ABSTRACT Non-isocyanate polyurethane(NIPU)foams using a hydrolysable tannin,also vulgarly called tannic acid,namely here commercial chestnut wood tannin extract was prepared.Compression strength did not appear to depe...ABSTRACT Non-isocyanate polyurethane(NIPU)foams using a hydrolysable tannin,also vulgarly called tannic acid,namely here commercial chestnut wood tannin extract was prepared.Compression strength did not appear to depend on the foam apparent density while the formulation composition of the NIPU foams has been shown to be more determinant.These NIPU foams appeared to be self-extinguishing once the high temperature flame is removed.The ignition time gave encouraging results but for improved fire resistance the foams may need some fire-retardant addition.FTIR spectrometry showed the formation of non-isocyanate urethane linkages.Thermogravimetric analysis indicated a good thermal resistance of these foams,with thermal degradation following four phases.First in the interval 25℃–120℃ range,mainly evaporation of water occurs with a maximal loss of 10%weight.In the 150℃–450℃ temperature range foams mass loss is of almost 70%.In particular in the 125℃–275℃ range occurs the degradation of some small molecular weight substances.In the 500℃–790℃ temperature range the foams do not present any further large degradation.展开更多
Super pure 2,5-dichloroterephthaloyl dichloride (DDC) was prepared by chlorination andcontrolled by Gas Chromatography(GC) method. As a third monomer, DDC waspolycondensated into chlorinated PPTA together with terepht...Super pure 2,5-dichloroterephthaloyl dichloride (DDC) was prepared by chlorination andcontrolled by Gas Chromatography(GC) method. As a third monomer, DDC waspolycondensated into chlorinated PPTA together with terephthaloyldichloide (TPDC) andparaphenylene diamine (PPDA). The polycondensation conditions and the relationship betweenthe thermal behavior, viscosity, solubility, phase transition temperature of the modifiedpolyamide and the third monomer content discussed in this paper.展开更多
The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder esc...The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.展开更多
The self-extinguishing behavior of kerosene spray fire was investigated in a completely enclosed compartment with the size of 3 m× 3 m × 3.4 m. The spray was generated by locating one BETE nozzle at the cent...The self-extinguishing behavior of kerosene spray fire was investigated in a completely enclosed compartment with the size of 3 m× 3 m × 3.4 m. The spray was generated by locating one BETE nozzle at the center of the bottom wall. A series of spray fire videos were obtained by changing BETE nozzle type and injecting pressure. The results show that spray ftre undergoes four stages： the growth stage, the quasi-steady stage, the stretch stage and the self-extinguishing stage. Consumption of large quantities of oxygen causes spray fire to first be stretched and then quench. In this process, fire base migrates away from spray region and leads to the emergence of ghost- hag fire. Ghosting fire promotes the instability of spray fire and large fluctuation of its height, which provides help to its self-extinguishing. With increasing the injecting pressure or the nozzle diameter, the self-extinguishing time decreases. It is found that the self-extinguishing time is approximately in inverse relation with injecting flow rate. Additionally, we also observed the occurrence of two-phase de flagration just after ignition, and it accelerates the spray fire growth and induces a larger fire height than the following quasi-steady spray fire. The deflagration turns stronger with increasing the injecting pressure.展开更多
Commercial-level sodium metal batteries require electrolytes with high ionic mobility and excellent thermo-mechanical and electrochemical stability.Conventional flammable liquid electrolytes,prone to dendrite growth a...Commercial-level sodium metal batteries require electrolytes with high ionic mobility and excellent thermo-mechanical and electrochemical stability.Conventional flammable liquid electrolytes,prone to dendrite growth and unstable interfacial reactions,rarely perform beyond coin-cell demonstrations.To address these shortcomings,a multifunctional composite quasi-solid polymer electrolyte(QSPE)that incorporates boron nitride(BN)as an engineered filler in a highly conductive polymer blend system has been developed.The optimized formation(15BN QSPE)delivers a room-temperature ionic conductivity of 2.15 m S cm^(-1)and a sodium-ion transference number of 0.80.Molecular dynamics simulations elucidate the coordination environment and show improved transport in the presence of BN.BN is chemically active and bifunctional:boron acts as an electron acceptor,interacting with solvents and macromolecules,while nitrogen coordinates with sodium ions,tailoring the solvation environment and transport pathways to promote efficient ion migration.The 15BN QSPE is self-extinguishing,resists oxidative thermal degradation,and enables stable cycling in symmetric sodium cells for>1400 h at0.5 m A cm^(-2).A Prussian blue full cell achieves>1500 stable cycles at 1C with -99% Coulombic efficiency in coin-cell configuration.A two-layer pouch cell with dual 15BN QSPE layers delivers 600 stable cycles at 0.125C and withstands rigorous mechanical abuse.These results position 15BN QSPE as a scalable,highperformance electrolyte offering enhanced safety and efficiency for next-generation sodium metal batteries.展开更多
This paper focuses on the superiority of organic?inorganic hybrid ion-gel electrolytes for lithiumion batteries(LiBs)over commercial electrolytes,such as 1 M LiPF6 in 1:1 ethylene carbonate(EC):dimethyl carbonate{DMC)...This paper focuses on the superiority of organic?inorganic hybrid ion-gel electrolytes for lithiumion batteries(LiBs)over commercial electrolytes,such as 1 M LiPF6 in 1:1 ethylene carbonate(EC):dimethyl carbonate{DMC){1 M LiPF6-EC:DMC},in terms of their flame susceptibility.These ion-gel electrolytes possess ionic liquid monomers,which are confined within the borosilicate or silicate matrices that are ideal for nonflammability.Naked flame tests confirm that the organicinorganic hybrid electrolytes are less susceptible to flames,and these electrolytes do not suffer from a major loss in terms of weight.In addition,the hybrids are self-extinguishable.Therefore,these hybrids are only oxidized when subjected to a flame unlike other commercial electrolytes used in lithium-ion batteries.Supplementary analyses using differential scanning calorimetric studies reveal that the hybrids are glassy until the temperature reaches more than 100℃.The current results are consistent with previously published data on the organic-inorganic hybrids.展开更多
Sealing the tunnel entrance is one of the effective ways to control the fire in tunnels.The fire characteristics of tunnels with entrances sealed are greatly different under various sealing distance,sealing time,seali...Sealing the tunnel entrance is one of the effective ways to control the fire in tunnels.The fire characteristics of tunnels with entrances sealed are greatly different under various sealing distance,sealing time,sealing ratio and heat release rate(HRR).The previous researches only focus on the influence of sealing ratio and sealing time on flame characteristics in the tunnel and did not consider sealing method,sealing distance and heat release rate,all of which directly impact the oxygen concentration in the tunnel,significantly affecting the flame combustion.In this work,we built a reduced-scale tunnel model to investigate the fire behaviors in the sealed tunnel;the major factors include sealing ratio,sealing method,sealing distance and heat release rate.The experimental results show that the flame tends to self-extinguish due to the less oxygen concentration with the tunnel entrances sealed.The greater HRR,the larger sealing ratio,the shorter sealing distance,the easier the fire in tunnels extinguish.Fire flame is easier to self-extinguish in up sealed tunnel comparing with the down sealed tunnel.It is found that there is a critical sealing ratio,at which the smoke temperature under the ceiling would reach the maximum;other than that ratio,the maximum smoke temperature would decrease.A theoretical analysis was performed to investigate the flame self-extinguishing time in fully sealed tunnels,and the correlation was established among the self-extinguishing time,heat release rate and sealing distance,which can approximately predict the self-extinguishing time of tunnel fires.展开更多
文摘ABSTRACT Non-isocyanate polyurethane(NIPU)foams using a hydrolysable tannin,also vulgarly called tannic acid,namely here commercial chestnut wood tannin extract was prepared.Compression strength did not appear to depend on the foam apparent density while the formulation composition of the NIPU foams has been shown to be more determinant.These NIPU foams appeared to be self-extinguishing once the high temperature flame is removed.The ignition time gave encouraging results but for improved fire resistance the foams may need some fire-retardant addition.FTIR spectrometry showed the formation of non-isocyanate urethane linkages.Thermogravimetric analysis indicated a good thermal resistance of these foams,with thermal degradation following four phases.First in the interval 25℃–120℃ range,mainly evaporation of water occurs with a maximal loss of 10%weight.In the 150℃–450℃ temperature range foams mass loss is of almost 70%.In particular in the 125℃–275℃ range occurs the degradation of some small molecular weight substances.In the 500℃–790℃ temperature range the foams do not present any further large degradation.
文摘Super pure 2,5-dichloroterephthaloyl dichloride (DDC) was prepared by chlorination andcontrolled by Gas Chromatography(GC) method. As a third monomer, DDC waspolycondensated into chlorinated PPTA together with terephthaloyldichloide (TPDC) andparaphenylene diamine (PPDA). The polycondensation conditions and the relationship betweenthe thermal behavior, viscosity, solubility, phase transition temperature of the modifiedpolyamide and the third monomer content discussed in this paper.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 50078057)Program for New Century Excellent Talents in University(Grant No. NCET-06-0340)
文摘The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.
基金supported by National Natural Science Foundation of China(Grant No.51276177)
文摘The self-extinguishing behavior of kerosene spray fire was investigated in a completely enclosed compartment with the size of 3 m× 3 m × 3.4 m. The spray was generated by locating one BETE nozzle at the center of the bottom wall. A series of spray fire videos were obtained by changing BETE nozzle type and injecting pressure. The results show that spray ftre undergoes four stages： the growth stage, the quasi-steady stage, the stretch stage and the self-extinguishing stage. Consumption of large quantities of oxygen causes spray fire to first be stretched and then quench. In this process, fire base migrates away from spray region and leads to the emergence of ghost- hag fire. Ghosting fire promotes the instability of spray fire and large fluctuation of its height, which provides help to its self-extinguishing. With increasing the injecting pressure or the nozzle diameter, the self-extinguishing time decreases. It is found that the self-extinguishing time is approximately in inverse relation with injecting flow rate. Additionally, we also observed the occurrence of two-phase de flagration just after ignition, and it accelerates the spray fire growth and induces a larger fire height than the following quasi-steady spray fire. The deflagration turns stronger with increasing the injecting pressure.
基金a seed grant from IIT Delhi(SGNF148)supported by the JST-ERATO Yamauchi Materials SpaceTectonics Project(JPMJER2003)+2 种基金the ARC Australian Laureate Fellowship(FL230100095)the UQ-Yonsei International Joint Research Projectthe support from JSPS Postdoctoral Fellowships for Research in Japan。
文摘Commercial-level sodium metal batteries require electrolytes with high ionic mobility and excellent thermo-mechanical and electrochemical stability.Conventional flammable liquid electrolytes,prone to dendrite growth and unstable interfacial reactions,rarely perform beyond coin-cell demonstrations.To address these shortcomings,a multifunctional composite quasi-solid polymer electrolyte(QSPE)that incorporates boron nitride(BN)as an engineered filler in a highly conductive polymer blend system has been developed.The optimized formation(15BN QSPE)delivers a room-temperature ionic conductivity of 2.15 m S cm^(-1)and a sodium-ion transference number of 0.80.Molecular dynamics simulations elucidate the coordination environment and show improved transport in the presence of BN.BN is chemically active and bifunctional:boron acts as an electron acceptor,interacting with solvents and macromolecules,while nitrogen coordinates with sodium ions,tailoring the solvation environment and transport pathways to promote efficient ion migration.The 15BN QSPE is self-extinguishing,resists oxidative thermal degradation,and enables stable cycling in symmetric sodium cells for>1400 h at0.5 m A cm^(-2).A Prussian blue full cell achieves>1500 stable cycles at 1C with -99% Coulombic efficiency in coin-cell configuration.A two-layer pouch cell with dual 15BN QSPE layers delivers 600 stable cycles at 0.125C and withstands rigorous mechanical abuse.These results position 15BN QSPE as a scalable,highperformance electrolyte offering enhanced safety and efficiency for next-generation sodium metal batteries.
文摘This paper focuses on the superiority of organic?inorganic hybrid ion-gel electrolytes for lithiumion batteries(LiBs)over commercial electrolytes,such as 1 M LiPF6 in 1:1 ethylene carbonate(EC):dimethyl carbonate{DMC){1 M LiPF6-EC:DMC},in terms of their flame susceptibility.These ion-gel electrolytes possess ionic liquid monomers,which are confined within the borosilicate or silicate matrices that are ideal for nonflammability.Naked flame tests confirm that the organicinorganic hybrid electrolytes are less susceptible to flames,and these electrolytes do not suffer from a major loss in terms of weight.In addition,the hybrids are self-extinguishable.Therefore,these hybrids are only oxidized when subjected to a flame unlike other commercial electrolytes used in lithium-ion batteries.Supplementary analyses using differential scanning calorimetric studies reveal that the hybrids are glassy until the temperature reaches more than 100℃.The current results are consistent with previously published data on the organic-inorganic hybrids.
基金financially supported by National Natural Science Foundation of China(NSFC)(Grant No.52038009).
文摘Sealing the tunnel entrance is one of the effective ways to control the fire in tunnels.The fire characteristics of tunnels with entrances sealed are greatly different under various sealing distance,sealing time,sealing ratio and heat release rate(HRR).The previous researches only focus on the influence of sealing ratio and sealing time on flame characteristics in the tunnel and did not consider sealing method,sealing distance and heat release rate,all of which directly impact the oxygen concentration in the tunnel,significantly affecting the flame combustion.In this work,we built a reduced-scale tunnel model to investigate the fire behaviors in the sealed tunnel;the major factors include sealing ratio,sealing method,sealing distance and heat release rate.The experimental results show that the flame tends to self-extinguish due to the less oxygen concentration with the tunnel entrances sealed.The greater HRR,the larger sealing ratio,the shorter sealing distance,the easier the fire in tunnels extinguish.Fire flame is easier to self-extinguish in up sealed tunnel comparing with the down sealed tunnel.It is found that there is a critical sealing ratio,at which the smoke temperature under the ceiling would reach the maximum;other than that ratio,the maximum smoke temperature would decrease.A theoretical analysis was performed to investigate the flame self-extinguishing time in fully sealed tunnels,and the correlation was established among the self-extinguishing time,heat release rate and sealing distance,which can approximately predict the self-extinguishing time of tunnel fires.
