This study shows that sulfide solid-state electrolytes,β-Li_(3)PS_(4)and Li_(6)PS_(5)Cl,are flammable solids.Both solid-state electrolytes release sulfur vapor in a dry,oxidizing environment at elevated temperature&l...This study shows that sulfide solid-state electrolytes,β-Li_(3)PS_(4)and Li_(6)PS_(5)Cl,are flammable solids.Both solid-state electrolytes release sulfur vapor in a dry,oxidizing environment at elevated temperature<300℃.Sulfur vapor is a highly flammable gas,which then auto-ignites to produce a flame.This behavior suggests that an O_(2)-S gas-gas reaction mechanism may contribute to all-solid-state battery thermal runaway.To improve all-solid-state battery safety,current work focuses on eliminating the O_(2)source by changing the cathode active material.The conclusion of this study suggests that all-solidstate battery safety can also be realized by the development of solid-state electrolytes with less susceptibility to sulfur volatilization.展开更多
Nowadays buildings contain innovative materials,materials from local resources,production surpluses and rapidly renewable natural resources.Phase Change Materials(PCM)are one such group of novel materials which reduce...Nowadays buildings contain innovative materials,materials from local resources,production surpluses and rapidly renewable natural resources.Phase Change Materials(PCM)are one such group of novel materials which reduce building energy consumption.With the wider availability of microencapsulated PCM,there is an opportunity to develop a new type of insulating materials,combinate PCM with traditional insulation materials for latent heat energy storage.These materials are typically flammable and are located on the interior wall finishing yet there has been no detailed assessment of their fire performance.In this research work prototypes of low-density insulating boards for indoor spaces from hemp shives using carbamide resin binder and cold pressing were studied.Bench-scale cone calorimeter tests were conducted to evaluate fire risk,with a focus on assessing material flammability properties and the influence of PCM on the results.In this research,the amount of smoke,heat release rate,effective heat of combustion,specific extinction coefficient,mass loss,carbon dioxide yield,specific loss factor,ignition time of hemp straws samples and samples of hemp straws with 10%and without PCM admixture were compared.There is a risk of flammability for PCM and their fire reaction has not been evaluated when incorporating PCM into interior wall finishing boards.The obtained results can be used by designers to balance the potential energy savings of using PCM with a more complete understanding and predictability of the associated fire risk when using the proposed boards.It also allows for appropriate risk mitigation strategies.展开更多
Since the 1980s,mass market upholstered furniture sold in the United Kingdom has incorporated flame retardant chemicals to meet regulatory flammability requirements.However,UK fire deaths remain com-parable with simil...Since the 1980s,mass market upholstered furniture sold in the United Kingdom has incorporated flame retardant chemicals to meet regulatory flammability requirements.However,UK fire deaths remain com-parable with similar European countries which have no such regulations.Quantitative measures of the effect that different chemical flame retardants additives have on the flammability and smoke toxicity of UK regulatory-compliant upholstered furniture remain limited.It has been shown that most fatal fires in-volve upholstered furniture;most fire deaths result from toxic gas inhalation;gas phase flame retardants increase the toxicity of smoke;and the fall in fire deaths over the last 30 years is the same in countries with and without furniture flammability regulations.Moreover,the presence of certain flame retardants in furniture is a significant obstacle to any meaningful end-of-life processing.The burning behaviour and smoke toxicity of nine upholstered furniture composites using a range of flame retardant technologies were assessed in the cone calorimeter.The total heat release(THR)varied from 46 MJ m^(−2) to 68 MJ m^(−2),the time-to-ignition(tti)from 8 s to 105 s,and peak heat release rate(pHRR)from 230 kW m^(−2) to 430 kW m^(−2).The composite filled with PET showed the longest tti while the expandable graphite fabric on the FR-foam showed the lowest pHRR.The composite with the Br-FR fabric and the FR-foam had the shortest tti,the greatest smoke,the second highest CO and the highest HCN yield.The composite with the non-FR fabric and the PET filling had the longest tti.For all the fabrics,the transition from non-FR to FR foam resulted in significant increases in the smoke,CO and HCN,except CO of Br-FR and FR-foam was slightly lower than non-FR foam.Smoke toxicity predictions show that the use of gas phase flame retardants in both the fabrics and fillings of upholstered furniture contributes to the high proportion of smoke-related fire casualties.The work shows that the smoke toxicity of upholstered furniture can be reduced by using condensed phase FRs,such as expandable graphite,or less flammable materials,such as polyester wadding.The regulatory component tests which focus on ignitability have been shown to be ineffective at assessing the fire safety of composites representative of furniture as sold.The alternative approach of assessing heat release and smoke toxicity,as described here,would improve the fire safety of furniture while reducing reliance on additive flame retardants acting in the gas phase.展开更多
This study deals with the analysis of dynamic mechanical,thermal and flammability properties of treated and untreated pineapple leaf fiber(PALF)and kenaf fiber(KF)phenolic composites.Results indicated that storage mod...This study deals with the analysis of dynamic mechanical,thermal and flammability properties of treated and untreated pineapple leaf fiber(PALF)and kenaf fiber(KF)phenolic composites.Results indicated that storage modulus was decreased for all composites with increases in temperature and pattern of slopes for all composites,having almost the same values of E′at glass transition temperature(Tg).The peak of the loss modulus of pure phenolic composites was shown to be much less.After the addition of kenaf/PALF,peaks were higher and shifted towards a high temperature.The Tan delta peak height was low for pure phenolic composites and maximum for 60%PALF phenolic composites.Cole-Cole analysis was carried out to understand the phase behavior of the composite samples.Thermogravimetric analysis(TGA)results indicated that pure phenolic composites have better thermal stability than PALF and kenaf phenolic composites.Vertical and horizontal UL-94 tests were conducted and showed pure phenolic resin is highly fire resistant.The overall results showed that treated KF composites enhanced the dynamic mechanical and thermal properties among all PALF/KF composites.展开更多
Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively （designated as BAPNCP, BAPBACP and BAPNPGCP, respectively...Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively （designated as BAPNCP, BAPBACP and BAPNPGCP, respectively）, were synthesized and characterized. In addition, the effects of backbone structures on curing behaviors of the monomers and thermal and flammability properties of the resulting polymers were systematically studied. The results indicated that BAPNPGCP displayed the highest enthalpy of the curing reaction associated with the ring-opening of benzoxazine, which was due to the effect of benzoxazine ring content per unit mass. Interestingly, the 5 wt% weight loss temperature and char residue after thermogravimetric test for poly（BAPNPGCP） were 8 ℃ and 7% higher than those of poly（BAPBACP）. Meanwhile, the total heat release of poly（BAPNPGCP） was less than half of that for poly（BAPBACP）, indicating the substantial effect of benzoxazine ring content on flammability and char formation. Furthermore, it was found that poly（BAPNCP） gave the best thermal stability and flame retardancy, which was due to the synergistic effect between naphthalene group and benzoxazine ring content. This study provides new insight into the curing behavior of benzoxazine and further understanding on the high performance of polybenzoxazine.展开更多
The effects of magnesium oxide （MgO） on the flame retardant performance of intumescent systems based on ammonium polyphosphate （APP） and pentaerythritol （PER） in ethylene vinyl acetate copolymer （EVA） were stu...The effects of magnesium oxide （MgO） on the flame retardant performance of intumescent systems based on ammonium polyphosphate （APP） and pentaerythritol （PER） in ethylene vinyl acetate copolymer （EVA） were studied. The results showed that MgO affects both the quality and quantity of residual char. There is an optimal value for the loading amount of MgO. More or less MgO loading may cause the formation of defective char layers and worsen the flame retardancy of EVA. According to the results of limiting oxygen index （LOI）, vertical flammability test （UL94 rating） and cone calorimetry （CONE）, the best flame retardancy with a strong and well intumescent char is obtained from the sample with 1 wt% of MgO, which has the highest LOI value of 27.9, UL94 rating of V-0 and the lowest peak heat release rate of 242 kW·m-2.展开更多
Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied.ABS/MWNTs composites were prepared via melt blending with ...Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied.ABS/MWNTs composites were prepared via melt blending with the MWNTs content varied from 0.2% to 4.0% by mass.Thermogravimetry results showed that the addition of MWNTs accelerated the degradation of ABS during the whole process under air atmosphere,and both onset and maximum degradation temperature were lower than those of pure ABS.The destabilization...展开更多
Background:Flammability is a compound plant trait that can vary significantly across natural populations within species.Investigating intraspecific variation in flammability provides insights into the evolution of pla...Background:Flammability is a compound plant trait that can vary significantly across natural populations within species.Investigating intraspecific variation in flammability provides insights into the evolution of plant flam-mability and inform understanding of wildfire risk and behaviour in different habitats.Methods:We measured four flammability variables,representing ignitibility(time to ignition),sustainability(total burning time),combustibility(maximum temperature during burning)and consumability(percentage of biomass consumed by fire)to assess the shoot-level flammability of Dracophyllum rosmarinifolium(G.Forst.)(Ericaceae),a polymorphic endemic species distributed throughout New Zealand.We examined the relationship between flammability components and a suite of climatic and geographic variables(elevation,latitude,mean annual temperature(MAT),mean annual rainfall(MAR)of the sample locations,etc.).Results:We measured shoot-level flammability components of 62 individuals across eight populations.Burning time,maximum temperature and burnt biomass were positively correlated with each other,while ignition score was independent of other flammability components.All flammability components varied significantly across the eight populations.The habitat conditions we considered were not related to any of the shoot-level flammability components of D.rosmarinifolium.Conclusions:Intraspecific variation in flammability in D.rosmarinifolium may be a byproduct of selection on other functional traits,such as leaf size,shoot lipid content,indicating that plant flammability is an incidental result,rather than selected for,at least in ecosystems without fire as a selective force.展开更多
A small cubic closed vessel with schlieren measurement technique combined with high-speed video camera were used to study limit flame properties under microgravity conditions at atmospheric pressure and room temperatu...A small cubic closed vessel with schlieren measurement technique combined with high-speed video camera were used to study limit flame properties under microgravity conditions at atmospheric pressure and room temperature.The rich flammability limit of C3H8/air was determined to be 9.2% C3H8.Stretched flame propagation speeds,stretched laminar burning velocities and unstretched laminar burning velocities near rich C3H8/air flammability limits were measured at different equivalence ratios.Outwardly propagating spherical flames were used to study the sensitivities of the flame propagation speeds and laminar burning velocities to flame stretch using Markstein lengths.Unstretched laminar burning velocity at rich flammability limit was determined to be 1.09cm/s.Lewis numbers were less than unity in rich C3H8/air and negative Markstein lengths were concluded.Absolute values of Markstein lengths were found to decrease linearly with equivalence ratios increase.展开更多
The consumption ofthermoset resins as building polymers is approximately over one million tone word wide. The thermoset resins are proven construction materials for the technical and highly demanding applications of t...The consumption ofthermoset resins as building polymers is approximately over one million tone word wide. The thermoset resins are proven construction materials for the technical and highly demanding applications of the transportation, electrical and building part industry. Heat stability, high thermal, low shrinkage, excellent mechanical properties are typical for their type of polymers. Above applications in addition to the mechanical properties also require good flame retardants of the materials. Undertaken activities refer to official draft, laws and legal recommendations in UE states. This paper presents positive effect of reduced flammability of thermoset resins （unsaturated polyester and epoxy resins） thanks to the use of nanocomposites containing multi-ingredient halogen-flee flame retardants which combine conventional phosphorus/nitrogen modifiers interacting with nanofillers （oMMT （organomodified montmorillonite）, EG （expandable graphite）, graphene, GO （graphene oxide）, nSi （nanosilica））.展开更多
Sustainable aviation fuel(SAF)blend has been confirmed to benefit for greenhouse gases reduction,and thus the property of blend fuel should be understanded the detail to support the utilization in aircraft.Low flammab...Sustainable aviation fuel(SAF)blend has been confirmed to benefit for greenhouse gases reduction,and thus the property of blend fuel should be understanded the detail to support the utilization in aircraft.Low flammability limit(LFL)is a key property of jet fuel which should be sufficiently flammable to burn in combustor of aero-engine and meanwhile should be non-flammable for safety storage in fuel tank of aircraft.LFL of fuel could be influenced by integrating effects including molecule structure,intramolecular chemical bond energy and binding energy of molecule to molecule.Three types of theoretical models,based on different individual view including LFL of every pure hydrocarbon,stoichiometric concentration,and combustion enthalpy,present unsatisfactory simulation results,which can be deduced without integrating all potential influence factors together.The arti-ficial neural network(ANN)approaches have been involved to bridge the relationship of the complex compo-sitions in jet fuels with LFL.For providing adequate and available composition input,the boundary of fuel compositions has been extracted based on constrains of boiling point,flash point and freeze point coupling with statistic petroleum-based jet fuels.By clustering analysis,43 critical classes of compositions,extracted as sur-rogate hydrocarbons based on with similar LFL within 1%deviation,have been deployed as input matrix.ANNLFL model,trained by only drop-in fuel with feature of Sigmoid function as an activation function,can distin-guish drop-in fuel with non-drop-in fuel.ANN LFL model can predict LFL of drop-in fuel with 0.988 accuracy.The predict output value of non-drop-in fuel could present obvious deviation with traditional jet fuel.The optimization methodologies of ANN-LFL model could be improved the understanding of LFL and extend ANN in SAF utilization.展开更多
In the present study, a novel model is proposed to evaluate the lower flammability limit(LFL) of alkane diluted with CO2. The LFL model is based on flame phenomenon simulation(FS-LFL). The model consists of combustion...In the present study, a novel model is proposed to evaluate the lower flammability limit(LFL) of alkane diluted with CO2. The LFL model is based on flame phenomenon simulation(FS-LFL). The model consists of combustion, turbulence, and igniter models, which are used to characterise the combustion based on the chemical kinetics and CFD, which is not feasible with traditional methods. The flame simulation phenomenon was validated by contrast with experiment and same criterion of flammability limit in the experiment was adopted. The FS-LFL model was used to predict the LFLs of a propane-CO2 mixture and propane at various temperatures. The model performance was analysed by comparing the results with experimental data and predictions obtained from existing methods. The AARDs between the predicted and experimentally determined LFLs of the propane-CO2 mixture are 0.34%, 1.19%, and 1.35% at 30℃, 50℃, and 70℃, respectively. The model also has a good predictive power with respect to the LFLs of propane at initial temperatures ranging from 30℃–300℃, with an AARD of 2.10%. When the dilution of CO2 is 90%, the model yields a better result due to the utilisation of the chemical kinetics mechanism. This result is instructive for the use of this method in the prediction of upper flammability limits.展开更多
Flammability properties of composites of wood fiber and recycled plastic were evaluated by the cone calorimeter and oxygen index chamber. Results were shown as follows: 1) Wood-PVC composite showed worse thermal stabi...Flammability properties of composites of wood fiber and recycled plastic were evaluated by the cone calorimeter and oxygen index chamber. Results were shown as follows: 1) Wood-PVC composite showed worse thermal stability on time to ignition (TTI) and mean heat release rate (MHRR), but better performance on heat release rate (HRR) and mean efficient heat of combustion (MEHC); wood-PP composite had better thermal stability properties, but was worse on other fire performance; 2) Compared with wood-PVC composite, wood-PP composite showed excellent thermal stability, but behaved dangerous as a whole; 3) Coupling agent PAPI changed fire performance of wood-PP composite and showed a longer TTI, lower EHC but higher HRR. It can be concluded that flame resistance treatment should be considered if wood-plastic composites are used as decorated materials.展开更多
As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group con...As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group contribution method,which is significative to the safe application of hydrocarbons in the ORC system.The whole modeling process is divided into two parts:pure compound prediction and mixture prediction.The contribution factors of inert gases and dilute concentration were first introduced in the group contribution method.Moreover,the respective 95%-confidence interval of the mixture based on linear superposition method has been proposed in the developed group contribution model to improve the safety coefficient.For CO2 as inert gas,the average relative error and correlation coefficient are 5.34%and 0.88 for lower flammability limit while 6.99%and 0.95 for upper flammability limit.For N2 as inert gas,the average relative error and correlation coefficient are 7.47%and 0.84 for lower flammability limit while 6.68%and 0.97 for upper flammability limit.Most importantly,this group contribution method has extended the application range to make up the shortcomings of other flammability limit prediction methods aiming at hydrocarbon and inert gas mixtures and proposed the uncertainty analysis to provide reliable prediction range.展开更多
1.Introduction.The ever-increasing demands for high-energy-density power supply systems have driven the rapid development of conventional lithium-ion batteries,of which properties are approaching to the ceiling.In the...1.Introduction.The ever-increasing demands for high-energy-density power supply systems have driven the rapid development of conventional lithium-ion batteries,of which properties are approaching to the ceiling.In the meantime,the safety of lithium-ion batteries also grabs more attention as their wide application in consumer electronics and electric vehicles.The safety of battery system can be enhanced inherently by replacing the flammable liquid electrolytes with inorganic solid electrolytes,which makes solid-state battery one of the most promising candidates of next-generation energy storage systems[1-3].Additionally,the improvements in energy density are foreseen as solid electrolytes enable lithium metal anode[4-11]and high-voltage cathodes[12-15].展开更多
Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This charact...Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This characteristic holds significant implications in the realm of novel satellite propulsion.Introducing a fraction of the electrical energy into energetic ionic liquid fuels,the thermal decomposition process is facilitated by reducing the apparent activation energy required,and electrical energy can trigger the electrochemical decomposition of ionic liquids,presenting a promising approach to enhance combustion efficiency and energy release.This study applied an external voltage during the thermal decomposition of 1-ethyl-3-methylimidazole nitrate([EMIm]NO_(3)),revealing the effective alteration of the activation energy of[EMIm]NO_(3).The pyrolysis,electrochemical decomposition,and electron assisted enhancement products were identified through Thermogravimetry-Differential scanning calorimetry-Fourier transform infrared-Mass spectrometry(TG-DSC-FTIR-MS)and gas chromatography(GC)analyses,elucidating the degradation mechanism of[EMIm]NO_(3).Furthermore,an external voltage was introduced during the combustion of[EMIm]NO_(3),demonstrating the impact of voltage on the combustion process.展开更多
Compared to currently commercialized lithium-ion batteries,which use flammable organic liquid electrolytes and low-energy-density graphite anodes,solid-state lithium-metal batteries(SSLMBs)offer enhanced energy densit...Compared to currently commercialized lithium-ion batteries,which use flammable organic liquid electrolytes and low-energy-density graphite anodes,solid-state lithium-metal batteries(SSLMBs)offer enhanced energy density and improved safety,making them promising alternatives for next-generation rechargeable batteries[1].As a crucial component of these batteries,solid-state electrolytes—divided into inorganic solid ceramic electrolytes(SCEs)and organic solid polymer electrolytes(SPEs)—are vital for lithium-ion transport and inhibiting lithium dendrite growth.Among them,SCEs exhibit high ionic conductivity,excellent mechanical properties,and outstanding electrochemical and thermal stability.Nevertheless,their brittleness,interfacial challenges with electrodes,and the requirement for high stacking pressure during battery operation significantly hinder their scalable application.In comparison,SPEs are more favourable for manufacturing due to their flexibility and good interfacial compatibility with electrodes[2].Despite these advantages,SPEs still face significant challenges in achieving practical application.Firstly,typical SPEs,such as poly(ethylene oxide)(PEO),poly(vinylidene fluoride)(PVDF),and poly(ethylene glycol)diacrylate(PEGDA),are characterized by high crystallinity,which causes polymer chains to be tightly packed and rigid.This restricts the segmental motion within the SPEs,resulting in low ionic conductivity.Secondly,compared to lithium ions,anions with large ionic radii and low charge density typically form weaker interactions with the polymer chains,which facilitates their mobility and results in a low lithium-ion transference number(tt).Thirdly,the weak interactions between polymer chains in typical SPEs lead to a low elastic modulus,which in turn compromises their poor mechanical strength.展开更多
Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is ov...Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is over mature forest, and accounts for much proportion. Fire season in this area is winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire season lasts from October to next February,but to April in an individual arid year. Most of the fires in this area are surface fires, crown fire, can occur after long time drought. Ground fires do not occur in the region.展开更多
In the period of the first twenty years after World War II the number of fires in Polish hard coal mines reached annually the value of several thousands of cases. About 80% of fires constituted spontaneous fires. Inve...In the period of the first twenty years after World War II the number of fires in Polish hard coal mines reached annually the value of several thousands of cases. About 80% of fires constituted spontaneous fires. Investigations into the development of new methods of fire hazard prediction and implementation of new methods and means of fire prevention as well as the introduction of prohibition concerning the use of products manufactured of combustible organic materials in underground mine workings re-duced considerably the hazard of underground fire rise. The worked out at the Central Mining Institute (GIG) new method of un-derground fire prediction allows the correct selection of fire prevention means. The introduction into common use of fire-resistant conveyor belts, the main factor giving rise to spontaneous fires, and methods of assessment of their fire resistance eliminated prac-tically the fire hazard. These activities contributed in an efficient way to the reduction of the number of underground fires to a sat-isfactory level.展开更多
A series of non-flammable high strength Mg-Al-Ca-Mn alloys with high Ca/Al ratio were fabricated by water-cooled casting and hot extrusion. Microstructure and mechanical properties were investigated to study the effec...A series of non-flammable high strength Mg-Al-Ca-Mn alloys with high Ca/Al ratio were fabricated by water-cooled casting and hot extrusion. Microstructure and mechanical properties were investigated to study the effect of hot extrusion. The experimental results showed that hot extrusion significantly improved the mechanical properties by grain refinement and precipitates. Ignition temperature was measured by furnace test, and the highest temperature is up to approximately 1040℃ due to the composite oxide layer consisting of CaO and MgO. In addition, a laboratory-scale flame test was conducted to evaluate the flammability of smaller specimens. These alloys exhibited marvelous flame resistance attributed to the protective effect of dense and stable oxide film.展开更多
文摘This study shows that sulfide solid-state electrolytes,β-Li_(3)PS_(4)and Li_(6)PS_(5)Cl,are flammable solids.Both solid-state electrolytes release sulfur vapor in a dry,oxidizing environment at elevated temperature<300℃.Sulfur vapor is a highly flammable gas,which then auto-ignites to produce a flame.This behavior suggests that an O_(2)-S gas-gas reaction mechanism may contribute to all-solid-state battery thermal runaway.To improve all-solid-state battery safety,current work focuses on eliminating the O_(2)source by changing the cathode active material.The conclusion of this study suggests that all-solidstate battery safety can also be realized by the development of solid-state electrolytes with less susceptibility to sulfur volatilization.
基金supported by the European Regional Development Fund Postdoctoral Research Support“Structures and Technology Development of Smart Insulation Materials for Indoor Microclimate Regulation”1.1.1.2/VIAA/1/16/152the European Social Fund within the Project“Development of the Academic Personnel of Riga Technical University in the Strategic Fields of Specialization”Nr.8.2.2.0/18/A/017.
文摘Nowadays buildings contain innovative materials,materials from local resources,production surpluses and rapidly renewable natural resources.Phase Change Materials(PCM)are one such group of novel materials which reduce building energy consumption.With the wider availability of microencapsulated PCM,there is an opportunity to develop a new type of insulating materials,combinate PCM with traditional insulation materials for latent heat energy storage.These materials are typically flammable and are located on the interior wall finishing yet there has been no detailed assessment of their fire performance.In this research work prototypes of low-density insulating boards for indoor spaces from hemp shives using carbamide resin binder and cold pressing were studied.Bench-scale cone calorimeter tests were conducted to evaluate fire risk,with a focus on assessing material flammability properties and the influence of PCM on the results.In this research,the amount of smoke,heat release rate,effective heat of combustion,specific extinction coefficient,mass loss,carbon dioxide yield,specific loss factor,ignition time of hemp straws samples and samples of hemp straws with 10%and without PCM admixture were compared.There is a risk of flammability for PCM and their fire reaction has not been evaluated when incorporating PCM into interior wall finishing boards.The obtained results can be used by designers to balance the potential energy savings of using PCM with a more complete understanding and predictability of the associated fire risk when using the proposed boards.It also allows for appropriate risk mitigation strategies.
基金support from Innovate UK and Silentnight Group Ltd for provision of funding for a Knowledge Transfer Partnership(No.KTP 011934)We are also very grateful to Katarina Handlovicova and Dr Nicola Jones for their help with sample preparation and analysis.
文摘Since the 1980s,mass market upholstered furniture sold in the United Kingdom has incorporated flame retardant chemicals to meet regulatory flammability requirements.However,UK fire deaths remain com-parable with similar European countries which have no such regulations.Quantitative measures of the effect that different chemical flame retardants additives have on the flammability and smoke toxicity of UK regulatory-compliant upholstered furniture remain limited.It has been shown that most fatal fires in-volve upholstered furniture;most fire deaths result from toxic gas inhalation;gas phase flame retardants increase the toxicity of smoke;and the fall in fire deaths over the last 30 years is the same in countries with and without furniture flammability regulations.Moreover,the presence of certain flame retardants in furniture is a significant obstacle to any meaningful end-of-life processing.The burning behaviour and smoke toxicity of nine upholstered furniture composites using a range of flame retardant technologies were assessed in the cone calorimeter.The total heat release(THR)varied from 46 MJ m^(−2) to 68 MJ m^(−2),the time-to-ignition(tti)from 8 s to 105 s,and peak heat release rate(pHRR)from 230 kW m^(−2) to 430 kW m^(−2).The composite filled with PET showed the longest tti while the expandable graphite fabric on the FR-foam showed the lowest pHRR.The composite with the Br-FR fabric and the FR-foam had the shortest tti,the greatest smoke,the second highest CO and the highest HCN yield.The composite with the non-FR fabric and the PET filling had the longest tti.For all the fabrics,the transition from non-FR to FR foam resulted in significant increases in the smoke,CO and HCN,except CO of Br-FR and FR-foam was slightly lower than non-FR foam.Smoke toxicity predictions show that the use of gas phase flame retardants in both the fabrics and fillings of upholstered furniture contributes to the high proportion of smoke-related fire casualties.The work shows that the smoke toxicity of upholstered furniture can be reduced by using condensed phase FRs,such as expandable graphite,or less flammable materials,such as polyester wadding.The regulatory component tests which focus on ignitability have been shown to be ineffective at assessing the fire safety of composites representative of furniture as sold.The alternative approach of assessing heat release and smoke toxicity,as described here,would improve the fire safety of furniture while reducing reliance on additive flame retardants acting in the gas phase.
文摘This study deals with the analysis of dynamic mechanical,thermal and flammability properties of treated and untreated pineapple leaf fiber(PALF)and kenaf fiber(KF)phenolic composites.Results indicated that storage modulus was decreased for all composites with increases in temperature and pattern of slopes for all composites,having almost the same values of E′at glass transition temperature(Tg).The peak of the loss modulus of pure phenolic composites was shown to be much less.After the addition of kenaf/PALF,peaks were higher and shifted towards a high temperature.The Tan delta peak height was low for pure phenolic composites and maximum for 60%PALF phenolic composites.Cole-Cole analysis was carried out to understand the phase behavior of the composite samples.Thermogravimetric analysis(TGA)results indicated that pure phenolic composites have better thermal stability than PALF and kenaf phenolic composites.Vertical and horizontal UL-94 tests were conducted and showed pure phenolic resin is highly fire resistant.The overall results showed that treated KF composites enhanced the dynamic mechanical and thermal properties among all PALF/KF composites.
基金supported by the National Natural Science Foundation of China(No.51103129)the National Basic Research Program of China("973 Program",No.2010CB631105)+1 种基金the Ningbo Natural Science Foundation(No.2012A610084)the Open Fund of Zhejiang Provincial Top Key Discipline of New Materials and Process Engineering(No.20110939)
文摘Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively （designated as BAPNCP, BAPBACP and BAPNPGCP, respectively）, were synthesized and characterized. In addition, the effects of backbone structures on curing behaviors of the monomers and thermal and flammability properties of the resulting polymers were systematically studied. The results indicated that BAPNPGCP displayed the highest enthalpy of the curing reaction associated with the ring-opening of benzoxazine, which was due to the effect of benzoxazine ring content per unit mass. Interestingly, the 5 wt% weight loss temperature and char residue after thermogravimetric test for poly（BAPNPGCP） were 8 ℃ and 7% higher than those of poly（BAPBACP）. Meanwhile, the total heat release of poly（BAPNPGCP） was less than half of that for poly（BAPBACP）, indicating the substantial effect of benzoxazine ring content on flammability and char formation. Furthermore, it was found that poly（BAPNCP） gave the best thermal stability and flame retardancy, which was due to the synergistic effect between naphthalene group and benzoxazine ring content. This study provides new insight into the curing behavior of benzoxazine and further understanding on the high performance of polybenzoxazine.
基金financially supported by the National Natural Science Foundation of China(No.51203136)the Scientific Special Fund of Zhejiang Province(No.2013C01074)
文摘The effects of magnesium oxide （MgO） on the flame retardant performance of intumescent systems based on ammonium polyphosphate （APP） and pentaerythritol （PER） in ethylene vinyl acetate copolymer （EVA） were studied. The results showed that MgO affects both the quality and quantity of residual char. There is an optimal value for the loading amount of MgO. More or less MgO loading may cause the formation of defective char layers and worsen the flame retardancy of EVA. According to the results of limiting oxygen index （LOI）, vertical flammability test （UL94 rating） and cone calorimetry （CONE）, the best flame retardancy with a strong and well intumescent char is obtained from the sample with 1 wt% of MgO, which has the highest LOI value of 27.9, UL94 rating of V-0 and the lowest peak heat release rate of 242 kW·m-2.
文摘Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied.ABS/MWNTs composites were prepared via melt blending with the MWNTs content varied from 0.2% to 4.0% by mass.Thermogravimetry results showed that the addition of MWNTs accelerated the degradation of ABS during the whole process under air atmosphere,and both onset and maximum degradation temperature were lower than those of pure ABS.The destabilization...
基金This work was supported by Lincoln University faculty funding(NO.3601-AGLS-45401-1128912).
文摘Background:Flammability is a compound plant trait that can vary significantly across natural populations within species.Investigating intraspecific variation in flammability provides insights into the evolution of plant flam-mability and inform understanding of wildfire risk and behaviour in different habitats.Methods:We measured four flammability variables,representing ignitibility(time to ignition),sustainability(total burning time),combustibility(maximum temperature during burning)and consumability(percentage of biomass consumed by fire)to assess the shoot-level flammability of Dracophyllum rosmarinifolium(G.Forst.)(Ericaceae),a polymorphic endemic species distributed throughout New Zealand.We examined the relationship between flammability components and a suite of climatic and geographic variables(elevation,latitude,mean annual temperature(MAT),mean annual rainfall(MAR)of the sample locations,etc.).Results:We measured shoot-level flammability components of 62 individuals across eight populations.Burning time,maximum temperature and burnt biomass were positively correlated with each other,while ignition score was independent of other flammability components.All flammability components varied significantly across the eight populations.The habitat conditions we considered were not related to any of the shoot-level flammability components of D.rosmarinifolium.Conclusions:Intraspecific variation in flammability in D.rosmarinifolium may be a byproduct of selection on other functional traits,such as leaf size,shoot lipid content,indicating that plant flammability is an incidental result,rather than selected for,at least in ecosystems without fire as a selective force.
基金Supported by the Research Foundation of Beijing Institute of Technology(20070242004)
文摘A small cubic closed vessel with schlieren measurement technique combined with high-speed video camera were used to study limit flame properties under microgravity conditions at atmospheric pressure and room temperature.The rich flammability limit of C3H8/air was determined to be 9.2% C3H8.Stretched flame propagation speeds,stretched laminar burning velocities and unstretched laminar burning velocities near rich C3H8/air flammability limits were measured at different equivalence ratios.Outwardly propagating spherical flames were used to study the sensitivities of the flame propagation speeds and laminar burning velocities to flame stretch using Markstein lengths.Unstretched laminar burning velocity at rich flammability limit was determined to be 1.09cm/s.Lewis numbers were less than unity in rich C3H8/air and negative Markstein lengths were concluded.Absolute values of Markstein lengths were found to decrease linearly with equivalence ratios increase.
文摘The consumption ofthermoset resins as building polymers is approximately over one million tone word wide. The thermoset resins are proven construction materials for the technical and highly demanding applications of the transportation, electrical and building part industry. Heat stability, high thermal, low shrinkage, excellent mechanical properties are typical for their type of polymers. Above applications in addition to the mechanical properties also require good flame retardants of the materials. Undertaken activities refer to official draft, laws and legal recommendations in UE states. This paper presents positive effect of reduced flammability of thermoset resins （unsaturated polyester and epoxy resins） thanks to the use of nanocomposites containing multi-ingredient halogen-flee flame retardants which combine conventional phosphorus/nitrogen modifiers interacting with nanofillers （oMMT （organomodified montmorillonite）, EG （expandable graphite）, graphene, GO （graphene oxide）, nSi （nanosilica））.
基金supported by Sino-Europe Research Program-China(MJ-2020-D-09).
文摘Sustainable aviation fuel(SAF)blend has been confirmed to benefit for greenhouse gases reduction,and thus the property of blend fuel should be understanded the detail to support the utilization in aircraft.Low flammability limit(LFL)is a key property of jet fuel which should be sufficiently flammable to burn in combustor of aero-engine and meanwhile should be non-flammable for safety storage in fuel tank of aircraft.LFL of fuel could be influenced by integrating effects including molecule structure,intramolecular chemical bond energy and binding energy of molecule to molecule.Three types of theoretical models,based on different individual view including LFL of every pure hydrocarbon,stoichiometric concentration,and combustion enthalpy,present unsatisfactory simulation results,which can be deduced without integrating all potential influence factors together.The arti-ficial neural network(ANN)approaches have been involved to bridge the relationship of the complex compo-sitions in jet fuels with LFL.For providing adequate and available composition input,the boundary of fuel compositions has been extracted based on constrains of boiling point,flash point and freeze point coupling with statistic petroleum-based jet fuels.By clustering analysis,43 critical classes of compositions,extracted as sur-rogate hydrocarbons based on with similar LFL within 1%deviation,have been deployed as input matrix.ANNLFL model,trained by only drop-in fuel with feature of Sigmoid function as an activation function,can distin-guish drop-in fuel with non-drop-in fuel.ANN LFL model can predict LFL of drop-in fuel with 0.988 accuracy.The predict output value of non-drop-in fuel could present obvious deviation with traditional jet fuel.The optimization methodologies of ANN-LFL model could be improved the understanding of LFL and extend ANN in SAF utilization.
基金supported by the National Natural Science Foundation of China (Grant No. 51676133)。
文摘In the present study, a novel model is proposed to evaluate the lower flammability limit(LFL) of alkane diluted with CO2. The LFL model is based on flame phenomenon simulation(FS-LFL). The model consists of combustion, turbulence, and igniter models, which are used to characterise the combustion based on the chemical kinetics and CFD, which is not feasible with traditional methods. The flame simulation phenomenon was validated by contrast with experiment and same criterion of flammability limit in the experiment was adopted. The FS-LFL model was used to predict the LFLs of a propane-CO2 mixture and propane at various temperatures. The model performance was analysed by comparing the results with experimental data and predictions obtained from existing methods. The AARDs between the predicted and experimentally determined LFLs of the propane-CO2 mixture are 0.34%, 1.19%, and 1.35% at 30℃, 50℃, and 70℃, respectively. The model also has a good predictive power with respect to the LFLs of propane at initial temperatures ranging from 30℃–300℃, with an AARD of 2.10%. When the dilution of CO2 is 90%, the model yields a better result due to the utilisation of the chemical kinetics mechanism. This result is instructive for the use of this method in the prediction of upper flammability limits.
文摘Flammability properties of composites of wood fiber and recycled plastic were evaluated by the cone calorimeter and oxygen index chamber. Results were shown as follows: 1) Wood-PVC composite showed worse thermal stability on time to ignition (TTI) and mean heat release rate (MHRR), but better performance on heat release rate (HRR) and mean efficient heat of combustion (MEHC); wood-PP composite had better thermal stability properties, but was worse on other fire performance; 2) Compared with wood-PVC composite, wood-PP composite showed excellent thermal stability, but behaved dangerous as a whole; 3) Coupling agent PAPI changed fire performance of wood-PP composite and showed a longer TTI, lower EHC but higher HRR. It can be concluded that flame resistance treatment should be considered if wood-plastic composites are used as decorated materials.
基金This work was supported by a grant from the National Natural Science Foundation of China(No.51676133)。
文摘As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group contribution method,which is significative to the safe application of hydrocarbons in the ORC system.The whole modeling process is divided into two parts:pure compound prediction and mixture prediction.The contribution factors of inert gases and dilute concentration were first introduced in the group contribution method.Moreover,the respective 95%-confidence interval of the mixture based on linear superposition method has been proposed in the developed group contribution model to improve the safety coefficient.For CO2 as inert gas,the average relative error and correlation coefficient are 5.34%and 0.88 for lower flammability limit while 6.99%and 0.95 for upper flammability limit.For N2 as inert gas,the average relative error and correlation coefficient are 7.47%and 0.84 for lower flammability limit while 6.68%and 0.97 for upper flammability limit.Most importantly,this group contribution method has extended the application range to make up the shortcomings of other flammability limit prediction methods aiming at hydrocarbon and inert gas mixtures and proposed the uncertainty analysis to provide reliable prediction range.
文摘1.Introduction.The ever-increasing demands for high-energy-density power supply systems have driven the rapid development of conventional lithium-ion batteries,of which properties are approaching to the ceiling.In the meantime,the safety of lithium-ion batteries also grabs more attention as their wide application in consumer electronics and electric vehicles.The safety of battery system can be enhanced inherently by replacing the flammable liquid electrolytes with inorganic solid electrolytes,which makes solid-state battery one of the most promising candidates of next-generation energy storage systems[1-3].Additionally,the improvements in energy density are foreseen as solid electrolytes enable lithium metal anode[4-11]and high-voltage cathodes[12-15].
基金supported by the National Natural Science Foundation of China(Grant No.52206165)。
文摘Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This characteristic holds significant implications in the realm of novel satellite propulsion.Introducing a fraction of the electrical energy into energetic ionic liquid fuels,the thermal decomposition process is facilitated by reducing the apparent activation energy required,and electrical energy can trigger the electrochemical decomposition of ionic liquids,presenting a promising approach to enhance combustion efficiency and energy release.This study applied an external voltage during the thermal decomposition of 1-ethyl-3-methylimidazole nitrate([EMIm]NO_(3)),revealing the effective alteration of the activation energy of[EMIm]NO_(3).The pyrolysis,electrochemical decomposition,and electron assisted enhancement products were identified through Thermogravimetry-Differential scanning calorimetry-Fourier transform infrared-Mass spectrometry(TG-DSC-FTIR-MS)and gas chromatography(GC)analyses,elucidating the degradation mechanism of[EMIm]NO_(3).Furthermore,an external voltage was introduced during the combustion of[EMIm]NO_(3),demonstrating the impact of voltage on the combustion process.
基金supported by the University of Wollongong,Wollongong,Australiafinancial support from the National Natural Science Foundation of China(22272086)Natural Science Foundation of Sichuan Province(2023NSFSC0009).
文摘Compared to currently commercialized lithium-ion batteries,which use flammable organic liquid electrolytes and low-energy-density graphite anodes,solid-state lithium-metal batteries(SSLMBs)offer enhanced energy density and improved safety,making them promising alternatives for next-generation rechargeable batteries[1].As a crucial component of these batteries,solid-state electrolytes—divided into inorganic solid ceramic electrolytes(SCEs)and organic solid polymer electrolytes(SPEs)—are vital for lithium-ion transport and inhibiting lithium dendrite growth.Among them,SCEs exhibit high ionic conductivity,excellent mechanical properties,and outstanding electrochemical and thermal stability.Nevertheless,their brittleness,interfacial challenges with electrodes,and the requirement for high stacking pressure during battery operation significantly hinder their scalable application.In comparison,SPEs are more favourable for manufacturing due to their flexibility and good interfacial compatibility with electrodes[2].Despite these advantages,SPEs still face significant challenges in achieving practical application.Firstly,typical SPEs,such as poly(ethylene oxide)(PEO),poly(vinylidene fluoride)(PVDF),and poly(ethylene glycol)diacrylate(PEGDA),are characterized by high crystallinity,which causes polymer chains to be tightly packed and rigid.This restricts the segmental motion within the SPEs,resulting in low ionic conductivity.Secondly,compared to lithium ions,anions with large ionic radii and low charge density typically form weaker interactions with the polymer chains,which facilitates their mobility and results in a low lithium-ion transference number(tt).Thirdly,the weak interactions between polymer chains in typical SPEs lead to a low elastic modulus,which in turn compromises their poor mechanical strength.
基金NSFC Project (No. 30371170)National Technology R&D Program (No.2006BAD04B05)
文摘Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is over mature forest, and accounts for much proportion. Fire season in this area is winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire season lasts from October to next February,but to April in an individual arid year. Most of the fires in this area are surface fires, crown fire, can occur after long time drought. Ground fires do not occur in the region.
文摘In the period of the first twenty years after World War II the number of fires in Polish hard coal mines reached annually the value of several thousands of cases. About 80% of fires constituted spontaneous fires. Investigations into the development of new methods of fire hazard prediction and implementation of new methods and means of fire prevention as well as the introduction of prohibition concerning the use of products manufactured of combustible organic materials in underground mine workings re-duced considerably the hazard of underground fire rise. The worked out at the Central Mining Institute (GIG) new method of un-derground fire prediction allows the correct selection of fire prevention means. The introduction into common use of fire-resistant conveyor belts, the main factor giving rise to spontaneous fires, and methods of assessment of their fire resistance eliminated prac-tically the fire hazard. These activities contributed in an efficient way to the reduction of the number of underground fires to a sat-isfactory level.
基金supported by the Boeing Company [No. 2015SDB-127]
文摘A series of non-flammable high strength Mg-Al-Ca-Mn alloys with high Ca/Al ratio were fabricated by water-cooled casting and hot extrusion. Microstructure and mechanical properties were investigated to study the effect of hot extrusion. The experimental results showed that hot extrusion significantly improved the mechanical properties by grain refinement and precipitates. Ignition temperature was measured by furnace test, and the highest temperature is up to approximately 1040℃ due to the composite oxide layer consisting of CaO and MgO. In addition, a laboratory-scale flame test was conducted to evaluate the flammability of smaller specimens. These alloys exhibited marvelous flame resistance attributed to the protective effect of dense and stable oxide film.
