Studying smoldering to flaming transition in polyurethane furniture subassemblies: Effects of fabrics,flame retardants,and material type

The transition from smoldering to flaming was studied on fabric, batting, and foam assemblies via an electric spot ignition source of similar intensity to a cigarette. The materials studied included four different fabrics (cotton, polyester, cotton/polyester blend, flame retardant cotton/polyester blend), two types of batting (cotton, polyester), and three types of polyurethane foam (nonflame retardant, flame retardant by FMVSS 302 testing, flame retardant by BS5852 testing). The results from testing found that materials highly prone to smoldering could propagate smoldering into foams and lead to ignition, whereas materials that tended to melt back from the ignition source did not. Flame retardant fabrics or foam can and do prevent the transition from smoldering to flaming provided sufficient levels of flame retardants are incorporated in the upholstery fabric or foam. The transition from smoldering to flaming of cotton fabric/nonflame retardant foam assembly was also studied using temperature measurements and evolved gas analysis. It was determined that the transition takes place when the oxygen consumption by accelerating smoldering front exceeds the oxygen supply. At this point, the solid fuel gasification becomes driven by thermal decomposition rather than by surface oxidation which leads to high enough concentrations of fuel for flaming combustion to occur.     

Influence of thermal behavior of phosphorus compounds on their flame retardant effect in PU rigid foam

Phosphorus‐containing compounds have been widely used as flame retardants for polyurethane rigid foam (PURF). In this work, a number of phosphorus compounds were utilized and studied as flame retardants for PURF, including ammonium polyphosphate, pentaerythritol phosphate, triethyl phosphate, and dimethyl methyl phosphonate. The thermal behavior of flame retardants was thoroughly investigated, such as degradation, vaporization, and the properties of degraded products. The influence of thermal behavior of phosphorus flame retardants on PURF was examined and analyzed. The results indicated that the effect of flame retardant was highly related to their thermal behavior. Phosphorus compounds for gas phase flame retardants were very effective in decreasing the heat release rate and increase limited oxygen index of PURF, while condensed phase flame retardants showed better comprehensive flame retardant effect, such as reducing the toxicity of combustion product. Copyright © 2015 John Wiley & Sons, Ltd.     

Flammability testing of pure and flame retardant-treated cotton fabrics

A Controlled-atomosphere cone calorimeter was used to investigate the burning of pure and flame retardant-treated cotton fabrics. The condensed-phase flame retardants used were Morguard (containing ammonium dihydrogen phosphate and diammonium hydrogen phoisphate) and Nochar (containing ammonium sulfate and a sodium salt). The fabrics were tested at 25 kW m^?2 incident heat flux in environments containing 15–30% oxygen. The flame retardants increased the time to ignition, residue yield, and CO and CO₂ yields. The flame retardants decreased the peak and average mass loss rates, the peak and average heat release rates, the effective heat of combustion at peak heat release rate, and the propensity to flashover. The effect of oxygen concentration on the burning of pure and flame retardant-treated cotton fabrics has also been investigated. The flame retardants had better performance when the treated fabrics burned in the lower oxyge concentrations. The result of this study indicate that the controlled-atmosphere cone calorimeter is a good tool for studying the effect of flame retardant and oxygen concentration on the burning of materials.     

含磷阻燃剂在聚氨酯弹性体中的阻燃机理研究

采用极限氧指数、TG—DTA分析、红外分析及元素组成分析。探讨了两种含磷阻燃剂磷酸酯1^#(P1^#)和TCP在异氰脲酸酯改性聚氨酯弹性体(IMPUE)中的阻燃机理。研究表明：P1^#和TCP阻燃IMPUE．既有气相阻燃机理和凝聚相阻燃机理．又有中断热交换阻燃机理。三者协同发挥阻燃作用。其中P1^#以气相阻燃和中断热交换阻燃为主,凝聚相阻燃为辅;TCP以凝聚相阻燃和中断热交换阻燃为主,气相阻燃为辅。     

新型聚乳酸阻燃体系研究进展

综述了新型聚乳酸（PLA）阻燃体系的研究进展。以PLA阻燃机理为主线,对以凝聚相阻燃为机理的膨胀型阻燃体系、新型成炭阻燃体系、催化成炭阻燃体系、次磷酸盐阻燃体系、纳米材料阻燃体系和以气相阻燃为机理的缓释体系、气相催化体系研究进展进行综述。最后以PLA高效环保阻燃为研究热点,对PLA阻燃研究趋势进行了预测。     

Flame retardant polyester by combination of organophosphorus compounds and an NOR radical forming agent

Polymer materials with different surface-to-volume ratios require different mechanisms of flame retardants regarding condensed phase and gas phase activity. The flame retardant formulations in poly(ethylene terephthalate) (PET) are investigated regarding a condensed phase and gas phase activity by using thermogravimetric analysis (TGA), TG-mass spectrometry (MS), TG-Fourier transform infrared (FTIR), UL94, cone calorimeter and scanning electron microscopy–energy-dispersive X-ray spectrometer measurements. The flame retardant formulations containing phosphates, phosphonates, and phosphinates as flame retardants are analyzed by using a simultaneous analysis consisting of a differential thermal analysis-TGA device which is in situ coupled to FTIR and MS. All analysis methods show a gas phase activity for the phosphonate (PCO 910), a condensed phase activity for the phosphate (3,9-bis(phenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-5,5-undecane-3,9-dioxide, (SPDPP) and a mixed condensed and gas phase activity for the new synthesized phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide containing flame retardant 3,9-bis(phenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro-5,5-undecane-3,9-dioxide (SPDPDOM). The fire behavior of PCO 910 can be improved by adding O,O'-Terephthaloyl-bis-N,N'-naphthalimide ester as NOR radical-forming agent (NOR-RF) reaching a total amount of 3 wt % of both active agents for a UL94 V-0 classification in PET. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47876.     

Synthesis of phosphorus-containing flame retardants and investigation of their flame retardant behavior in textile applications

Flame retardants are a growing area of research interest. Nonhalogenated, durable, and nonleachable flame retardants are one of the main strategies used in the research of flame retardant polymers. In this regard, the covalent attachment of phosphorus-containing flame retardants onto cotton fabric has been developed. Two types of reactive phosphorus-containing flame retardants (MKT-1 and MKT-2) have been synthesized and used as a surface coating for cotton fabric. MKT-1 possesses anhydride and acid functionalities that can react with the  OH functionalities in cellulose. In addition, MKT-2 has both acid and organosilicon groups that can also react with the hydroxy group present in cellulose. The structures of the reactive flame retardants (MKT-1 and MKT-2) were characterized using ¹³C and ³¹P nuclear magnetic resonance spectroscopy. Thermal properties of the coated and uncoated cotton fabrics were investigated using thermogravimetric analysis. Surface characterization was carried out using scanning electron microscopy and X-ray photoelectron spectroscopy. A standard test method used to evaluate the flammability of blankets (BS 5852) was also applied to characterize the fire retardant properties of the coated and uncoated cotton fabrics studied. Different loadings of MKT-1 and MKT-2 on the fabric (10, 20, and 30% by weight in dimethylformamide solution) were applied in the dip coating process. The cotton fabric coated with 30% MKT-2 does not burn after being subjected to a propane burner for 20 s and also produced the highest char yield (36%) at 500 °C. Inductively coupled plasma–optical emission spectrometry showed that MKT-1 contains 8.23 ± 0.33 P% whereas MKT-2 contains 3.88 ± 0.15 P%. Although MKT-1 possess a higher P content than MKT-2, the additive effect caused by the organosilicon and nitrogen groups present in MK-2 enhance its flame retardant properties. Furthermore, the covalently attached flame retardant materials are durable and do not hydrolyze during washing. The mechanical properties of coated fabrics were characterized by a tensile test and significant change in elongation at break was observed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47935.     

Ecological issue of polymer flame retardancy

The use of polymer flame retardants has an important role in saving lives. The main flame retardant systems for polymers currently in use are based on halogenated, phosphorous, nitrogen, and inorganic compounds. All of these flame retardant systems basically inhibit or even suppress the combustion process by chemical or physical action in the gas or condensed phase. Conventional flame retardants, such as halogenated, phosphorous, or metallic additives, have a number of negative attributes. An ecological issue of the application of conventional flame retardants demands the search of new polymer flame retardant systems. Among the new trends of flame retardancy are intumescent systems, polymer nanocomposites, preceramic additives, low‐melting glasses, different types of char formers, and polymer morphology modification processing. The brief explanations on the three major types of flame retardant systems (intumescent systems, polymer nanocomposites, and polymer organic char formers) are the subject of this overview. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2449–2462, 2002     

用于超纤革PU浆料的无卤阻燃改性

选择了有机磷系和磷氮协同两种不同的无卤阻燃剂与溶剂型PU进行共混制备无卤阻燃PU,对其力学性能、阻燃性能及耐碱性能进行了系统研究。结果发现:相较于磷氮协同阻燃剂(SN-605),采用有机磷系阻燃剂(JL-30)改性PU显示出更好的阻燃性能与耐碱性能;当阻燃剂质量分数为11.1%时,阻燃PU的LOI可以达到29.1%,垂直燃烧测试达到V-0级;并且具有较好的耐碱性能,在90℃、30 g/L NaOH溶液中碱处理40 min后,其LOI仍然可以达到28.7%,垂直燃烧测试等级没有下降;但两种阻燃剂的加入均会使PU的抗张强度出现不同程度的下降。此外,热失重测试(TG)显示,两种阻燃PU的阻燃机制不同,JL阻燃剂的加入使PU的热分解温度降低,并且在800℃时的残炭量没有明显增加,呈现明显的气相阻燃机制;而SN阻燃剂的加入使PU的残炭量明显增加,呈现明显的凝聚相阻燃机制。     

GMA改性磷酸腺苷的制备及其对棉织物的阻燃整理

为了提高磷酸腺苷单体在棉织物上的接枝改性程度及其阻燃效果,采用甲基丙烯酸缩水甘油酯（GMA）对一磷酸腺苷（AMP）、二磷酸腺苷（ADP）、三磷酸腺苷（ATP）进行改性,制得三种带有不饱和双键的阻燃单体AMP-m-GMA、ADP-m-GMA、ATP-m-GMA;然后通过紫外光接枝法将三种阻燃单体分别接枝到棉织物上,制备光接枝AMP-m-GMA、ADP-m-GMA和ATP-m-GMA阻燃棉织物;对三种阻燃单体进行了结构表征和热稳定性分析,并探究了三种阻燃单体光接枝阻燃棉织物的热稳定性、阻燃性能、燃烧行为和残炭结构。结果表明,三种磷酸腺苷通过GMA环氧基开环引入不饱和双键,且具有良好的热稳定性。相比于原棉织物,三种阻燃棉织物的最大热降解速率分别降低了60.0%、52.0%、60.0%,极限氧指数由16.1%分别提升到25.4%、27.4%、26.4%,织物热释放速率分别下降了15.09%、60.47%、37.82%,说明三种磷酸腺苷阻燃单体均有助于棉织物形成致密炭层,阻止热量扩散,获得良好的阻燃效果。其中,光接枝ADP-m-GMA阻燃棉织物的增重率可达22.4%,燃烧后损毁长度由30 cm缩短至14.2 cm,表现出更优异的阻燃性能。     

Methods of calculating the physical acation of flame retardants

The chemical mechanisms for the action of flame retardants are often mentioned in the literature but the physical modes of action are seldom. Discussed. This article presents one way to quantify their efficiency. The technique is based on literature data for the physical and thermal properties of flams retardants for temperatures from 25°C up to 1000°C. The prolongation of the time to ignition by heat absorption by the retardant and the amount of inert gas evolved by the retardant are calculated at a given radiation for a material flame-proofed with a given amount of the flame retardant. The ability to form an insulating surface layer is considered but not quantified. It is assumed that a medium density wood fibre building boards is treated with 2 kg of flame retardant per m². The flame retardants included are borates, boric acid, phosphates and silicates. The board is assumed to be irradiated with an intensity of 15 k W m^?2. Under these conditions an untreated board ignites after 6–7 min. The time to ignition is prolonged by 1–5 min through heat absorption by the different retardants, and the amount of inert gases evolved may be as high as 2.6 m³ per m² board. The formation of an insulating surface layer is more difficult to quantify. The results confirm the importance of the physical modes of action of flame retardants and the technique could form the basis for evaluating materials in simulated fire situations.     

未来的高效阻燃系统

介绍了４类未来的高效阻燃系统,它们或者通过高效的气相阻燃,或者通过在凝上中抑制自由基的工部或者通过催化作用改变聚合物的热分解模式并促进成炭而发挥阻燃功能。在用量极少的情况下即能满足很多领域的阻燃要求,是阻燃剂的发展方向,这类阻燃系统有：（１）催化阻燃系统：（２）芳香族磺酸盐（酯）;（３）凝聚相中的自由基抑制;（４）高效气相阻燃剂。     

Microintumescent mechanism of flame‐retardant water‐based chitosan–ammonium polyphosphate multilayer nanocoating on cotton fabric

Layer‐by‐layer (LbL) assembly of nanocoatings on fabric substrates has been very successful in terms of reduction of flammability. In particular, an LbL system comprised ammonium polyphosphate as the polyanion and chitosan as the polycation, applied to cotton fabric, dramatically reduced cotton flammability. At this point, the fire‐retardant (FR) mechanism of action of this system has never been fully elucidated. Sonicated and nonsonicated coated cotton fabrics were evaluated using a vertical flame test and mass loss calorimeter. Coating morphology was investigated before and after burning. Thermal analyses and chemical analyses in the condensed phase (and in the gas phase) were conducted to reveal the FR mechanism of action. At the cotton surface, a combination of both condensed (formation of aromatic char) and gas phase (release of water and highly flammable gases) mechanisms impart the FR behavior, promoting a kind of “microintumescence” phenomenon. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43783.     

磷系阻燃剂对楠竹粉阻燃特性的研究与分析

以楠竹粉为研究对象,采用三种磷系阻燃剂:磷酸三钠、磷酸二氢铵、聚磷酸铵,以溶液混合的方法制备不同质量分数的阻燃样,并设置空白对照样,对各样品进行热重实验。实验测试了不同种类及浓度阻燃样的燃烧热重曲线,并基于热重实验数据计算了阻燃样的各项燃烧特性参数,再分析其对竹粉的阻燃性能。结果表明,在各阻燃剂的最佳水平浓度下的阻燃性能排序为:磷酸二氢铵>磷酸三钠>聚磷酸铵,33%磷酸二氢铵阻燃样在共9个阻燃样品中对竹粉的阻燃效果最优。     

锥形量热法研究木质素基膨胀型阻燃剂对环氧树脂阻燃抑烟效果

以来自自然界储量第二的木质素作为膨胀型阻燃剂的基体,通过接枝氮、磷元素成功合成碳源、酸源、气源三位一体的木质素基膨胀型阻燃剂（Lig-T）,实现了良好的阻燃性能。将Lig?T按照不同含量添加到环氧树脂（EP）中制备EP/Lig-T复合材料,以锥形量热测试考察复合材料的热稳定性能和阻燃性能,并重点考察复合材料在接近真实火灾事故时的热释放和烟释放规律。结果表明,当Lig-T含量为20 %（质量分数,下同）时,复合材料的热释放速率峰值为1 374 kW/m²、热释放总量为41.63 MJ/m²、烟释放总量为1 634 m²/m²,与EP参比试样的数值相比,均呈现下降的趋势,燃烧结束的残炭率从4.26 %增至10.01 %。基于气相和凝聚相的协效阻燃机理,木质素作为膨胀型阻燃剂的碳源使得复合材料在高温条件下具备更好的成炭效果,在燃烧过程中形成稳定且致密的炭层结构,在实现高效阻燃的同时减少有毒烟气的释放,降低火灾的危害。     

Overview of recent developments in the flame retardancy of polycarbonates

This paper presents an overview of the recent literature on flame retardancy of polycarbonate (PC) and polycarbonate‐based resins. A brief survey of the major mechanisms of thermal decomposition of PC is also presented because it gives insight in the mechanisms of flame retardant action. Mostly industrial laboratories are involved in the development of new flame retardants for PC and, to a much lesser extent, academic laboratories are doing research on the mechanistic aspects of flame retardancy. The number of patents published annually on the flame retardancy of PC and its blends significantly exceeds the number of patents on flame retardancy of any other polymer. Because PC is a naturally high charring polymer, the condensed phase active flame retardants, in particular phosphorus‐based ones, are widely used in PC‐based blends. Plain PC can pass stringent flame retardant tests with very low additions of some sulfur‐ or silicone‐based flame retardants. Copyright © 2005 Society of Chemical Industry     

Correlation between limiting oxygen index and phosphorus/nitrogen content of cotton fabrics treated with a hydroxy‐functional organophosphorus flame‐retarding agent and dimethyloldihydroxyethyleneurea

The combination of a hydroxyl‐functional organophosphorus flame‐retarding agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame‐retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame‐retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame‐retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003     

The effect of ammonium sulphate—decabromobiphenyl oxide on the flammability of polyester/cotton blend

A 87.5:12.5 polyester/cotton blended fabric was treated with various concentrations of ammonium sulphate and decabromobiphenyl oxide (DBBO) as well as mixtures of the two additives. The flammability of the resulting systems was determined by the limiting oxygen index (LOI) method and their thermal decomposition by thermogravimetry. Ammonium sulphate was particularly less effective as a flame retardant than the DBBO. Decabromobiphenyl oxide acts in the gas phase to retard the flammability of the polyester while the inorganic salt acts in the condensed phase to decrease that of the cotton. A mechanism for the interaction of ammonium sulphate with cotton was suggested. When a mixture of the two additives containing a high percentage of the bromo-compound was used a significant increase in the LOI values was observed compared to one having the same total loading but containing a higher percentage of ammonium sulphate. This may be attributed to the stabilizing effect of the released ammonia on the intermediate species formed after the liberation of the bromine radicals from the DBBO.     

无卤阻燃聚对苯二甲酸丙二酯的研究

使用无卤磷系阻燃剂二乙基次膦酸铝(ADP)和氮系阻燃剂三聚氰胺氰尿酸盐(MCA)作为阻燃剂,马来酸酐接枝聚烯烃弹性体(POE-g-MAH)为增韧剂,对聚对苯二甲酸丙二酯(PTT)进行阻燃改性,分别研究两种不同体系阻燃剂对PTT阻燃性能和力学性能的影响,并通过热失重(TG)分析仪、差示扫描量热(DSC)仪,扫描电子显微镜(SEM)对其阻燃机理进行研究。实验结果表明,添加质量分数10%的ADP时,阻燃PTT达到V–0级,极限氧指数(LOI)达到30.0%,ADP主要在凝聚相中发挥阻燃作用;添加质量分数20%的MCA时,阻燃PTT达到V–0级,LOI达到24.9%,MCA主要在气相中发挥阻燃作用;ADP与MCA的加入都降低了阻燃PTT的综合力学性能。TG和DSC测试结果说明,ADP与PTT间的相容性良好,可以有效地促进PTT成炭并提高材料的阻燃性能;MCA与PTT间的相容性较差,且MCA对PTT成炭没有影响。添加质量分数5%的ADP和10%的MCA时,阻燃PTT达到V–0级,LOI达到26.9%,说明ADP与MCA具有协效阻燃作用。     

环保型阻燃湿法合成革的研制

用液态的磷酸酯阻燃剂对涤/棉配比基布进行浸渍处理,处理量占基布质量的5 %（干重比）,可使基布达到美国FMVSS-302阻燃标准的B级阻燃效果。通过6种阻燃剂在聚氨酯树脂中的不同配比试验,考察了不同阻燃剂组合及其用量对聚氨酯树脂阻燃性能的影响。结果表明,氢氧化铝/间苯二酚双/磷酸酯（12/2/2,质量份,下同）复合阻燃剂配方体系所制试样燃烧速度为0 mm/min,阻燃效果可达到A级;将其涂覆于阻燃处理的基布上即可制得环保型阻燃合成革,阻燃性能可以通过多国的阻燃标准。