polyurethane foam, when burned gives off

The polyisocyanurate, on the other hand, produced slightly more HCN than the rigid foam (17mgg1 vs 12mgg1). The flexible foam produced ~175mgg1 of CO and 5mgg1 of HCN. In a report from the same laboratory, Braun et al. combustion modified high resilience polyurethane foam, Alarie Y (2002) Toxicity of Fire Smoke. The authors tested a rigid polyurethane foam using a NBS cup furnace (as described in Levin et al. Insulation, like all building products, has an 'embodied' carbon footprint resulting from energy use during the manufacturing process. Google Scholar, Schartel B, Hull TR (2007) Development of fire-retarded materials - interpretation of cone calorimeter data. The most commonly reported adverse health effects after airborne isocyanate exposure is asthma due to sensitisation (Piiril et al. 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). Draeger tubes), conventional or Fourier transform infrared spectroscopy (FTIR) gas analysis, despite significant problems of reproducibility. 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). Woolley et al. 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. Thermal decomposition of polyurethanes is usually the reverse of polymerisation, resulting in the formation their precursor functional compoundsdiisocyanates, diamines and dihydroxy compounds. (2011) developed a mechanism based on both condensed and gas-phase decomposition in air. The presence of oxygen in the atmosphere directly interacts with the solid phase, which accelerates decomposition. Oxygen depletion can be lethal if the oxygen concentration falls below tenable levels (~6%). 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). Polymer-Plastics Technology and Engineering 45:p95108, Singh H, Jain AK (2009) Ignition, Combustion, Toxicity, and Fire Retardancy of Polyurethane Foams: A Comprehensive Review. This slight decrease is probably within the limits of experimental error, as it does not follow the general trend shown by most materials. Similarly, the polyether based foam produced 15.1mgg1 to 28.1mgg1. The methods of assessment of fire toxicity are outlined in order to understand how the fire toxicity of polyurethane foams may be quantified. (1972) suggested that the decomposition was initiated by the release of a nitrogen-rich material at 200300C which in turn decomposes into low molecular weight nitrogenous fragments above 500C. 50 1). Asphyxiant or narcotic gases cause a decrease in oxygen supplied to body tissue, resulting in central nervous system depression, with loss of consciousness and ultimately death. Most fuel nitrogen is released as N2, but in well-ventilated combustion conditions a proportion is released as oxides of nitrogen (mainly NO) and in under-ventilated combustion conditions a proportion is released as HCN (Purser & Purser 2008a). The smoke density chamber (ISO 5659-2) showing a sampling probe for fire smoke toxicity. Self-addition reaction of two isocyanates to produce a uretidione, Self-addition reaction of three isocyanates to produce a isocyanurate ring, Reaction of two isocyanates to produce a carbodiimide. Cite this article. 5). However, from a fire toxicity perspective it is generally assumed that heat and other gases will have already prevented survival, while other toxicants such as CO or HCN, will be present in lethal quantities further from the fire where the oxygen depletion would not be considered harmful. 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. Conversely, nitric oxide gas at low concentrations(~20 ppm) has been used to aid breathing in the treatment of respiratory disorders (Kavanagh & Pearl 1995). Avar G, Meier WU, Casselmann H, Achten D (2012) Polymer Science: A Comprehensive Reference, Polymer Science: A Comprehensive Reference, 10, p411-441. Most rigid foams and speciality polyurethanes use polymeric MDI derivatives which are mixtures components such as dimers and trimers (Fig. 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. The authors would like to thank Dr. Linda Bengtstrom for her contribution regarding the toxicity of isocyanates. Unfortunately, your body heat appears . In the large scale test room, the sample smouldered for 1.5 to 2h, resulting in a HCN yield of 1.03mgg1. The applied heat flux must be large enough for burning to continue at oxygen concentrations as low as 5%. 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. 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. Fire Safety Science - Proceedings of the First International Symposium, p1111-1122, Markets and Markets report (2011) Methylene Diphenyl Diisocyanate (MDI), Toluene Diisocyanate (TDI) and Polyurethane Market (2011 2016): Markets and Markets CH 1596, July 2011, Marsh ND, Gann RG (2013) Smoke Component Yields from Bench-Scale Fire Tests: 4. 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. 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. 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). When =1 the theoretical amount of air is available for complete combustion to carbon dioxide (CO2) and water. The full size ISO 9705 test resulted in well-ventilated flaming ( 0.260.5) due to the relatively large volume of air and relatively small sample size. statement and MDI is a diaromatic diisocyanate compound that boils at 208C and is primarily used in the production of rigid foams. ISO 13571 (2007) considers the four major hazards from fire which may prevent escape (toxic gases, irritant gases, heat and smoke obscuration). Since HCN is a major contributor to the fire toxicity of polyurethane foams, the mechanisms by which they decompose are vital in understanding why they produce large-quantities of HCN during under-ventilated burning. Reliable rate of heat release, fire effluent toxicity and smoke generation data are all essential components of such an assessment. (1990) also reported increased HCN yields when the sample was allowed to smoulder before flaming in similar apparatus as above. Preliminary calculations suggested that 27% of the TDI should be recovered as DAT. Experimental data reported a 28% recovery of DAT which supports the proposed decomposition mechanism. Performing hot work on or near polyurethane foam may lead to potential exposures to isocyanates and other toxic emissions. The dimerisation of two isocyanates is a reversible reaction that produces uretidione ring (Scheme6). At lower temperatures, decomposition differs, depending on the composition and physical properties of the polymer, although clear trends can be identified. Manage cookies/Do not sell my data we use in the preference centre. 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. Summing these contributions generates a fractional effective dose (FED). Investigations by Woolley et al. Their apparently transient nature results from their very high reactivity with amines and their fairly high reactivity with water (which is almost always present in fire effluent). Journal of Fire Sciences 8:p6379, BS 6853 (1999) Code of practise for fire precautions in the design and construction of passenger carrying trains. 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. Springer Nature. The uptake, distribution, metabolism and excretion of cyanide is much more complex than for CO and quantifying CN- in fire victims is more expensive and not routinely undertaken. 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. The authors compiled toxicological data from a range of primary online databases and also requests were made to collect unpublished data that were not publically available. 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. 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). Journal of Analytical and Applied pyrolysis 113:p202215, Gharehbagh A, Ahmadi Z (2012) Chapter 6: Polyurethane Flexible Foam Fire Behaviour, Polyurethane. 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. Fire Hazards of Insulation Materials | American Family Insurance When a one gram sample of foam was decomposed in air, CO was formed at a lower temperature than in nitrogen (300C vs 400C), with a relative concentration of 5000ppm at 500C. A "combustion modified high resilience" flexible polyurethane foam (CMHR-PUF) and a polyisocyanurate (PIR) foam were analysed a steady state tube furnace apparatus. During these tests, the PIR was set up as wall panels covered on two faces with aluminium foil. 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 (). But many products or materials continue off-gassing even after the "new smell" has gone awaythe fumes are just much more subtle. 23. 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. al, 2014). However, no amines were detected in the vapour phase. 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. The samples tested included both commercial rigid polyurethane foam and polyisocyanurate foam. PDF The fire toxicity of polyurethane foams - SpringerOpen 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. Diesel engines use the principle of _____ to ignite fuel vapor. The use of 13C labelling by Chambers et al. 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 . 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. The authors reported GC/MS analysis of the condensed phase products obtained. 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. The radiant heat flux in the ISO/TS 19700 apparatus has been measured (Stec et al. For example, Levin and coworkers reported that melamine-treated flexible polyurethane foam generated 6 times more HCN than an equal amount of non-melamine treated foam. The CACC and SDC show reasonable agreement for well-ventilated burning, but fail to replicate the more hazardous under-ventilated fire conditions. (1981) reported similar data by analysing the inert-atmosphere pyrolysis of a series of biscarbamates to act as model compounds representing polyurethane foams. Hydrogen cyanide is approximately 25 times more toxic than carbon monoxide through the formation of the cyanide ion, which is formed by hydrolysis in the blood (Hartzell 1993). 1982), and a three . Both of the materials showed a clear relationship with the HCN yield increasing with . 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). 2008; Kaplan 1987b). However, there is verylittle literature available regarding the yields of isocyanates produced by the combustion of polyurethane foams. Global usage is expected to expand from 13.65 Mt in 2010 to 17.95 Mt by 2016. The rigid polyurethane foam yielded ~55mgg1 CO and ~0.5mgg1 of HCN. 1982), a developmental method (SwRI/NIST method) which used a radiant heater on the sample which lead into a 200L exposure chamber, a cone calorimeter (ISO 5660 2002), a furniture calorimeter (as described in Babrauskas et al. The standard specifies four test conditions, but fails to link them to particular fire scenarios. 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. It is generally accepted that the thermal decomposition occurring during flaming combustion is best represented by the thermal decomposition of a material in an inert atmosphere. 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. 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. As the toxic product yields of polyurethane foams are directly related to the ventilation conditions, so is the materials LC50 value. 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. 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. 1982), and a three-compartment large scale test. 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. False True. One analysis of fire victims' blood showed a trend of declining COHb and a rise in cyanide concentrations (Anderson et al. 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. 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. A comprehensive review of fire retardants and their use in polyurethane foams was published by Singh and Jain (2009). The general approach, described in ISO 13571 (2012), is to ensure that the available safe escape time (ASET) before escape routes become obscured by smoke and/or filled with toxic gases, exceeds the required safe escape time (RSET). In a letter to the editor of the journal, Barbrauskas et al. These nucleophiles include amines, alcohols, carboxylic acids, thiols, water, ureas and urethanes (Aneja 2002). The reaction of an isocyanate functional group with water (Scheme2) results in the formation of an unstable carbamic acid group, which in turn decomposes to release an amine and carbon dioxide. 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. Work published as early as 1959 supported this mechanism of decomposition at higher temperatures and noted that up to 70% of the nitrogen in the foam could be converted to HCN at 1000C (Saunders 1959). Journal of Analytical and Applied pyrolysis 108:p143150, Hartzell G (1993) Overview of Combustion Toxicology. 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. 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). 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. 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). 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). 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). They attributed the different decomposition mechanisms to the physical form of the polyurethane foam, rather than to any chemical differences. Generalised decomposition mechanism for polyurethane foams both in nitrogen and in air. In most countries, there are no regulations covering the fire toxicity of building components, or for most road vehicles, including goods vehicles in tunnels. Rigid foam decomposed between 200 and 410C, while flexible foam decomposed between 150 to 500C. From this, the library of data was sorted into categories of combustion/pyrolysis conditions, material/product, type of test animal and toxicological endpoint. 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. 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). While the link between CO yield and equivalence ratio is well established, the yield of HCN in ventilation limited conditions shows more complicated behaviour for polyurethanes. Toxic Materials in Foam Mattresses? Are We Safe? Memory foam is a type of polyurethane foam. Carbodiimides are produced by the reaction of isocyanates in the presence of a catalyst (such as phospholine oxides) (Scheme8) (Avar et al. Urethane Foam Health Effects | livestrong 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. Nitric oxide (NO) and nitrogen dioxide (NO2) are non-flammable gases present in fire effluents. CORE - Aggregating the world's open access research papers 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). PDF Polyurethanes and Thermal Degradation Guidance Data from large scale fires in enclosures, such as a room, shows much higher levels of thetwo of the major toxicants, carbon monoxide (CO) and hydrogen cyanide (HCN) under conditions of developed flaming (Andersson et al. This range of functional groups and their ratios in the polymer are a large contributing factor to the wide range of properties that polyurethane materials can possess. This causes deterioration in mental and muscular performance. 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. Equation Polyurethane and polyisocyanate both release polyols and isocyanates during blowing, but the rates diminish rapidly over time as the product cures, provided they dialed in the temps & chemical mix correctly. During polymerisation, isocyanates undergo a number of distinct reactions. 2013). The average CO yield expected from under-ventilated flaming is ~200mgg1 for polyurethane materials. 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. Over 90% of all industrial polyurethanes are based on either TDI or MDI (Avar et al. More recent work by Shufen et al. Polyurethane. The polyester based polyurethane began to decompose at 284C with a secondary decomposition step at 359C. In addition totheir flammability, polyurethanes form carbon monoxide, hydrogen cyanide and other toxic products on decomposition and combustion. Its widespread availability has encouraged its adaptation to toxic gas generation and assessment. 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). TNO Report. P.J. A more recent review, by Levchik and Weil (2004), assessed the decomposition, combustion and fire-retardancy of polyurethanes. Ask if the mattress materials are generally free of VOC and HAPs. 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. (2015) questioned their methodology and noted that the authors did not address the release of HCl and its contribution to the acute fire toxicity of the fire retarded foam. The fire department was not immediately called, so the oil burned completely. 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. J Ind Eng Chem 13(7):p11881194. Burning foam will emit mainly carbon monoxide, carbon dioxide and small traces of other toxic gases, such . PDF Fire Properties of Polyvinyl Chloride 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). In a compartment fire, the reactions of under-ventilated flaming occur in both the flame zone and in the hot upper layer. The heating of polyurethanes in an inert-atmosphere results in the progressive rupturing of bonds as a function of temperature. The relation of the FED to the material-LC50 is given in equation4. The three compartments were connected by doors and the target room contained an open vent. When polyurethane and polystyrene burn, they create a very smoky fire that . This value decreased to 18mgg1 at ~2.0. Routes of entry in this case are inhalation, ingestion (saliva), and skin absorption. Whether one or other of these mechanisms predominates, or their interrelationship, remains unclear. At >800C these compounds further fragment into simple molecules (such as HCN, CO, CH4 and CH2O) and PAHs. The yields of some of the most toxic gases from unwanted fires (such as CO, HCN and some organic irritants) have been demonstrated to be directly related to the combustion conditions (Purser 2002). The peak HCN value reached was 10mg per g1 in the under-ventilated tests. Cookies policy. (2003) used a cone calorimeter to assess the yields of amines, aminoisocyanates and isocyanates from the flaming combustion of a flexible polyurethane foam. 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. In both rigid and flexible foams, aniline and p-aminotoluene were reported, which correlates with the work of Ravey and Pearce (1997) who reported that isocyanates that did not volatilise were converted into amines in the condensed phase. Fire and Materials 9:p125134, Levin BC, Paabo M, Bailey CS, Harris SE (1986) Toxicity of the combustion products from a flexible polyurethane foam and a polyester fabric evaluated separately and together by the NBS Toxicity Test Method. 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. Fire Safety Journal 7:p11, Kavanagh BP, Pearl RG (1995) Inhaled nitric oxide in anesthesia and critical care medicine. The controlled atmosphere cone calorimeter. International Association for Fire Safety Science, Ravey M, Pearce EM (1997) Flexible Polyurethane foam. Fire and Materials 31:p495521, Bott B, Firth JG, Jones TA (1969) Evolution of toxic gases from heated plastics. Anderson RC, Croce PA, Feeley FG, Sakura JD (1983) Study to assess the feasibility of incorporating combustion toxicity requirements into building materials and furnishing codes of New York State: Final report, vol I, II, III, Arthur D. Little, Inc. Report, Reference 88712, May 1983. Most fire deaths and injuries actually occur in residential fires, although assessment of fire toxicity is currently focused on areas where escape is restricted, such as aeroplanes, railway carriages, and passenger ships, which include requirements to quantify the fire toxicity of internal components.

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