MPHPB was prepared from melamine,phenylphosphonic acid and boric acid,and its flame retardant effect in PE was investigated.Compared to the intermediate product(melamine phenyl hypophosphite(MPHP)),the residual char i...MPHPB was prepared from melamine,phenylphosphonic acid and boric acid,and its flame retardant effect in PE was investigated.Compared to the intermediate product(melamine phenyl hypophosphite(MPHP)),the residual char increased from 17.9% of MPHP to 41.2% of MPHPB at 800℃.The limiting oxygen index(LOI)of PE/20%MPHPB is 23.6%,which reaches V-0 rating.After the addition of 20%MPHPB,the total heat release(THR),peak heat release rate(pK-HRR),and average effective thermal combustion rates(av-EHC)of PE decreased.Additionally,characterizations including the pyrolysis gas chromatography-mass spectrometry(Py-GC-MS),scanning electron microscopy(SEM),raman spectroscopy test(LRS)and fourier transform infrared(FT-IR)were taken to investigate the flame retardant mechanism,and the results show that MPHPB plays roles in both gas and condensed phases.展开更多
By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,t...By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.展开更多
The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in ...The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.展开更多
Sodium-ion batteries hold great promise as next-generation energy storage systems.However,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of SIBs.In p...Sodium-ion batteries hold great promise as next-generation energy storage systems.However,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of SIBs.In particular,an unstable cathode–electrolyte interphase(CEI)leads to successive electrolyte side reactions,transition metal leaching and rapid capacity decay,which tends to be exacerbated under high-voltage conditions.Therefore,constructing dense and stable CEIs are crucial for high-performance SIBs.This work reports localized high-concentration electrolyte by incorporating a highly oxidation-resistant sulfolane solvent with non-solvent diluent 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether,which exhibited excellent oxidative stability and was able to form thin,dense and homogeneous CEI.The excellent CEI enabled the O3-type layered oxide cathode NaNi_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)to achieve stable cycling,with a capacity retention of 79.48%after 300 cycles at 1 C and 81.15%after 400 cycles at 2 C with a high charging voltage of 4.2 V.In addition,its nonflammable nature enhances the safety of SIBs.This work provides a viable pathway for the application of sulfolane-based electrolytes on SIBs and the design of next-generation high-voltage electrolytes.展开更多
The oxidation behavior and mechanism of Mg-Ca alloys in air and under flame exposure were studied.Results show that for the oxidation in air,the Mg-Ca-O oxide film with Ca accumulation and low Mg vapor pressure on the...The oxidation behavior and mechanism of Mg-Ca alloys in air and under flame exposure were studied.Results show that for the oxidation in air,the Mg-Ca-O oxide film with Ca accumulation and low Mg vapor pressure on the surface of Mg-Ca alloys with high Ca content shows good protective effect.However,the falling off phenomenon of the oxide film on Mg_(2)Ca results in the further oxidation.Hence,the Mg-Ca alloys with high Ca content only show good protective effect.For the oxidation in flame,the molten alloys release the Ca atoms to diffuse outward.The Mg-Ca-O oxide film with high Ca accumulation layer forms in Mg-Ca alloys with high Ca content.Despite the high Mg vapor pressure in the molten alloy,the Mg-Ca-O oxide film with high Ca accumulation layer shows excellent protective effect.展开更多
To further expand the application of Mg alloys at high temperatures,the oxidation resistance of Mg-0.3Ca and Mg-3.6Ca alloys with protective coating under flame exposure was studied.Results show that the oxidation res...To further expand the application of Mg alloys at high temperatures,the oxidation resistance of Mg-0.3Ca and Mg-3.6Ca alloys with protective coating under flame exposure was studied.Results show that the oxidation resistance of Mg-Ca alloys under flame exposure is significantly improved by the protective coating,and Mg-3.6Ca alloy shows better oxidation resistance performance.The surface temperature of Mg-Ca alloys is reduced by the coating,therefore improving the oxidation resistance under flame exposure.However,the thermal insulation effect of the coating on Mg-3.6Ca alloy is better,which can be attributed to the Ca accumulation on the surface film.In addition,the surface film with Ca accumulation layer plays a crucial role in protecting the alloy.No obvious Ca accumulation layer exists on the Mg-0.3Ca alloy surface,presenting a restricted protective effect.Nevertheless,the surface film containing Ca accumulation layer is formed on Mg-3.6 Ca alloy,which shows an excellent protective effect.展开更多
Developing polymer materials combining high strength,toughness,multifunctionality,and environmental sustainability remains a major challenge.Herein,high-performance PVA-PCSx composite films were successfully fabricate...Developing polymer materials combining high strength,toughness,multifunctionality,and environmental sustainability remains a major challenge.Herein,high-performance PVA-PCSx composite films were successfully fabricated by incorporating H_(3)PO_(3)-protonated chitosan(PCS)into the PVA matrix as both a bio-based multi-hydrogen-bonding crosslinking agent and a macromolecular flame retardant.Specifically,a comprehensive investigation was conducted on the hydrogen bonding interactions,microstructure,mechanical properties,antibacterial performance,and flame retardancy of the PVA-PCSx films.Strong hydrogen bonds between PCS and PVA enabled excellent compatibility and formed a unique mechanical interlocking interface architecture.This further resulted in superior transparency and synchronous reinforcement and toughening effects in the composites films.Compared with pure PVA,the PVA-PCSx films showed a 23%-51%increase in tensile strength and an 80%-108%improvement in fracture toughness.Moreover,PVA-PCSx films exhibited superior fire safety performance,achieving an LOI value of 31.3%,attaining UL-94 V-0 rating,and reducing the heat release rate by up to 73.1%.Additionally,PVA-PCSx films demonstrated 99.99%antibacterial efficacy against both Escherichia coli and Staphylococcus aureus.Collectively,this study presents a simple yet effective strategy for fabricating high-strength,high-toughness,multifunctional composites using biopolysaccharides as additives.展开更多
In this manuscript,we conveniently prepared a series of polyester-polycarbonate copolymer(PPC-P)/polybutylene adipate terephthalate(PBAT)blends that exhibit both flame-retardant properties and toughness.Piperazine pyr...In this manuscript,we conveniently prepared a series of polyester-polycarbonate copolymer(PPC-P)/polybutylene adipate terephthalate(PBAT)blends that exhibit both flame-retardant properties and toughness.Piperazine pyrophosphate(PAPP),melamine phosphate(MPP)and ZnO were used as synergistic flame retardants for PPC-P/PBAT blends.The effects of synergistic flame retardants on thermal stability,combustion behavior and flame retardancy of PPC-P/PBAT blends were investigated.The results showed that when the ratio of PAPP/MPP/ZnO was 18.4:9.2:2.4,the LOI of PPC-P/PBAT composite was 42.8%,and UL-94 reached V-0 level.The results of cone calorimetry showed that the mass loss rate(MLR),the peak value of the biggest smoke production rate(pSPR)and total smoke production(TSP)of the material decreased,and a continuously expanded carbon layer with a compact structure was formed after combustion.The carbon layer formed after surface combustion protects the material from decomposition over a long temperature range.In terms of mechanical properties,compared with the composites with only PAPP and MPP,PAPP/MPP/ZnO composites can improve the mechanical properties.After adding 2.4 wt% ZnO,the tensile strength and impact strength of the polymer increased to 34.2 MPa and 28.5 kJ/m^(2),respectively.The results showed that the use of non-toxic,environmentally friendly,halogen-free flame retardants to enhance the flame retardant properties of biodegradable polymer composites is a promising direction in the future.展开更多
Generally,gaining fundamental insights into chain processes during the combustion of flame-retardant polymers relies on the qualitative and quantitative characterization of key chain carriers.However,polymer combustio...Generally,gaining fundamental insights into chain processes during the combustion of flame-retardant polymers relies on the qualitative and quantitative characterization of key chain carriers.However,polymer combustion processes based on conventional solid-fuel combustion strategies,due to the high coupling of pyrolysis,combustion,soot formation and oxidation,exhibit relatively high complexity and poor flame stability,and lead to a huge obstacle to the use of optical diagnostics.Herein,a spatial-confinement combustion strategy,which can produce a special staged flame with multi-jets secondary wave,is devised to provide a highly decoupled combustion environment.Glowing soot particles are therefore decoupled from main chemiluminescence region and confined to the flame tip to provide a well-controlled,opticalthin test environment for combustion diagnostic.Based on this strategy,a multi-nozzle-separation(MNS)burner is designed and fabricated,and the combustion processes associated with four model compounds,PVC,PS,PP/TBBA blends and PP/RP blends are investigated by spontaneous spectral diagnosis,and the chemiluminescence fingerprint of key diatomic/triatomic intermediates(such as OH,CH,C_(2),ClO,Br_(2),and PHO)are clearly observed.This encouraging result means that the strategy of spatial-confinement combustion we proposed shows promising prospect in many subjects associated with combustion chain regulation,such as efficient design of flame retardants.展开更多
Hydrogen,with its carbon-free composition and the availability of abundant renewable energy sources for its production,holds significant promise as a fuel for internal combustion engines(ICEs).Its wide flammability li...Hydrogen,with its carbon-free composition and the availability of abundant renewable energy sources for its production,holds significant promise as a fuel for internal combustion engines(ICEs).Its wide flammability limits and high flame speeds enable ultra-lean combustion,which is a promising strategy for reducing NOx emissions and improving thermal efficiency.However,lean hydrogen-air flames,characterized by low Lewis numbers,experience thermo-diffusive instabilities that can significantly influence flame propagation and emissions.To address this challenge,it is crucial to gain a deep understanding of the fundamental flame dynamics of hydrogen-fueled engines.This study uses high-speed planar SO_(2)-LIF to investigate the evolutions of the early flame kernels in hydrogen and methane flames,and analyze the intricate interplay between flame characteristics,such as flame curvature,the gradients of SO_(2)-LIF intensity,tortuosity of flame boundary,the equivalent flame speed,and the turbulent flow field.Differential diffusion effects are particularly pronounced in H_(2)flames,resulting in more significant flame wrinkling.In contrast,CH_(4)flames,while exhibiting smoother flame boundaries,are more sensitive to turbulence,resulting in increased wrinkling,especially under stronger turbulence conditions.The higher correlation between curvature and gradient of H_(2)flames indicates enhanced reactivity at the flame troughs,leading to faster flame propagation.However,increased turbulence can mitigate these effects.Hydrogen flames consistently exhibit higher equivalent flame speeds due to their higher thermo-diffusivity,and both hydrogen and methane flames accelerate under high turbulence conditions.These findings provide valuable insights into the distinct flame behaviors of hydrogen and methane,highlighting the importance of understanding the interactions between thermo-diffusive effects and turbulence in hydrogen-fueled engine combustion.展开更多
A novel eco-friendly charring agent(L-OH)was successfully synthesized by combining pentaerythritol(PER)with lignin through a simple two-step reaction.The structure of L-OH was characterized using Fourier transform inf...A novel eco-friendly charring agent(L-OH)was successfully synthesized by combining pentaerythritol(PER)with lignin through a simple two-step reaction.The structure of L-OH was characterized using Fourier transform infrared(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and EDS.In addition,L-OH was introduced into polypropylene(PP)together with melamine(MEL)and ammonium polyphosphate(APP)as an intumescent flame retardant(IFRR).The flame retardancy of PP/IFRR composites were investigated using limited oxygen index(LOI),UL-94,thermogravimetric analysis(TGA)and cone calorimeter(CC)test.The experimental results indicate that the PP/IFRR composites pass the V-0 grade of the UL-94 test when the addition amount of IFRR is no less than 20%,and the LOI value of the composite reaches 32.2%at 30%IFRR addition.The peak heat release rate(PHRR)and peak smoke production rate(PSPR)of the composite decrease by 72.8%and 70.4%compared with pure PP,respectively.The flame retardancy mechanism was investigated by TGA,TG-FTIR and residual carbon analysis.These analyses indicate that L-OH can form a more continuous and dense carbon layer during the combustion process,which is the main factor contributing to the improved flame retardancy of PP.展开更多
We aimed to enhance the flame retardancy of epoxy resin(EP)by synthesizing a novel,halogen-free flame retardant through a one-pot method.The synthesis utilized 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide(DOPO)...We aimed to enhance the flame retardancy of epoxy resin(EP)by synthesizing a novel,halogen-free flame retardant through a one-pot method.The synthesis utilized 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide(DOPO),furfurylamine(FA),and benzene propionaldehyde(BPA)as raw materials.We conducted differential scanning calorimetry(DSC)analysis to investigate the effects of FPD on the curing process and thermal properties of EP.Our findings reveal that incorporating FPD into EP can facilitate a faster curing process and increase the carbon residue post-combustion.Specifically,the FPD/EP-7 composite demonstrates a limiting oxygen index(LOI)of 34.9%and achieves a UL-94V-0 rating with a phosphorus content of 0.91wt%.These results indicate that FPD significantly enhances the thermal stability and charring rate of EP,thereby improving its flame retardancy.Although the addition of FPD slightly reduces the mechanical properties of EP,the composite material maintains excellent performance.展开更多
Although lightweight aramid paper honeycombs are highly desirable for microwave absorption owing to their dual functions of both load-bearing and microwave-absorbing,unsatisfactory microwave absorption,inferior mechan...Although lightweight aramid paper honeycombs are highly desirable for microwave absorption owing to their dual functions of both load-bearing and microwave-absorbing,unsatisfactory microwave absorption,inferior mechanical and inadequate thermal properties present significant challenges for practical applications in diverse complex scenarios.Herein,lightweight,high-strength and flame-retardant aramid nanofibers-based honeycombs(MANHs)for integrated microwave absorption and thermal insulation are successfully fabricated via the hydrogen bonding assembly,mold forming and aerogel filling strategy using aramid waste as raw material.The dense network structure formed by the interwoven aramid nanofibers(ANFs)in the honeycomb body acts as a framework endows the MANH with impressive mechanical performance,and the specific strength and toughness of MANH reach 153.6 MPa g^(−1) cm^(−3) and 13.9 MJ m^(−3),respectively,which are 3.5 and 19 times higher than those of commercial microwave absorption honeycombs(CMAH).The ultralight MXene/ANFs aerogels(a density of 25 mg cm^(−3))with multiscale pore structure filled in the honeycomb apertures give the honeycomb outstanding microwave absorption performance,with a minimum reflection loss of−62.5 dB,and can cover the entire X-band with a thickness of only 3.5 mm.Meanwhile,compared with CMAH,the thermal insulation and flame-retardant performance of MANH are also significantly improved.Notably,MANH also demonstrates favorable sound absorption performance at high-frequency bands.The MANH is considered to be a promising candidate for aerospace and military stealth applications as a result of its lightweight,high strength,exceptional microwave absorption,and remarkable thermal insulation performance.展开更多
In recent years,polymer-based triboelectric nanogenerators(TENGs)have been increasingly applied in the field of flexible wearable electronics.However,the lack of flame retardancy of existing TENGs greatly lim-its thei...In recent years,polymer-based triboelectric nanogenerators(TENGs)have been increasingly applied in the field of flexible wearable electronics.However,the lack of flame retardancy of existing TENGs greatly lim-its their applications in extreme circumstances.Herein,an ultra-thin and highly flexible aramid nanofiber(ANF)/MXene(Ti_(3)C_(2)T_(x))/Ni nanochain composite paper was prepared through vacuum-assisted filtration and freeze-drying technology.Owing to the synergistic effect between ANF and MXene,the composite paper not only possessed excellent mechanical properties,which were able to withstand over 10,000 times its own weight,but also exhibited outstanding flame-retardant and controllable Joule heating ca-pabilities.Moreover,the mechanical energy capture characteristics of the composite paper-based TENG were evaluated,resulting in the open-circuit voltage(55.6 V),short-circuit current(0.62μA),and trans-ferred charge quantity(25μC).It also could enable self-powering as a wearable electronic device with an instantaneous power of 15.6μW at the optimal external resistance of 10 MΩ.This work is intended to set TENG as safe energy harvesting devices for reducing fire hazards,and will provide a new strategy to broaden the application ranges of TENG.展开更多
Oxide films hinder diffusion and resist external forces,which determines the flame ignition mechanism of magnesium alloys.The effects of the continuity,compactness and mechanical properties of oxide films on the ignit...Oxide films hinder diffusion and resist external forces,which determines the flame ignition mechanism of magnesium alloys.The effects of the continuity,compactness and mechanical properties of oxide films on the ignition mechanism were analyzed,by investigating the flame ignition behaviors of AZ80(ZM5),EZ30K(ZM6)and WE43 Mg alloys.The results show that the rupture of the oxide films caused by liquid gravity was the key to causing ignition.According to thermodynamic calculations,compared with Mg,Al cannot be preferentially oxidized;while Nd can be preferentially oxidized through significant enrichment,resulting in a discontinuous Nd_(2)O_(3)inner layer in the ZM6 alloy;in contrast,Y has a strong preferential oxidation ability,which gives the WE43 alloy a continuous Y_(2)O_(3)inner layer and self-healing ability.In addition,the oxide film of the ZM5 alloy is loose and has poor mechanical properties,so it cannot effec-tively hinder diffusion and resist liquid gravity.Differently,the oxide films of the ZM6 and WE43 alloys are dense and have better mechanical properties,leading to higher ignition temperatures and longer igni-tion times.In addition,a criterion was proposed to predict the ignition time based on the law of energy conservation,and it was simplified to predict the ignition temperature.The errors between the predicted and measured values are within 11%.展开更多
Highly flame-retardant bio-based composites were prepared in this study.Firstly,glucose-citric acid(GC)resin was synthesized through the interaction of glucose and citric acid derived from agricultural and forestry so...Highly flame-retardant bio-based composites were prepared in this study.Firstly,glucose-citric acid(GC)resin was synthesized through the interaction of glucose and citric acid derived from agricultural and forestry sources.Polyvinyl alcohol(PVA)served as a toughening agent,whereas walnut shell powder(WSP)functioned as a filler in the formulation of a thermosetting bio-based GC-PVA-WSP(GCPW)composite with GC resin.The findings demonstrated that boric acid increased the limited oxygen index(LOI)value of GCPW to 33%,while simultaneously diminishing its total smoke production(TSP)by 99.9%,and achieving a flame retardant index(FRI)of 5.04.In addition,the incorporation of WSP enhanced the compressive strength of the GCPW composite to 9.15 MPa.Concurrently,the GCPW composite demonstrates excellent hydrophobic properties,with a thermal conductivity as low as 0.086 W/m·K.展开更多
Electromagnetic pollution is becoming significantly serious.Therefore,it is critical to prepare the advanced electromagnetic interference(EMI)shielding materials with thinness,flexibility and high mechanical strength....Electromagnetic pollution is becoming significantly serious.Therefore,it is critical to prepare the advanced electromagnetic interference(EMI)shielding materials with thinness,flexibility and high mechanical strength.Herein,the copperbased metal-organic framework(MOF-Cu)and polyethyleneiminemodified ammonium polyphosphate(PEI-APP)were successfully synthesized.The flame-retardant thermoplastic polyurethane(TPU)composite was successfully prepared by compounding MOF-Cu and PEI-APP.The Cotton@PDA@MXene composite was fabricated via a sequential loading process of polydopamine(PDA)and MXene onto cotton fabric.Then,the multilayer TPU composites were prepared by layer-by-layer hot-pressing.The TPU/9PAPP/1MOF/C-3PM composite exhibited exceptional EMI effectiveness of 20.5 dB in X-band and 23.0 dB in K-band,exceeding commercial standards.The TPU/9P-APP/1MOF/C-3PM composite also demonstrated significantly enhanced flame retardancy.Compared with pure TPU/Cotton sample,the peak heat release rate,total heat release and total smoke release of TPU/9PAPP/1MOF/C-3PM composite decreased by 40.7%,31.1%,and 33.3%,respectively.Furthermore,the thickness of the multilayer TPU composites was only 1 mm,demonstrating excellent flexibility.As the outer encapsulation material,TPU endowed the multilayer TPU composites outstanding durability and effectively addressed the common issues of fabric abrasion and conductive filler detachment.This study provides a novel strategy for preparing flexible electromagnetic interference shielding materials with superior flame retardancy.展开更多
This study systematically investigated the effects of different gas stove structures on flame combustion characteristics using spectral diagnostic techniques,aiming to provide optimized design guidelines for clean ene...This study systematically investigated the effects of different gas stove structures on flame combustion characteristics using spectral diagnostic techniques,aiming to provide optimized design guidelines for clean energy applications.To explore the combustion behaviors of various gas stove structures,UV cameras,high-speed cameras,and K-type thermocouples were employed to measure parameters such as flame OH radicals(OH*),flame morphology,pulsation frequency,flame temperature,and heat flux.The results demonstrate that flame stability was achieved at an inner/outer cover flow rate ratio of 0.5/4.0 L/min,beyond which further flow rate increases led to reduced combustion efficiency.Compared to covered stoves,top-uncovered stove exhibited 5.5%and 12.4%higher temperatures at the inner and outer covers,respectively,along with a 35%increase in heat flux.Comprehensive analysis revealed an approximately 20%enhancement in overall flame intensity.The experimental results show that top-uncovered gas stoves exhibit higher flame intensity,greater combustion efficiency,and overall higher stove efficiency.In contrast,covered gas stoves feature a more controllable and stable flame with a gentler temperature rise.This study underscores the importance of optimizing gas stove designs to enhance combustion efficiency and reduce emissions,contributing to the transition from fossil fuels to renewable energy sources and promoting sustainable development.展开更多
Poly(vinyl alcohol)(PVA)is a biodegradable and environmentally friendly material known for its gas barrier characteristics and solvent resistance.However,its flammability and water sensitivity limit its application in...Poly(vinyl alcohol)(PVA)is a biodegradable and environmentally friendly material known for its gas barrier characteristics and solvent resistance.However,its flammability and water sensitivity limit its application in specialized fields.In this study,phytic acid(PA)was introduced as a halogen-free flame retardant and biochar(BC)was introduced as a reinforcement to achieve both flame resistance and mechanical robustness.We thoroughly investigated the effects of BC particle sizes(100-3000 mesh)and addition amounts(0 wt%-10 wt%),as well as PA addition amounts(0 wt%-15 wt%),on the properties of PVA composite films.Notably,the PA10/1000BC5 composite containing 10 wt%PA and 5 wt%1000 mesh BC exhibited optimal properties.The limiting oxygen index increased to 39.2%,and the UL-94 test achieved a V-0 rating.Additionally,the PA10/1000BC5 composite film demonstrated significantly enhanced water resistance,with a swelling ratio reaching 800%without dissolving,unlike that of the control PVA.The water contact angle was 70°,indicating that hydrophilic properties remained essentially unaffected.Most importantly,the tensile modulus and elongation at break were 213 MPa and 281.7%,respectively,nearly double those of the PVA/PA composite film.This study presents an efficient and straightforward method for preparing PVA composite films that are flame-retardant,tough,and waterresistant,expanding their potential applications in various fields.展开更多
A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and ...A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and the lower portal sealed.In this study,the effects of tunnel slope on flame shape,flame length,along with smoke mass flow rate and induced velocity at the tunnel portal,are numerically investigated.The results show that,in all scenarios,flames initially rise vertically but tilt toward the sealed portal during the quasi-steady stage,with the largest tilt angle observed in tunnels sealed at the lower portal.The slope significantly affects the flame tilt angle.The flame tilt angle in tunnels with the lower portal sealed varies irregularly with the slope,while it decreases as the slope increases in tunnels with the upper portal sealed.Subsequently,the smoke mass flow rate and induced velocity at the tunnel portal are analyzed in detail.Drawing on the obtained data,the flame length prediction models for impinging flames and non-impinging flames under different sealing conditions are developed,along with dimensionless models for smoke mass flow rate and induced wind velocity.These findings provide a theoretical foundation for the formulation of fire rescue strategies and emergency evacuation plans in inclined tunnels with one portal sealed.展开更多
基金Funded by the Natural Science Foundation of Guangdong(Nos.2014A030313241,2014B090901068,and 2016A010103003)。
文摘MPHPB was prepared from melamine,phenylphosphonic acid and boric acid,and its flame retardant effect in PE was investigated.Compared to the intermediate product(melamine phenyl hypophosphite(MPHP)),the residual char increased from 17.9% of MPHP to 41.2% of MPHPB at 800℃.The limiting oxygen index(LOI)of PE/20%MPHPB is 23.6%,which reaches V-0 rating.After the addition of 20%MPHPB,the total heat release(THR),peak heat release rate(pK-HRR),and average effective thermal combustion rates(av-EHC)of PE decreased.Additionally,characterizations including the pyrolysis gas chromatography-mass spectrometry(Py-GC-MS),scanning electron microscopy(SEM),raman spectroscopy test(LRS)and fourier transform infrared(FT-IR)were taken to investigate the flame retardant mechanism,and the results show that MPHPB plays roles in both gas and condensed phases.
基金financially supported by the Science and Technology Innovation Program of Hunan Province(2024RC3003)the Central South University Innovation-Driven Research Programme(2023CXQD012)the Initiative for Sustainable Energy for its financial support。
文摘By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.
基金support from the National Natural Science Foundation of China(22268025,52473083,and 22475176)Key Research and Development Program of Yunnan Province(202403AP140036)+2 种基金Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)Applied Basic Research Program of Yunnan Province(202201AT070115 and 202201BE070001-031)supported by the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57).
文摘The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.
基金financial support by National Natural Science Foundation(NNSF)of China(Nos.52202269,52002248,U23B2069,22309162)Shenzhen Science and Technology program(No.20220810155330003)+1 种基金Shenzhen Basic Research Project(No.JCYJ20190808163005631)Xiangjiang Lab(22XJ01007).
文摘Sodium-ion batteries hold great promise as next-generation energy storage systems.However,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of SIBs.In particular,an unstable cathode–electrolyte interphase(CEI)leads to successive electrolyte side reactions,transition metal leaching and rapid capacity decay,which tends to be exacerbated under high-voltage conditions.Therefore,constructing dense and stable CEIs are crucial for high-performance SIBs.This work reports localized high-concentration electrolyte by incorporating a highly oxidation-resistant sulfolane solvent with non-solvent diluent 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether,which exhibited excellent oxidative stability and was able to form thin,dense and homogeneous CEI.The excellent CEI enabled the O3-type layered oxide cathode NaNi_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)to achieve stable cycling,with a capacity retention of 79.48%after 300 cycles at 1 C and 81.15%after 400 cycles at 2 C with a high charging voltage of 4.2 V.In addition,its nonflammable nature enhances the safety of SIBs.This work provides a viable pathway for the application of sulfolane-based electrolytes on SIBs and the design of next-generation high-voltage electrolytes.
基金National Natural Science Foundation of China(52405425)Project of Natural Science Research in Higher Education Institutions in Jiangsu Province(23KJB430039)+1 种基金Major Natural Science Research Project of Higher Education Institutions in Jiangsu Province(21KJA460007)333 High Level Talent Training Project in Jiangsu Province(2022-3-12-182)。
文摘The oxidation behavior and mechanism of Mg-Ca alloys in air and under flame exposure were studied.Results show that for the oxidation in air,the Mg-Ca-O oxide film with Ca accumulation and low Mg vapor pressure on the surface of Mg-Ca alloys with high Ca content shows good protective effect.However,the falling off phenomenon of the oxide film on Mg_(2)Ca results in the further oxidation.Hence,the Mg-Ca alloys with high Ca content only show good protective effect.For the oxidation in flame,the molten alloys release the Ca atoms to diffuse outward.The Mg-Ca-O oxide film with high Ca accumulation layer forms in Mg-Ca alloys with high Ca content.Despite the high Mg vapor pressure in the molten alloy,the Mg-Ca-O oxide film with high Ca accumulation layer shows excellent protective effect.
基金General Project of Natural Science Research in Higher Education Institutions in Jiangsu Province(23KJB430039)Major Natural Science Research Project of Higher Education Institutions in Jiangsu Province(21KJA460007)National Natural Science Foundation of China(51905462)。
文摘To further expand the application of Mg alloys at high temperatures,the oxidation resistance of Mg-0.3Ca and Mg-3.6Ca alloys with protective coating under flame exposure was studied.Results show that the oxidation resistance of Mg-Ca alloys under flame exposure is significantly improved by the protective coating,and Mg-3.6Ca alloy shows better oxidation resistance performance.The surface temperature of Mg-Ca alloys is reduced by the coating,therefore improving the oxidation resistance under flame exposure.However,the thermal insulation effect of the coating on Mg-3.6Ca alloy is better,which can be attributed to the Ca accumulation on the surface film.In addition,the surface film with Ca accumulation layer plays a crucial role in protecting the alloy.No obvious Ca accumulation layer exists on the Mg-0.3Ca alloy surface,presenting a restricted protective effect.Nevertheless,the surface film containing Ca accumulation layer is formed on Mg-3.6 Ca alloy,which shows an excellent protective effect.
基金financially supported by the National Natural Science Foundation of China(Nos.51991351,52173100)the Taishan Scholars Program(No.tsqn202312176)the Youth Innovation Team Project of Shandong Province(No.2022KJ304)。
文摘Developing polymer materials combining high strength,toughness,multifunctionality,and environmental sustainability remains a major challenge.Herein,high-performance PVA-PCSx composite films were successfully fabricated by incorporating H_(3)PO_(3)-protonated chitosan(PCS)into the PVA matrix as both a bio-based multi-hydrogen-bonding crosslinking agent and a macromolecular flame retardant.Specifically,a comprehensive investigation was conducted on the hydrogen bonding interactions,microstructure,mechanical properties,antibacterial performance,and flame retardancy of the PVA-PCSx films.Strong hydrogen bonds between PCS and PVA enabled excellent compatibility and formed a unique mechanical interlocking interface architecture.This further resulted in superior transparency and synchronous reinforcement and toughening effects in the composites films.Compared with pure PVA,the PVA-PCSx films showed a 23%-51%increase in tensile strength and an 80%-108%improvement in fracture toughness.Moreover,PVA-PCSx films exhibited superior fire safety performance,achieving an LOI value of 31.3%,attaining UL-94 V-0 rating,and reducing the heat release rate by up to 73.1%.Additionally,PVA-PCSx films demonstrated 99.99%antibacterial efficacy against both Escherichia coli and Staphylococcus aureus.Collectively,this study presents a simple yet effective strategy for fabricating high-strength,high-toughness,multifunctional composites using biopolysaccharides as additives.
基金Financial support from National Natural Science Foundation of China(Grant No.22075298)National Key R&D Program of China(2022YFD2301204)is gratefully acknowledged.
文摘In this manuscript,we conveniently prepared a series of polyester-polycarbonate copolymer(PPC-P)/polybutylene adipate terephthalate(PBAT)blends that exhibit both flame-retardant properties and toughness.Piperazine pyrophosphate(PAPP),melamine phosphate(MPP)and ZnO were used as synergistic flame retardants for PPC-P/PBAT blends.The effects of synergistic flame retardants on thermal stability,combustion behavior and flame retardancy of PPC-P/PBAT blends were investigated.The results showed that when the ratio of PAPP/MPP/ZnO was 18.4:9.2:2.4,the LOI of PPC-P/PBAT composite was 42.8%,and UL-94 reached V-0 level.The results of cone calorimetry showed that the mass loss rate(MLR),the peak value of the biggest smoke production rate(pSPR)and total smoke production(TSP)of the material decreased,and a continuously expanded carbon layer with a compact structure was formed after combustion.The carbon layer formed after surface combustion protects the material from decomposition over a long temperature range.In terms of mechanical properties,compared with the composites with only PAPP and MPP,PAPP/MPP/ZnO composites can improve the mechanical properties.After adding 2.4 wt% ZnO,the tensile strength and impact strength of the polymer increased to 34.2 MPa and 28.5 kJ/m^(2),respectively.The results showed that the use of non-toxic,environmentally friendly,halogen-free flame retardants to enhance the flame retardant properties of biodegradable polymer composites is a promising direction in the future.
基金supported by the National Natural Science Foundation of China(No.51827803)the Fundamental Research Funds for the Central Universities,111 Center(No.B20001)Institutional Research Fund from Sichuan University(No.2021SCUNL201).
文摘Generally,gaining fundamental insights into chain processes during the combustion of flame-retardant polymers relies on the qualitative and quantitative characterization of key chain carriers.However,polymer combustion processes based on conventional solid-fuel combustion strategies,due to the high coupling of pyrolysis,combustion,soot formation and oxidation,exhibit relatively high complexity and poor flame stability,and lead to a huge obstacle to the use of optical diagnostics.Herein,a spatial-confinement combustion strategy,which can produce a special staged flame with multi-jets secondary wave,is devised to provide a highly decoupled combustion environment.Glowing soot particles are therefore decoupled from main chemiluminescence region and confined to the flame tip to provide a well-controlled,opticalthin test environment for combustion diagnostic.Based on this strategy,a multi-nozzle-separation(MNS)burner is designed and fabricated,and the combustion processes associated with four model compounds,PVC,PS,PP/TBBA blends and PP/RP blends are investigated by spontaneous spectral diagnosis,and the chemiluminescence fingerprint of key diatomic/triatomic intermediates(such as OH,CH,C_(2),ClO,Br_(2),and PHO)are clearly observed.This encouraging result means that the strategy of spatial-confinement combustion we proposed shows promising prospect in many subjects associated with combustion chain regulation,such as efficient design of flame retardants.
基金supported by the Deutsche Forschungsgemeinschaft through FOR 2687“Cyclic variations in highly optimized spark-ignition engines:experiment and simulation of a multiscale causal chain”(No.423224402).
文摘Hydrogen,with its carbon-free composition and the availability of abundant renewable energy sources for its production,holds significant promise as a fuel for internal combustion engines(ICEs).Its wide flammability limits and high flame speeds enable ultra-lean combustion,which is a promising strategy for reducing NOx emissions and improving thermal efficiency.However,lean hydrogen-air flames,characterized by low Lewis numbers,experience thermo-diffusive instabilities that can significantly influence flame propagation and emissions.To address this challenge,it is crucial to gain a deep understanding of the fundamental flame dynamics of hydrogen-fueled engines.This study uses high-speed planar SO_(2)-LIF to investigate the evolutions of the early flame kernels in hydrogen and methane flames,and analyze the intricate interplay between flame characteristics,such as flame curvature,the gradients of SO_(2)-LIF intensity,tortuosity of flame boundary,the equivalent flame speed,and the turbulent flow field.Differential diffusion effects are particularly pronounced in H_(2)flames,resulting in more significant flame wrinkling.In contrast,CH_(4)flames,while exhibiting smoother flame boundaries,are more sensitive to turbulence,resulting in increased wrinkling,especially under stronger turbulence conditions.The higher correlation between curvature and gradient of H_(2)flames indicates enhanced reactivity at the flame troughs,leading to faster flame propagation.However,increased turbulence can mitigate these effects.Hydrogen flames consistently exhibit higher equivalent flame speeds due to their higher thermo-diffusivity,and both hydrogen and methane flames accelerate under high turbulence conditions.These findings provide valuable insights into the distinct flame behaviors of hydrogen and methane,highlighting the importance of understanding the interactions between thermo-diffusive effects and turbulence in hydrogen-fueled engine combustion.
基金the equipment support of Sharing Platform of Scientific Equipments,Ministry of Education's Research Center for Comprehensive Utilization and Clean Process Engineering of Phosphrous Resources,Sichuan University。
文摘A novel eco-friendly charring agent(L-OH)was successfully synthesized by combining pentaerythritol(PER)with lignin through a simple two-step reaction.The structure of L-OH was characterized using Fourier transform infrared(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and EDS.In addition,L-OH was introduced into polypropylene(PP)together with melamine(MEL)and ammonium polyphosphate(APP)as an intumescent flame retardant(IFRR).The flame retardancy of PP/IFRR composites were investigated using limited oxygen index(LOI),UL-94,thermogravimetric analysis(TGA)and cone calorimeter(CC)test.The experimental results indicate that the PP/IFRR composites pass the V-0 grade of the UL-94 test when the addition amount of IFRR is no less than 20%,and the LOI value of the composite reaches 32.2%at 30%IFRR addition.The peak heat release rate(PHRR)and peak smoke production rate(PSPR)of the composite decrease by 72.8%and 70.4%compared with pure PP,respectively.The flame retardancy mechanism was investigated by TGA,TG-FTIR and residual carbon analysis.These analyses indicate that L-OH can form a more continuous and dense carbon layer during the combustion process,which is the main factor contributing to the improved flame retardancy of PP.
基金Funded by the Fundamental Research Funds for the Central Universities(WUT:2023III012JL)。
文摘We aimed to enhance the flame retardancy of epoxy resin(EP)by synthesizing a novel,halogen-free flame retardant through a one-pot method.The synthesis utilized 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide(DOPO),furfurylamine(FA),and benzene propionaldehyde(BPA)as raw materials.We conducted differential scanning calorimetry(DSC)analysis to investigate the effects of FPD on the curing process and thermal properties of EP.Our findings reveal that incorporating FPD into EP can facilitate a faster curing process and increase the carbon residue post-combustion.Specifically,the FPD/EP-7 composite demonstrates a limiting oxygen index(LOI)of 34.9%and achieves a UL-94V-0 rating with a phosphorus content of 0.91wt%.These results indicate that FPD significantly enhances the thermal stability and charring rate of EP,thereby improving its flame retardancy.Although the addition of FPD slightly reduces the mechanical properties of EP,the composite material maintains excellent performance.
基金supported by the Key Research and Development Project of Shaanxi Province(No.2024GX-YBXM-331)the Scientific Research Plan Projects of Shaanxi Education Department(Program No.24JC009)the National Natural Science Foundation of China(No.22278260).
文摘Although lightweight aramid paper honeycombs are highly desirable for microwave absorption owing to their dual functions of both load-bearing and microwave-absorbing,unsatisfactory microwave absorption,inferior mechanical and inadequate thermal properties present significant challenges for practical applications in diverse complex scenarios.Herein,lightweight,high-strength and flame-retardant aramid nanofibers-based honeycombs(MANHs)for integrated microwave absorption and thermal insulation are successfully fabricated via the hydrogen bonding assembly,mold forming and aerogel filling strategy using aramid waste as raw material.The dense network structure formed by the interwoven aramid nanofibers(ANFs)in the honeycomb body acts as a framework endows the MANH with impressive mechanical performance,and the specific strength and toughness of MANH reach 153.6 MPa g^(−1) cm^(−3) and 13.9 MJ m^(−3),respectively,which are 3.5 and 19 times higher than those of commercial microwave absorption honeycombs(CMAH).The ultralight MXene/ANFs aerogels(a density of 25 mg cm^(−3))with multiscale pore structure filled in the honeycomb apertures give the honeycomb outstanding microwave absorption performance,with a minimum reflection loss of−62.5 dB,and can cover the entire X-band with a thickness of only 3.5 mm.Meanwhile,compared with CMAH,the thermal insulation and flame-retardant performance of MANH are also significantly improved.Notably,MANH also demonstrates favorable sound absorption performance at high-frequency bands.The MANH is considered to be a promising candidate for aerospace and military stealth applications as a result of its lightweight,high strength,exceptional microwave absorption,and remarkable thermal insulation performance.
基金financially supported by the Zhejiang Provin-cial Natural Science Foundation of China(No.LQ22E030016)the National Natural Science Foundation of China(Nos.52275137,51705467),the China Postdoctoral Science Foundation(No.2022M722831)+2 种基金the Postdoctoral Research Selected Funding Project of Zhejiang Province(No.ZJ2022063)the Self-Topic Fund of Zhe-jiang Normal University(No.2020ZS04)the National Key Re-search and Development Program of China(No.2018YFE0199100).
文摘In recent years,polymer-based triboelectric nanogenerators(TENGs)have been increasingly applied in the field of flexible wearable electronics.However,the lack of flame retardancy of existing TENGs greatly lim-its their applications in extreme circumstances.Herein,an ultra-thin and highly flexible aramid nanofiber(ANF)/MXene(Ti_(3)C_(2)T_(x))/Ni nanochain composite paper was prepared through vacuum-assisted filtration and freeze-drying technology.Owing to the synergistic effect between ANF and MXene,the composite paper not only possessed excellent mechanical properties,which were able to withstand over 10,000 times its own weight,but also exhibited outstanding flame-retardant and controllable Joule heating ca-pabilities.Moreover,the mechanical energy capture characteristics of the composite paper-based TENG were evaluated,resulting in the open-circuit voltage(55.6 V),short-circuit current(0.62μA),and trans-ferred charge quantity(25μC).It also could enable self-powering as a wearable electronic device with an instantaneous power of 15.6μW at the optimal external resistance of 10 MΩ.This work is intended to set TENG as safe energy harvesting devices for reducing fire hazards,and will provide a new strategy to broaden the application ranges of TENG.
基金supported by the National Key Research and Development Program of China(No.2021YFB3501002)the National Science and Technology Major Project(No.J2019-Ⅷ-0003-0165)the National Natural Science Foundation of China(No.52301059).
文摘Oxide films hinder diffusion and resist external forces,which determines the flame ignition mechanism of magnesium alloys.The effects of the continuity,compactness and mechanical properties of oxide films on the ignition mechanism were analyzed,by investigating the flame ignition behaviors of AZ80(ZM5),EZ30K(ZM6)and WE43 Mg alloys.The results show that the rupture of the oxide films caused by liquid gravity was the key to causing ignition.According to thermodynamic calculations,compared with Mg,Al cannot be preferentially oxidized;while Nd can be preferentially oxidized through significant enrichment,resulting in a discontinuous Nd_(2)O_(3)inner layer in the ZM6 alloy;in contrast,Y has a strong preferential oxidation ability,which gives the WE43 alloy a continuous Y_(2)O_(3)inner layer and self-healing ability.In addition,the oxide film of the ZM5 alloy is loose and has poor mechanical properties,so it cannot effec-tively hinder diffusion and resist liquid gravity.Differently,the oxide films of the ZM6 and WE43 alloys are dense and have better mechanical properties,leading to higher ignition temperatures and longer igni-tion times.In addition,a criterion was proposed to predict the ignition time based on the law of energy conservation,and it was simplified to predict the ignition temperature.The errors between the predicted and measured values are within 11%.
基金supported by the Natural Science Foundation of China(32460363)Yunnan Province Agricultural Joint Key Foundation(No.202401BD070001-029)+3 种基金Yunnan Agricultural Joint General Foundation(202101BD070001-105)the Yunnan Provincial Youth Top Talent Project(Grant No.YNWR-QNBJ-2020-166)the Foreign ExpertWorkstation(202305AF150006)the 111 Project(D21027).
文摘Highly flame-retardant bio-based composites were prepared in this study.Firstly,glucose-citric acid(GC)resin was synthesized through the interaction of glucose and citric acid derived from agricultural and forestry sources.Polyvinyl alcohol(PVA)served as a toughening agent,whereas walnut shell powder(WSP)functioned as a filler in the formulation of a thermosetting bio-based GC-PVA-WSP(GCPW)composite with GC resin.The findings demonstrated that boric acid increased the limited oxygen index(LOI)value of GCPW to 33%,while simultaneously diminishing its total smoke production(TSP)by 99.9%,and achieving a flame retardant index(FRI)of 5.04.In addition,the incorporation of WSP enhanced the compressive strength of the GCPW composite to 9.15 MPa.Concurrently,the GCPW composite demonstrates excellent hydrophobic properties,with a thermal conductivity as low as 0.086 W/m·K.
基金supported by the National Natural Science Foundation of China(No.52173070).
文摘Electromagnetic pollution is becoming significantly serious.Therefore,it is critical to prepare the advanced electromagnetic interference(EMI)shielding materials with thinness,flexibility and high mechanical strength.Herein,the copperbased metal-organic framework(MOF-Cu)and polyethyleneiminemodified ammonium polyphosphate(PEI-APP)were successfully synthesized.The flame-retardant thermoplastic polyurethane(TPU)composite was successfully prepared by compounding MOF-Cu and PEI-APP.The Cotton@PDA@MXene composite was fabricated via a sequential loading process of polydopamine(PDA)and MXene onto cotton fabric.Then,the multilayer TPU composites were prepared by layer-by-layer hot-pressing.The TPU/9PAPP/1MOF/C-3PM composite exhibited exceptional EMI effectiveness of 20.5 dB in X-band and 23.0 dB in K-band,exceeding commercial standards.The TPU/9P-APP/1MOF/C-3PM composite also demonstrated significantly enhanced flame retardancy.Compared with pure TPU/Cotton sample,the peak heat release rate,total heat release and total smoke release of TPU/9PAPP/1MOF/C-3PM composite decreased by 40.7%,31.1%,and 33.3%,respectively.Furthermore,the thickness of the multilayer TPU composites was only 1 mm,demonstrating excellent flexibility.As the outer encapsulation material,TPU endowed the multilayer TPU composites outstanding durability and effectively addressed the common issues of fabric abrasion and conductive filler detachment.This study provides a novel strategy for preparing flexible electromagnetic interference shielding materials with superior flame retardancy.
基金supported by Ningxia Natural Science Foundation Innovative Group Project(2023AAC01001)the Postdoctoral Research Excellence Funding Project of Zhejiang Province ofChina(ZJ2023135).
文摘This study systematically investigated the effects of different gas stove structures on flame combustion characteristics using spectral diagnostic techniques,aiming to provide optimized design guidelines for clean energy applications.To explore the combustion behaviors of various gas stove structures,UV cameras,high-speed cameras,and K-type thermocouples were employed to measure parameters such as flame OH radicals(OH*),flame morphology,pulsation frequency,flame temperature,and heat flux.The results demonstrate that flame stability was achieved at an inner/outer cover flow rate ratio of 0.5/4.0 L/min,beyond which further flow rate increases led to reduced combustion efficiency.Compared to covered stoves,top-uncovered stove exhibited 5.5%and 12.4%higher temperatures at the inner and outer covers,respectively,along with a 35%increase in heat flux.Comprehensive analysis revealed an approximately 20%enhancement in overall flame intensity.The experimental results show that top-uncovered gas stoves exhibit higher flame intensity,greater combustion efficiency,and overall higher stove efficiency.In contrast,covered gas stoves feature a more controllable and stable flame with a gentler temperature rise.This study underscores the importance of optimizing gas stove designs to enhance combustion efficiency and reduce emissions,contributing to the transition from fossil fuels to renewable energy sources and promoting sustainable development.
基金supported by the Zhejiang Provincial"Vanguard"and"Leading Goose"R&D Program(No.2025C02203)the Zhejiang Provincial Natural Science Foundation of China(No.LTGS24C130001)the Fund for Key Scientific Research in the Public Interest of Ningbo(No.2024S009)。
文摘Poly(vinyl alcohol)(PVA)is a biodegradable and environmentally friendly material known for its gas barrier characteristics and solvent resistance.However,its flammability and water sensitivity limit its application in specialized fields.In this study,phytic acid(PA)was introduced as a halogen-free flame retardant and biochar(BC)was introduced as a reinforcement to achieve both flame resistance and mechanical robustness.We thoroughly investigated the effects of BC particle sizes(100-3000 mesh)and addition amounts(0 wt%-10 wt%),as well as PA addition amounts(0 wt%-15 wt%),on the properties of PVA composite films.Notably,the PA10/1000BC5 composite containing 10 wt%PA and 5 wt%1000 mesh BC exhibited optimal properties.The limiting oxygen index increased to 39.2%,and the UL-94 test achieved a V-0 rating.Additionally,the PA10/1000BC5 composite film demonstrated significantly enhanced water resistance,with a swelling ratio reaching 800%without dissolving,unlike that of the control PVA.The water contact angle was 70°,indicating that hydrophilic properties remained essentially unaffected.Most importantly,the tensile modulus and elongation at break were 213 MPa and 281.7%,respectively,nearly double those of the PVA/PA composite film.This study presents an efficient and straightforward method for preparing PVA composite films that are flame-retardant,tough,and waterresistant,expanding their potential applications in various fields.
基金financially supported by National Natural Science Foundation of China(NSFC)under Grant No.52208115Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of Chain(No.2023KJ122)+2 种基金Leading Researcher Studio Fund of Jinan(No.202333050)Natural Science Foundation of Shandong Province(ZR2024ME027)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTA077).
文摘A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and the lower portal sealed.In this study,the effects of tunnel slope on flame shape,flame length,along with smoke mass flow rate and induced velocity at the tunnel portal,are numerically investigated.The results show that,in all scenarios,flames initially rise vertically but tilt toward the sealed portal during the quasi-steady stage,with the largest tilt angle observed in tunnels sealed at the lower portal.The slope significantly affects the flame tilt angle.The flame tilt angle in tunnels with the lower portal sealed varies irregularly with the slope,while it decreases as the slope increases in tunnels with the upper portal sealed.Subsequently,the smoke mass flow rate and induced velocity at the tunnel portal are analyzed in detail.Drawing on the obtained data,the flame length prediction models for impinging flames and non-impinging flames under different sealing conditions are developed,along with dimensionless models for smoke mass flow rate and induced wind velocity.These findings provide a theoretical foundation for the formulation of fire rescue strategies and emergency evacuation plans in inclined tunnels with one portal sealed.
