by enhancing the high-value utilization of FCC,benefiting both resource conservation and environmental protection.The optimized composite(Si@Void@C1)delivers a robust electrochemical performance,exhibiting a specific capacity of 601.9 mAh/g and maintaining electrode integrity with a negligible thickness expansion of only 7%after 1000 cycles.Si@Void@C1 capitalizes on the well-dispersed silicon(Si)nanoparticles and the intact hollow core–shell structure to effectively buffer against the volume expansion stress of Si,thus maintaining electrode structural integrity and achieving superior cycling performance.This work provides a scalable,sustainable pathway for transforming petrochemical byproducts into advanced energy storage materials.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.52293472,22473096 and 22471164)。
文摘Among various architectures of polymers,end-group-free rings have attracted growing interests due to their distinct physicochemical performances over the linear counterparts which are exemplified by reduced hydrodynamic size and slower degradation.It is key to develop facile methods to large-scale synthesis of polymer rings with tunable compositions and microstructures.Recent progresses in large-scale synthesis of polymer rings against single-chain dynamic nanoparticles,and the example applications in synchronous enhancing toughness and strength of polymer nanocomposites are summarized.Once there is the breakthrough in rational design and effective large-scale synthesis of polymer rings and their functional derivatives,a family of cyclic functional hybrids would be available,thus providing a new paradigm in developing polymer science and engineering.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(No.52325506)the Fundamental Research Funds for the Central Universities(No.DUT22LAB501)。
文摘Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.
基金National Defense Basic Scientific Research Program of China(JCKY2020408B002,WDZC2022-12)Key Research and Development Program of Shanxi Province(202102050201011,202202050201014)Fundamental Research Program of Shanxi Province(20210302124178,20210302123061,202103021224183)。
文摘A gradient structure was introduced into a metal laminated target plate,and the anti-penetration simulation of the gradient structure was compared with that of a uniform-layer-thickness target plate by finite element simulation.The analysis was verified by an impact experiment.Results show that the high-level thickness and appropriate percentage of Ti alloy at the upper side of the gradient structure provide greater impact resistance against the bullet,which increases the warhead breakage and enhances the anti-penetration performance.In addition,during the impact process,the stress is transmitted and reflected in the form of waves in each layer of the target plate,and the interaction between the compression and tension waves causes non-synergistic deformation of the target plate and leads to delamination.The gradient target plate takes penetration resistance a step further through the higher energy absorption rate and more consumption of the bullet kinetic energy.This research provides a theoretical basis for the application of gradient structures in metallic laminated armor.
基金Supported by the Autonomous Research Project of SKLCC(2024BWZ003)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0390401)the Doctoral Research Start-up Funding of Shanxi Institute of Technology(026012).
文摘KIT-5/Beta composite supports were synthesized using an in situ self-assembly hydrothermal method,and NiW/KIT-5/Beta catalysts were prepared by impregnation.A series of characterization techniques were utilized to evaluate the influence of varying hydrothermal synthesis temperatures on the physicochemical properties of both the KIT-5/Beta supports and the resulting catalysts.The catalytic performances of catalysts were evaluated under reaction conditions of 320℃,4 MPa H_(2)pressure,and a weight hourly space velocity(WHSV)of 4.8 h^(-1)for hydrodenitrogenation(HDN)of quinoline.The results indicated that the specific surface area and pore structure of the materials could be effectively regulated by adjusting the hydrothermal synthesis temperature,which in turn influenced the number of active sites on the catalyst.The NiW/KB-125 catalyst,synthesized at 125℃,presented the highest quinoline HDN efficiency(96.8%),which can be attributed to its favorable pore channel structure,greater Brønsted acid number,higher degree of metal sulfidation(80.12%)and appropriate metal-support interaction(MSI).
基金National Natural Science Foundation of China(52272075,52472053)Research Fund of Youth Innovation Promotion Association of CAS,China(2021190)Defense Industrial Technology Development Program(JCKY2021130B007)。
文摘Carbon fiber-reinforced carbon aerogel(C/CA)composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities.The preparation of anti-oxidation coatings on C/CA to address its susceptibility to oxidation is a feasible approach to promote its application in oxidative environments.However,the currently reported coatings on C/CA mainly focus on improving the ablation performance and coating preparation process typically necessitating high-temperature heat treatment.This procedure can increase its thermal conductivity and reduce its thermal insulation ability.In this study,a series of ceramic-resin coatings were fabricated on C/CA through a simple slurry brushing-drying approach at room temperature.The effects of phenolic resin content on the coating structure,residual stress,thermal shock,and oxidation behaviors were investigated.Due to the adhesive properties and curing-induced shrinkage,the PR-7.5 coating(containing 7.5%(in mass)phenolic resin in the slurry)exhibits bonding strength close to fracture strength of the substrate and residual compressive stress of 0.853 GPa,which is beneficial for resisting thermal shock cracking.However,excessive resin content(PR-10.0 containing 10.0%(in mass)phenolic resin in the slurry)induces tensile stress due to uneven curing shrinkage,thereby leading to thermal shock cracking.Meanwhile,oxidation tests reveal significantly reduced weight losses for PR-7.5(17.46%at 800℃/100 min,8.15%at 1000℃/120 min,3.15%at 1200℃/120 min)versus uncoated C/CA’s 44.60%loss at 800℃/20 min.This work provides a brand-new and simple approach to improving the anti-oxidation performance of C/CA and expands its application in mild oxidative environments.
文摘The poor electrical conductivity of metal-organic frameworks(MOFs)limits their electrocatalytic performance in the oxygen evolution reaction(OER).In this study,a Py@Co-MOF composite material based on pyrene(Py)molecules and{[Co2(BINDI)(DMA)_(2)]·DMA}_(n)(Co-MOF,H4BINDI=N,N'-bis(5-isophthalic acid)naphthalenediimide,DMA=N,N-dimethylacetamide)was synthesized via a one-pot method,leveragingπ-πinteractions between pyrene and Co-MOF to modulate electrical conductivity.Results demonstrate that the Py@Co-MOF catalyst exhibited significantly enhanced OER performance compared to pure Co-MOF or pyrene-based electrodes,achieving an overpotential of 246 mV at a current density of 10 mA·cm^(-2) along with excellent stability.Density functional theory(DFT)calculations reveal that the formation of O*in the second step is the rate-determining step(RDS)during the OER process on Co-MOF,with an energy barrier of 0.85 eV due to the weak adsorption affinity of the OH*intermediate for Co sites.CCDC:2419276.
文摘A comparative analysis was performed on poly(lactic acid)(PLA),poly(caprolactone)(PCL),basalt fiber(BF)composites produced using two distinct approaches:direct blending and masterbatching.The limitations of PLA-BF composites with regard to distribution and adhesion are well-documented,as are chemical treatment methods(addition of compatibilisers,surface treatments,silanization).This work aimed to study an industrially relevant potential solution of utilising a PCL-BF masterbatch,prepared as a 50/50 wt.%blend using planetary roller extrusion(PEX)to both improve the distribution and homogeneity of the fibers as well as provide a secondary adhesion site to facilitate improved mechanical properties of the final PLA-PCL-BF composite.The resultant materials were injection moulded to prepare ISO standard test specimens and tested on the basis of their physical properties via tensile testing,impact strength testing,flexural analysis,Fourier transforminfrared spectroscopy and water absorption capability.The results displayed that the incorporation of PCL and BF led to an increase in ductility of the composite materials,allowing for improvements in the inherent brittleness of virgin PLA.Major increases in the impact strength were achieved with the utilisation of a 25% PCL/BF masterbatch,allowing for a greater than 50%increase.As an overall observation,the use of a masterbatching process,opposed to direct blending of the constituent materials allows for a greater consistency of composite to be achieved at the expense of increased gains.
文摘A new,cost-effective porous polymer composite was developed by reinforcing polypropylene(PP)with cenosphere particles.This study investigates how the composite’s dielectric properties are affected by their porosity.Dielectric constant(ε′)measurements were taken over a range of frequencies at roomtemperature.A theoreticalmodel was developed to explain the electrical conductivity of the porous PP/cenosphere composites.The study thoroughly examined how the inclusion of cenosphere particles influenced key electrical parameters,including dielectric constant,dissipation factor(tanδ),DC(direct current)conductivity,and AC(alternating current)conductivity.The results revealed that increasing the cenosphere content caused a decrease in the dielectric constant,while the dissipation factor increased.The developed porous PP/cenosphere composite exhibits a unique balance of low dielectric constant,lightweight structure making it suitable for several practical applications.Its low dielectric constant and reduced DC conductivity make it an excellent candidate for electronic packaging,insulating layers,and high-frequency components,where minimal energy loss and signal interference are required.The lightweight nature of the cenosphere-reinforced structure also suggests potential use in aerospace and automotive industries for lightweight insulation panels or structural components.Furthermore,its cost-effectiveness and tunable porosity could enable applications in microwave substrates,radar-absorbing materials,and energy-efficient building materials where dielectric control and weight reduction are critical.Additionally,DC conductivity was found to decline with higher cenosphere concentrations.The theoretical model was in good agreement with the experimental data.
基金support provided by the Center for Fabrication and Application of Electronic Materials at Dokuz Eylül University,Türkiye。
文摘Biochar and biochar composites are versatile materials that can be used in many applications.In this study,biochar was prepared from sawdust and combined with the yttrium iron garnet(YIG)nanocrystal to investigate the shielding effectiveness of the composite structure.Firstly,the effect of the pyrolysis temperature on the shielding effectiveness of biochar was investigated.Secondly,biochars combined with YIG nanocrystals with different contents and shielding effectiveness of the composites were investigated.The electromagnetic effectiveness of the samples was investigated within the X band(8-12 GHz).The findings indicate that biochar demonstrates enhanced absorption properties with elevated pyrolysis temperatures.Biochars demonstrated an approximate 40 d B shielding effectiveness,while YIG exhibited approximately 7 d B,corresponding to absorption at 8 GHz.However,the combination of biochar and YIG exhibited exceptional absorption,reaching 67.12 d B at 8 GHz.
基金financially supported by the Fundamental Research Funds for the Central Universities,China(No.21624408)the Guangdong Basic and Applied Basic Research Foundation,China(Nos.2023A1515012850,2024A1515010416)+2 种基金Guangzhou Science and Technology Planning Project,China(No.2024A04J9966)the National Natural Science Foundation of China(Nos.52271132,52004101)the Key Laboratory of Advanced Materials of Yunnan Province,China(No.2024KF02)。
文摘To exploit the combined strengthening effects of nanotwins and carbon nanotubes(CNTs)in Cu matrix composites,the nanotwins with a width ranging from 3 to 30 nm were incorporated into the CNTs-reinforced Cu matrix composites using cryogenic rolling and optimizing the initial particle size of the raw Cu powders.The formation of nanotwins in the Cu matrix composite reinforced by only 0.2 wt.%CNTs is accompanied by the increased dislocation density and refined Cu grain size,resulting in much better strength−ductility synergy than the referenced composite without significant nanotwins formation.The analysis of strengthening and toughening mechanisms demonstrates that the strength increment mainly derives from grain refinement strengthening,dislocation strengthening,and nanotwin strengthening.The strength increment from the contribution of the nanotwins accounts for 19.9%of the overall strength increment for the composite.Meanwhile,the retention of good tensile ductility can be reasonably explained by the increased dislocation accommodation ability due to the formed nanotwins and the decreased induced dislocation proliferation.
文摘This study evaluates the stabilizing effect of lignin, extracted from Eucalyptus globulus, on an energetic composite of nitrated cellulose carbamate (NCC) plasticized with diethylene glycol dinitrate (DEGDN), compared to conventional stabilizers 2-nitrodiphenylamine (2-NDPA) and 1,3-dimethyl-1,3-diphenylurea (C-II). FTIR analysis confirms lignin's capacity to scavenge nitroxyl radicals formed during thermolysis of nitrocarbamate and nitrate ester bonds, thereby inhibiting decomposition. Moreover, the incorporation of C-II, 2-NDPA, and lignin significantly raised the peak temperature of the main thermolysis, as confirmed by DSC and TGA, indicating a progressive stability enhancement in the order: NCC/DEGDN < NCC/DEGDN/C-II < NCC/DEGDN/lignin < NCC/DEGDN/2-NDPA. Additionally, the effect of each stabilizer on the decomposition pathway was characterized by TGA-FTIR. The findings show that stabilizer type significantly affects the intensity of gaseous products released during decomposition without altering their nature. Notably, NH2 groups formed during NCC degradation play a key role in nitrogen conversion, particularly by reducing toxic NO emissions.
基金the support from the National Key Research and Development Program of China(No.2021YFB3701400)the Fundamental Research Funds for the Central Universities(No.104972025KFYjc0100)+1 种基金the support from the National Natural Science Foundation of China(Nos.52494933 and 11972267)the support from the National Natural Science Foundation of China(Nos.U2441215 and U2341244).
文摘The ablation behavior of ZrC-coated C/C composites is a complex coupling process involving thermal,mechanical,chemical interactions,formation and propagation of cracks.In the present study,we propose a peridynamic(PD)thermo-mechanical-oxidation-diffusion coupled model to describe such a phenomenon comprehensively.Firstly,motion and heat transfer equations are formulated,incorporating growth strain governed by the Clarke model.The oxidation rate of the material is evaluated using diffusion equilibrium and oxidation equations.In addition,the effects of oxidation on different materials are considered,such as growth strain in ZrC materials and material consumption caused by oxidation of C/C composites.To characterize the material failure caused by mechanical and chemical reactions in ablation,a porosity criterion is proposed and its effect on diffusion is considered.The reliability and accuracy of the proposed PD model are validated by analyzing the oxidation process of C/C composites and ZrC and comparing with experimental results.Further,the model effectively captured the crack propagation and oxidation of ZrC-coated C/C composites in an oxyacetylene environment.
基金financially supported by National Natural Science Foundation of China(No.52175321)the Fund of Key Laboratory of High Temperature Electromagnetic Materials and Structure of MOE(No.KB202505)。
文摘There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172045,U2241240,and 12221002)the National Program on Key Basic Research Project,China(Grant No.2019-JCJQ-ZD-308-00).
文摘The curing behavior of composites significantly influences their performance,making it crucial to understand the curing process.This study experimentally measured specific heat capacity,thermal conductivity,glass transition temperature,coefficient of thermal expansion,and cure shrinkage of materials.A simulation model of its curing deformation was established and validated against strain data obtained from fiber Bragg grating experiments.The effects of thickness,heating rate,and cooling rate on the curing temperature field and residual stress field during the molding of thick-section composite plates were analyzed.
基金supported by the National Natural Science Foundation of China(No.52303092)Talent Recruitment Project of Guangdong Province(No.2023QN10X078)+2 种基金Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(No.YPML-2023050278)National Key R&D Project from Ministry of Science and Technology of China(No.2022YFA1203100)Shenzhen Science and Technology Research Funding(No.JCYJ20200109114401708)。
文摘The increasing power density of chips poses a significant challenge in the form of material aging for aluminumfilled polydimethylsiloxane(Al/PDMS)composites,which are widely used in thermal interface materials.Despite the growing importance of this issue,the specific mechanisms behind the interfacial aging process remain elusive,hindering a comprehensive grasp of the aging dynamics in these composites.In our research,we have developed an in-situ Raman aging monitoring system that leverages the non-contact and high-resolution capabilities of Raman spectroscopy to study the interface aging process.Our findings indicate a notable decrease in the intensity of the Raman peak as further cross-linking of the molecules during aging,with the most pronounced decline occurring at the interface between aluminum and PDMS.This insight could potentially elucidate why the interface in composite materials is frequently the site of failure during aging.Our study offers a versatile methodology for investigating the interfacial aging of polymer composites,contributing to a broader understanding of the interface behavior in composite materials at the molecular level.
文摘The demand for extended electric vehicle(EV)range necessitates advanced lightweighting strategies.This study introduces a materials genome approach,augmented by machine learning(ML),for optimizing lightweight composite designs for EVs.A comprehensive materials genome database was developed,encompassing composites based on carbon,glass,and natural fibers.This database systematically records critical parameters such as mechanical properties,density,cost,and environmental impact.Machine learning models,including Random Forest,Support Vector Machines,and Artificial Neural Networks,were employed to construct a predictive system for material performance.Subsequent material composition optimization was performed using amulti-objective genetic algorithm.Experimental validation demonstrated that an optimized carbon fiber/bio-based resin composite achieved a 45%weight reduction compared to conventional steel,while maintaining equivalent structural strength.The predictive accuracy of the models reached 94.2%.A cost-benefit analysis indicated that despite a 15%increase in material cost,the overall vehicle energy consumption decreased by 12%,leading to an 18%total cost saving over a five-year operational lifecycle,under a representative mid-size battery electric vehicle(BEV)operational scenario.
基金financially supported by the National Key Research and Development Project of China(No.2022YFB3806900)。
文摘The complex interactions and conflicting performance demands in multi-component composites pose significant challenges for achieving balanced multi-property optimization through conventional trial-and-error approaches.Machine learning(ML)offers a promising solution,markedly improving materials discovery efficiency.However,the high dimensionality of feature spaces in such systems has long impeded effective ML-driven feature representation and inverse design.To overcome this,we present an Intelligent Screening System(ISS)framework to accelerate the discovery of optimal formulations balancing four key properties in 15-component PTFE-based copper-clad laminate composites(PTFE-CCLCs).ISS adopts modular descriptors based on the physical information of component volume fractions,thereby simplifying the feature representation.By leveraging the inverse prediction capability of ML models and constructing a performance-driven virtual candidate database,ISS significantly reduced the computational complexity associated with high-dimensional spaces.Experimental validation confirmed that ISSoptimized formulations exhibited superior synergy,notably resolving the trade-off between thermal conductivity and peel strength,and outperform many commercial counterparts.Despite limited data and inherent process variability,ISS achieved an average prediction accuracy of 76.5%,with thermal conductivity predictions exceeding 90%,demonstrating robust reliability.This work provides an innovative,efficient strategy for multifunctional optimization and accelerated discovery in ultra-complex composite systems,highlighting the integration of ML and advanced materials design.
基金supported by the National Key R&D Program of China(No.2023YFC3707900)the National Natural Science Foundation of China(No.51978157).
文摘Biochar and zero-valent iron are promising materials for the removal of trichloroethylene(TCE)from groundwater,but further research is still required on the synergistic mechanism and hydraulic performance in the permeable reactive barriers(PRBs)with biochar-iron composites.In this work,biochar-iron composites were synthesized by two different methods,and subjected to the microscopic analysis,batch experiments and the PRB’s model tests.The results indicated that the removal rates of TCE on biochar-iron composites reached above 90%,and the optimal removal conditions were the initial pH of 6.0 and a biochar/iron mass ratio of 5:1.The removal of TCE on biochar-iron composites followed the pseudo-second-order and Freundlich models,and the maximum adsorption capacity of TCE was 25.95 mg/g.The adsorption of biochar and dechlorination of nZVI dominated the removal of TCE.Biochar significantly enhanced the dechlorination of TCE on nZVI through modifying the electrochemical characteristics to lower its corrosion potential of nZVI,promote direct electron transfer,and improve electronic transfer capability.M-5BC-1nZVI exhibited excellent hydraulic performance for maintaining an adequate permeability coefficient(10^(−6)to 10^(−5)m/s).
基金supported by the National Natural Science Foundation of China(32171884)the Applied Basic Research Foundation of Yunnan Province(202301AS070041)+4 种基金the Major Science and Technology Project of Yunnan Province(202402AE090027)L.Y.acknowledges the Candidates of the Young and Middle-Aged Academic Leaders of Yunnan Province(202105 AC160048)the Ten Thousand Talent Program for Young Topnotch Talents of Yunnan Province(YNWR-QNBJ-2020-136)G.D.acknowledges the 111 Project(D21027)the Yunnan Provincial Academician Workstation(YSZJGZZ-2020052).
文摘Biomass structural materials can effectively address the issues of high energy consumption and environmental degradation brought by traditional engineering structural materials.However,natural structural materials often suffer from drawbacks such as low mechanical performance and flammability.Therefore,this study has developed an ultra-strong fire-resistant bamboo composite(UFBC).Natural bamboo(NB)was used as the raw material.After delignification treatment,bamboo fibers are grafted with epoxy groups through in-situ chemical bonding.Subsequently,polymer chains underwent in-situ chemical cross-linking within the bamboo fiber framework,combined with reinforcement from nano silica,resulting in strengthened cell walls.In addition,the softened and expanded cell walls can facilitate the deposition of phosphate and borate salt on the cell walls,forming an N-P-B flame-retardant system within the system.The tensile strength(463 MPa vs NB 112 MPa)and flexural strength(655 MPa vs NB 157 MPa)of UFBC increased fourfold,with a Limiting Oxygen Index(LOI)of 54.4%.Compared to similar bamboo-based composite materials,UFBC exhibits superior environmental friendliness and sustainability throughout its lifecycle,with all 18 environmental factors being optimized(up to a 92%reduction).This study provides an important reference for the application of high-performance biomass structural materials in construction and industry.
基金financially supported by National Key Research and Development Program of China(2022YFB3504000)the National Natural Science Foundation of China(22508430).
文摘Petroleum-based polycyclic aromatic hydrocarbons(PAHs),as by-products of petroleum,offer the advantages of abundant availability and high carbon content,making them ideal high-quality raw materials for the fabrication of carbon anode materials in lithium batteries(LIBs).This study presents a novel,dual-purpose strategy to fabricate hollow core–shell silicon-carbon composites(Si@Void@Cx)via the in-situ catalytic polycondensation of Fluid Catalytic Cracking(FCC)slurry.Unlike traditional synthesis routes employing metallic Lewis acids(e.g.,AlCl_(3),FeCl_(3)),silicon tetrachloride(SiCl_(4))was used as a cleaner,bifunctional catalyst that avoids metallic contamination while facilitating the precise polymerization of the carbon matrix.This approach not only circumvents the integration of heteroatoms via the catalyst,but also simplifies the process flow,reduces energy consumption,and contributes to a greener,sustainable technology by enhancing the high-value utilization of FCC,benefiting both resource conservation and environmental protection.The optimized composite(Si@Void@C1)delivers a robust electrochemical performance,exhibiting a specific capacity of 601.9 mAh/g and maintaining electrode integrity with a negligible thickness expansion of only 7%after 1000 cycles.Si@Void@C1 capitalizes on the well-dispersed silicon(Si)nanoparticles and the intact hollow core–shell structure to effectively buffer against the volume expansion stress of Si,thus maintaining electrode structural integrity and achieving superior cycling performance.This work provides a scalable,sustainable pathway for transforming petrochemical byproducts into advanced energy storage materials.
