Study on aqueous film-forming foam extinguishing agent based on fluorocarbon cationic–hydrocarbon anionic surfactants mixture system

Fluorocarbon surfactants were the main components of aqueous film-forming foam extinguishing agents (AFFF). Unfortunately, the widely used fluorocarbon surfactant perfluorooctane sulfonate (PFOS) was limited due to its toxicity, bioaccumulation and biodegradability. In this paper, an environmentally friendly quaternary ammonium cationic fluorocarbon surfactant with high surface activity and simple synthesis route was reported. The surface performance and aggregation behavior of the mixed solution of this fluorocarbon surfactant and sodium n-octyl sulfate were studied by means of surface tension meter and transmission electron microscope (TEM). The results showed that the synergistic effect of sodium n-octyl sulfate and this fluorocarbon surfactant was significant, and many vesicles could be observed in the mixed solution with the concentration of 0.1 mol/L under TEM. Subsequently, three environmental friendly AFFF formulations (F-1, F-2, F-3) were designed with the mixture of the fluorocarbon surfactant, sodium n-octyl sulfate and lauryl betaine BS-12 as foaming agent. Through its foam performance test, it could be seen that F-3 showed relatively excellent foam performance. The initial foam height h₀ was 70 mm, the 25% drainage time was 315 s, the extinguishing time was 28 s, and the burn-back time was 720 s. This kind of fire extinguishing agent had the potential of fire protection application.     

Research on a noble extinguish material for the underground fire prevention

The three-phase foam consisted of solid, liquid and gas is regarded as a highly effective measure for the underground mine fire prevention. In this study, the three-phase foam technology is introduced and a visualization platform is established to exhibit the foam flow in a physical goaf. The diffusion rule and extinguishing performance for three-phase foam are researched. Test results show that the three-phase foam has a superior heat resistance than expansion foam in the top goaf. The coal heating rate is postponed after the three-phase foam processing and the active functional groups are suppressed effectively. Increasing the foam expansion ratio is adverse to the three-phase foam stability. The field application of three-phase foam was evaluated via the practical extinguishment effect. The marked reduction in the sealed zone temperature and CO concentration proved that the proposed three-phase foam technology was effective on controlling the concealed goaf fire.     

泡沫灭火剂中全氟辛烷磺酸类物质的管控行为及替代物研究进展

全氟辛烷磺酸（perfluorooctane sulfonic acid, PFOS）使水成膜泡沫灭火剂（aqueous film forming foam,AFFF）具有较好的耐高温和抗烧能力,但由于PFOS的难降解性、生物富集性及毒性,国内外相继对PFOS类物质进行了管控。本文简述和分析了泡沫灭火剂中PFOS类物质的管控行为及替代物研究,分析表明管控行动逐步从限制走向淘汰,研究泡沫灭火剂中PFOS类物质的替代物极为迫切;替代物的研究方向主要有两个,一个是泡沫灭火剂中短氟碳链类表面活性剂研究及短氟碳链泡沫灭火剂的灭火效果验证,但短氟碳链类表面活性剂可能存在长期环境持久性的问题;另一个是泡沫灭火剂中无氟类表面活性剂的研究,如有机硅表面活性剂、甜菜碱型表面活性剂、纯化皂苷表面活性剂,但无氟类表面活性剂可能会影响无氟泡沫灭火剂的表面活性、灭火能力、灭火效果等。泡沫灭火剂中PFOS类物质的替代物研发尚任重而道远。     

A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry     

氟表面活性剂和氟聚合物(XII)——含氟灭火剂

介绍了氟表面活性剂在水成膜泡沫灭火剂(AFFF)、氟蛋白泡沫灭火剂(FP)、成膜氟蛋白泡沫灭火剂(FFFP)及抗复燃超细干粉灭火剂以及Halon灭火剂替代物中的应用。分析了国内研究生产现状,对含氟灭火剂的发展趋势和前景进行了展望。     

Experimental investigation on the spread of aqueous foam over ethanol surface

The presence of ethanol has an adverse effect on foam spreading, and ethanol fire is difficult to extinguish with aqueous fire-fighting foams. Thus, it is necessary to explore the foam formulation suitable for ethanol fuels and study the spreading behavior of foam over ethanol surface. In the current work, stable foams based on hydrocarbon surfactant (SDS), fluorocarbon surfactant (FC1157), and polymers (XG) were prepared by using the compressed-air foam system. The spreading behaviors of foam on polar ethanol and non-polar heptane surface were observed and compared. Furthermore, the effects of stabilizer concentrations, foam flow rates and expansion ratios on foam spreading performance were investigated, respectively. The results indicate that aqueous SDS foam can spread on the heptane layer continuously, but it is difficult to cover the ethanol surface. The addition of XG and FC1157 can synergistically improve the spreading performance of aqueous foam over ethanol. Depending on stabilizer concentrations, there are remarkable differences in foam spreading behaviors. Besides, different foam application parameters including expansion ratios and foam flow rates significantly affect the foam spreading rate, despite the same foam formulation. The research methods and results guide the optimal design of foam formulations as well as the practical application of aqueous foam for ethanol fire extinguishment.     

Experimental investigation on the spread of aqueous foam over ethanol surface

The presence of ethanol has an adverse effect on foam spreading, and ethanol fire is difficult to extinguish with aqueous fire-fighting foams. Thus, it is necessary to explore the foam formulation suitable for ethanol fuels and study the spreading behavior of foam over ethanol surface. In the current work, stable foams based on hydrocarbon surfactant (SDS), fluorocarbon surfactant (FC1157), and polymers (XG) were prepared by using the compressed-air foam system. The spreading behaviors of foam on polar ethanol and non-polar heptane surface were observed and compared. Furthermore, the effects of stabilizer concentrations, foam flow rates and expansion ratios on foam spreading performance were investigated, respectively. The results indicate that aqueous SDS foam can spread on the heptane layer continuously, but it is difficult to cover the ethanol surface. The addition of XG and FC1157 can synergistically improve the spreading performance of aqueous foam over ethanol. Depending on stabilizer concentrations, there are remarkable differences in foam spreading behaviors. Besides, different foam application parameters including expansion ratios and foam flow rates significantly affect the foam spreading rate, despite the same foam formulation. The research methods and results guide the optimal design of foam formulations as well as the practical application of aqueous foam for ethanol fire extinguishment.     

粉体对泡沫灭火剂发泡能力和热稳定性影响研究

研究了纳米二氧化硅、硅微粉、石墨、纳米级铜粉对于蛋白泡沫的发泡能力及热稳定性的影响,并且测试了形成的复合泡沫的热稳定性,结果表明：将耐烧粉体直接添加进灭火泡沫中有望增强其抗烧能力和灭火性能。在常温下纳米二氧化硅以及纳米级铜粉能与蛋白泡沫较好的结合为复合泡沫,添加测试粉体后复合泡沫的热稳定性均有明显增强,其中添加纳米二氧化硅和纳米级铜粉的复合泡沫整体性能良好,无泡沫排液和聚并现象,可以起到良好的隔热作用。     

碳氢/有机硅/低碳醇三元系泡沫及抑制煤自燃的效果分析

泡沫灭火剂是常用的火灾扑救方法之一,但常规泡沫灭火剂存在半衰期短,析液、聚并迅速而影响灭火效能的问题,基于火灾化学和活性剂技术,提出碳氢表面活性剂SDS、有机硅表面活性剂LS-99和低碳醇的三元系泡沫体系,并系统探究碳氢/有机硅/低碳醇的复配配比。通过表面张力、发泡高度、稳泡系数的大量测试,发现LS-99的临界胶束浓度为0.0083%。LS-99和SDS二元系在降低表面张力、提升发泡高度和稳泡系数方面具有良好的协同增效作用。在此基础上引入适量浓度的能够延缓泡沫析液、聚并的异丁醇,设计出了性能优良的碳氢/有机硅/低碳醇泡沫灭火剂。LS-99、SDS和异丁醇的质量分数为0.1%时,测试结果表明SDS/LS-99/醇三元系泡沫的发泡倍数可达52.5倍,25%析液时间可达210 s,300 s时的稳泡系数高达0.958,半衰期远超常规泡沫。煤自燃的灭火抑制实验表明,SDS/LS-99/醇三元系泡沫作用下,煤自燃各反应阶段的活化能相较于空气氛围均增大,反应难度增强;最大失重速率下降,反应剧烈程度减弱。初期吸热阶段的吸热量为78.3 J/g,大于空气氛围下煤氧复合的吸热量,吸热增幅高达2.16倍。放热阶段的放热量为1765.4 J/g,相较于空气氛围放热降幅达到15.15%,表明SDS/LS-99/醇三元系泡沫对煤自燃具有良好的灭火效果。     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

An Analytically Defined Fire‐Suppressing Foam Formulation for Evaluation of Fluorosurfactant Replacement

A 4‐component, analytically defined, reference fluorosurfactant formulation (Ref‐aqueous film forming foam [AFFF]) composed of 0.3% fluorocarbon‐surfactant concentrate (Capstone 1157), 0.2% hydrocarbon‐surfactant concentrate (Glucopon 215 UP), and 0.5% diethylene glycol mono butyl ether by volume in distilled water was found to have rapid fire extinction comparable to a commercial AFFF in tests conducted on a bench scale and a large scale (28 ft², part of US Military Specification, MIL‐F‐24385F). The Ref‐AFFF was analytically characterized to provide the identity and quantity of the chemical structures of the surfactant molecules that were lacking for commercial AFFF formulations. To arrive at an acceptable Ref‐AFFF formulation, 3 candidate formulations containing different hydrocarbon surfactants in varying amounts were evaluated and ranked relative to a commercial AFFF using a bench‐scale fire‐extinction apparatus; varying the hydrocarbon surfactant was found to affect the fire‐extinction time. The ranking was confirmed by the large‐scale tests suggesting that the bench‐scale apparatus is a reasonable research tool for identifying surfactants likely to succeed in the large‐scale test. In the future, replacing the fluorocarbon surfactant with an alternative surfactant in the Ref‐AFFF enables a direct comparison of fire extinction and environmental impact to identify an acceptable fluorine‐free formulation.     

电力封堵用缩合型硅橡胶泡沫防火材料的制备及性能

研究了不同黏度和用量的乙烯基硅油、具有不同形态的防火填料对脱氢缩合型硅橡胶泡沫材料泡孔结构及防火性能的影响,使用橡胶加工分析仪表征了硅橡胶发泡过程中的发泡速率和交联速率,同时考察了氢氧化铝、云母、硅灰石3种填料对硅橡胶泡沫材料防火性能的影响。结果表明,不加入乙烯基硅油时,硅橡胶泡沫材料的储能模量较低,泡孔以闭孔结构为主;乙烯基硅油的加入提高了硅橡胶泡沫材料的交联速率和储能模量,使之形成较多的开孔结构,同时对硅橡胶泡沫材料泡孔尺寸分布也有影响;加入片状云母容易造成泡孔的坍塌或破裂,但是经火焰烧蚀后泡孔结构和烧蚀面的完整性保持较好,所形成的完整的陶瓷化阻隔层可起到较好的防火作用,而加入氢氧化铝和硅灰石后硅橡胶泡沫材料烧蚀后开裂比较严重。     

泡排井用起泡剂室内评价及影响因素研究

起泡剂作为泡排工艺的核心化学助剂,在现场实际应用前,对其各项性能的评价是必不可少的一个环节。本文对目前使用较为广泛的UT-11C型起泡剂开展了室内研究,采用经典的静态评价方法,并结合自行设计的泡沫管流可视化实验装置进行动态评价。研究结果表明:该型起泡剂起泡和稳泡性能良好,起泡基液浓度、温度和矿化度对起泡剂有较为明显的影响,起泡剂浓度5‰、温度40℃时起泡性能最佳,而在矿化度高于60 g/L的环境中泡沫稳定性极差。通过静态、动态评价实验方法的综合考查,能够更加全面的认识起泡剂性能。     

全水发泡阻燃聚氨酯硬质泡沫塑料的制备与性能

采用多元醇、异氰酸酯、催化剂、发泡剂和阻燃剂等为原料制备了全水发泡阻燃聚氨酯硬质泡沫(PURF),讨论了聚醚多元醇种类、催化剂、发泡剂、异氰酸酯指数以及阻燃剂对PURF性能的影响。结果表明,聚酯多元醇能够改善泡孔结构,但降低压缩强度和尺寸稳定性;不同催化剂复配,可以控制发泡工艺;水发泡剂与泡沫的密度、泡孔结构、力学性能有关;异氰酸酯指数在1.1～1.2时,泡沫的压缩强度、尺寸稳定性等较好;三(2-氯异丙基)磷酸酯(TCPP)可赋予PURF一定的阻燃性,但对泡体结构、压缩强度和尺寸稳定性有影响。     

提高聚丙烯冲击强度的改性研究

为提高聚丙烯的冲击强度,采用在其中加入利用钛酸酯偶联剂经过表面活化的无机刚性粒子-硅灰石的办法,对添加不同含量的硅灰石所产生的力学性能的改变进行了测试。以测试结果为基点,利用电子显微镜观察了硅灰石/聚丙烯复合材料脆断面的结构情况,分析了两相界面的相容性、聚丙烯结晶行为的改变等对聚丙烯力学性能改性的影响,同时讨论了关于作用能量吸收的部分原因。从而实现了聚丙烯在某些应用需求方面的改性目的,给出了提高聚丙烯冲击强度的一个有效方法。     

Processing and properties of new high-temperature,lightweight composites based on foam polyimide binder

We report a method for making novel, lightweight (ρ = 0.3–1.1 kg/dm³) polymer composites based on high-temperature foam polyimide binder, carbon fibers, and organic fibers. The density and mechanical properties of the foam composite can be varied over a relatively wide range, depending on the volume contents of the fiber and air pores. The resin's high glass transition temperature of 260°C, coupled with the high thermal stability of carbon or polyimide fibers, contributes to its excellent retention of mechanical properties at elevated temperatures. The temperature at the beginning of weight loss is not lower than 570°C and depends on the kind of fiber felt. The combination of excellent thermal and specific mechanical properties of foam composites together with exceptional thermal stability and processability on conventional molding equipment can provide unusual performance for the new design of advanced materials and structures.     

Fracture response of wollastonite fiber-reinforced cementitious composites: Evaluation using micro-indentation and finite element simulation

The paper presents indentation studies on wollastonite fiber incorporated cementitious systems. The acicular nature of the fibers is poised to delay the coalescence of micro-cracks in such systems thus leading to tougher building materials. Towards that end, load-penetration depth results from the indentation studies are employed to ascertain elastic and fracture properties of wollastonite-incorporated cementitious composites. While up to 10% mass-based cement-replacement by wollastonite results in comparable elastic moduli as compared to conventional binders, the fracture toughness increases by as much as 33%. In order to gain insights into the toughening mechanisms brought about by the fine fibers, a microstructure-guided numerical simulation strategy is adopted towards effective fracture performance prediction. The performance enhancement of the wollastonite systems is corroborated by the finite element-based simulations carried out on the virtual microstructures that accurately capture the heterogeneity of such systems. Besides fracture performance enhancement, the wollastonite-incorporated cementitious systems also contribute towards development of sustainable cement replacing compositions. Moreover, the micromechanical predictive tool developed in this study facilitate efficient means to tune the materials structure for desired performance.     

表面活性剂浓度对泡沫体系稳定性的影响

主要探讨了在泡沫体系内,表面活性剂对泡沫稳定性的影响,以表活剂浓度为主要研究点,总结了不同表活剂浓度下气泡的聚并过程,还分析了液膜的排液过程,指出界面流变学因素以及表活剂高浓度情况下的胶束分层现象是影响泡沫稳定的主要因素.表活剂浓度低于CMC时,界面流变学因素起主要决定作用;表活剂浓度高于CMC时,胶团分层起主要决定作用.     

起泡剂的起泡性能及使用浓度优选研究

起泡剂的起始发泡体积和泡沫稳定性是决定起泡剂起泡性能的两个重要因素,也是实际应用当中筛选起泡剂的重要指标.采用Ross-Miles法对13种不同类型起泡剂在常温下的起泡性能进行了评价.结果表明：不同类型起泡剂的起始发泡体积和泡沫稳定性具有显著的不同.不同起泡剂的起始发泡体积随浓度的增加而增大.当起泡剂浓度增加到0.5％时,起始发泡体积趋于稳定,由此确定起泡剂的最佳使用浓度为0.5％.