Combustion behaviour of fabric and polyurethane flexible foam mock-up combinations under Cone Calorimetry test conditions

The relative contributions of fabric and foam on important fire hazard parameters as measured in the cone calorimeter were determined for various mock-up combinations. Three commercial types of high-resilience PU flexible slabstock foams, representing a wide range of combustion performance, were combined with three different fabrics: polyester, polypropylene and combustion-modified cotton. Total heat release of the combinations correspond well with the value calculated from the individual components and is determined by the density and effective heat of combustion of the components, and the foam/fabric weight ratio. The foams show a smaller variation in effective heat of combustion than the fabrics. Covering of PU flexible foams with a fabric results in general in a delay of ignition and peak rate of heat release. Performance of the mock-ups is mainly determined by the fabric but is also influenced by the quality of the foam.     

Ignition and combustion of low‐density polyimide foam

The ignition, flaming and smoldering combustion of low‐density polyimide foam have been studied using a cone calorimeter. Low‐density polyimide foam exhibits a high ignition resistance. The minimum heat flux for the ignition of flaming combustion ranges from 48 to 54 kW/m². This minimum heat flux also indicates the heat flux for transition from smoldering to flaming combustion. The flaming combustion results show that the heat release rate of low‐density polyimide foam is very low even at a high incident heat flux of 75 kW/m². The smoldering combustion results show that the smoldering of low‐density polyimide foam becomes significant when the incident heat flux is greater than 30 kW/m². The smoldering combustion of low‐density polyimide foam cannot be self‐sustaining when the external heat source is removed. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of variations in incident heat flux when using cone calorimeter test data for prediction of full‐scale heat release rates of polyurethane foam

The development of methods to predict full‐scale fire behaviour using small‐scale test data is of great interest to the fire community. This study evaluated the ability of one model, originally developed during the European Combustion Behaviour of Upholstered Furniture (CBUF) project, to predict heat release rates. Polyurethane foam specimens were tested in the furniture calorimeter using both centre and edge ignition locations. Input data were obtained using cone calorimeter tests and infrared video‐based flame area measurements. Two particular issues were investigated: how variations in incident heat flux in cone calorimeter tests impact heat release rate predictions, and the ability of the model to predict results for different foam thicknesses. Heat release rate predictions showed good agreement with experimental results, particularly during the growth phase of the fire. The model was more successful in predicting results for edge ignition tests than for centre ignition tests and in predicting results for thinner foams. Results indicated that because of sensitivity of the burning behaviour to foam specimen geometry and ignition location, a single incident heat flux could not be specified for generating input for the CBUF model. Potential methods to determine appropriate cone calorimeter input for various geometries and ignition locations are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparison of cone and OSU calorimetric techniques to assess the flammability behaviour of fabrics used for aircraft interiors

Two test methods for measuring the heat release rate, HRR have been compared on fabric composites used for aircraft interior materials as side‐wall panels. These methods are based on the principles of direct measurement of the convective and radiant heat by thermopiles using an Ohio State University (OSU) calorimeter, and oxygen consumption using a cone calorimeter. It has been observed when tested by standard procedures, cone results at 35 kW/m² incident heat flux do not correlate with OSU results at the same heat flux. This is because in the cone calorimeter, the sample is mounted horizontally whereas the OSU calorimetric method requires vertical sampling with exposure to a vertical radiant panel. A further difference between the two techniques is the ignition source—in the cone it is spark ignition, whereas in the OSU it is flame ignition; hence, samples in the OSU calorimeter ignite more easily compared to those in the cone under the same incident heat fluxes. However, in this paper we demonstrate that cone calorimetric exposure at 50 kW/m² heat flux gives similar peak heat release results as the 35 kW/m² heat flux of OSU calorimeter, but significantly different average and total heat release values over a 2 min period. The performance differences associated with these two techniques are also discussed. Moreover, the effects of structure, i.e. type of fibres used in warp/weft direction and design of fabric are also analysed with respect to heat release behaviour and their correlation discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Grafting modification bamboo kraft lignin and its performance in rigid polyurethane foams

In order to improve the efficiency of intumescent flame retardant (IFR), bamboo kraft lignin (BKL) was chemically functionalized by grafting melamine (MEL) and diethyl phosphite (DEP) and used for rigid polyurethane (RPU) foam. The BKL, MEL, and DEP in IFR system were used as char forming agent, gas, and acid source, respectively. The FTIR and XPS results indicated that the nitrogen (N) and phosphorus (P) containing BKL was successfully synthesized. The limiting oxygen index (LOI) value of N-BKL and N/P-BKL RPU foams were higher than BKL RPU foam, suggesting that N-BKL and N/P-BKL improved flame retardancy of the foams. The total heat release (THR), heat release rate (HRR), effective heat of combustion (EHC), and fire growth rate (FIGRA) values of N-BKL and N/P-BKL RPU foams were much lower than that of BKL RPU foam. The flame retardancy index value of N/P-BKL RPU foams was higher comparing to N-BKL RPU foam. These results indicated that the synergistic interaction between N containing compound of MEL and P containing compound of DEP led to the improvement flame retardant properties. Comparing to BKL RPU foam, the N/P-BKL RPU foam increased 74°C of maximum weight loss temperature and decreased 18.1 wt% of mass loss, indicating enhanced thermal stability. The morphology of char after cone calorimeter testing showed the N/P-BKL RPU foam presented more continuous and compact char residues, which could reduce heat and mass transfer, protecting underlying materials from further combustion in a fire, thus resulting in good flame retardancy and thermal stability properties. This work suggests a promising route to enhancing the flame-retardant performance of RPU foam using nontoxic and more environmentally friendly grafted bamboo lignin.     

Experimental study on ignition and combustion characteristics of typical oils

The impact of radiant heat flux on ignition and combustion behavior of typical oils (diesel, lubricating oil, and aviation kerosene) was conducted in a cone calorimeter. A circular steel pan with a diameter of 10 cm was used to contain diesel, lubricating oil, and aviation kerosene without water sublayer. Using the standard oxygen consumption method, we obtained ignition time, heat release rate, mass loss rate, extinction coefficient, CO, and CO₂ yield, and average specific extinction area was calculated from the extinction coefficient. Janssens' method was adopted in this study to deal with ignition time and radiant heat flux under a 0.55 power rule. Results show that the fitting through Janssens' method is good for ignition time of diesel, lubricating oil, and aviation kerosene and radiant heat flux. Moreover, heat release rate, mass loss rate, and CO/CO₂ ratio appear to positively correlate with radiant heat flux, whereas average specific extinction area varies in a certain range. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and characterization of bio-based intumescent flame retardant and its application in polyurethane

A novel bio-based P-N containing intumescent flame retardant melamine starch phytate (PSTM) was prepared via the reaction of phytic acid starch ester with melamine and characterized by Fourier transform infrared, scanning electron microscopy and thermogravimetric analysis (TGA). The effects of PSTM on thermal properties and flammability of rigid polyurethane (PU) foams were analyzed by TGA, limit oxygen index (LOI), vertical burning tests (UL-94) and cone calorimeter measurement. The TGA results demonstrated that the thermal stabilities of PU/PSTM foam at high temperature was enhanced with the increasing additive amount of PSTM. The results showed that PU foam with 30 php PSTM (PU/PSTM-30%) observed an LOI value of 25.9 and a UL-94 rating of V-0. Cone calorimetry data showed that peak heat release rate, total heat release and smoke production rate of PU/PSTM-30% were distinctly lower than that of pure PU. Further experimental results demonstrated that PSTM promotes well charring of PU which could protect the foam from combustion. This work developed a novel bio-based intumescent flame retardant by suing phytic acid and starch as the acid source and carbon source, respectively, which is of great significance to the preparation of environmental-friendly flame retardants.     

Thermal and fire behavior of isophorone diisocyanate based polyurethane foams containing conventional flame retardants

This work reports on the fire behavior of isophorone diisocyanate‐based polyurethane foams containing different conventional flame retardants (FRs) such as melamine, ammonium polyphosphate, aluminum hydroxide, expandable graphite, and their combinations. The foams were obtained in a laboratory scale and characterized in terms of their morphology, density, thermal stability, and fire behavior. According to atomic force microscopy, the incorporation of FRs decreased the phase separated domain size. The cellular structure of the foams was examined qualitatively by scanning electron microscopy while the quantitative analysis of the surrounding skin was performed by optical microscopy and Image J. The FR containing foams showed more and smaller cells. The thermogravimetric analysis showed that the FRs had no influence in the initial degradation temperature of the foams. However, the obtained residue values were higher than the theoretical ones, indicating that there was some type of interaction between the FRs and the foams. The fire behavior of polyurethane foams was studied by the cone calorimeter and the data showed that the introduction of expandable graphite and combinations of ammonium polyphosphate/melamine to the reference foam gave rise to a significant reduction in the total heat release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45944.     

用锥形量热仪研究聚氨酯泡沫的阻燃性能

在50 kW/m2辐射功率下,利用锥形量热仪研究了氢氧化铝、卤系阻燃剂、氮系阻燃剂和磷系阻燃剂阻燃聚氨酯泡沫(PUF)的阻燃特性,获得了点燃时间、最大热释放速率、总热释放、比消光面积及质量损失速度等参数。结果表明,将热释放速率、燃烧总释放热和烟气释放量作为材料阻燃性能好坏的评价指标,阻燃剂聚磷酸铵（APP）和三聚氰胺磷酸盐（MP）是PUF的理想阻燃剂。     

Experimental study on the radiative ignition of silicones

Silicones comprise a wide variety of materials such as fluids, elastomers, resins, and foams. This paper reports the ignitability of some typical silicones under various external radiant heat fluxes. The ignitability of silicones was studied using a cone calorimeter under radiant heat flux levels of 0.5–60 kW m⁻². The time to ignition of the silicones was found to be proportional to a power of the incident heat flux that varies from −1.33 to −2.84. For silicone fluids, viscosity (or molecular size) is the key variable in controlling the ignitability. For silicone elastomers, the fillers play an important role in controlling the ignitability, especially at incident heat fluxes lower than 35 kW m⁻². The ignitability of silicone resins depends on the chemical structure of the resins: the pure trifunctional resin has the lowest ignitability. The ignitability of the silicone foams having the same density depends on the foam thickness, especially at incident heat fluxes lower than 30 kW m⁻². © 1998 John Wiley & Sons, Ltd.     

Relationship between the thermal degradation chemistry and flammability of commercial flexible polyurethane foams

In this article, we report the use of a variety of analytical methods, in particular, solid‐state ¹H‐NMR and ¹³C‐NMR to characterize the relationship between the condensed‐phase chemistry and burning behavior as determined by a series of combustion tests for two commercially derived flexible polyurethane foams, one combustion‐modified. The combustion tests showed that the foams met several regulatory requirements in terms of their fire performance, whether or not they were combustion‐modified. Both foams passed the MV SS 302 and CAL 117 small‐flame tests. The nonmodified foam failed the Crib 5 test, but this test had a much larger ignition source. The particular problem with the nonmodified foam was melt drip into the flame zone. This led to a steady maintenance of the fuel feed and a rapid escalation of the fire. In contrast, the combustion‐modified foam showed little melt drip and self‐extinguished. Thermal analysis data for the two foams showed that melamine acted in part as an endothermic heat sink. This alone did not account for the much reduced melt flow and drip of the combustion‐modified foam, but the solid‐state ¹H‐NMR data clearly showed that the molecular mobility of the combustion char from combustion‐modified foam was lower than the unmodified foam char, which indicated that the flame‐retardant formulation in the combustion‐modified foam acted by a condensed‐phase mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3024–3033, 2006     

MPP/PER/APP阻燃PP的阻燃及热裂解行为

采用聚磷酸蜜胺(MPP)／季戊四醇(PER)／聚磷酸铵(APP)三元膨胀型阻燃剂(IFR)阻燃聚丙烯(PP),测定了阻燃PP的极限氧指数(LOI)、UL94V阻燃性及热稳定性,以傅里叶变换红外光谱(FTIR)分析了阻燃PP的热分解残余物。以锥形量热仪(CONE)测定了阻燃PP的诸多与火灾有关的阻燃参数,包括释热速度、质量损失速度、总释热量、有效燃烧热、比消光面积及引燃时间等,以光电子能谱(XPS)测定了阻燃PP残炭表面的元素组成及XPS曲线拟合数据,还以扫描电镜(SEM)观测了阻燃PP残炭的形态。     

Apparatus for the vertical orientation cone calorimeter testing of flexible polyurethane foams

Of concern to regulators and fire safety engineers is how flexible polyurethane foam drips and flows during burning. Specifically, flexible polyurethane foam forms a burning ‘pool’ of liquid as the foam decomposes, which can lead to accelerated flashover events. To fully study this phenomenon where the ‘pool fire’ accelerates heat release, large‐scale tests like the furniture calorimeter (American Society of Testing and Materials (ASTM) E1537) are used, and no small‐scale technique exists. In this paper, we present our work in developing a new sample holder that works with a bench‐scale heat release test, the cone calorimeter (ASTM E1354). The holder was built upon designs developed by the National Institute of Standards and Technology, which placed the foam in a cage in a vertical orientation during cone calorimeter testing. In this paper, we show the schematics for this test apparatus, as well as results obtained with this apparatus on four different flexible foams (shape memory and high‐density foam, flame retarded and non‐flame retarded). We compare the results from the vertical testing with that obtained via traditional horizontal ASTM E1354 testing. The advantages and disadvantages of this new apparatus are discussed in this paper. Copyright © 2014 John Wiley & Sons, Ltd.     

利用锥形量热仪研究聚氨酯硬泡的燃烧性能

利用锥形量热仪对硬质聚氨酯泡沫(RP UF)的燃烧特性进行了研究.通过对RP UF燃烧过程中的热释放速率、热释放总量、烟生成速率和总产烟量等进行系统性测试,讨论了聚醚多元醇、聚酯多元醇以及异氰酸酯指数(R值)对RP UF热危险性和烟气危险性的影响.结果表明,聚酯多元醇替代聚醚多元醇制备的RP UF燃烧过程中的热释放速率...     

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.     

Investigation on flammability of rigid polyurethane foam‐mineral fillers composite

This study investigates the incorporation of castor oil–based rigid polyurethane foam with mineral fillers feldspar or kaolinite clay in order to enhance the mechanical, thermal, and flame retardant properties. Influence of mineral fillers on the mechanical strength was characterized by compressive strength and flexural strength measurement. Thermogravimetric analysis (TGA) was performed to diagnose the changes in thermal properties, while cone calorimeter test was performed to ascertain the flame retardancy of the mineral filler–incorporated rigid polyurethane foam composites. Results showed that the foams incorporated with mineral filler demonstrated up to 182% increase in compressive strength and 351% increase in flexural strength. Thermal stability of these composite foams was also found to be enhanced on the incorporation of kaolinite clay filler with an increase in 5% weight loss temperature (T_5%) from 192°C to 260°C. Furthermore, peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), and total smoke release (TSR) were also found to decreased on the incorporation of mineral filler in the rigid polyurethane foam. So mineral fillers are ascertained as a potential filler to enhance the mechanical, thermal, and flame retardant behaviors of bio‐based rigid polyurethane foam composites.     

原竹纤维增强酚醛泡沫材料的燃烧特性

采用锥形量热仪研究了不同原竹纤维加入量对酚醛泡沫材料的燃烧性能和烟气释放特性的影响。结果表明,酚醛泡沫材料的引燃时间随着原竹纤维加入量的增大而缩短,热释放速率、总放热量、质量损失速率、生烟速率和总发烟量随原竹纤维加入量的增大而总体呈增大趋势,但由于酚醛泡沫材料具有良好的阻燃性能,其燃烧快速成炭特性阻碍了热量在材料内层传递,减缓了原竹纤维在0~480 s燃烧阶段的热释放和烟气释放,使得加入量为1.5 %~3.5 %的原竹纤维作为其增强材料时,对酚醛泡沫材料的阻燃性能影响较小;而原竹纤维的加入量≥5.0 %时,对酚醛泡沫材料的阻燃性能有较大的降低作用,必须进行阻燃改性。     

Flammability studies of thermally resistant polymers using cone calorimetry

The effectiveness of a set of thermally resistant polymers was evaluated for aircraft applications using the cone calorimeter (ASTM E1354/ISO 5660) under heat fluxes simulating real scale fires. This study included eight developmental and commercial thermally resistant polymers available in the literature and/or marketplace. The polymers included were aromatic polyester, polyetherimide, fluorine‐containing polyetherketone, phosphorus and fluorine‐containing co‐polyetherketone, fluorine and phosphorus‐containing polyether, fluorine‐containing polyester, poly(dimethylsiloxane)etherimide and polysulfone. The effects of fluorine, phosphorus, silicon and sulfone group in polymers were examined. This evaluation was based on time to ignition, peak, average and total heat release rates obtained at an external heat flux of 50 kW/m². Other parameters such as effective heat of combustion, mass loss and rate of smoke and toxic gas evolution were collected during the cone calorimeter test. Copyright © 2000 John Wiley & Sons Ltd.     

Melamine amino trimethylene phosphate as a novel flame retardant for rigid polyurethane foams with improved flame retardant,mechanical and thermal properties

Melamine amino trimethylene phosphate (MATMP) as a novel nitrogen‐phosphorus flame retardant, was synthesized by the reaction of melamine with amino trimethylene phosphonic acid (ATMP) in aqueous solution. The structure of MATMP was characterized by Fourier transform infrared spectroscopy, solid state 31 P nuclear magnetic resonance, and thermogravimetric analysis. Rigid polyurethane (RPU) foams were prepared by one‐shot and free‐rise method, using MATMP as a flame retardant. The flame retardant, mechanical and thermal properties of MATMP in RPU foams were studied. It is found that the RPU foam containing 15 wt % MATMP (sample RPUMA‐15) can pass the UL‐94 V0 test with a limiting oxygen index of 25.5%. The cone calorimeter test results show that the peak heat release rate of RPUMA‐15 is reduced about 34% compared with that of untreated RPU foam. SEM results indicate that the RPU foams with MATMP can form the good and compact char during burning which provides better flame retardancy. The compressive strength of the RPU foams filled with MATMP first increases and then slightly decreases with an increase in the MATMP content comparing with that of untreated RPU foam. Moreover, thermal conductivities of the MATMP filled RPU foams are about 0.03 W/m K. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45234.     

网化聚氨酯泡沫塑料的研制

以聚酯多元醇、甲苯二异氰酸酯、特种催化剂及表面活性剂等为原料,采用水发泡,制备了大孔径块状软质聚氨酯泡沫,泡沫经网化液化学法处理,制得性能较好的网化聚氨酯泡沫塑料。介绍了块泡生产的基本配方,对影响泡沫孔径的因素进行了探讨,并对几种网化液的处理效果进行了研究。网化后泡沫的拉伸强度及伸长率增加,硬度降低;泡孔增大,则拉伸强度和伸长率降低。