In some cases the effluent continues to burn as it emerges from the chamber, (secondary flaming in Fig. . Short chains with high functionality results in highly cross-linked polyurethane polymers which is characteristic of rigid foams. Urethane Foam Health Effects | livestrong Most bench-scale methods have non-constant combustion conditions, such as those in closed chambers exposed to a constant source of heat, including the smoke density chamber (SDC) (ISO 56592 2012), and static tube furnace tests, such as the NF X 70100 (2006). Additionally, NO was detected during the well-ventilated tests and NH3 during the under-ventilated tests. (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. The smoke density chamber (ISO 5659-2) showing a sampling probe for fire smoke toxicity. Early work by Voorhees (1975) identified what they described as extreme toxicity of the combustion products of a phosphate fire retarded polyurethane foam. Insulation, like all building products, has an 'embodied' carbon footprint resulting from energy use during the manufacturing process. The methods of assessment of fire toxicity are outlined in order to understand how the fire toxicity of polyurethane foams may be quantified. 1992), shown in Fig. Additionally, HCN yields in both flaming and non-flaming conditions increases with temperature. 1982), and a three-compartment large scale test. Using polyurethane indoors can expose you to fumes with a number of potential side effects. The yields of toxic products followed the expected trend of being higher in the under-ventilated conditions. 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. 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. Global usage is expected to expand from 13.65 Mt in 2010 to 17.95 Mt by 2016. The authors reported GC/MS analysis of the condensed phase products obtained. Polymer International 53:p15851610. For a fixed chamber volume (0.51m3), assuming complete combustion, the sample thickness will dictate the ventilation condition, thus a thin sample will burn under well-ventilated conditions with minimum toxic products, while a thicker sample might be expected to produce a high yield of CO and other products of incomplete combustion. Syntheticpolymeric materials may be divided into thermoplastics and thermosets. Each of the decomposition steps took place at a lower temperature in air than in nitrogen, which further suggests the direct interaction of oxygen with the foam during decomposition. Polyurethane foam when burned gives off - wiehoch.com The authors tested a rigid polyurethane foam using a NBS cup furnace (as described in Levin et al. 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. Voorhees suggested that the compound was a bicyclic phosphate compound and noted grand mal seizures followed by death in rats with a loading as low as 4% by weight of the fire retardant. 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. Rigid polyurethanes primarily produced aromatic compounds in the condensed phase products of decomposition, whereas flexible polyurethanes produced aromatics, alcohols, aldehydes and heterocycles. Only the SSTF has a heated reaction zone which replicates the hot layer. Additionally, the authors reported a yield of 1315mgg1 of CO, 1.41.5mgg1 of HCN, and 1012mgg1 of NO. The time available for escape is the interval between the time of ignition and the time after which conditions become untenable, such that occupants can no longer take effective action to accomplish their own escape. 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. This causes deterioration in mental and muscular performance. This was enough to cause deaths both during and post-exposure. This results from PVC having 56.8% chlorine in its base polymer weight and it is well known that chlorine is one of the few elements that confers good fire properties to a polymer1,2. This equation only relates to lethality, or cause of death. Equation 3 calculatesthe Fractional Effective Concentration (FEC) of sensory irritants in the fire effluent which limit escape. 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). Respiratory Issues First, polyurethane is a petrochemical resin that contains known . Similarly, the polyether based foam produced 15.1mgg1 to 28.1mgg1. 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. While there were some problems, the data does show that the yields of toxicants from the polyurethane foam were generally most representative of post-flashover conditions in the test methods that were designed for ventilation controlled conditions, such as the steady state tube furnace and the controlled atmosphere cone calorimeter. In a letter to the editor of the journal, Barbrauskas et al. 2008) and is 40kWm2 in the centre of the furnace at 650C and 78kWm2 at 825C. California Privacy Statement, eff, should be used, rather than an averaged local equivalence ratio, based on the oxygen supply to the chamber, because, in some experiments, substantial secondary flaming occurred outside the test chamber, such that the amount of oxygen available to combustion exceeded the amount that was fed to the enclosed chamber. TRH wrote the fire toxicity section of the manuscript. Correspondence to Combustion Science and Technology 183(7):p627644, Saunders JH (1959) the Reactions of Isocyanates and Isocyanate Derivatives at Elevated Temperatures. Does Polyurethane Foam Give Off Toxic Fumes? 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. 7) (Avar et al. The reaction of a urethane with another isocyanate will produce an allophanate (Scheme 5). 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)). Toxic product yield data from the smoke density chamber (ISO 56592 2012), the controlled atmosphere cone calorimeter (based on ISO 56601 2002), the fire propagation apparatus (FPA) (ASTM E 2058), the French railway test (NFX) (NF X 70100 2006), and the steady state tube furnace (SSTF) (ISO/TS 19700 2013) were compared to published large-scale enclosure fire data (from a standard ISO 9705 room) for two polymers, polypropylene (PP) and polyamide 6.6 (PA 6.6). In the case of flaming combustion, one of the most important factors relating to the toxic product yield is the fuel/air ratio which, as defined earlier, can be expressed as an equivalence ratio (). 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). This can be explained by the fragmentation of nitrogen containing organics in the flame and in the effluent, as suggested bystudies of the inert-atmosphere decomposition of polyurethane materials. The mechanisms of decomposition are well understood and the decomposition products of both rigid and flexible polyurethane foams are very similar at high temperatures. This resulted in the reported HCN yields for the under-ventilated conditions being lower than expected in all of the tests. Refer to MSDS. The overall toxicity of the combined materials was higher, and the average concentrations of the gases throughout the tests were consistently higher than that of the individual materials in both flaming and non-flaming conditions. It is usually used in isomeric mixtures of varying ratios, with 80:20 2,4 to 2,6 being the most commonly used (Fig. 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. 11) ultimately giving well-ventilated flaming. 2), also results in cross-linking in the polymer. 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. 2012). 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). . Burning foam will emit mainly carbon monoxide, carbon dioxide and small traces of other toxic gases, such . HAZWOPER 40 - Lesson 3 - Toxicology Flashcards | Quizlet The polyester fabric produced 9293mgg1 of CO when burned with very little difference in the flaming or non-flaming conditions. In a compartment fire, the reactions of under-ventilated flaming occur in both the flame zone and in the hot upper layer. Journal of Applied Polymer Science 111:p11151143, Stec AA, Hull TR (2011) Assessment of the fire toxicity of building insulation materials. 5-step decomposition mechanism for flexible polyurethane foam (Rogaume et al. However, PVC will typically not burn once the source of heat or flame is removed. Polyurethane Fume Exposure And Your Health: What You Need To Know 3 Cite this article. Rigid foam decomposed between 200 and 410C, while flexible foam decomposed between 150 to 500C. The three compartments were connected by doors and the target room contained an open vent. Common polyurethane functional groups i) urethane ii) urea iii) carbodiimide iv) uretdione v) isocyanurate. True. The authors noted that the polyester polyols were more stable than the polyether polyols, with the latter fragmenting at a lower temperature (300400C). DiNenno et al., eds.). At lower temperatures, decomposition differs, depending on the composition and physical properties of the polymer, although clear trends can be identified. 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. 2013). At high concentrations nitric oxide is rapidly oxidised in air to form nitrogen dioxide, however, at the concentrations found in fire gases, most of the nitric oxide remains unoxidised. However, many people fail to escape from fires because of the incapacitating effect of smoke (obscuring visibility) and its irritant components which cause pain, preventing breathing and escape or reason death occurred. It is inexpensive and easy to install, however, it is a severe fire risk and requires a thermal barrier to make it safe. Free of VOCs and HAPs. Rigid MDI based foams are primarily used for insulation in the construction industryand can also be found in the transport industry. The yields of CO and HCN at varying and temperature are presented in Table5. Similarly, Busker et al. 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. The author acknowledged that there is a range of contradictory results available in the literature regarding their fire toxicity. The difference with other polyurethane foams is that memory foam also contains added chemicals that increase its viscosity and elasticity, hence its alternate name, viscoelastic foam. The danger of using urethane products is when the foam burns. P.J. 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. In China and Japan, there are specific restrictions on the use of materials with high fire toxicity in high risk applications such as tall buildings, while an increasing number of jurisdictions permit the alternative performance based design approaches to fire safety. HCN also causes rapid incapacitation, preventing escape, and then, with CO, contributes to death from asphyxiation. The authors noted that a large number of the data available relating to the test conditions were vague or completely undefined. 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. While limited data were available regarding the flaming combustion of rigid polyurethane foams, the results were of a similar scale to those presented by Stec and Hull (2011). The authors noted that in both the flaming and non-flaming combustion of the polyurethane foam, the concentrations of toxicants did not reach high enough concentrations to predict deaths. 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 formation of HCN was at a higher temperature in both air and nitrogen (400C and 550C respectively) with an average concentration of 200ppm at 500C. This results in relativelyhigh yields of CO and HCN during under-ventilated flaming and relatively low yields during well-ventilated flaming. 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. Heat, smoke and irritant gases may impair escape, increasing the risk of a lethal exposure to asphyxiant gases, andcan sometimes lung damage causes death in those managing to escape. In another investigation, using a steady state tube furnace, Blomqvist et al. By using this website, you agree to our 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. It can be used for testing samples 100100mm and up to 50mm thick, in both the horizontal and vertical orientation. Animal studies provide most of what we know about the dangerous effects of toxic substances. 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. Is Polyurethane Foam Toxic, And Should You Avoid it? - The Safe Parent Some of these methods attempt to address the transition through the fire stages by monitoring the formation of toxic gases as a function of time, as the oxygen concentration falls, and the fire condition changes from well-ventilated to under-ventilated. Google Scholar, Allan D, Daly J, Liggat JJ (2013) Thermal volatilisation analysis of TDI-based flexible polyurethane foam. During polymerisation, isocyanates undergo a number of distinct reactions. Once sensitisation has occurred, even extremely low concentrations of airborne isocyanates can trigger fatal asthma attacks (Henneken et al. However, when the TDI was unable to enter the pyrolysis zone, the slower, irreversible decomposition to diaminotoluene (DAT) would occur. The results showed a HCN yield of 15.8mgg1 at 600C. 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. Babrauskas V, Lawson JR, Walton WD, Twilley WH (1982) Upholstered Furniture Heat Release Rates Measured with a Furniture Calorimeter. There is some contradiction the literature as to the effect fire retardants have on the overall toxicity of polyurethane foams. However, instead of finding my answer I found seemingly endless reports on websites claiming that memory foam gives off potentially toxic fumes. 4)). 1981), probably because of increased use of nitrogen-containing synthetic polymers. 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). When polyurethane and polystyrene burn, they create a very smoky fire that . Journal of Applied Polymer Science 63:p4774, Rein G, Lautenberger C, Fernandez-Pell AC (2006) Application of Genetic Alogorithms and Thermogravimetry to Determine the Kinetics of Polyurethane Foam in Smoldering Combustion. 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. Others, such as the NF X 70100, and the ISO/TS 19700 SSTF use the furnace temperature setting to ensure a consistent radiant heat flux. Will polyurethane melt under heat? - remodelormove.com This step dramatically reduced fire deaths, which was considered a triumph at the time. Causes of UK fire deaths from 1955 to 2013 (UK Fire Statistics 2013). Polymer Degradation and Stability 98:535541, Anderson RA, Watson AA, Harland WA (1981) Fire Deaths in the Glasgow Area: I General Considerations and Pathology. 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 process of . In a 12-square-foot area, urethane was totally burned off, but the rest suffered more minor damage. 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. 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. Acrolein and formaldehyde are formed especially from cellulosic materials under non-flaming decomposition conditions, but products of vitiated combustion contain other organic irritants. 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. A comprehensive review of fire retardants and their use in polyurethane foams was published by Singh and Jain (2009). Potential Chemical Exposures From Spray Polyurethane Foam Foam: Fire Hazard and Fire Barrier | Monolithic.org At >800C these compounds further fragment into simple molecules (such as HCN, CO, CH4 and CH2O) and PAHs. Thermogravimetric analysis and differential scanning calorimetry (TGA/DSC) showed that the polyether based polyurethane began to decompose at 258C, with a second decomposition stage at 350C (which could be attributed to the fragmentation of the polyether polyol). Alongside this, the decomposition of the foam into an amine, alkene and carbon dioxide was also proposed. Fire Sci Rev 5, 3 (2016). Woolley WD, Fardell PJ, Buckland IG (1975) The Thermal Decomposition Products of Rigid Polyurethane. 2005; Blomqvist & Lonnermark 2001). Equation 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. p 102-120. ISO 56592 (2012) Plastics - Smoke generation - Part 2: Determination of optical density by a single-chamber test, ISO 56601 (2002) Fire tests Reaction to fire Part 1: Rate of heat release from building products (cone calorimeter method), ISO 9705 (1993) Fire tests Full-scale room tests for surface products, Kaplan HL (1987b) Effects of irritant gases on avoidance/escape performance and respiratory response of the baboon. A summary of these structures is shown in Fig. combustion modified high resilience polyurethane foam, Alarie Y (2002) Toxicity of Fire Smoke. The most notable and abundant of these was hydrogen cyanide which increased in yield from 700 to 1000C. These polyols will fragment and volatilise as the temperature increases, leaving behind a char (>600C). 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. Journal of Analytical and Applied pyrolysis 108:p143150, Hartzell G (1993) Overview of Combustion Toxicology. 1986). Instead polyureas were detected in the vapour phase and also in the condensed phase as a waxy, insoluble white substance. 12, feeds the sample (typically around 25g of pellets or granules) into its hot zone at a fixed rate, under a controlled air supply, inside a horizontal silica tube of diameter 48mm, allowing adequate mixing of fuel and oxidant. These processes occur at around 300C with the precursor chemicals including TDI, MDI, HDI, polyols (both polyether and polyester-polyols) and aromatic amines. In particular, the ventilation condition has a . Fire and Materials 23:p171185, Hull TR, Paul KT (2007) Bench-scale assessment of combustion toxicity-A critical analysis of current protocols. 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). 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). 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. A "combustion modified high resilience" flexible polyurethane foam (CMHR-PUF) and a polyisocyanurate (PIR) foam were analysed a steady state tube furnace apparatus. These isocyanate derived cross-links can include biurets and allophanates (Fig. Equations2 and 3 have been taken from ISO 13571 (2007). 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. Isocyanates also react with themselves in various ways to produce dimers, trimers and completely new functional groups. Nitrogen dioxide dissolves rapidly in water to form nitric and nitrous acid. Is Your Mattress Releasing Toxins While You Sleep? - WebMD 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. Furniture, upholstery and curtains The heating of polyurethanes in an inert-atmosphere results in the progressive rupturing of bonds as a function of temperature. The chemical additives to the polyurethane are said to give off a distinct chemical odor that lessens after adequate ventilation. 1982) to that of a large scale test room. National Fire Protection Association, Quincy MA, USA, pp 296, Purser DA, Purser JA (2008a) HCN yields and fate of fuel nitrogen for materials under different combustion conditions in the ISO 19700 tube furnace. Equation 2 calculates the FED of the major asphyxiants, CO and HCN, but without taking oxygen depletion or CO2 driven hyperventilation into account. (such as polyurethane foam) burn slower (have a lower (HRR) than higher-density materials (cotton padding) of similar makeup. The sample is a 7575mm square solid sheet and the standard for smoke measurement states that the results are only valid at the thickness tested (typically 14mm).
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