In this modification, the controlled atmosphere cone calorimeter (CACC) (Babrauskas et al. The two main market uses for polyurethane are in the furniture and interior industry and the construction industry with 28% and 25% of the market, respectively (Markets & Markets report 2011). Stec and Hull (2011) presented material-LC50 data for rigid polyurethane foam and polyisocyanurate foam, calculated using rat lethality data from ISO 13344 (1996). As the main reactive group that isocyanates react with, polyols are a major component of the resulting polyurethane product. The mechanisms of decomposition are well understood and the decomposition products of both rigid and flexible polyurethane foams are very similar at high temperatures. The radiant heat flux in the ISO/TS 19700 apparatus has been measured (Stec et al. To a lesser extent, parameters such as temperature and oxygen concentration also affect the yields of toxic products. 1982) to that of a large scale test room. (1991a) compared a number of test methods. Faster. Busker RW, Hammer AH, Kuijpers WC, Poot CAJ, Bergers WWA, Bruijnzeel, PLB (1999) Toxicity testing of combustion products of polyurethane and polyvinylchloride. But many products or materials continue off-gassing even after the "new smell" has gone awaythe fumes are just much more subtle. A comprehensive review of fire retardants and their use in polyurethane foams was published by Singh and Jain (2009). Additionally, a polyol-rich residue is left behind that begins to fragment and volatilise between 300 and 600C. The FED value is calculated using the exposed dose relationship (concentration-time product, Ct) for CO. Test methods, such as the steady state tube furnace (ISO/TS 19700) and the controlled atmosphere cone calorimeter (ASTM E 1354), facilitate ventilated controlled conditions which give yields of CO and HCN comparable to those observed in under-ventilated post-flashover compartment fires. More recent work by Shufen et al. Equation 2 calculates the FED of the major asphyxiants, CO and HCN, but without taking oxygen depletion or CO2 driven hyperventilation into account. 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. Overall, the results suggested that the polyether based polyurethane was less thermally stable in the presence of oxygen than the polyester, and both were generally less stable in air than in a nitrogen atmosphere. Fire Safety Journal 43:243251, Piiril PL, Meuronen A, Majuri ML, Luukkonen R, Mntyl T, Wolff HJ (2008) Inflammation and functional outcome in diisocyanate-induced asthma after cessation of exposure. The authors tested a rigid polyurethane foam using a NBS cup furnace (as described in Levin et al. Acrolein and formaldehyde are formed especially from cellulosic materials under non-flaming decomposition conditions, but products of vitiated combustion contain other organic irritants. The second results in a brief stimulation, followed by severe depression, of respiratory frequency, also starving the body of oxygen, and causing convulsions, respiratory arrest and death (Alarie 2002). Nitric oxide (NO) and nitrogen dioxide (NO2) are non-flammable gases present in fire effluents. The authors made this assertion based on the yield of average CO from post-flashover fires being 2009mgg1. 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. The authors acknowledged that further investigation of the steady state tube furnace was warranted as in some of the testing they suspected an instrumental error, since they were unable to account for roughly two-thirds of the total carbon from the sample and detected unusually low levels of CO2 during the under-ventilated tests. The reaction of a urethane with another isocyanate will produce an allophanate (Scheme5). The study also suggested that any remaining isocyanates residue would react with themselves to produce polycarbodiimides, thus anchoring the isocyanate precursors in the condensed phase until around 600C, where they would fragment. The three compartments were connected by doors and the target room contained an open vent. 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. In another investigation, using a steady state tube furnace, Blomqvist et al. 2007). When formed at the site, there is a potential for a completed-operations exposure. 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. The flexible foam produced ~175mgg1 of CO and 5mgg1 of HCN. I. However, spray foam insulation is a highly energy-efficient product and quickly offsets its manufacturing footprint. Carbon monoxide binds to the haemoglobin in red blood cells resulting in the formation of carboxyhaemoglobin (COHb), with stability 200 times greater than that of oxyhaemoglobin, impeding the transport of oxygen from the lungs to the cells in the body. The polyester based foam produced nearly double the amount of HCN between 900 and 1000C than the polyether foam with an increase from 20.8mgg1 to 38.0mgg1. The steady state tube furnace (ISO/TS 19700 2013), shown in Fig. 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. (PDF) The fire toxicity of polyurethane foams - ResearchGate The samples tested included both commercial rigid polyurethane foam and polyisocyanurate foam. ISO 13571 (2007) considers the four major hazards from fire which may prevent escape (toxic gases, irritant gases, heat and smoke obscuration). Research predicting the carbon monoxide evolution from flames of simple hydrocarbons, reviewed by Pitts (1995), has shown the importance of the equivalence ratio . 8-80, addressing . TDI is primarily used in the production of flexible foams, which are used in the furniture and interior industries. 95% of the demand for polyurethanes is situated in North America, Asian-pacific, and European markets; with demand expected to increase in Eastern Europe and South America in the next 1015 years. STM would like to acknowledge the University of Central Lancashire for provision of a studentship. Fire Science Reviews al, 2014). While this may occur to some degree, it is generally accepted that the majority of the diisocyanates produced in the decomposition of polyurethanes are either volatilised or converted into their amine derivative and then volatilised. 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. However, a non-standard modification of the apparatus has been described, enclosing the fire model in a controlled ventilation chamber, in an attempt to replicate oxygen-depleted conditions. 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. In the smoke chamber, the highest reported yield during flaming combustion was 1.02mgg1. Work by Ravey and Pearce (1997) on the decomposition of a polyether based flexible polyurethane foam suggested that up to 360C the decomposition of the foam was achieved by two main mechanisms. Investigations by Hertzberg et al. 10. Secondary air is added in a mixing chamber to give a total gas flow of 50Lmin1. The overall toxicity of the polyisocyanurate foam shows a clear increase as the fire became more under-ventilated, while the rigid polyurethane foam showed a slight decrease at 1.242.00. Toxicology 47:165170, Kaplan HL, Grand AF, Hartzell GE (1984a) Toxicity and the smoke problem. 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. 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). Using the methodology in ISO 13344, the authors also calculated the fractional effective dose (FED) of the individual toxicants sampled. The results indicated that the formation of the precursor, TDI, was much faster and preferable to depolymerisation when the volatile compounds could escape. Short chains with high functionality results in highly cross-linked polyurethane polymers which is characteristic of rigid foams. The authors presented a large set of data for all of the test methods, including a range of test conditions, air flow rates, oxygen concentration, and mass loadings. Other fire retardants such as melamine are reported to significantly increase the HCN yield of polyurethane foams. The CACC and SDC show reasonable agreement for well-ventilated burning, but fail to replicate the more hazardous under-ventilated fire conditions. The authors did not specify which analytical methods were used in the quantification of the fire gases, only that they were sampled via a sampling bag. 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). EN 2826. This was enough to cause deaths both during and post-exposure. This will result in a HCN yield related that specific furnace temperature. NO. 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. 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. Levin BC, Fowell AJ, Birky MM, Paabo M, Stolte A, Malek D (1982) Further development of a test method for the assessment of the acute inhalation toxicity of combustion products. This suggests that any amines formed would have reacted with isocyanates in the vapour phase to form ureas, some of which would have condensed to produce the observed waxy white substance. Additionally, the amount of CO generated for both materials began to taper off at 1.2-2.0 as the available oxygen becomes so low that the generation of CO becomes limited, while the yield of HCN continues to increase with equivalence ratio and temperature. Polyurethane is widely used, with its two major applications, soft furnishings and insulation, having low thermal inertia, and hence enhanced flammability. The process of . 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. Journal of Fire and Materials 4:p5058, Farrar DG, Hartzell GE, Blank TL, Galster WA (1979) Development of a protocol for the assessment of the toxicity of combustion products resulting from the burning of cellular plastics, University of Utah Report, UTEC 79/130; RP-75-2-1 Renewal, RP-77-U-5. 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. Higher temperatures resulted in the volatilisation of most of the polyurethane precursors via the formation of lower molecular weight compounds. A "combustion modified high resilience" flexible polyurethane foam (CMHR-PUF) and a polyisocyanurate (PIR) foam were analysed a steady state tube furnace apparatus. Privacy J Ind Eng Chem 13(7):p11881194. Gaithersberg, MD, Babrauskas V, Twilley WH, Janssens M, Yusa S (1992) Cone calorimeter for controlled-atmosphere studies. Ureas and urethanes decompose between 160 and 200C. 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). DiNenno et al. Polyurethane foam when burned gives off - wiehoch.com An equivalence ratio of 0.5 represents a well-ventilated scenario, typical of an early growing fire, while a ratio of 2 corresponds to the under-ventilated stage responsible for high yields of toxic effluents. Fire and Materials 11:p129, Paul KT, Hull TR, Lebek K, Stec AA (2008) Fire smoke toxicity: The effect of nitrogen oxides. eds. 1992), shown in Fig. 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. (2003) used a cone calorimeter to assess the yields of amines, aminoisocyanates and isocyanates from the flaming combustion of a flexible polyurethane foam. Therefore, in certain conditions, polyurethanes foams can reach their auto-ignition temperature and ignite which will significantlyalter the effect the decomposition mechanisms and resulting products. Similarly, Busker et al. Unfortunately, your body heat appears . As the availability of oxygen becomes lower in proportion to the amount of fuel, the yields of certain toxic gases will increase. 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. This suggests that the nitrogen in the char will more readily form HCN, even when the flaming is well-ventilated. VOCs and Other Toxic Chemicals in Mattresses: What to Know 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. Fire Technology 51:p213217, Blais M, Carpenter K (2015) Flexible Polyurethane Foams: A comparative measurement of toxic vapors and other toxic emissions in controlled combustion environments of foams with and without fire retardants. Both may be present in fire effluent, for example from PVC or halogenated flame retardants, and since the damage caused by the acidity (the concentration of H+ ions) is independent of the specificanion (Cl or Br), the discussion on HCl is also applicable to HBr. (2006) and also Garrido and Font (2015). 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. However, as the fire condition became under-ventilated (>1.5), the yields of both CO and HCN increased for both rigid polyurethane and the polyisocyanurate, while the yields of CO2 and NO2 decreased. The non-flaming decomposition of non-fire retarded polyurethane foams in air is generally quite well understood and comparable to the inert atmosphere decomposition, in terms of both products and mechanisms. Polyvinyl chloride, formaldehyde, boric acid, antimony trioxide and different types of petrochemicals. Ann occup Hyg 19:269273, Levchik SV, Weil ED (2004) Thermal Decomposition, combustion and fire-retardancy of polyurethanes - a review of the recent literature. Causes of UK fire deaths from 1955 to 2013 (UK Fire Statistics 2013). Equation National Fire Protection Association, 82, p 161, Vilar WD (2002) Chemistry and Technology of Polyurethanes - Chapter 1. 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. Biuret and allophanate bonds will decompose first between 100 and 125C. They attributed the different decomposition mechanisms to the physical form of the polyurethane foam, rather than to any chemical differences. At >800C these compounds further fragment into simple molecules (such as HCN, CO, CH4 and CH2O) and PAHs. The polyester based polyurethane began to decompose at 284C with a secondary decomposition step at 359C. The authors noted a primary depolymerisation of the foam which would release volatile TDI and leave the polyol precursors in the condensed phase. The controlled atmosphere cone calorimeter. The fire toxicity of polyurethane foams - Fire Science Reviews CO and HCN are the main asphyxiants produced during the combustion of polyurethanes and there have been a large number of studies published regarding their yields. 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. New memory foam smell? This is due to the large range of available fire retardants found in polyurethane foams, which suggests that the toxicity will likely follow the general trends in the literature for all materials regarding fire retardants. Its widespread availability has encouraged its adaptation to toxic gas generation and assessment. Studies have found that infant mattressesespecially those made with polyurethane foam, which contains the hydrocarbon tolueneare a major off-gassing culprit (Boor, et. The trimerisation results in a highly stable isocyanurate ring which confer additional thermalstability to polyisocyanurates (Scheme7). Sensory and upper respiratory tract irritation stimulates the trigeminal and vagus nerve receptors in the eyes, nose, throat and upper respiratory tract causing discomfort, then severe pain. 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. Using a smoke chamber set up for animal exposure experiments (as described in Levin et al. In: Fahima Z, Eram S (eds), InTech. Provided by the Springer Nature SharedIt content-sharing initiative. Rigid foam decomposed between 200 and 410C, while flexible foam decomposed between 150 to 500C. At 1000C the hydrogen cyanide produced accounted for a range of between 3.8 and 7.3% by weight. Interscience Publications, London, Purser DA (2008b) Chapter 2: SFPE Handbook of Fire Protection Engineering (Ed. The initial decomposition of the foam, at >300C, results in the volatilisation of isocyanates, amines and Woolleys yellow smoke, leaving behind polyols in the condensed phase. 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. However, bench-scale methods which allow the combustion conditions to change during the test are much more difficult to relate to full-scale fires, because the duration of each condition is unknown, and the behaviour of fires changes on scale-up. As polyurethane foams have very low thermal inertia, application of heat or a small flame can be enough to ignite them. 3 ISO 19706 (2011) Guidelines for assessing the fire threat to people. Toxic Materials in Foam Mattresses? Are We Safe? Additionally, the authors reported a yield of 1315mgg1 of CO, 1.41.5mgg1 of HCN, and 1012mgg1 of NO. In a report from the same laboratory, Braun et al. The average well-ventilated yield of HCN was found to be 4mgg1, while it was 9mgg1 for under-ventilated conditions. The full-scale test showed good accordance with the SSTF data considering the inherent unreliability of large-scale testing. Journal of Analytical and Applied pyrolysis 113:p202215, Gharehbagh A, Ahmadi Z (2012) Chapter 6: Polyurethane Flexible Foam Fire Behaviour, Polyurethane. Polymer International 53:p15851610. Similarly, the polyether based foam produced 15.1mgg1 to 28.1mgg1. The author acknowledged that there is a range of contradictory results available in the literature regarding their fire toxicity. (1999) tested both rigid and flexible polyurethane foams using a bespoke smoke chamber apparatus to assess the toxicity of the flaming combustion products of the materials to rats. Over this period there was a corresponding shift from the main cause of death in fires being attributed to burns to being attributed to inhalation of smoke and toxic gases. Interflam Conference Proceedings. decomposition products will burn. The results of these experiments and the mechanism of decomposition derived correlated well with work by Rein et al. The resulting substituted urea can then react with another isocyanate to pro-duce a biuret linkage (Scheme 4). The half-scale ISO 9705 experiments showed a wider range of ventilation conditions up to ~2.0. Andersson B, Markert F, Holmstedt G (2005) Combustion products generated by hetero-organic fuels on four different fire test scales. Purser model, [AGI] is the concentration of inorganicacid gas irritants, [OI] is the concentration of organic irritants, A is an acidosis factor equal to [CO2]0.05. 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). Before you take it for a test drive, make sure to give your new mattress time to off-gas in a well-ventilated environment. (2011) Aerospace series - Burning behaviour of non-metallic materials under the influence of radiating heat and flames - Determination of gas components in the smoke; ABD 0031 Fire-Smoke-Toxicity (FST) Test Specification (Airbus Industries); Boeing BSS 7239, Test method for toxic gas generation by materials on combustion. Early work by Voorhees (1975) identified what they described as extreme toxicity of the combustion products of a phosphate fire retarded polyurethane foam. However, the lower yields can be attributed to the fact that the cone calorimeter is a well-ventilated scenario, estimated as ~0.7 (Schartel & Hull 2007). Top of Page. If exposed to sufficient heat and flame, polyurethane foam will burn. Isocyanates were primarily produced during the first stage, and in the second stage primarily carbonyls (R2-C=O) and hydrocarbons were detected using infrared analysis. Equation3 uses a similar principle to equation1 to estimate the combined effect of all irritant gases. During flaming combustion of polyurethane foams, the yield of toxicants can be directly related to the fuel/air ratio, expressed as an equivalence ratio ().