polyurethane foam, when burned gives off

p 102-120. City, Salt Lake, UK Fire Statistics 2013 (and preceding years) United Kingdom, Fire Test Procedure Code (2010) Maritime Safety Committee, (MSC 87/26/Add.3) Annex 34, Part 2 Smoke and Toxicity Test. 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). 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. Other fire retardants such as melamine are reported to significantly increase the HCN yield of polyurethane foams. 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. The authors declare that they have no competing interests. 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. Chem Co., Dow, Hertzberg T, Blomqvist P, Dalene M, Skarping G (2003) Particles and Isocyanates from Fires. Over 90% of all industrial polyurethanes are based on either TDI or MDI (Avar et al. Polyurethane and other organic foam materials are finding increased use on vessels because of their excellent insulating properties and light weight. However there was significant scattering of the results with both high and low outliers (26mgg1 at 1.22 and 9mgg1 at 1.95). The effects range from tears and reflex blinking of the eyes, pain in the nose, throat and chest, breath-holding, coughing, excessive secretionof mucus, to bronchoconstriction and laryngeal spasms (Purser 2008b). NBSIR 822604. They also asserted that the toxicity of the fire retarded foam was less than or equal to wood on a mass/mass basis and that wood contributes significantly more to residential fires in terms of fire smoke toxicity. Various apparatus and protocols for quantifying fire effluent toxicity in different jurisdictions and industries have been critically reviewed (Hull & Paul 2007). (2013) further supported the presence of two separate decomposition mechanisms for flexible foams. The authors would like to thank Dr. Linda Bengtstrom for her contribution regarding the toxicity of isocyanates. I recently purchased a memory foam (polyurethane) mattress and was looking online to see how long they take to "air out". Although these temperatures can provide a good general idea of which bonds will be likely to break down with heating, the steric and electronic effects of the attached groups can affect the strength of the bonds and thus the temperature at which the bond will decompose. Equation 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. Performing hot work on or near polyurethane foam may lead to potential exposures to isocyanates and other toxic emissions. 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. Rigid polyurethanes primarily produced aromatic compounds in the condensed phase products of decomposition, whereas flexible polyurethanes produced aromatics, alcohols, aldehydes and heterocycles. Animal studies provide most of what we know about the dangerous effects of toxic substances. Once sensitisation has occurred, even extremely low concentrations of airborne isocyanates can trigger fatal asthma attacks (Henneken et al. 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. Bott et al. Taking into consideration the issues with repeatability of large-scale testing, the authors asserted that the similar trend in HCN yields supported the good relationship between the tube-furnace and large-scale results. As polyurethane foams have very low thermal inertia, application of heat or a small flame can be enough to ignite them. Similarly, the polyether based foam produced 15.1mgg1 to 28.1mgg1. Isocyanates are a highly reactive family of compounds that are characterised by the RN=C=O functional group (where R can be any aliphatic or aromatic functionality). Isocyanate structure also affects the reactivity of the isocyanate group. Table1 shows the relative reactivity of isocyanates with nucleophiles at 25C without the presence of a catalyst. 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 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). Substituted aromatics containing electron withdrawing groups further increase the reactivity of isocyanates by increasing the partial positive charge on the isocyanate carbon via a resonance withdrawing effect. The revised protocol is based on continuous sampling of the fire effluent. In general, How do low-density materials (such as polyurethane foam) burn compared to higher-density materials (cotton padding) of similar makeup? Anal Bioanal Chem 387:p219236, Herrington R, Hock K (1998) Flexible Polyurethane Foams, 2nd edn. Spray Foam Insulation: Helping Achieve Sustainability. 11) ultimately giving well-ventilated flaming. Polymer International 53:p15851610. Routes of entry in this case are inhalation, ingestion (saliva), and skin absorption. 13) (UK Fire Statistics 2013). Ann occup Hyg 19:269273, Levchik SV, Weil ED (2004) Thermal Decomposition, combustion and fire-retardancy of polyurethanes - a review of the recent literature. These reactions are accelerated in the presence of oxygen, which reduces the temperature of the decomposition steps. 2005; Blomqvist & Lonnermark 2001). A comprehensive review of fire retardants and their use in polyurethane foams was published by Singh and Jain (2009). In a letter to the editor of the journal, Barbrauskas et al. (1986) investigated the toxicity of flexible polyurethane foam and a polyester fabric both separately and together. 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. The cone calorimeter (ISO 56601 2002) is probably the most widely used apparatus for measurement of flammability properties such as ignitability and heat release rate (Schartel & Hull 2007). This makes the isocyanate functional group highly reactive towards nucleophiles with an available hydrogen. Equation 2012). The authors intended to compare the HCN yields for the non-flaming and flaming combustion of the foam in a smoke chamber apparatus (as described in Levin et al. 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. The sample is spread evenly in a silica boat over a length of 800mm and fed into a tube furnace at a typical rate of 1gmin-1 with flowing airat a rate of 2-10 L min-1. 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). Fire Safety Science 11:p404418, Stec AA, Hull TR, Lebek K (2008) Characterisation of the steady state tube furnace (ISO TS 19700) for fire toxicity assessment. TNO Report. Biuret and allophanate bonds will decompose first between 100 and 125C. The difference in the decomposition of rigid and flexible polyurethane foams was investigated by Chun et al. In this case, the main reason for including isocyanate reactivity data is to explain the reactivity of isocyanates that are released into fire effluent during combustion. That smell comes from volatile organic compounds, or VOCs, chemicals used in the mattress manufacturing process. While the data presented is a useful compilation of toxic potency data from the available literature before 2004, the report does not take into consideration the conclusions of individual authors, the exact specifics of the test condition, and the validity of the results. 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). However, instead of finding my answer I found seemingly endless reports on websites claiming that memory foam gives off potentially toxic fumes. 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. PML 1998-A97. This was observed by Levin et al. Based on the available literature, the non-flaming decomposition of both rigid and flexible polyurethane foams, in both air and nitrogen, can be generalised into a number of key steps (Fig. 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. Ureas and urethanes decompose between 160 and 200C. NO. These polyols will fragment and volatilise as the temperature increases, leaving behind a char (>600C). 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. 10. VOCs have the ability to vaporize, or off-gas, at room temperature. 2008) and is 40kWm2 in the centre of the furnace at 650C and 78kWm2 at 825C. Both types of foam yielded very similar products at temperatures above 600C. The NFX generates data intermediate between the well-ventilated and under-ventilated fire conditions. The average combined yield of isocyanates recovered was 0.869mgg1 and the average yield of amines and aminoisocyanates was 0.321mgg1. In particular, the ventilation condition has a . 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. According to Tim Rodrique, the director of the DFS, investigators suspect that the fires were caused by the exothermic reaction that results from the mixing of the two chemicals used to make . Syntheticpolymeric materials may be divided into thermoplastics and thermosets. The radiant heat flux in the ISO/TS 19700 apparatus has been measured (Stec et al. Before you take it for a test drive, make sure to give your new mattress time to off-gas in a well-ventilated environment. However, the yield of CO was lower in both the non-flaming and flaming combustion. 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 non-flaming decomposition of polyurethanes in air or nitrogen can be summarised effectively usinga generalised mechanism based on the available literature (Fig. 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. 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. Bench-scale methods used for generating toxic effluents from polyurethane foams have met with controversy. 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. As the availability of oxygen becomes lower in proportion to the amount of fuel, the yields of certain toxic gases will increase. (1990) also reported increased HCN yields when the sample was allowed to smoulder before flaming in similar apparatus as above. 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 . 5). The specific mass of the polyurethane sample was not provided by the author and the ventilation conditions were not clear as a result of this. This slight decrease is probably within the limits of experimental error, as it does not follow the general trend shown by most materials. 2011). McKenna, S.T., Hull, T.R. 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 CACC and SDC show reasonable agreement for well-ventilated burning, but fail to replicate the more hazardous under-ventilated fire conditions. (1981) on polycarbodiimides and polyureas enabled the determination of the source of the organonitriles and HCN during thermal decomposition. Using the methodology in ISO 13344, the authors also calculated the fractional effective dose (FED) of the individual toxicants sampled. 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. countries without interpol, 2 year stacked comps calculation, snowflake print variable,

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