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
In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding s...In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding strengths,oxygen index,and fluidity of rigid polyurethane foam(RPUF).The results revealed that EG significantly increased the oxygen index of RPUF,enlarged the diameter of foam cells,and decreased the cell-closed content in foam;thus,leading to a pressure drop in RPUF.However,excessive EG was capable of reducing the fluidity of polyurethane slurry.TEA exhibited significant influence on the compressive strength of RPUF,which dropped initially,and then increased.DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF.Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP,and achieved the maximum value at DMMP dosage of 4%.DMMP could effectively reduce the diameter of RPUF cells leading to an increase in the percentage of close area in foam.DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF.Moreover,the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO_2.The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.展开更多
GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results...GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results showed that GCP is in advance of APP. From the thermal analysis and char composition analysis, it is concluded that GCP mainly functions in condensed phase.展开更多
The N-cyan-N′-hydroxymethyl guanidine(CHMG) was synthesized and the effect of various facts during reaction to the yield was studied. The structure of the product was determined by IR spectrometry. An aqueous solutio...The N-cyan-N′-hydroxymethyl guanidine(CHMG) was synthesized and the effect of various facts during reaction to the yield was studied. The structure of the product was determined by IR spectrometry. An aqueous solution of CHMG, melamine(MA) and phosphoric acid (PA) was compounded according to a certain molar ratio. After the wood samples were impregnated with the aqueous solution in certain condition, they were dried step by step, and were cured, then the amino resin flame retardants were obtained. We emphasized studying on the effects of the molar ratio of the three components to the flame retardancy. The oxygen index(OI) of the wood test samples and the leach resistance value(LRV) of the flame retardants were determined. While the molar ratio of CHMG: MA: PA was 5: 1: 6.5, and the loading agents ratio(RFR) was 1.92%, the OI of dahurian larch came up to 45, and the average of LRV was 49.59%. The results show that if the optimum molar ratio of CHMU: MA: PA is chosen and the wood is treated in special conditions, amino resin flame retardant with leach resistance to wood can be obtained.展开更多
In this paper, the Sb2O3 nanoparticles prepared with SbCl3 by the alky hydrolysis, processed with the surfactants, were assembled on mica substrates. The morphology and the assembled behavior of the nano-Sb2O3 on the ...In this paper, the Sb2O3 nanoparticles prepared with SbCl3 by the alky hydrolysis, processed with the surfactants, were assembled on mica substrates. The morphology and the assembled behavior of the nano-Sb2O3 on the mica were analyzed by means of TEM. The flame retardant properties of nano-Sb2O3 and Sb2O3/mica complex were studied by combustion test and thermal analysis. The results show that the Sb2O3 nanoparticles are assembled uniformly on the mica substrates. The nano-Sb2O3 was characterized with small size, narrow size distribution, uniform crystal and monodispersed particles. Compared with nano-Sb2O3, the Sb2O3/mica complexes have been achieved the same coordinated effects with Chlorinated Paraffin(CP) and excellent flame retardant properties.展开更多
High flammability of polymers has become a major issue which has restricted its applications.Recently,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,...High flammability of polymers has become a major issue which has restricted its applications.Recently,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,have been intensively employed as novel fire retardants(FRs)for a variety of polymers(MOF/polymer).The MOFs possessed abundant transition metal species,fire-retardant elements and potential carbon source accompanied with the facile tuning of the structure and property,making MOF,its derivatives and MOF hybrids promising for fire retardancy research.The recent progress and strategies to prepare MOF-based FRs are emphasized and summarized.The fire retardancy mechanisms of MOF/polymer composites are explained,which may guide the future design for efficient MOF-based FRs.Finally,the challenges and prospects related to different MOFbased FRs are also discussed and aim to provide a fast and holistic overview,which is beneficial for researchers to quickly get up to speed with the latest development in this field.展开更多
Lithium–sulfur batteries have been regarded as the most promising high-energy electrochemical energy storage device owing to the high energy density, low cost and environmental friendliness. However, traditional lith...Lithium–sulfur batteries have been regarded as the most promising high-energy electrochemical energy storage device owing to the high energy density, low cost and environmental friendliness. However, traditional lithium–sulfur batteries using ether-based electrolytes often suffer from severe safety risks(i.e. combustion). Herein, we demonstrated a novel kind of flame-retardant concentrated electrolyte(6.5 M lithium bis(trifluoromethylsulphonyl)imide/fluoroethylene carbonate) for highly-safe and widetemperature lithium–sulfur batteries. It was found that such concentrated electrolyte showed superior flame retardancy, high lithium-ion transference number(0.69) and steady lithium plating/stripping behavior(2.5 m Ah cm^(-2) over 3000 h). Moreover, lithium–sulfur batteries using this flame-retardant concentrated electrolyte delivered outstanding cycle performance in a wide range of temperatures(-10 °C, 25 °C and 90 °C). This superior battery performance is mainly attributed to the LiF-rich solid electrolyte interphase formed on lithium metal anode, which can effectively suppress the continuous growth of lithium dendrites. Above-mentioned fascinating characteristics would endow this flame-retardant concentrated electrolyte a very promising candidate for highly-safe and wide-temperature lithium–sulfur batteries.展开更多
Na +-montmorillonite(Na +-MMT) was converted to organic montmorillonite(OMMT) using modifier which was synthesized at authors’ laboratory. PA6/OMMT nanocomposite was prepared via in situ intercalative polymerization....Na +-montmorillonite(Na +-MMT) was converted to organic montmorillonite(OMMT) using modifier which was synthesized at authors’ laboratory. PA6/OMMT nanocomposite was prepared via in situ intercalative polymerization. The limiting oxygen index (LOI), UL 94V flame retardancy and thermal stability of PA6/OMMT using thermal gravity analysis (TGA) were measured. The Fourier transform infrared (FTIR) technique was used to analyze the pyrolytic residuum and the cone calorimeter (CONE) was applied to determine a number of combustion parameters which were closely related to fire safety, including heat release rate, mass loss rate, effective combustion heat, total heat release, specific extinction area and the time of ignition. In addition, the elemental composition of the surface pyrolytic residuum and the corresponding X-ray photoelectron spectroscopy (XPS) data were obtained, and the morphology of the residuum from CONE measurement was examined by scanning electron microscope (SEM).展开更多
Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs)via their influence on the pyrolysis process.In this work,the effects of hexa(5-methyl-2-pyridinoxyl)cyc...Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs)via their influence on the pyrolysis process.In this work,the effects of hexa(5-methyl-2-pyridinoxyl)cyclotriphosphazene(HMPOP)incorporation on the initial pyrolysis of an EP at 500–3500 K were studied using the ReaxFF method.The pyrolysis fragments,initial reaction pathways,and main products were identified for the EP and EP/HMPOP composites.The activation energies were derived by fitting the weight percentage curves for solid species during the pyrolysis reactions and the obtained values were in good agreement with experimental data.The initial EP pyrolysis reactions included four major decomposition modes,which primarily involved the cleavage of C–O and C–N bonds.The main pyrolysis products were H_(2)O,CO,C_(2)H_(4),and CH_(2)O.HMPOP bonded with the oxygen-containing fragments to form larger molecular fragments and reduced the amounts of C_(0)–C_(4) products,especially that of the harmful gas CH_(2)O.Thus,HMPOP promoted the formation of carbon clusters and reduced the generation of combustible gases,ultimately decreasing the capacity for fire propagation.展开更多
An aliphatic epoxy monomer＂polypropyleneglycol-diglycidylether（PPGDGE,YF878）＂is loaded in the epoxy resins（EP）to evaluate the influence of epoxy structure on the blowing-out effect,which is caused by 9,10-dihydr...An aliphatic epoxy monomer＂polypropyleneglycol-diglycidylether（PPGDGE,YF878）＂is loaded in the epoxy resins（EP）to evaluate the influence of epoxy structure on the blowing-out effect,which is caused by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide（DOPO）and octaphenyl silsesquioxane（OPS）.The flame retarding properties of these EP composites were tested using the LOI and UL-94 procedures.The pyrolytic gases produced and the thermal stability of the EP composites with different flame retardants were detected by TGA-FTIR in air.The negative effect of YF878 was detected from the TTI,HRR,and p-HRR results after the cone calorimeter test.The char produced by the EP composites after the cone calorimeter test was investigated by FTIR.It is proposed that the aliphatic chain of the YF878 is easy to break down and produce combustible gases,so it does not easily form a crosslinked structure in the condensed phase.These results are very helpful for investigation of the conditions under which the blowing-out effect in epoxy resins can be caused by synergy of phosphorous and silicon.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
The rapid development of communication technology and high-frequency electronic devices has created a need for more advanced electromagnetic interference(EMI)shielding materials.In response to this demand,a study has ...The rapid development of communication technology and high-frequency electronic devices has created a need for more advanced electromagnetic interference(EMI)shielding materials.In response to this demand,a study has been conducted to develop multifunctional carbon nanofibers(CNFs)/polyaniline(PANI)aerogels with excellent electromagnetic interference shielding,flame retardancy,and thermal insulation performance.The process involved freeze-drying of electrospun CNFs and PANI nanoparticles followed by in situ growth PANI to coat the CNFs,creating the core-shell structured CNFs/PANI composite fiber and its hybrid aerogels(CP-3@PANI).The interaction between PANI and aniline(ANI)provides attachment sites,allowing additional ANI adsorption into the aerogel for in situ polymerization.This results in PANI uniformly covering the surface of the CNFs,creating a core-shell composite fiber with a flexible CNF core and PANI shell.This process enhances the utilization rate of the ANI monomer and increases the PANI content loaded onto the aerogel.Additionally,effective connections are established between the CNFs,forming a stable,conductive three-dimensional network structure.The prepared CP-3@PANI aerogels exhibit excellent EMI shielding efficiency(SE)of 85.4 dB and specific EMI SE(SE d^(-1))of 791.2 dB cm^(3)g^(-1)in the X-band.Due to the synergistic flame-retardant effect of CNFs,PANI,and the dopant(phytic acid),the CP-3@PANI aerogels demonstrate outstanding flame-retardant and thermal insulation properties,with a peak heat release rate(PHRR)as low as 7.8 W g^(-1)and a total heat release of only 0.58 kJ g^(-1).This study provides an effective strategy for preparing multifunctional integrated EMI shielding materials.展开更多
High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polym...High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.展开更多
The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite grow...The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety.With the merit of convenience,the method of designing functional separator has been adapted.Concretely,the carbon aerogel confined with CoS_(2)(CoS_(2)-NCA)is constructed and coated on Celgard separator surface,acquiring CoS_(2)-NCA modified separator(CoS_(2)-NCA@C),which holds the promoted electrolyte affinity and flame retardance.As revealed,CoS_(2)-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle,much higher than that of Celgard cell(987.1 mAh/g).Moreover,the thermal runaway triggering time is dramatically prolonged by 777.4 min,corroborating the promoted thermal safety of cell.Noticeably,the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS_(2)-NCA@C in suppressing the lithium dendrite growth.Overall,this work can provide useful inspirations for designing functional separator,coping with the vexing issues of LSBs.展开更多
Accurate measurement of the average plasma parameters in the edge region,including the temperature and density of electrons and ions,is critical for understanding the characteristics of the scrape-off layer(SOL) and d...Accurate measurement of the average plasma parameters in the edge region,including the temperature and density of electrons and ions,is critical for understanding the characteristics of the scrape-off layer(SOL) and divertor plasma transport in magnetically confined fusion research.On the J-TEXT tokamak,a multi-channel retarding field analyzer(RFA) probe has been developed to study average plasma parameters in the edge region under various poloidal divertor and island divertor configurations.The edge radial profile of the ion-to-electron temperature ratio,τ_(i/e),has been determined,which gradually decreases as the SOL ion self-collisionality,v_(SOL)*,increases.This is broadly consistent with what has been observed previously from various tokamak experiments.However,the comparison of experimental results under different configurations shows that in the poloidal divertor configuration,even under the same v_(SOL)*,τ_(i/e) in the SOL region becomes smaller as the distance from the X-point to the target plate increases.In the island divertor configuration,τ_(i/e) near the O-point is higher than that near the X-point at the same v_(SOL)*,and both are higher than those in the limiter configuration.These results suggest that the magnetic configuration plays a critical role in the energy distributions between electrons and ions at the plasma boundary.展开更多
Poly(ethylene oxide)(PEO)and its derivatives based gel polymer electrolytes(GPEs)are severely limited in advanced and safe lithium-ion batteries(LIBs)owing to the intrinsically high flammability of liquid electrolytes...Poly(ethylene oxide)(PEO)and its derivatives based gel polymer electrolytes(GPEs)are severely limited in advanced and safe lithium-ion batteries(LIBs)owing to the intrinsically high flammability of liquid electrolytes and PEO.Directly adding flame retardants to the GPEs can suppress their flammability and thus improve the safety of LIBs,but results in deteriorative electrochemical performance.Herein,a novel GPE with chemically bonded flame retardant(i.e.diethyl vinylphosphonate)in cross-linked polyethylene glycol diacrylate matrix,featuring both high-safety and high-performance,is designed.This as-prepared GPE storing the commercial 1 mol L^(-1) LiPF6 electrolyte resists high temperature of 200℃and cannot be ignited as well as possesses a high ionic conductivity(0.60 m S cm^(-1))and good compatibility with lithium.Notably,the LiFePO_(4)/Li battery with this GPE delivers a satisfactory capacity of 142.2 m A h g^(-1) and a superior cycling performance with a capacity retention of 96.3%and a coulombic efficiency of close to 100%for 350 cycles at 0.2 C under ambient temperature.Furthermore,the battery can achieve steady charge–discharge for 100 cycles with a coulombic efficiency of 99.5%at 1 C under 80℃and run normally even at a high temperature of 150℃or under the exposure to butane flame.Differential scanning calorimetry manifests significantly improved battery safety compared to commercial battery systems.This work provides a new pathway for developing next-generation advanced LIBs with enhanced performance and high safety.展开更多
The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent s...The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.展开更多
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supported by the National Natural Science Foundation of China(No.51304027)China Postdoctoral Science Foundation(2014M560567 and 2015T80730)+4 种基金Shandong Province Science and Technology Development Plan(2014GSF120012)the State Key Program of Coal Joint Funds of National Natural Science Foundation of China(Nos.51134020 and U1261205)Shandong Province Natural Science Foundation(No.ZR2011EL036)the Doctoral Scientific Research Foundation of Binzhou University(No.2013Y06)the Key Technology Projects for Preventing Major Accident of National Security State Administration of Work Safety
文摘In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding strengths,oxygen index,and fluidity of rigid polyurethane foam(RPUF).The results revealed that EG significantly increased the oxygen index of RPUF,enlarged the diameter of foam cells,and decreased the cell-closed content in foam;thus,leading to a pressure drop in RPUF.However,excessive EG was capable of reducing the fluidity of polyurethane slurry.TEA exhibited significant influence on the compressive strength of RPUF,which dropped initially,and then increased.DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF.Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP,and achieved the maximum value at DMMP dosage of 4%.DMMP could effectively reduce the diameter of RPUF cells leading to an increase in the percentage of close area in foam.DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF.Moreover,the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO_2.The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.
文摘GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results showed that GCP is in advance of APP. From the thermal analysis and char composition analysis, it is concluded that GCP mainly functions in condensed phase.
文摘The N-cyan-N′-hydroxymethyl guanidine(CHMG) was synthesized and the effect of various facts during reaction to the yield was studied. The structure of the product was determined by IR spectrometry. An aqueous solution of CHMG, melamine(MA) and phosphoric acid (PA) was compounded according to a certain molar ratio. After the wood samples were impregnated with the aqueous solution in certain condition, they were dried step by step, and were cured, then the amino resin flame retardants were obtained. We emphasized studying on the effects of the molar ratio of the three components to the flame retardancy. The oxygen index(OI) of the wood test samples and the leach resistance value(LRV) of the flame retardants were determined. While the molar ratio of CHMG: MA: PA was 5: 1: 6.5, and the loading agents ratio(RFR) was 1.92%, the OI of dahurian larch came up to 45, and the average of LRV was 49.59%. The results show that if the optimum molar ratio of CHMU: MA: PA is chosen and the wood is treated in special conditions, amino resin flame retardant with leach resistance to wood can be obtained.
基金Project 50574092 supported by National Natural Science Foundation of China OH 4508 Supported by Science Foundation of China University of Mining &Technology
文摘In this paper, the Sb2O3 nanoparticles prepared with SbCl3 by the alky hydrolysis, processed with the surfactants, were assembled on mica substrates. The morphology and the assembled behavior of the nano-Sb2O3 on the mica were analyzed by means of TEM. The flame retardant properties of nano-Sb2O3 and Sb2O3/mica complex were studied by combustion test and thermal analysis. The results show that the Sb2O3 nanoparticles are assembled uniformly on the mica substrates. The nano-Sb2O3 was characterized with small size, narrow size distribution, uniform crystal and monodispersed particles. Compared with nano-Sb2O3, the Sb2O3/mica complexes have been achieved the same coordinated effects with Chlorinated Paraffin(CP) and excellent flame retardant properties.
基金This research is partly supported by the scholarship from China Scholarship Council under the Grant CSC(201608060071).
文摘High flammability of polymers has become a major issue which has restricted its applications.Recently,highly crystalline materials and metal–organic frameworks(MOFs),which consisted of metal ions and organic linkers,have been intensively employed as novel fire retardants(FRs)for a variety of polymers(MOF/polymer).The MOFs possessed abundant transition metal species,fire-retardant elements and potential carbon source accompanied with the facile tuning of the structure and property,making MOF,its derivatives and MOF hybrids promising for fire retardancy research.The recent progress and strategies to prepare MOF-based FRs are emphasized and summarized.The fire retardancy mechanisms of MOF/polymer composites are explained,which may guide the future design for efficient MOF-based FRs.Finally,the challenges and prospects related to different MOFbased FRs are also discussed and aim to provide a fast and holistic overview,which is beneficial for researchers to quickly get up to speed with the latest development in this field.
基金financially supported by the National Key R&D Program of China (Grant No. 2017YFE0127600)the National Natural Science Foundation of China (Nos. 51703236 and U1706229)+1 种基金the National Science Fund for Distinguished Young Scholars (No. 51625204)Key Scientific and Technological Innovation Project of Shandong (No. 2017CXZC0505)。
文摘Lithium–sulfur batteries have been regarded as the most promising high-energy electrochemical energy storage device owing to the high energy density, low cost and environmental friendliness. However, traditional lithium–sulfur batteries using ether-based electrolytes often suffer from severe safety risks(i.e. combustion). Herein, we demonstrated a novel kind of flame-retardant concentrated electrolyte(6.5 M lithium bis(trifluoromethylsulphonyl)imide/fluoroethylene carbonate) for highly-safe and widetemperature lithium–sulfur batteries. It was found that such concentrated electrolyte showed superior flame retardancy, high lithium-ion transference number(0.69) and steady lithium plating/stripping behavior(2.5 m Ah cm^(-2) over 3000 h). Moreover, lithium–sulfur batteries using this flame-retardant concentrated electrolyte delivered outstanding cycle performance in a wide range of temperatures(-10 °C, 25 °C and 90 °C). This superior battery performance is mainly attributed to the LiF-rich solid electrolyte interphase formed on lithium metal anode, which can effectively suppress the continuous growth of lithium dendrites. Above-mentioned fascinating characteristics would endow this flame-retardant concentrated electrolyte a very promising candidate for highly-safe and wide-temperature lithium–sulfur batteries.
文摘Na +-montmorillonite(Na +-MMT) was converted to organic montmorillonite(OMMT) using modifier which was synthesized at authors’ laboratory. PA6/OMMT nanocomposite was prepared via in situ intercalative polymerization. The limiting oxygen index (LOI), UL 94V flame retardancy and thermal stability of PA6/OMMT using thermal gravity analysis (TGA) were measured. The Fourier transform infrared (FTIR) technique was used to analyze the pyrolytic residuum and the cone calorimeter (CONE) was applied to determine a number of combustion parameters which were closely related to fire safety, including heat release rate, mass loss rate, effective combustion heat, total heat release, specific extinction area and the time of ignition. In addition, the elemental composition of the surface pyrolytic residuum and the corresponding X-ray photoelectron spectroscopy (XPS) data were obtained, and the morphology of the residuum from CONE measurement was examined by scanning electron microscope (SEM).
基金the National Natural Science Foundation of China(51901209).
文摘Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs)via their influence on the pyrolysis process.In this work,the effects of hexa(5-methyl-2-pyridinoxyl)cyclotriphosphazene(HMPOP)incorporation on the initial pyrolysis of an EP at 500–3500 K were studied using the ReaxFF method.The pyrolysis fragments,initial reaction pathways,and main products were identified for the EP and EP/HMPOP composites.The activation energies were derived by fitting the weight percentage curves for solid species during the pyrolysis reactions and the obtained values were in good agreement with experimental data.The initial EP pyrolysis reactions included four major decomposition modes,which primarily involved the cleavage of C–O and C–N bonds.The main pyrolysis products were H_(2)O,CO,C_(2)H_(4),and CH_(2)O.HMPOP bonded with the oxygen-containing fragments to form larger molecular fragments and reduced the amounts of C_(0)–C_(4) products,especially that of the harmful gas CH_(2)O.Thus,HMPOP promoted the formation of carbon clusters and reduced the generation of combustible gases,ultimately decreasing the capacity for fire propagation.
基金Supported by the National Natural Science Foundation of China(51273023)China Postdoctoral Science Foundation(2014M550023)
文摘An aliphatic epoxy monomer＂polypropyleneglycol-diglycidylether（PPGDGE,YF878）＂is loaded in the epoxy resins（EP）to evaluate the influence of epoxy structure on the blowing-out effect,which is caused by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide（DOPO）and octaphenyl silsesquioxane（OPS）.The flame retarding properties of these EP composites were tested using the LOI and UL-94 procedures.The pyrolytic gases produced and the thermal stability of the EP composites with different flame retardants were detected by TGA-FTIR in air.The negative effect of YF878 was detected from the TTI,HRR,and p-HRR results after the cone calorimeter test.The char produced by the EP composites after the cone calorimeter test was investigated by FTIR.It is proposed that the aliphatic chain of the YF878 is easy to break down and produce combustible gases,so it does not easily form a crosslinked structure in the condensed phase.These results are very helpful for investigation of the conditions under which the blowing-out effect in epoxy resins can be caused by synergy of phosphorous and silicon.
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the financial support from the Shenzhen Biodegradable Polymer Materials and Materials Genetic Evaluation Research Project Team (JCYJ20220818100217037)Science and Technology Program of Shenzhen (JSGG20200924171000001)+4 种基金the Key-Area Research and Development Program of Guangdong Province (2019B010941001)the Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(2018B030322001)the National Key Research and Development Program of China (2018YFB0704100)Joint Laboratory of Radiation Protection and Material Genetic Engineering Applications in Nuclear Facilitiessupported by the Pico Center at SUSTech CRF which receives support from the Presidential Fund and Development and Reform Commission of Shenzhen Municipality。
文摘The rapid development of communication technology and high-frequency electronic devices has created a need for more advanced electromagnetic interference(EMI)shielding materials.In response to this demand,a study has been conducted to develop multifunctional carbon nanofibers(CNFs)/polyaniline(PANI)aerogels with excellent electromagnetic interference shielding,flame retardancy,and thermal insulation performance.The process involved freeze-drying of electrospun CNFs and PANI nanoparticles followed by in situ growth PANI to coat the CNFs,creating the core-shell structured CNFs/PANI composite fiber and its hybrid aerogels(CP-3@PANI).The interaction between PANI and aniline(ANI)provides attachment sites,allowing additional ANI adsorption into the aerogel for in situ polymerization.This results in PANI uniformly covering the surface of the CNFs,creating a core-shell composite fiber with a flexible CNF core and PANI shell.This process enhances the utilization rate of the ANI monomer and increases the PANI content loaded onto the aerogel.Additionally,effective connections are established between the CNFs,forming a stable,conductive three-dimensional network structure.The prepared CP-3@PANI aerogels exhibit excellent EMI shielding efficiency(SE)of 85.4 dB and specific EMI SE(SE d^(-1))of 791.2 dB cm^(3)g^(-1)in the X-band.Due to the synergistic flame-retardant effect of CNFs,PANI,and the dopant(phytic acid),the CP-3@PANI aerogels demonstrate outstanding flame-retardant and thermal insulation properties,with a peak heat release rate(PHRR)as low as 7.8 W g^(-1)and a total heat release of only 0.58 kJ g^(-1).This study provides an effective strategy for preparing multifunctional integrated EMI shielding materials.
文摘High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.
基金financially supported by the National Natural Science Foundation of China(52104197)Hongkong Scholar Program(XJ2022022)+5 种基金National Science Foundation for Post-doctoral Scientists of China(2021M691549,2021M703082)National Natural Science Foundation of China(52272396,52306090)Jiangsu Provincial Double-Innovation Doctor Program(JSSCBS20210402)Natural Science Foundation of the Jiangsu Higher Education Institutions(21KJB620001)The Open Fund of the State Key Laboratory of Fire Science(SKLFS)Program(HZ2022-KF04)Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX22-0457)。
文摘The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety.With the merit of convenience,the method of designing functional separator has been adapted.Concretely,the carbon aerogel confined with CoS_(2)(CoS_(2)-NCA)is constructed and coated on Celgard separator surface,acquiring CoS_(2)-NCA modified separator(CoS_(2)-NCA@C),which holds the promoted electrolyte affinity and flame retardance.As revealed,CoS_(2)-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle,much higher than that of Celgard cell(987.1 mAh/g).Moreover,the thermal runaway triggering time is dramatically prolonged by 777.4 min,corroborating the promoted thermal safety of cell.Noticeably,the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS_(2)-NCA@C in suppressing the lithium dendrite growth.Overall,this work can provide useful inspirations for designing functional separator,coping with the vexing issues of LSBs.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China (No.2018YFE0309100)National Natural Science Foundation of China (No.51821005)。
文摘Accurate measurement of the average plasma parameters in the edge region,including the temperature and density of electrons and ions,is critical for understanding the characteristics of the scrape-off layer(SOL) and divertor plasma transport in magnetically confined fusion research.On the J-TEXT tokamak,a multi-channel retarding field analyzer(RFA) probe has been developed to study average plasma parameters in the edge region under various poloidal divertor and island divertor configurations.The edge radial profile of the ion-to-electron temperature ratio,τ_(i/e),has been determined,which gradually decreases as the SOL ion self-collisionality,v_(SOL)*,increases.This is broadly consistent with what has been observed previously from various tokamak experiments.However,the comparison of experimental results under different configurations shows that in the poloidal divertor configuration,even under the same v_(SOL)*,τ_(i/e) in the SOL region becomes smaller as the distance from the X-point to the target plate increases.In the island divertor configuration,τ_(i/e) near the O-point is higher than that near the X-point at the same v_(SOL)*,and both are higher than those in the limiter configuration.These results suggest that the magnetic configuration plays a critical role in the energy distributions between electrons and ions at the plasma boundary.
基金supported by the National Natural Science Foundation of China(51773134)the Sichuan Science and Technology Program(2019YFH0112)the Fundamental Research Funds for the Central Universities。
文摘Poly(ethylene oxide)(PEO)and its derivatives based gel polymer electrolytes(GPEs)are severely limited in advanced and safe lithium-ion batteries(LIBs)owing to the intrinsically high flammability of liquid electrolytes and PEO.Directly adding flame retardants to the GPEs can suppress their flammability and thus improve the safety of LIBs,but results in deteriorative electrochemical performance.Herein,a novel GPE with chemically bonded flame retardant(i.e.diethyl vinylphosphonate)in cross-linked polyethylene glycol diacrylate matrix,featuring both high-safety and high-performance,is designed.This as-prepared GPE storing the commercial 1 mol L^(-1) LiPF6 electrolyte resists high temperature of 200℃and cannot be ignited as well as possesses a high ionic conductivity(0.60 m S cm^(-1))and good compatibility with lithium.Notably,the LiFePO_(4)/Li battery with this GPE delivers a satisfactory capacity of 142.2 m A h g^(-1) and a superior cycling performance with a capacity retention of 96.3%and a coulombic efficiency of close to 100%for 350 cycles at 0.2 C under ambient temperature.Furthermore,the battery can achieve steady charge–discharge for 100 cycles with a coulombic efficiency of 99.5%at 1 C under 80℃and run normally even at a high temperature of 150℃or under the exposure to butane flame.Differential scanning calorimetry manifests significantly improved battery safety compared to commercial battery systems.This work provides a new pathway for developing next-generation advanced LIBs with enhanced performance and high safety.
基金supported by National Natural Science Foundation of China (No. 51473095)the Program of Innovative Research Team for Young Scientists of Sichuan Province (2016TD0010)
文摘The synergistic effect of conventional flame-retardant elements and graphene has received extensive attention in the development of a new class of flame retardants. Compared to covalent modification, the noncovalent strategy is simpler and expeditious and entirely preserves the original quality of graphene. Thus, non-covalently functionalized graphene oxide(FGO) with a phosphorus–nitrogen compound was successfully prepared via a one-pot process in this study. Polyethyleneimine and FGO were alternatively deposited on the surface of a poly(vinyl alcohol)(PVA) film via layer-by-layer assembly driven by electrostatic interaction, imparting excellent flame retardancy to the coated PVA film. The multilayer FGO-based coating formed a protective shield encapsulating the PVA matrix, effectively blocking the transfer of heat and mass during combustion. The coated PVA has a higher initial decomposition temperature of about 260 °C and a nearly 60% reduction in total heat release than neat PVA does. Our results may have a promising prospect for flame-retardant polymers.
