In order to reduce the number of accidents due to explosions of flammable gases in the goaf of coalmines,the conditions for explosion of flammable gases and their explosion limits,affected to a considerable extent by ...In order to reduce the number of accidents due to explosions of flammable gases in the goaf of coalmines,the conditions for explosion of flammable gases and their explosion limits,affected to a considerable extent by CO2,are explored.With the use of our experimental equipment suitable for the study of explosion of polybasic explosive gas mixtures,we investigated the effect of CH4/H2=10/1 and CH4/C2H4=10/1 gases mixed with CO2 on their explosion limits.The results indicate that after adding CO2,the explosion limit of the CH4/H2(or C2H4) =10/1 gas mixtures decreased markedly with increasing amounts of CO2.When the amount of CO2 exceeded 25%,the CH4/C2H4=10/1 flammable gas mixture did not lead to explosions.Similar results were obtained when the amount of CO2 exceeded 23% in the CH4/H2=10/1 flammable gas mixture.We also compared the explosion limits and the explosion suppression effect of N2 or CO2 on the explosion limits of the CH4+CO and CH4+C2H4 dual explosive gas mixtures.Along with the increases in the amounts of CO2 or N2,the area of the explosion limits of gas mixtures decreased.Under the same conditions,the explosion suppression effect of CO2 was greater than that of N2.CO2 has clearly the better suppression effect on the explosion of flammable gases in goafs.展开更多
In this study, we analyze factors affecting the explosion limits of flammable refrigerants. We conclude that any method used for measuring flammable refrigerant explosion limits has its conditional restrictions. Flamm...In this study, we analyze factors affecting the explosion limits of flammable refrigerants. We conclude that any method used for measuring flammable refrigerant explosion limits has its conditional restrictions. Flammable refrigerants in the atmosphere can also explode under certain conditions, when the concentration is approaching the explosion limits. An experimental study on the explosion limits of six kinds of flammable refrigerants is carried out with a mixture of refrigerant and combustible refrigerant, which has a similar effect to a flame retardant. An experimental apparatus was designed to test the explosion limits of mixtures made from three different nonflammable refrigerants and six different flammable refrigerants. Two practical models were developed to estimate the critical concentration for inhibiting explosion of refrigerant mixtures: one was made up of two flammable components with one nonflammable component, and the second was made up of one flammable component with two nonflammable components.展开更多
<div style="text-align:justify;"> In order to reduce the arson or accidental fire losses, we developed a gas sensitive detector used for the rapid detection and early warning of flammables in crowded p...<div style="text-align:justify;"> In order to reduce the arson or accidental fire losses, we developed a gas sensitive detector used for the rapid detection and early warning of flammables in crowded places such as buses. A MEMS (Micro-Electro-Mechanical System) based thin film semiconductor was fabricated as the gas sensor. To obtain the target gas selective response, the surface of the sensitive film was modified with highly active metal catalytic nano-particles. Thus the anti-interference ability was improved and the false alarm rate was effectively reduced. Furthermore, the modular embedded system for information acquisition and transmission was developed. Supported by the Airflow Precision control system (APs), the rapid warning of volatile gas of flammable substances was realized. Experiments showed that RAs has satisfied selectivity to volatiles of usual flammable liquid, such as the output voltage reaches 3 V (0 - 3.3 V). With simulation about the actual installation state in bus, MWs sounds an alarm at 2 minutes after splashing 50 mL 92# petrol to the floor. For the last two years, FEVMEW has been integrated into more than 4000 buses in Hefei. This design has been proved feasible according to the actual operation. </div>展开更多
Wireless Sensor Network based on ZigBee technology is a wireless network which is composed of many nodes of ZigBee RF chips, sensors and MCUs, especially suitable for application of the remote monitoring system in fla...Wireless Sensor Network based on ZigBee technology is a wireless network which is composed of many nodes of ZigBee RF chips, sensors and MCUs, especially suitable for application of the remote monitoring system in flammable and explosive environments. This paper presents the characteristics and advantages of ZigBee technology, also discusses the system for hardware and software design. This system effectively fulfills the remote monitoring in flammable and explosive environments and posses high practical values.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
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
Transient electronics represent an emerging class of technology comprising materials that can vanish in a controlled manner in response to stimuli. In contrast to conventional electronic devices that are designed to o...Transient electronics represent an emerging class of technology comprising materials that can vanish in a controlled manner in response to stimuli. In contrast to conventional electronic devices that are designed to operate over the longest possible period, transient electronics are defined by operation typically over a short and well-defined period; when no longer needed, transient electronics undergo self-deconstruction and disappear completely. In this work, we demonstrate the fabrication of thermally triggered transient electronic devices based on a paper substrate, specifically, a nitrocellulose paper. Nitrocellulose paper is frequently used in acts of magic because it consists of highly flammable components that are formed by nitratil^g cellulose by exposure to nitric acid. Therefore, a complete and rapid destruction of electronic devices fabricated on nitrocellulose paper is possible without producing any residue （i.e., ash）. The transience rates can be modified by controlling radio frequency signal-induced voltages that are applied to a silver （Ag） resistive heater, which is stamped on the backside of the nitrocellulose paper. The Ag resistive heater was prepared by a simple, low-cost stamping fabrication, which requires no harsh chemicals or complex thermal treatments. For the electronics on the nitrocellulose paper substrate, we employed semiconducting carbon nanotube （CNT） network channels in the transistor for superior electrical and mechanical properties.展开更多
Metal−organic framework-derived materials have attracted significant attention in the applications of functional materials.In this work,the rod-like nickel-based metal−organic frameworks were first synthesized and sub...Metal−organic framework-derived materials have attracted significant attention in the applications of functional materials.In this work,the rod-like nickel-based metal−organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology.Then,the nickel phyllosilicate whiskers were evaluated to enhance the mechanical,thermal,flammable,and tribological properties of epoxy resin.The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix,improving the tensile strength and elastic modulus by 13.6%and 56.4%,respectively.Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings,it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities.Additionally,it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature.Moreover,the wear rate of epoxy resin nanocomposites was reduced significantly by 80%for pure epoxy resin by adding 1 phr whiskers.The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites.展开更多
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
An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinesenational standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a,R152a/R13...An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinesenational standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a,R152a/R134a, R161/N2 and R152a/N2 were measured with this apparatus at atmospheric pressure and ambienttemperature. The fuel inertization points (FIP) of these mixtures can be found from the envelopes. Comparisonswere made with the literature data; good agreement for most measurements was obtained. R134a was found tohave a better dilution effect than nitrogen in reducing the flammability of hydrofluorocarbons.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 aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugi...This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable gases.The multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak conditions.The CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0 ℃ to 400 ℃.It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the predictions.In order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice diameter.It was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic emissions.The deviation from the ideal gas behavior in the reservoir,achieved by applying the Soave–Redlich–Kwong equation of state, also has not significantly influenced the extension and volume of the explosive atmosphere.The results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the reservoir.The diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir.展开更多
An incinerator was built up in 1987 in Shanghai. In this paper, the devices of the incinerator, main parameters of the process, the results of combustion tests for nonradioactive waste and simulated radwaste are given...An incinerator was built up in 1987 in Shanghai. In this paper, the devices of the incinerator, main parameters of the process, the results of combustion tests for nonradioactive waste and simulated radwaste are given. The instructive information for radwaste treatment were provided.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
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
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
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
基金provided by the National Natural Science Foundation of China (No.50874088)the Project of Creative Team by the Ministry of Education of China (No.IRT0856)+1 种基金the Excellent Talent Project of the New Century supported by the Ministry of Education of China (No.NECT050874)the Natural Science Foundation of the Education Department of Shaanxi Province (No.08JK351)
文摘In order to reduce the number of accidents due to explosions of flammable gases in the goaf of coalmines,the conditions for explosion of flammable gases and their explosion limits,affected to a considerable extent by CO2,are explored.With the use of our experimental equipment suitable for the study of explosion of polybasic explosive gas mixtures,we investigated the effect of CH4/H2=10/1 and CH4/C2H4=10/1 gases mixed with CO2 on their explosion limits.The results indicate that after adding CO2,the explosion limit of the CH4/H2(or C2H4) =10/1 gas mixtures decreased markedly with increasing amounts of CO2.When the amount of CO2 exceeded 25%,the CH4/C2H4=10/1 flammable gas mixture did not lead to explosions.Similar results were obtained when the amount of CO2 exceeded 23% in the CH4/H2=10/1 flammable gas mixture.We also compared the explosion limits and the explosion suppression effect of N2 or CO2 on the explosion limits of the CH4+CO and CH4+C2H4 dual explosive gas mixtures.Along with the increases in the amounts of CO2 or N2,the area of the explosion limits of gas mixtures decreased.Under the same conditions,the explosion suppression effect of CO2 was greater than that of N2.CO2 has clearly the better suppression effect on the explosion of flammable gases in goafs.
文摘In this study, we analyze factors affecting the explosion limits of flammable refrigerants. We conclude that any method used for measuring flammable refrigerant explosion limits has its conditional restrictions. Flammable refrigerants in the atmosphere can also explode under certain conditions, when the concentration is approaching the explosion limits. An experimental study on the explosion limits of six kinds of flammable refrigerants is carried out with a mixture of refrigerant and combustible refrigerant, which has a similar effect to a flame retardant. An experimental apparatus was designed to test the explosion limits of mixtures made from three different nonflammable refrigerants and six different flammable refrigerants. Two practical models were developed to estimate the critical concentration for inhibiting explosion of refrigerant mixtures: one was made up of two flammable components with one nonflammable component, and the second was made up of one flammable component with two nonflammable components.
文摘<div style="text-align:justify;"> In order to reduce the arson or accidental fire losses, we developed a gas sensitive detector used for the rapid detection and early warning of flammables in crowded places such as buses. A MEMS (Micro-Electro-Mechanical System) based thin film semiconductor was fabricated as the gas sensor. To obtain the target gas selective response, the surface of the sensitive film was modified with highly active metal catalytic nano-particles. Thus the anti-interference ability was improved and the false alarm rate was effectively reduced. Furthermore, the modular embedded system for information acquisition and transmission was developed. Supported by the Airflow Precision control system (APs), the rapid warning of volatile gas of flammable substances was realized. Experiments showed that RAs has satisfied selectivity to volatiles of usual flammable liquid, such as the output voltage reaches 3 V (0 - 3.3 V). With simulation about the actual installation state in bus, MWs sounds an alarm at 2 minutes after splashing 50 mL 92# petrol to the floor. For the last two years, FEVMEW has been integrated into more than 4000 buses in Hefei. This design has been proved feasible according to the actual operation. </div>
文摘Wireless Sensor Network based on ZigBee technology is a wireless network which is composed of many nodes of ZigBee RF chips, sensors and MCUs, especially suitable for application of the remote monitoring system in flammable and explosive environments. This paper presents the characteristics and advantages of ZigBee technology, also discusses the system for hardware and software design. This system effectively fulfills the remote monitoring in flammable and explosive environments and posses high practical values.
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.
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.
文摘Transient electronics represent an emerging class of technology comprising materials that can vanish in a controlled manner in response to stimuli. In contrast to conventional electronic devices that are designed to operate over the longest possible period, transient electronics are defined by operation typically over a short and well-defined period; when no longer needed, transient electronics undergo self-deconstruction and disappear completely. In this work, we demonstrate the fabrication of thermally triggered transient electronic devices based on a paper substrate, specifically, a nitrocellulose paper. Nitrocellulose paper is frequently used in acts of magic because it consists of highly flammable components that are formed by nitratil^g cellulose by exposure to nitric acid. Therefore, a complete and rapid destruction of electronic devices fabricated on nitrocellulose paper is possible without producing any residue （i.e., ash）. The transience rates can be modified by controlling radio frequency signal-induced voltages that are applied to a silver （Ag） resistive heater, which is stamped on the backside of the nitrocellulose paper. The Ag resistive heater was prepared by a simple, low-cost stamping fabrication, which requires no harsh chemicals or complex thermal treatments. For the electronics on the nitrocellulose paper substrate, we employed semiconducting carbon nanotube （CNT） network channels in the transistor for superior electrical and mechanical properties.
基金the Key research and development project in Anhui Province(Grant No.2022i01020016)the National Natural Science Foundation of China(Grant No.51775001)+3 种基金the Anhui Province Natural Science Foundation(Grant Nos.1908085J20,2008085QE269)the University Synergy Innovation Program of Anhui Province(Grant Nos.GXXT-2019-027,GXXT-2020-057)the Natural Science Research Project of Universities in Anhui Province(Grant No.KJ2020A0326)the Leading Talents Project in Colleges and Universities of Anhui Province.
文摘Metal−organic framework-derived materials have attracted significant attention in the applications of functional materials.In this work,the rod-like nickel-based metal−organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology.Then,the nickel phyllosilicate whiskers were evaluated to enhance the mechanical,thermal,flammable,and tribological properties of epoxy resin.The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix,improving the tensile strength and elastic modulus by 13.6%and 56.4%,respectively.Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings,it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities.Additionally,it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature.Moreover,the wear rate of epoxy resin nanocomposites was reduced significantly by 80%for pure epoxy resin by adding 1 phr whiskers.The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites.
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support of the National Natural Science Foundation of China (NSFC, Grant No.50776096).
文摘An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinesenational standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a,R152a/R134a, R161/N2 and R152a/N2 were measured with this apparatus at atmospheric pressure and ambienttemperature. The fuel inertization points (FIP) of these mixtures can be found from the envelopes. Comparisonswere made with the literature data; good agreement for most measurements was obtained. R134a was found tohave a better dilution effect than nitrogen in reducing the flammability of hydrofluorocarbons.
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.
基金Petrobras (0050.0093154.14.9)–Petróleo Brasileiro S.A.for the financial and technical support
文摘This study aimed to describe a Computational Fluid Dynamics(CFD) procedure using the ANSYS CFX software 16.1 and Design of Experiments for the determination of volume and extension of explosive atmospheres due to fugitive emissions of flammable gases.The multidimensional statistical sampling technique Latin Hypercube was used, which defined 100 simulations of random methane gas leak conditions.The CFD model proved to be robust in predicting the extension and volume of the explosive atmosphere for orifice diameters from 0.1 to2.5 mm, pressure from 0.1 MPa to 12 MPa and temperatures from 0 ℃ to 400 ℃.It was found that the calculation domain must be parameterized 8 m in length for each millimeter of the diameter of the source of release to ensure the predictions.In order not to lose precision for very small diameters, the mesh was parameterized with 50 elements along the orifice diameter.It was proved that gravity does not influence the extension and volume of the explosive atmosphere at sonic emissions.The deviation from the ideal gas behavior in the reservoir,achieved by applying the Soave–Redlich–Kwong equation of state, also has not significantly influenced the extension and volume of the explosive atmosphere.The results showed that the size of the explosive atmosphere varies directly with the diameter of the source emission and reservoir pressure, and inversely with the temperature of the reservoir.The diameter of the source is the parameter that has the major effect on the extension of the explosive atmosphere, followed by the pressure and lastly the temperature of the reservoir.
文摘An incinerator was built up in 1987 in Shanghai. In this paper, the devices of the incinerator, main parameters of the process, the results of combustion tests for nonradioactive waste and simulated radwaste are given. The instructive information for radwaste treatment were provided.
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.
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 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.
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...
