polyurethane foam, when burned gives off

Polyurethane. Fire and Materials 16:p3743, Barbrauskas V, Harris RH, Gann RG, Levin BC, Lee BT, Peakcock RD, Paabo M, Twilley W, Yoklavich MF, Clark HM (1988) Fire hazard comparison of fire-retarded and non-fire-retarded products, Special Publication 749. The authors reported GC/MS analysis of the condensed phase products obtained. Equation The toxic product yields may be quantified from the gas concentrations and mass feed rate during the steady state burn period. Memory foam is a type of polyurethane foam. As a result of this, studies that use ventilation controlled conditions, such as those using the steady state tube furnace (ISO/TS 19700 2013), are more likely to give a realistic representation of these reduced oxygen environment fire conditions. Irritant gases cause pain and breathing difficulties, leading to incapacitation, such that the victim can no longer effect their own escape (ISO 13571 2012). This slight decrease is probably within the limits of experimental error, as it does not follow the general trend shown by most materials. The use of 13C labelling in this case allowed the authors to confirm that the nitrogenous compounds, HCN and organonitriles, originated from the thermal fission of the aromatic rings with the nitrile carbon being the 2-,4- or 6- carbon of the MDI ring. Early work by Voorhees (1975) identified what they described as extreme toxicity of the combustion products of a phosphate fire retarded polyurethane foam. The authors also noted that the presence of aldehydes was detected during the flaming combustion of the flexible foam, albeit in extremely low yields. Cyanide gas. What does polyurethane foam give off when burned? The average combined yield of isocyanates recovered was 0.869mgg1 and the average yield of amines and aminoisocyanates was 0.321mgg1. It has been suggested that the reproducibility problems arise from the single point measurement (the tip of the probe may be in the centre of the plume, below it, or if mixing is more efficient, the upper layer may be recirculated through the flame), or the timing of the effluent sampling may cause instabilities (for example an initial proposal to sample after 8min was replaced by a proposal to sample when the smoke density reached its maximum). The results from the SSTF and FPA show the best agreement with those from the full and 1/3 scale ISO room for both materials under a range of fire conditions. 1982), a developmental method (SwRI/NIST method) which used a radiant heater on the sample which lead into a 200 L exposure chamber, a cone calorimeter (ISO 5660 2002), a furniture calorimeter (as described in Babrauskas et al. The difficulty of replicating the conditions of fully developed under-ventilated flaming on a bench-scale is caused by several practical problems. Fire Safety Journal 40:439465, Aneja A (2002) Chapter 2, Structureproperty Relationships of Flexible Polyurethane Foams, PhD. They produce a strong odor for awhile after manufacture. HCN, in particular, contributes significantly to the overall fire toxicity of polyurethane foams. The process of . Equation 3 calculatesthe Fractional Effective Concentration (FEC) of sensory irritants in the fire effluent which limit escape. There is some contradiction the literature as to the effect fire retardants have on the overall toxicity of polyurethane foams. However, unlike a real fire, the heat flux remains constant, and so when the oxygen concentration falls, the flame may be extinguished. Reaction between an isocyanate and an alcohol to produce a urethane, Reaction of an isocyanate with water to produce a carbamic acid which decomposes to produce an amine and carbon dioxide, Reaction of an isocyanate with an amine to produce a urea, Reaction of an isocyanate with a urea to produce a biuret linkage, Reaction of a urethane with an isocyanate to produce an allophanate linkage. Equation Polyurethane foam, when burnt, gives off: Sulfuric acid Cyanide gas Ethane Phosphine. To a lesser extent, parameters such as temperature and oxygen concentration also affect the yields of toxic products. A detailed understanding of the thermal decomposition chemistry of polyurethane foams is necessary in order to relate the toxicants generated during bothflamingand non-flaming combustion of the polymer to its structure. It is usually used in isomeric mixtures of varying ratios, with 80:20 2,4 to 2,6 being the most commonly used (Fig. The open cone calorimeter replicates the early well-ventilated stage of flaming where a fire would be too small to produce enough toxicants to cause harm except in very small enclosures. These isocyanate derived cross-links can include biurets and allophanates (Fig. The Purser model, presented in equation1, uses \( {\mathrm{V}}_{{\mathrm{CO}}_2} \) a multiplication factor for CO2 driven by hyperventilation, therefore increasing the FED contribution from all the toxic species, and incorporates an acidosis factor A to account for toxicity of CO2 in its own right (ISO 13344 1996). ISO 13571 (2007) considers the four major hazards from fire which may prevent escape (toxic gases, irritant gases, heat and smoke obscuration). The use of 13C labelling by Chambers et al. Do memory foam mattresses give off toxic fumes? https://doi.org/10.1186/s40038-016-0012-3, DOI: https://doi.org/10.1186/s40038-016-0012-3. For example, polyurethane foam, when burned, gives off cyanide gas. During flaming combustion, many fire retarded flexible polyurethane foams showed similar or slightly higher toxic potency than the non-fire retarded foams in both well-ventilated and under-ventilated conditions. Again, above 600C the compound and any yellow smoke present was decomposed into smaller volatile fragments. Summing these contributions generates a fractional effective dose (FED). The first step is the decomposition of the urethane bonds to release and volatilise isocyanates up to 300C, with long chain alcohols being left behind in the condensed phase, followed by the alcohols degrading at around 400C. If exposed to sufficient heat and flame, polyurethane foam will burn. Table1 shows the relative reactivity of isocyanates with nucleophiles at 25C without the presence of a catalyst. 2023 BioMed Central Ltd unless otherwise stated. Thermal decomposition of polyurethanes is usually the reverse of polymerisation, resulting in the formation their precursor functional compoundsdiisocyanates, diamines and dihydroxy compounds. Building renovations, demolition, or building disassembly done years later can disturb spray foam insulation. Polyurethane and other organic foam materials are finding increased use on vessels because of their excellent insulating properties and light weight. Polyurethane Fume Exposure And Your Health: What You Need To Know The radiant heat apparatus, smoke chamber and controlled atmosphere cone calorimeter produced much lower CO yields than would be expected for under-ventilated flaming. Fire and Materials 31:p495521, Bott B, Firth JG, Jones TA (1969) Evolution of toxic gases from heated plastics. The presence of both amines and water in the decomposition products of polyurethane foams are discussed in later sections. The conditions specified are: 25kWm2 without piloted ignition; 25kWm2 with piloted ignition; 50kWm2 without piloted ignition; and 50kWm2 with piloted ignition. Fire Safety Science Proceedings of the ninth international symposium. Using the methodology in ISO 13344, the authors also calculated the fractional effective dose (FED) of the individual toxicants sampled. (1981) on polycarbodiimides and polyureas enabled the determination of the source of the organonitriles and HCN during thermal decomposition. A review by Paabo and Levin (1987) found that there is no difference in the decomposition products of rigid and flexible polyurethane foams at high temperatures regardless of their differing degradation mechanisms at lower temperatures. Bott et al. The samples tested included both commercial rigid polyurethane foam and polyisocyanurate foam. The two main families of polyols used are polyether polyols and polyester polyols (Fig. This is unusual as this test method is usually well-ventilated and the results are not similar to reports of other authors (such as Levin et al. 2012). Historically, material-LC50 data has been reported directly based on animal lethality testing, however due to the declining use of animal testing in fire toxicity assessment, calculations based on standard lethality data(such as ISO 13344 1996) are more commonly used. VOCs have the ability to vaporize, or off-gas, at room temperature. Off-gassing. Google Scholar, Allan D, Daly J, Liggat JJ (2013) Thermal volatilisation analysis of TDI-based flexible polyurethane foam. Fire and Materials 11:p129, Paul KT, Hull TR, Lebek K, Stec AA (2008) Fire smoke toxicity: The effect of nitrogen oxides. Despite their name, the term polyurethane is used to describe a family of polymers whose monomers are joined by a range of functional groups primarily derived from the polyaddition of polyisocyanates and polyalcohols. In a real fire, involving cycles of growth and decay of flaming combustion, the resulting yields of HCN from the combustion of polyurethane foams are likely to be higher than predicted in some bench-scale methods as a result of this two-step decomposition mechanism. (1985) when a flexible polyurethane foam was first heated at a temperature below its auto-ignition temperature, followed by flaming combustion of the remaining char and residue at a higher temperature. In the UK, the rapid rise in fire deaths, in particular those from smoke toxicity, between the late 1950s and the early 1980s has been attributed to the rapid growth in low cost polyurethane foam furniture, with superior comfort and lower cost than the natural fillings that preceded it. The peak HCN value reached was 10mg per g1 in the under-ventilated tests. Some fire models, such as the cone calorimeter, fire propagation apparatus and smoke density chamber use the temperature of the radiant heater to preselect the radiant heat flux, and then check this using a radiant heat flux meter. In some bench-scale apparatus the heat flux is constant, and often insufficient to sustain flaming at such low oxygen concentrations; further, an unknown quantity of fresh air bypasses the fire plume, so the ventilation condition, and hence, remains undefined. A sample of rigid polyurethane foam was heated in a static tube furnace with an air flow of 50mlmin1 at a range of temperatures from 600 to 1200C and the yield of HCN was quantified. Damage was most severe to the exterior. Similarly to the trend reported by Stec and Hull (2011) in well-ventilated conditions, this can be attributed to gas phase free radical quenching in the material by the chlorine present in both the CMHR-PUF and PIR (2.53% and 3.56% chlorine by weight, respectively). An understanding of the relative reaction rates is vital in controlling the production of the polymer and producing the desired physical properties (Herrington & Hock 1998). Those with constant combustion conditions are more suited to producing data suitable for comparison and modelling: the steady state tube furnace (SSTF) (ISO/TS 19700 2013) has been specifically designed to achieve this. 10. The highest concentration these compounds were formed at occurred at a decomposition temperature of 350400C which indicated no new degradation steps had occurred beyond 350C. The polyester fabric produced 9293mgg1 of CO when burned with very little difference in the flaming or non-flaming conditions. Isocyanurate rings are the most thermally stable in an inert atmosphere and decompose between 270 and 300C. A more recent review, by Levchik and Weil (2004), assessed the decomposition, combustion and fire-retardancy of polyurethanes. Google Scholar, Schartel B, Hull TR (2007) Development of fire-retarded materials - interpretation of cone calorimeter data. Aromatic diisocyanates, which are commonly used in the production of polyurethanes, have a slightly more complicated chemistry compared to monoiscyanates due to the electronic effects of two isocyanate groups. The widespread use of flexible polyurethane foams in furniture and other upholstery, where they are usually covered in some kind of fabric has prompted some authors to investigate the effects of covering the foam on the yield of toxic products. 1 Fire and Materials 6:p1315, Neviaser JL, Gann RG (2004) Evaluation of Toxic Potency values for Smoke from Products and Materials. 1982), and a three . Combustion Science and Technology 183(7):p627644, Saunders JH (1959) the Reactions of Isocyanates and Isocyanate Derivatives at Elevated Temperatures. In particular, reports that used non-standard tube furnace apparatus lacked sufficient information about the conditions of the experiment and as such were not included. 2011). Further decomposition occurred about 600C with the fragmentation of the yellow smoke, primarily into hydrogen cyanide and small quantities of acetonitrile, acrylonitrile and benzonitrile. Top of Page. Smouldering was forced by an electrically heated resistance wire embedded in the sample and a load cell measured the mass of the sample throughout the experiment. Once the material ignited, the yield of HCN increased to 3.8mgg1. It forces combustion by driving the sample into a furnace of increasing heat flux at a fixed rate, so that, by running several tests with the same material with different ventilation conditions, each fire stage can be replicated by steady state burning. Chambers et al. Secondary air is added in a mixing chamber to give a total gas flow of 50Lmin1. New memory foam smell? Fumes Tiny particles are produced from heating, volatilization, and condensation of metals (examples: zinc oxide fumes from welding of galvanized metal). It can be used for testing samples 100100mm and up to 50mm thick, in both the horizontal and vertical orientation. Fire Res 1:p1121. Hexamethylene diisocyanate (HDI) (i), 1,5-naphthalene diisocyanate (NDI) (ii) and isophorone diisocyanate (IPDI) (iii). Additionally, the authors reported a yield of 1315mgg1 of CO, 1.41.5mgg1 of HCN, and 1012mgg1 of NO. In the large scale test room, the sample smouldered for 1.5 to 2h, resulting in a HCN yield of 1.03mgg1. Alongside this, the decomposition of the foam into an amine, alkene and carbon dioxide was also proposed. Additionally, aromatic isocyanates with more steric hindrance are likely to be less reactive (such as the 2 position in 2,4-TDI (Fig. The authors noted that a large number of the data available relating to the test conditions were vague or completely undefined. The toxic product generation during flaming combustion of polyurethane foams is reviewed, in order to relate the yields of toxic products and the overall fire toxicity to the fire conditions. The test conditions were designed so that the fire conditions met the ISO 19706 (2007) fire type 2 (well-ventilated flaming fire <0.75) and fire type 3b (post-flashover fire in large or open compartments ~2.0). The incapacitating Ct product corresponds to CO at a dose of 35 000LL1min (approximately equal to ppm min), predicting incapacitation at around 1200ppm for 30min exposure, and an exponential relationship for HCN (because asphyxiation by HCN exposure does not fit a linear relationship), predicting incapacitation at around 82ppm for 30min exposure. Ann occup Hyg 19:269273, Levchik SV, Weil ED (2004) Thermal Decomposition, combustion and fire-retardancy of polyurethanes - a review of the recent literature. When polyurethane foam is burned, it gives off a wide variety of potentially harmful substances. HCN also causes rapid incapacitation, preventing escape, and then, with CO, contributes to death from asphyxiation. However, as fires tend to grow exponentially, they do not produce constant concentrations of asphyxiant gases. Toxic product yields frommaterials involved in fires depend on a number of factors. The rigid polyurethane foam yielded ~55mgg1 CO and ~0.5mgg1 of HCN. Nitrogen dioxide dissolves rapidly in water to form nitric and nitrous acid. These nucleophiles include amines, alcohols, carboxylic acids, thiols, water, ureas and urethanes (Aneja 2002). Woolley WD, Wadley AI, Field P (1972) Studies of the thermal decomposition of flexible polyurethane foams in air. The radiant heat flux in the ISO/TS 19700 apparatus has been measured (Stec et al. PDF Fire Properties of Polyvinyl Chloride The toxic hazards associated with fire and the inability of victims to escape from fire atmospheres may be considered in terms of major hazard factors: heat, smoke and toxic combustion products (Hartzell 1993). Springer Nature. Although the authors intended for the bench scale test methods and the large scale test to represent post-flashover room fires, the tests resulted in CO and HCN yields that suggested the combustion conditions were not under-ventilated (Table7). 1982), and a three-compartment large scale test. Known as "solid gasoline" in the insurance industry, once a polyurethane fire starts, it usually results in a total loss of property and loss of life, according to Federated Insurance. As the global usage of polyurethane foams is expected to continue to increase yearly, it is important that the fire community have a clear understanding of the fire toxicity of polyurethane foams and the reasons why they produce significant amounts of toxic gases during combustion. Comparison with Room Fire Results, NIST Technical Note 1763, National Institute of Standards and Technology, Gaithersburg, MD, Michal J (1982) Determination of Hydrogen Cyanide in Thermal Degradation Products of Polymeric Materials. Levin et al. At 850C the yield of HCN was higher with 16mgg1 at ~2.0. The transport industries have adopted the smoke density chamber (SDC) ISO 56592 (2012) and ASTM E662, for quantification of toxic product yields (Fire Test Procedure Code 2010; CEN/TS 455452 2009) using simple pass/fail chemical detection (e.g. Brit Polym J 1:p203204, Braun E, Gann RG, Levin BC, Paabo M (1990) Combustion product toxic potency measurements: comparison of a small scale test and real-world fires. Acrolein and formaldehyde are formed especially from cellulosic materials under non-flaming decomposition conditions, but products of vitiated combustion contain other organic irritants. SP Swedish National Testing and Research Institute, Bors, Hietaniemi J, Kallonen R, Mikkola E (1999) Burning characteristics of selected substances: Production of heat, smoke and chemical species. Comparing the toxic potencies of different materials, the lower the material-LC50 (the smaller the amount of materials necessary to reach the toxic potency) the more toxic the material is. 14) (UK Fire Statistics 2013). 9). Higher temperatures resulted in the volatilisation of most of the polyurethane precursors via the formation of lower molecular weight compounds. The main toxic combustion products can be divided into two classes: asphyxiant gases, which prevent oxygen uptake by cells, with loss of consciousness and ultimately death; and irritant gases which cause immediate incapacitation, mainly by effects on the eyes and upper respiratory tract, and longer term damage deeper in the lung. Aromatic isocyanates are more reactive than aliphatic isocyanates due to the electronic effects of the aromatic ring. FED model from ISO 13571, Equation Additionally, HCN yields in both flaming and non-flaming conditions increases with temperature. Stec and Hull (2011) assessed the fire toxicity of building insulation materials using a steady state tube furnace asdescribed in ISO/TS 19700 (2013). National Bureau of Standards, Gaithersburg MD, Barbrauskas V, Singla V, Lucas D, Rich D (2015) Letter to the Editor- Questions about the conclusions in Blais and Carpenter 2013. . In a report from the same laboratory, Braun et al. However, spray foam insulation is a highly energy-efficient product and quickly offsets its manufacturing footprint. Hietaniemi et al. Primarily, isocyanates react with alcohols to produce urethane linkages in the polymer (Scheme1). to FED. The smoke density chamber (ISO 5659-2) showing a sampling probe for fire smoke toxicity. (2007). (2007) suggests that their yields are not heavily dependent on the ventilation conditions and that the yields would likely only increase by a small amount during under-ventilated flaming. True. However, due to the poor reproducibility of smoke chamber experiments, the tendency for it to give very low HCN yields, and the fact that the experiment is well-ventilated, the reported toxicity is likely much lower than in a real fire situation. Fire Science Reviews It is difficult to draw more general conclusion from this work because the fuel-to-air ratio was not quantified, and the degree of mixing of fresh air and fire effluent, in the exposure chamber, is unknown. More recent work by Shufen et al. Polyurethane foam may be formed at a construction site or installed in the form of board stock (see the "Composite Insulations, Structural Insulated Panels" section). When tested with the polyester covering the polyurethane, the yield of HCN during flaming combustion was higher than that of just the polyurethane foam on its own. Interflam Conference Proceedings. In the gas phase, isocyanates, amines and yellow smoke will begin to decompose at >600C into low molecular weight nitrogen containing fragments (such as benzonitrile, aniline and hydrogen cyanide (HCN)). Ask Pablo: How Bad Is Memory Foam? Fire Hazards Of Polyurethane Foam - Klausbruckner In 1975, California passed flammability standards known as Technical Bulletin 117 (TB117), which required polyurethane foam and fabrics produced in state to be treated with flame-retardant chemicals . the sum of each of the concentrations multiplied by the exposure time, for each product; upper respiratory tract irritants are believed to depend on the concentration alone (Purser 2007). The dimerisation of two isocyanates is a reversible reaction that produces uretidione ring (Scheme6). National Bureau of Standards, Gaithersburg, MD, Levin BC, Paabo M, Birky MM (1983b) Interlaboratory evaluation of the 1980 version of the national bureau of standards test method for assessing the acute inhalation toxicity of combustion products, NBSIR 832678, National Bureau of Standards, Gaithersberg, MD, Levin BC, Paabo M, Fultz ML, Bailey CS (1985) Generation of Hydrogen Cyanide from Flexible Polyurethane Foam Decomposed under Different Combustion Conditions. The most commonly reported adverse health effects after airborne isocyanate exposure is asthma due to sensitisation (Piiril et al. It has been designed to generate data for input to fire hazard assessments, using the methodology in ISO 13344 (1996) and ISO 13571 (2012), particularly in relation to the ISO fire stages. (2006) has supported the claim that polyether based polyurethanes are less stable than their polyester based counterparts when decomposed in air. Terms and Conditions, Equations2 and 3 have been taken from ISO 13571 (2007). DiNenno) Fourth Edition. (2011) developed a mechanism based on both condensed and gas-phase decomposition in air. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. When a liquid fuel gives off enough vapors so that it can be . The detection of the amino MDI derivative in the tar further supports the literature reports of a secondary decomposition mechanism where isocyanates trapped in the condensed phase are converted irreversibly into their amine derivatives. The presence of oxygen in the atmosphere directly interacts with the solid phase, which accelerates decomposition. Equation 2 calculates the FED of the major asphyxiants, CO and HCN, but without taking oxygen depletion or CO2 driven hyperventilation into account. The polyester based polyurethane began to decompose at 284C with a secondary decomposition step at 359C. However, as noted by Paabo and Levin (1987), many studies into the decomposition of polyurethane foams do not differentiate between flaming and non-flaming decomposition, and focus on the temperature of decomposition rather than the presence of flames. The polyisocyanurate, on the other hand, produced slightly more HCN than the rigid foam (17mgg1 vs 12mgg1). (2007) assessed the toxic product yields of a flexible polyurethane foam that was designed for use in hospital mattresses. When the black char was burned at 600C, it yielded 14.95mg of HCN (65mg per gram of char) and the yellow oil yielded 21mg per gram of oil. Anal Bioanal Chem 387:p219236, Herrington R, Hock K (1998) Flexible Polyurethane Foams, 2nd edn. Elemental analysis of the polymers showed that the CMHR-FPUR contained 8.22% nitrogen by weight and the PIR contained 6.15% nitrogen by weight. Fire and Materials 23:p171185, Hull TR, Paul KT (2007) Bench-scale assessment of combustion toxicity-A critical analysis of current protocols. STM would like to acknowledge the University of Central Lancashire for provision of a studentship. 11, a conical heater used as a fire model is enclosed in a heat resistant glass chamber (400mm high with 300300mm base) so that the air flowaround the specimen may be controlledby diluting the oxygen content with nitrogen. Combustion and Flame 146(12):p95108, Rogaume T, Bustamante-Valencia L, Guillaume E, Richard F, Luche J, Rein G, Torero JL (2011) Development of the Thermal Decomposition Mechanism of Polyether Polyurethane Foam Using Both Condensed and Gas-Phase Release Data. At this temperature around one third of the compounds mass was lost as volatile products, and the regenerated alcohol products were mainly present in the residue of the sample. The relationship between equivalence ratio and yields of CO and other products has been studied in detail for a wide range of materialsduring flaming combustion using two small-scale apparatus designed specifically for this purposethe ASTM E2058 fire propagation apparatus (Tewarson 2002) and the ISO/TS 19700 tube furnace apparatus (ISO/TS 19700 2013), in conjunction with a series of large-scale experiments used for validation (Gottuk & Lattimer 2002; Blomqvist & Lonnermark 2001; Purser & Purser 2008a). When =1 the theoretical amount of air is available for complete combustion to carbon dioxide (CO2) and water. (1990) also reported increased HCN yields when the sample was allowed to smoulder before flaming in similar apparatus as above. Isocyanate structure also affects the reactivity of the isocyanate group. Free of VOCs and HAPs. Bench-scale methods used for generation of toxic fire effluentsideally should be capable of reproducing individual fire stages or combustion conditions, for input into models of combustion toxicity. Results from these burn tests are used for comparison with the model developed to simulate flame spread, heat fluxes, and smoke development over time (Figure 1). Fire and Materials 31:p327354, Schnipper L, Smith-Hansen ES (1995) Reduced combustion efficiency of chlorinated compounds, resulting in higher yields of carbon monoxide. Thermosets are cross-linked polymer molecules which, on heating, do not melt but will eventually decompose. HCN yields reported in under-ventilated conditions vary depending on the composition of the material; with flexible foams producing less than rigid foams and polyisocyanurates producing the most overall. Farrar DG, Galster WA (1980) Biological end-points for the assessment of the toxicity of products of combustion of material. 6). Additionally, assorted nitrogenous organics were detected in the tar including aniline, quinoline, pyridine, benzonitrile, indole and acridine derivatives with more than 50% of the tar nitrogen being bound as 4-[(4-aminophenyl)methyl]aniline (the amino analogue of MDI). Woolley WD, Fardell PJ, Buckland IG (1975) The Thermal Decomposition Products of Rigid Polyurethane.

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