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•Hierarchical interfacial catalysts (Co3O4/Co3O4; Co3O4/NiCo2O4 DSNCs) are designed.•Efficient removal of smoke and toxic gases are obtained after their low additions.•Flame ...retardancy comparison with reported works strongly affirms their superiorities.•Satisfactory promotions in mechanical property are acquired.
The emission of considerable smoke and toxic gases has been the notorious stumbling block on the extended usage of epoxy resin (EP), which often causes serious fire casualties in real fire. Hence, metal organic frameworks (MOFs)-derived self‐sacrificing template strategy is adopted, to prepare metal oxides double-shelled nanocages (Co3O4/Co3O4 and Co3O4/NiCo2O4 DSNCs) as hierarchical interfacial catalysts for suppressing the releases of smoke and toxic gases. With the addition of 2.0 wt% Co3O4/Co3O4 DSNCs, the peak smoke production rate (PSPR), total smoke production (TSP), peak CO production rate (PCOP) and total CO production (TCOP) are reduced by 15.8%, 46.9%, 36.2% and 49.1%, separately. When 2.0 wt% Co3O4/NiCo2O4 DSNCs is incorporated, the PSPR, TSP, PCOP and TCOP are markedly decreased by 40.8%, 55.5%, 46.6% and 48.5%, respectively. These results strongly corroborate the efficacy of DSNCs in suppressing the emission of smoke and toxic CO gas. Additionally, the values of peak heat release rate are reduced by 15.9% and 28.4%, reflecting the inhibited heat release. Flame retardancy comparison with reported works corroborates the prominent merit of DSNCs in inhibiting the smoke release. The clear evidence for suppressed toxic CO and NO gases releases is also acquired from TG-IR test. Profiting from the well-formed nanoflake-polymer interfaces, the mechanical performance is obviously improved. In short, these designed DSNCs possess great efficacy in smoke as well as toxic gases removal and mechanical enhancement of EP. This investigation may provide useful inspirations for designing MOFs-derived hierarchical interfacial catalysts, towards impairing the fire toxicity of polymer.
High fire hazard of releasing considerable toxicants and heat is regarded as a notorious issue for hindering the further application of epoxy resin (EP). Hence, a hierarchical structure (MLBCN) based ...on LDH anchored boron-doped g-C3N4 assembled with MnO2 nanosheets is rationally constructed as flame retardant additive for EP. Concretely, the incorporation of 1.0 wt% MLBCN leads to the decreases of 31.9% and 25.3% in peak heat release rate and total heat release, separately, reflecting the impeded heat release. Meanwhile, the peak smoke production rate and total smoke release are reduced by 37.1% and 33.4%, respectively, corroborating the hindered fire toxicity. The clear evidence for inhibited emissions of toxic CO and NO gases can be acquired from TG-IR spectra. These results collectively confirm the efficacy of MLBCN in reducing the toxicants generation and fire hazard of EP, deriving from its physical barrier, chemical catalyzing and charring promotion actions. Besides, the tensile and flexural strength are improved by 43.9% and 10.6%, by adding 1.0 wt% MLBCN, demonstrating the promoted mechanical performance. Overall, using MLBCN achieves the simultaneous enhancements in fire safety and mechanical capability of polymer. This work may provide valuable inspirations for constructing multicomponent hierarchical structure, optimizing their prospects in polymer-matrix composite and other areas.
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•LDH anchored boron-doped g-C3N4 assembled with MnO2 nanosheets (MLBCN) is designed.•Marked impedances on heat release and toxicants emission are achieved by using MLBCN.•Flame retardancy comparison with reported works affirms the superiority of MLBCN.•Obviously promoted mechanical property is also acquired.
One of the major natural hazards occurring during the process of mining exploitation are endogenous fires. They cause very large material losses and constitute a threat to the health and life of the ...workers. Such fires usually start and develop in the goafs. The remaining coal and the oxygen-containing air flowing at a certain rate may lead to endogenous fires. The basic element of the assessment of the occurrence of an endogenous fire and the degree of its development is the chemical composition of the air flowing out of the longwall and the goafs. The monitoring of this composition also makes it possible to assess the severity of such a fire. The damage that can be caused by the endogenous fire requires scientific and experimental research being carried out on a wide scale in order to limit its occurrence and development. All papers and research mentioned in the paper aim to find a tool that will help to control the fires. The paper discusses the development of a new and original method of combating the threat of endogenous fires. It is based on the installation designed to feed an ash and water mixture or an ash and water mixture with carbon dioxide to goafs. The foundation of the paper is a method based on a vast depth of expertise and knowledge gained by the authors in the field of combating endogenous fires. The developed installation prepares and transports ash and water mixtures together with carbon dioxide to the zones with high probability of endogenous fires. The mixture is a preparation of the surface of a mine, and later, it is transported underground by pipelines to the goafs where a high level of the fire hazard was identified. The construction of the system and the composition of the mixture used are both original solutions; their practical application limited the process of spontaneous heating of coal. Monitoring the chemical composition of gases in the air of the goafs made it possible to control the effects of applied measures; it proved that carbon dioxide used as an inert gas disturbs the process of carbon oxidation, and the water and ash mixture limits the inflow of the air with oxygen. The advantage of the method is particularly evident in the case of the exploitation of deposits where coal has a short incubation time. This original approach allows for a better and more effective response to endogenous fires.
Fire emergencies impose significant threats to building occupants. During evacuation, fire has significant impacts on evacuees' behaviors, by e.g., changing their route availability, disturbing their ...perception of the environment due to reduced visibility, impairing their mobility that is usually associated with severe injuries, and causing significant mental stress that may lead to complicated and unpredictable navigation decisions. Despite the detrimental effects of fire on crowd evacuation, most existing building evacuation simulation models and tools do not account for the impacts of fire on the evacuation process; at most they rely on oversimplified assumptions and simulation settings. In this study, a new fire evacuation simulation model, named FREEgress (Fire Risk Emulated Environment for Egress), is developed to simulate the dynamic influences of heat, temperature, toxic gas and smoke particles on evacuees' mobility, navigation decision making and health conditions. FREEgress (1) introduces evacuee agents who are aware of and able to assess the fire hazards, and can make fire risk-informed navigation decisions; and (2) models the interactions between evacuee agents and the dynamic fire emergency environments and the consequent evacuation process. The verification of FREEgress is conducted by comparing its simulation results with two existing simulation tools, SAFEgress and FDS + Evac. In addition, a case study using FREEgress is carried out to simulate the evacuation in a museum for 30 different fire emergency scenarios. The simulation results are analyzed to assess the impacts of three important factors, namely initial fire location, evacuation delay time and evacuee behavior, on the evacuation process and evacuation outcomes. The case study demonstrated the potential value of FREEgress to support both the safety design of new buildings and maintenance and emergency management of constructed facilities.
•FREEgress is developed to simulate dynamic fire impacts on indoor fire evacuation.•Impacts of heat, temperature, toxic gas and smoke particles are incorporated.•Fire impacts on evacuees' mobility, navigation and health conditions are simulated.•FREEgress is verified by comparing its performance to existing simulation tools.•Impacts of three key factors on evacuation outcomes are assessed using FREEgress.
Elastic biomass aerogels have attracted widespread attention but are seriously hindered by environmentally unfriendly cross-linkers and fire hazards for functional applications. This study outlines ...the fabrication of a fully bio-based, low fire-hazard and superelastic aerogel without any cross-linkers for excellent thermal insulation and oil absorption, via creating highly oriented wave-shaped layer microstructures and subsequently depositing nonflammable siloxane coating on the surface of the aerogel skeleton. The resultant environmental-safety aerogel showed the combined advantages of anisotropic super-elasticity, hydrophobicity, low density and high flame retardancy (limiting oxygen index value of 42%, UL-94 V-0 rating, and extremely low heat release), thus leading to many benefits for solving environmental hazards. For instance, this fire-safety biomass aerogel can be used as the high-performance thermal insulator with low thermal conductivity and high shielding efficiency. The aerogel also exhibited a great selectively oil clean-up absorption with a high absorption capacity of 117 times its own weight and excellent recyclability. Especially, due to the highly oriented microstructures, the aerogel as a filter showed the fastest separation rates of oil/water mixture (flux rate of 145.78 L h−1 g−1) ever reported. Such a method of preparing super-elastic biomass aerogels will provide new insights into their multifunctional applications with high environmental safety.
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•Fully bio-based aerogels without any cross-linkers were fabricated via a facile strategy
•The aerogel showed anisotropic super-elasticity, hydrophobicity, and low fire hazard
•High-performance thermal insulation and oil clean-up absorption were achieved
•The fast oil/water separation rate (145.78 L h-1 g-1) ever reported
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•DOPO-based FR wrapped PZS nanotubes were synthesized via one-pot method.•EP/FR@PZSshowedsignificantdecreaseinpHRR, THR and the amount of CO.•Incorporation of FR@PZS provided a ...compact and stable char layer.•The barrier effect of distributed PZS network retards the heat and mass transfer.
The structure of polyphosphazene nanotubes (PZS) is similar to that of carbon nanotubes (CNTs) before modification. For applications of CNTs in polymer composites, surface wrapping is an economically attractive route to achieve functionalized nanotubes. Based on this idea, functionalized polyphosphazene nanotubes (FR@PZS) wrapped with a cross-linked DOPO-based flame retardant (FR) were synthesized via one-step strategy and well characterized. Then, the obtained FR@PZS was introduced into epoxy resin (EP) to investigate flame retardancy and smoke toxicity suppression performance. Thermogravimetric analysis indicated that FR@PZS significantly enhanced the thermal stability of EP composites. Cone calorimeter results revealed that incorporation of FR@PZS obviously improved flame retardant performance of EP, for example, 46.0% decrease in peak heat release rate and 27.1% reduction in total heat release were observed in the case of epoxy composite with 3wt% FR@PZS. The evolution of toxic CO and other volatile products from the EP decomposition was significantly suppressed after the introduction of FR@PZS, Therefore, the smoke toxicity associates with burning EP was reduced. The presence of both PZS and a DOPO-based flame retardant was probably responsible for this substantial diminishment of fire hazard.
In this article, a sodium silicate surface‐modified phenolic resin microsphere (SSMPHM) was prepared to reduce the fire hazard of thermoplastic polyurethane (TPU). The characterization results ...demonstrated that sodium silicate was successfully deposited on the surface of the phenolic resin microsphere (PHM). The results of the combustion test demonstrated that the introduction of SSMPHM remarkably reduced the fire hazard of thermoplastic polyurethane (TPU) composites (e.g., ∼66.0% and 77.0% decline in peak heat release rate (pHRR) and smoke factor (SF) at 4 wt% content (TPU/SSM‐4)). At the same time, the peak value of COP reduced from 0.029 to 0.009 g s−1 compared with TPU. The results of condensed phase analysis demonstrated that compared with TPU, the char residue layer of TPU/SSM‐4 was relatively dense and continuous. In addition, mechanical performance tests showed that SSMPHM could make up for the loss of mechanical performance caused by PHM. The work provides new insights into modifying PHM for effectively reducing the fire hazard of TPU.
Fire accidents induced by indoor energy combustion occurred frequently and caused tremendous loss. This paper investigated the evolution laws of important fire risk parameters for quantitatively ...assessing the thermal hazard of room with triangular windows by reduced-scale experiments. The fire hazard was characterized by the risk parameters of hot gas temperature inside the room and facade flame height. Results show that the neutral plane position is hardly affected by total heat release rate of fire source, and it mainly depends on triangular opening height rather than base width. The ratios of neutral plane height above opening bottom to opening height are about 0.25, 0.25 and 0.61 for isosceles, right and inverted right triangular openings respectively. Based on theoretical derivation, an appropriate ventilation factor for triangular opening was defined to describe air mass inflow rate during under-ventilated condition. The hot gas temperature inside the room can be predicted based on the newly defined ventilation factor. Finally, a non-dimensional correlation was proposed to characterize facade flame height as a 0.53 power function of a normalized excess heat release rate. This work is of benefits to evaluate the fire hazard of buildings and then to provide calculation basis for building fire protection design.
•Under-ventilated flame with triangular window induced by indoor energy was studied.•Neutral plane position and air mass inflow rate was quantitatively discussed.•A correlation on hot gas temperature in under-ventilated fire room was developed.•The proposed non-dimensional model can well correlate facade flame height.
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•A hierarchical ternary structure of FNPCN is rationally designed.•Obvious suppression on heat release is observed by incorporating FNPCN.•Marked hinderances on toxic CO and HCN ...emissions are found by using FNPCN.•Flame retardancy comparison with reported works confirms the meliority of FNPCN.
High fire hazard of generating a great deal of heat and toxic volatiles has been deemed as notorious issue of thermoplastic polyurethane (TPU), severely impeding its practical usage. Hence, a hierarchical ternary structure (FNPCN) based on NiAl LDH anchored phosphorus-doped g-C3N4 dotted with Fe3O4 nanoparticles is rationally designed as flame retarded additive for TPU. Specifically, by adding 1.0 wt% FNPCN, the obvious reductions of 30.9% and 21.8% in peak heat release rate and total heat release are obtained, suggesting the suppressed heat release. Meanwhile, a marked decrease of 31.9% in peak smoke production rate is discovered, implying the reduced fire toxicity. Moreover, the direct evidence for hindered releases of toxic CO and HCN gases is provided by TG-IR spectra. These results jointly corroborate the efficacy of FNPCN in impairing the fire hazard of TPU, originating from its physical barrier and chemical catalyst characters. This work may shed a light on the designing of hierarchical ternary structure, optimizing their prospects in polymer-matrix composite and other areas.
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•Inertants may have the opposite effect on the combustion of dust clouds and dust layers.•Inertants enhance the combustion of Mg dust layer by destroying the oxide crust.•The ...exothermic reaction of inertants with Mg directly leads to violent combustion.•The inerting effect should consider the impact on both dust clouds and dust layers.
Adding solid inertants to combustible dust is an effective means of reducing dust explosion risk through both preventive and mitigative measures. However, since dust layers and dust clouds differ in their flame spread mechanisms, they may also differ in their response to solid inertants. In this paper, inerting efficacy of four commonly used solid inertants in Mg dust layers and dust clouds was investigated. As concentration increased, all four inertants effectively suppressed burning in Mg dust clouds. However, CaCO3, NaHCO3, and SiO2 greatly increased the fire hazard in Mg dust layers. CO2 produced by thermal decomposition of CaCO3 destroyed the MgO layer formed on the surface of Mg dust layers and caused more burning of Mg vapor in the gas phase. The water vapor produced by NaHCO3 reacted with Mg to generate hydrogen which intensified combustion. SiO2 emitted heat through a substitution reaction with Mg powder to thrust the mixed dust layer upwards, causing violent combustion similar to that in dust clouds. As inertant proportion increased, the fire hazard in dust layers was initially enhanced but was later decreased, although the fire hazard at 70% inertant remained much higher than that with pure Mg dust. Only NaCl, which is chemically stable and does not react with metal dust, can effectively inert both Mg dust layers and dust clouds. Research on the use of solid inertant technology to prevent or mitigate dust explosions should therefore consider the impact on both dust clouds and dust layers.
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