Polyurethane is widely used, with its two major applications, soft furnishings and insulation, having low thermal inertia, and hence enhanced flammability. California Privacy Statement, 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. The PIR at 1.75 resulted in 15% of the fuel nitrogen being recovered as HCN. MathSciNet The production of HCN and other low molecular weight nitrogenous compounds from the high temperature decomposition of polyurethanes has been reported in the literature in recent years. Does the foam give off toxic fumes if burned? This prompted the authors to perform further studies in order to understand why allowing the foam to smoulder increased the yield of HCN during flaming combustion. p 102-120. 1982), and a three-compartment large scale test. As with all foams, memory foam compresses under pressure. Isocyanate structure also affects the reactivity of the isocyanate group. Insulation, like all building products, has an 'embodied' carbon footprint resulting from energy use during the manufacturing process. Apparatus where changes rapidly allow little time for sampling and measurement of mass loss and effluent compositionat a specific value of, with resultant errors and uncertainties. In a 12-square-foot area, urethane was totally burned off, but the rest suffered more minor damage. Spray foam can potentially generate toxic emissions under these circumstances. At sufficiently high concentrations, or when attached to submicron particles, such as soot, most irritants can penetrate deeper into the lungs, causing pulmonary irritation effects which may cause post-exposure respiratory distress and death, generally occurring from a few hours to several days after exposure, due to pulmonary oedema (flooding of the lungs) (ISO 13571 2007). This causes deterioration in mental and muscular performance. Thermal Decomposition of Polyether-based, Water-blown Commerical type of Flexible Polyurethane Foam. Interflam Conference Proceedings. The yield was much lower at 800C with 7.4mgg1 but at 1000C and 1200C the yield increased significantly to 33.9mgg1 and 48.1mgg1 respectively. 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). The increased yield of HCN for the CMHR-FPUR between 650C and 850C is likely due to the increased fragmentation of nitrogenous organic compounds in the flame, similar to the behaviour during non-flaming combustion in air reported by Woolley et al. Med Sci Law 21:60. Preliminary calculations suggested that 27% of the TDI should be recovered as DAT. A more recent assessment by Marsh and Gann (2013) tested a flexible polyurethane foam with a cotton polyester cover in a range of test methods including the radiant heat apparatus (NFPA 269 2012), the ISO 56592 (2012) smoke density chamber, a controlled atmosphere cone calorimeter (ASTM E 1354) and the steady state tube furnace (ISO/TS 19700 2013). To a lesser extent, parameters such as temperature and oxygen concentration also affect the yields of toxic products. However, PVC will typically not burn once the source of heat or flame is removed. Polyurethanes are a diverse family of synthetic polymers that were first synthesised in 1937 by Otto Bayer. The dangerous concentrations of some important toxic fire gases are shown in Table4 alongside the influence of ventilation condition on their yields. Over 90% of all industrial polyurethanes are based on either TDI or MDI (Avar et al. Again, above 600C the compound and any yellow smoke present was decomposed into smaller volatile fragments. (1990) also reported increased HCN yields when the sample was allowed to smoulder before flaming in similar apparatus as above. 4 8). Journal of Analytical and Applied pyrolysis 108:p143150, Hartzell G (1993) Overview of Combustion Toxicology. LC50 values should be referenced to the fire condition under which they were measured. Studies have found that infant mattressesespecially those made with polyurethane foam, which contains the hydrocarbon tolueneare a major off-gassing culprit (Boor, et. Centre for Fire and Hazard Science, University of Central Lancashire, Preston, PR1 2HE, UK, Sean Thomas McKenna&Terence Richard Hull, You can also search for this author in Levin et al. This is due to the concentration of oxygen directly under a flame being close or equal to 0% (Schartel & Hull 2007). However, when the TDI was unable to enter the pyrolysis zone, the slower, irreversible decomposition to diaminotoluene (DAT) would occur. The first is by combination with the ferric ion in mitochondrial cytochrome oxidase, preventing electron transport in the cytochrome system and inhibiting the use of oxygen by the cells. As the availability of oxygen becomes lower in proportion to the amount of fuel, the yields of certain toxic gases will increase. The two main families of polyols used are polyether polyols and polyester polyols (Fig. The relativelyhigh yields of CO from under-ventilated fires are held responsible for most deaths through inhalation of smoke and toxic gases. 1999). Syntheticpolymeric materials may be divided into thermoplastics and thermosets. In the large scale test room, the sample smouldered for 1.5 to 2h, resulting in a HCN yield of 1.03mgg1. When =1 the theoretical amount of air is available for complete combustion to carbon dioxide (CO2) and water. Fire Safety Journal 42:p340365, ISO 12136 (2011) Reaction to fire tests Measurement of material properties using a fire propagation apparatus, ISO 13344 (1996) Estimation of lethal toxic potency of fire effluents, ISO 13571 (2012) Life-threatening components of fire-Guidelines for the estimation of time available for escape using fire data. These reactions are accelerated in the presence of oxygen, which reduces the temperature of the decomposition steps. Humans may react differently than animals exposed to toxic materials. Polymer Degradation and Stability 93:p20582065, Tewarson A (2002) SFPE Handbook of Fire Protection Engineering, 3rd ed. But many products or materials continue off-gassing even after the "new smell" has gone awaythe fumes are just much more subtle. Around 1015% of the nitrogen in the polymer can be converted into HCN with some being released in isocyanates, aminoisocyanates and amines in the fire effluent. 8-80, addressing . 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. NBSIR 822532. From this, the library of data was sorted into categories of combustion/pyrolysis conditions, material/product, type of test animal and toxicological endpoint. A large majority of the literature indicates that the addition of fire retardants does not increase toxicity of polyurethane foams. However, while the char produced when the polymer was heated at 370C contained only 20% of the total nitrogen from the polymer, 40% of that (8% of the total nitrogen in the polymer) was recovered as HCN when the char was burned at 600C. The relation of the FED to the material-LC50 is given in equation4. combustion modified high resilience polyurethane foam, Alarie Y (2002) Toxicity of Fire Smoke. 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. Additionally, the authors suggested the positions on the polyol chain where bond scission could occur, explaining the presence of the short-chain alkenes, aldehydes and ketones (Scheme9). 3) (Aneja 2002). Faster. PubMedGoogle Scholar. . The authors noted that the total concentrations of CO and HCN during flaming combustion were greater than the sum of those from the individual materials. The significant increased yields at 1000C and 1200C could also be attributed to pyrolysis of the nitrogenous combustion products into HCN due to the low air flow rate. The authors noted that the yields of the toxicantsproduced an atmosphere in the tests which fell well below their Immediately Dangerous to Life and Health (IDLH) values. Busker RW, Hammer AH, Kuijpers WC, Poot CAJ, Bergers WWA, Bruijnzeel, PLB (1999) Toxicity testing of combustion products of polyurethane and polyvinylchloride. (2006) and also Garrido and Font (2015). Woolley WD, Fardell PJ, Buckland IG (1975) The Thermal Decomposition Products of Rigid Polyurethane. Toxic Materials in Foam Mattresses? Are We Safe? The polyester fabric produced 9293mgg1 of CO when burned with very little difference in the flaming or non-flaming conditions. Top of Page. Therefore the contribution of HCN to fire deaths is difficult to assess, and analysis for CN is limited to cases where lethal concentrations of CO are absent. National Bureau of Standards, Washington D.C. Levin BC, Paabo M, Fultz ML, Bailey C, Yin W, Harris SE (1983a) Acute inhalation toxicological evaluation of combustion products from fire-retarded and non-fire retarded flexible polyurethane foam and polyester. This suggests that the nitrogen in the char will more readily form HCN, even when the flaming is well-ventilated. The fire toxicity of polyurethane foams - Fire Science Reviews In an attempt to improve the understanding of the thermal decomposition of polyurethanes, Rogaume et al. Thermal decomposition of polyurethanes is usually the reverse of polymerisation, resulting in the formation their precursor functional compoundsdiisocyanates, diamines and dihydroxy compounds. The yields of CO and HCN from five bench-scale methods have been compared to large-scale data under a range of flaming fire conditions (Stec & Hull 2014). The first being a depolymerisation which would dissociate the polymer to isocyanates and alcohols, the second being dissociation to a primary amine, an olefin and carbon dioxide. However, during the combustion of polyurethane foams, the HCN yield is notably higher when the fire progresses from smouldering to flaming combustion. Toxic product yields frommaterials involved in fires depend on a number of factors. Combustion Science and Technology 183(7):p627644, Saunders JH (1959) the Reactions of Isocyanates and Isocyanate Derivatives at Elevated Temperatures. Using a cup furnace with a 200L sampling chamber (identical in design to the one used in the smoke chamber experiments), a 3.88g sample of foam was heated to just below its ignition temperature (370C) which yielded <1mgg1 HCN. 1982) to that of a large scale test room. 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 use of 13C labelling by Chambers et al. The applied heat flux must be large enough for burning to continue at oxygen concentrations as low as 5%. The authors would like to thank Dr. Linda Bengtstrom for her contribution regarding the toxicity of isocyanates. The polyurethane market was estimated to be worth $33 billion in 2010 and is expected to continue to grow to over $55 billion by 2016. Instead polyureas were detected in the vapour phase and also in the condensed phase as a waxy, insoluble white substance. This amine may then undergo further reaction with other isocyanates present to produce a urea (Scheme3). Polyether polyols are more resistant to hydrolysis, but less stable to oxidation, while for polyester polyols it is the opposite. Potential Chemical Exposures From Spray Polyurethane Foam The isocyanate precursors used in the production of polyurethane foams usually consist of aromatic diisocyanates such as toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI). Taking this into consideration, the reported yields of isocyanates, aminoisocyanates and amines are still relevant, as the results of Blomqvist et al. Fire retardants, such as gas-phase free radical quenchers, have been reported to increase the yields of CO in well-ventilated conditions by preventing the oxidation of CO to CO2. 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). Polyurethane. decomposition products will burn. Fire Hazards Of Polyurethane Foam - Klausbruckner Ask if the mattress materials are generally free of VOC and HAPs. As the main reactive group that isocyanates react with, polyols are a major component of the resulting polyurethane product. The most commonly reported adverse health effects after airborne isocyanate exposure is asthma due to sensitisation (Piiril et al. Google Scholar, Allan D, Daly J, Liggat JJ (2013) Thermal volatilisation analysis of TDI-based flexible polyurethane foam. Performing hot work on or near polyurethane foam may lead to potential exposures to isocyanates and other toxic emissions. Manage cookies/Do not sell my data we use in the preference centre. In general, isocyanate (R-NCO) exposure causes irritation to the skin, mucous membranes, eyes and respiratory tract (NIOSH 1989). ISO 13571 (2007) considers the four major hazards from fire which may prevent escape (toxic gases, irritant gases, heat and smoke obscuration). These fumes could lead to irritation of the eyes, throat, and lungs, and could cause more severe allergic reactions for individuals with chemical sensitivities. Using the methodology in ISO 13344, the authors also calculated the fractional effective dose (FED) of the individual toxicants sampled. Fire Technology 51:p318, Blomqvist P, Lonnermark A (2001) Characterization of the combustion products in large-scale fire tests: comparison of three experimental configurations. The products generated in the flame zone then pass through the heated furnace tube, maintaining a high temperature, as in the upper layer of a compartment fire. HCN analysis was performed using infrared (IR) spectroscopy using a short path-length gas cell, which is a questionable method for the quantification of HCN due to its poor IR absorption, high potential for interferences and a poor limit of detection. UPDATED 8/16/2011 The Massachusetts Division of Fire Safety (DFS) is investigating the causes of three house fires that were ignited while insulation contractors were installing spray polyurethane foam. Acrolein and formaldehyde are formed especially from cellulosic materials under non-flaming decomposition conditions, but products of vitiated combustion contain other organic irritants. \( \phi =\frac{actual\; fuel\;to\; air\; ratio}{stoichiometric\; fuel\;to\; air\; ratio} \). Similarly, well-ventilated fires are generally small, and of low toxicity. While the smoke chamber experiment is known to give low HCN yields, and both scenarios are well-ventilated, the yield of HCN was almost 4 times as high during flaming combustion if the sample was allowed to smoulder first. 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. As polyurethane foams have very low thermal inertia, application of heat or a small flame can be enough to ignite them. . The chemistry of polyurethane foams and their thermal decomposition are discussed in order to assess the relationship between the chemical and physical composition of the foam and the toxic products generated during their decomposition. In others, under reduced oxygen concentrations, the fuel lifts from the surface, but ignition does not occur (Christy et al. (P.J. Suggested points of chain scission on a polyether polyol resulting in aldehydes, ketones and alkenes (Allan et al. The authors proposed that once formed, these compounds could partially polymerise with volatilised TDI in the vapour phase to produce Woolleys yellow smoke. The reported yields were extremely low for both CO and HCN, as the NBS smoke chamber apparatus is a well-ventilated fire scenario reported to give low HCN yields (Table6). Terms and Conditions, Secondary air is added in a mixing chamber to give a total gas flow of 50Lmin1. The presence of oxygen in the atmosphere directly interacts with the solid phase, which accelerates decomposition. Once the material ignited, the yield of HCN increased to 3.8mgg1. Will polyurethane melt under heat? - remodelormove.com 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. Allergy 63:p583591, Pitts WM (1995) The global equivalence ratio concept and the formation mechanisms of carbon monoxide in enclosure fires. The yields of CO and HCN at varying and temperature are presented in Table5. At 300C, free isocyanates and alcohols were produced from the decomposition of these biscarbamates. Gaithersberg, MD, Babrauskas V, Twilley WH, Janssens M, Yusa S (1992) Cone calorimeter for controlled-atmosphere studies. Toxicology 115:7, Henneken H, Vogel M, Karst U (2007) Determination of airborne isocyanates. 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 fire department was not immediately called, so the oil burned completely. The test room was 2.43.03.0m with a door (dimensions not specified) and a 1 to 2kg slab of foam in the centre of the room. For example, polyurethane foam, when burned, gives off cyanide gas. In order to reduce the ignitability, and to a less extent the surface spread of flame and peak heat release rate, fire retardants are commonly added to commercial polyurethane foams in order to meet specific regulatory demands. HCN also causes rapid incapacitation, preventing escape, and then, with CO, contributes to death from asphyxiation. 1995). For the purpose of estimating toxicity in fires, fire growth has been classified into a number of stages (ISO 19706 2011): Although on some occasions smouldering (oxidative pyrolysis) can generate toxicologically significant quantities of effluent (for example smouldering cotton, or polyurethane foam), typicallythe rate of reaction, and hence the amount of toxic species generated will be small, so it is unlikely to affect anyone outside the immediate vicinity. Polyurethane Fume Exposure And Your Health: What You Need To Know 1982), and a three . These substances can include carbon dioxide, carbon monoxide, formaldehyde, aldehydes, and other volatile organic compounds (VOCs), as well as soot and particulates. 2007). TDI is produced as the 2,4- and the 2,6- isomer which have a boiling point of 121C and 120C respectively. CO also combines with myoglobin in the muscle cells, impairing diffusion of oxygen to cardiac and skeletal muscles (Purser 2008b). In order to relate the fire effluent toxicity to a "maximum permissible loading", the FED can be related to the mass of material in a unit volume which would cause 50% lethality for a given fire condition. Based on this data, the HCN recovery fraction was calculated for both materials. Table1 shows the relative reactivity of isocyanates with nucleophiles at 25C without the presence of a catalyst. During these tests, the PIR was set up as wall panels covered on two faces with aluminium foil. In: Fahima Z, Eram S (eds), InTech. Off-gassing & Outgassing: What's the Difference? Where is it From Their analysis indicated that, above 600C, the high temperature decomposition of MDI generated a large number of volatile fragments, including benzene, toluene, benzonitrile and toluonitrile. CO yields are generally very low for well-ventilated conditions (in the absence of halogens) but increase considerably under-ventilated combustion conditions. 4)). The reported yields for the tests performed can be found in Table8. 2008), where inhaled isocyanates rapidly form conjugates with epithelial lung cell proteins (Wisnewski et al. p 111711128. National Fire Protection Association, Quincy, pp 283, Purser DA (2007) The application of exposure concentration and dose to evaluation of effects of irritants as components of fire hazard. Woolley WD, Wadley AI, Field P (1972) Studies of the thermal decomposition of flexible polyurethane foams in air. eds. 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. The rigid polyurethane foam produced slightly more CO than the polyisocyanurate at ~2.0 (240mgg1 vs 225mgg1). The higher flammability of these new furniture products took people by surprise, and has been blamed for an increased number of serious fires and a tripling of fire deaths over 20years (Fig. Fire and Materials 25:p7181, Blomqvist P, Hertzberg T, Tuovinen H, Arrhenius K, Rosell L (2007) Detailed determination of smoke gas contents using a small-scale controlled equivalence ratio tube furnace method. As polyols are prepolymers, their molecular mass is relevant to their application, with flexible foams being derived from 1000 to 6000 daltons and few hydroxyl groups, while those used in rigid foams have short chains from 250 to 1000 daltons with high functionality (312 hydroxyl groups per chain). The flexible foam produced ~175mgg1 of CO and 5mgg1 of HCN. The peak HCN value reached was 10mg per g1 in the under-ventilated tests. National Fire Protection Association, Quincy, MA, pp 5482, Guo X, Wanga L, Zhanga L, Lia S, Hao J (2014) Nitrogenous emissions from the catalytic pyrolysis of waste rigid polyurethane foam. Three Massachusetts Home Fires Linked to Spray-Foam Installation J Ind Eng Chem 13(7):p11881194. Before you take it for a test drive, make sure to give your new mattress time to off-gas in a well-ventilated environment. 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. These VOCs come mainly from the polyurethane used in the mattress, but also from other chemicals used in flame retardants and plastics, the researchers said. Polyol fragments in the gas phase will also begin to decompose at >800C to produce simple organic fragments and PAHs. Under well-ventilated flaming (<0.8), the yields of CO2 and NO2 were at their highest, while the yields of CO and HCN were at their lowest. A summary of the bond decomposition temperatures in polyurethanes is shown in Table2 (Gharehbagh & Ahmadi 2012). The formation of the toxicant in question was the result of an unusual reaction of the polyol in the foam, trimethylol propane, with the phosphate fire retardant in the gas phase. Bott et al. Fire gases contain a mixture of fully oxidised products, such as carbon dioxide (CO2), partially oxidised products, such as carbon monoxide (CO) and aldehydes, fuel and fuel degradation products, such as aliphatic or aromatic hydrocarbons, and other stable gas molecules, such as hydrogen halides (HCl, HBr) and hydrogen cyanide (HCN) (Kaplan et al. More recent work by Shufen et al. Reliable rate of heat release, fire effluent toxicity and smoke generation data are all essential components of such an assessment. 2012). Provided by the Springer Nature SharedIt content-sharing initiative. However, there is verylittle literature available regarding the yields of isocyanates produced by the combustion of polyurethane foams. The test method that produced toxic product yields associated with under-ventilated flaming was the NBS cup furnace toxicity method, which yielded 180210mgg1 of CO and 1620mgg1. The authors studied decomposition at 900C of foams, partly decomposed foams, smokes, and pure MDI to assess the hydrogen cyanide (HCN) content and noted that the yields of HCN were directly related to the nitrogen content. NBSIR 822604. The calculations showed that, for both the rigid polyurethane and the polyisocyanurate, hydrogen cyanide is the major toxicant in smouldering, well-ventilated and under-ventilated flaming. Isocyanate derived functional groups that cross-link polyurethane chains i) biurets ii) allophanates. The full-scale test showed good accordance with the SSTF data considering the inherent unreliability of large-scale testing. (2007). Ureas and urethanes decompose between 160 and 200C. ISBN 978-953-51-0726-2, Gottuk DT, Lattimer BY (2002) SFPE Handbook of Fire Protection Engineering, 3rd ed. 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. 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). The polyisocyanurate, on the other hand, produced slightly more HCN than the rigid foam (17mgg1 vs 12mgg1). 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. At higher temperatures the decomposition of the foams produced increasing amounts of HCN from 600 to 900C, followed by a sharp rise between 9001000C. These processes occur at around 300C with the precursor chemicals including TDI, MDI, HDI, polyols (both polyether and polyester-polyols) and aromatic amines. The FED is expressed as the sum of contributions to toxicity from individual species and normalised to 1g of fuel in 200L fire effluent, as used in BS 6853 (1999). The overall toxicity of polyurethane materials followed a similar trend to their HCN yields; with flexible foams generally being the least toxic, rigid foams being slightly more toxic and polyisocyanurate foams being the most toxic. Additionally, aromatic isocyanates with more steric hindrance are likely to be less reactive (such as the 2 position in 2,4-TDI (Fig. 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). Overall, the report provides access to a large pool of data organised into a material-LC50 and also helps demonstrate that the large majority of data available is for well-ventilated tests. This agrees with the fact that oxidation of NH3 and HCN to NO (and NO2, although it was not analysed in these experiments) would occur more readily during well-ventilated burning.