polyurethane foam toxicity
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. The formation of HCN was at a higher temperature in both air and nitrogen (400 °C and 550 °C respectively) with an average concentration of 200 ppm at 500 °C. (1991a) compared a number of test methods. The general approach in generating toxic potency data from chemical analysis is to assume additive behaviour of individual toxicants, and to express the concentration of each as its fraction of the lethal concentration for 50 % of the population for a 30 min exposure (gas-LC50). Further reactions occur with amines, water, ureas, urethanes and even other isocyanates to produce a diverse range of functional groups including urethanes, ureas, isocyanurates, carbodiimides and uretdiones. Some heat‐resistant groups such as carbodiimide‐, isocyanurate‐, and nitrogen‐containing heterocycles formed with polyurethane foams also render urethane foams fire‐retardant. A comprehensive review of fire retardants and their use in polyurethane foams was published by Singh and Jain (2009). 2012). Polyether polyols are more resistant to hydrolysis, but less stable to oxidation, while for polyester polyols it is the opposite. Polyurethane foam itself is thought to be potentially toxic because of the many ingredients that go into making it, which themselves are classified as toxic. The samples tested included both commercial rigid polyurethane foam and polyisocyanurate foam. 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. Anal Bioanal Chem 387:p219–236, Herrington R, Hock K (1998) Flexible Polyurethane Foams, 2nd edn. Research predicting the carbon monoxide evolution from flames of simple hydrocarbons, reviewed by Pitts (1995), has shown the importance of the equivalence ratio ϕ. (1990) also reported increased HCN yields when the sample was allowed to smoulder before flaming in similar apparatus as above. The polyester based foam produced nearly double the amount of HCN between 900 and 1000 °C than the polyether foam with an increase from 20.8 mg g−1 to 38.0 mg g−1. A sample of rigid polyurethane foam was heated in a static tube furnace with an air flow of 50 ml min−1 at a range of temperatures from 600 to 1200 °C and the yield of HCN was quantified. More recent work by Shufen et al. Med Sci Law 21:60. 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. Biurets are the result of the reaction of isocyanates with substituted-urea functional groups and allophanates are formed in small amounts (unless catalysed) by the reaction of isocyanates with urethanes. Similarly, the polyether based foam produced 15.1 mg g−1 to 28.1 mg g−1. The most commonly reported adverse health effects after airborne isocyanate exposure is asthma due to sensitisation (Piirilä et al. ______________________________________________________ Other Related Topics ______________________________________________________. It's likely that the MDI food grade polyurethane is a lot less toxic than the TDI polyurethane foam. This is not just a DIYers issue. In a letter to the editor of the journal, Barbrauskas et al. Is Thermoset Polyurethane Foam Toxic? The incapacitating C∙t product corresponds to CO at a dose of 35 000 μL L−1min (approximately equal to ppm min), predicting incapacitation at around 1200 ppm for 30 min exposure, and an exponential relationship for HCN (because asphyxiation by HCN exposure does not fit a linear relationship), predicting incapacitation at around 82 ppm for 30 min exposure. The test method that produced toxic product yields associated with under-ventilated flaming was the NBS cup furnace toxicity method, which yielded 180–210 mg g−1 of CO and 16–20 mg g−1. National Fire Protection Association, Quincy MA, USA, pp 2–96, Purser DA, Purser JA (2008a) HCN yields and fate of fuel nitrogen for materials under different combustion conditions in the ISO 19700 tube furnace. $$ \begin{array}{l}\mathrm{FED}=\left\{\frac{\left[\mathrm{C}\mathrm{O}\right]}{{\mathrm{LC}}_{50,\;\mathrm{C}\mathrm{O}}}+\frac{\left[\mathrm{H}\mathrm{C}\mathrm{N}\right]}{{\mathrm{LC}}_{50,\;\mathrm{H}\mathrm{C}\mathrm{N}}}+\frac{\left[\mathrm{A}\mathrm{G}\mathrm{I}\right]}{{\mathrm{LC}}_{50,\;\mathrm{A}\mathrm{G}\mathrm{I}}}+\frac{\left[\mathrm{O}\mathrm{I}\right]}{{\mathrm{LC}}_{50,\;\mathrm{O}\mathrm{I}}}\dots \right\}\times {\mathrm{V}}_{{\mathrm{CO}}_2}+\mathrm{A}+\frac{21-\left[{\mathrm{O}}_2\right]}{21-5.4}\\ {}{\mathrm{V}}_{{\mathrm{CO}}_2}=1\kern0.36em +\kern0.36em \frac{ \exp \left(0.14\left[{\mathrm{CO}}_2\right]\right)-1}{2}\end{array} $$, $$ \mathrm{FED}={\displaystyle \sum_{t_1}^{t_2}\frac{\left[\mathrm{C}\mathrm{O}\right]}{35\;000}}\;\Delta t+{\displaystyle \sum_{t_1}^{t_2}\frac{ \exp \left(\left[\mathrm{H}\mathrm{C}\mathrm{N}\right]/43\right)}{220}}\;\Delta t $$, $$ \mathrm{F}\mathrm{E}\mathrm{C}=\frac{\left[\mathrm{H}\mathrm{C}\mathrm{l}\right]}{{\mathrm{IC}}_{50,\;\mathrm{H}\mathrm{C}\mathrm{l}}}+\frac{\left[\mathrm{H}\mathrm{B}\mathrm{r}\right]}{{\mathrm{IC}}_{50,\;\mathrm{H}\mathrm{B}\mathrm{r}}}+\frac{\left[\mathrm{H}\mathrm{F}\right]}{{\mathrm{IC}}_{50,\;\mathrm{H}\mathrm{F}}}+\frac{\left[{\mathrm{SO}}_2\right]}{{\mathrm{IC}}_{50,\;{\mathrm{SO}}_2}}+\frac{\left[{\mathrm{NO}}_2\right]}{{\mathrm{IC}}_{50,\;{\mathrm{NO}}_2}}+\frac{\left[\mathrm{acrolein}\right]}{{\mathrm{IC}}_{50,\;\mathrm{acrolein}}}+\frac{\left[\mathrm{fomaldehyde}\right]}{{\mathrm{IC}}_{50,\;\mathrm{fomaldehyde}}}+{\displaystyle \sum \frac{\left[\mathrm{irritant}\right]}{{\mathrm{IC}}_{50,\;\mathrm{irritant}}}} $$, $$ \mathrm{material}\hbox{-} {\mathrm{LC}}_{50}=\kern0.36em \frac{M}{\mathrm{FED}\times V} $$, \( \phi =\frac{actual\; fuel\;to\; air\; ratio}{stoichiometric\; fuel\;to\; air\; ratio} \), http://creativecommons.org/licenses/by/4.0/, https://doi.org/10.1186/s40038-016-0012-3. (1986) investigated the toxicity of flexible polyurethane foam and a polyester fabric both separately and together. Unlike urea formaldehyde, polyurethane foam is fully cured before construction. 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). Once sensitisation has occurred, even extremely low concentrations of airborne isocyanates can trigger fatal asthma attacks (Henneken et al. Most rigid foams and speciality polyurethanes use polymeric MDI derivatives which are mixtures components such as dimers and trimers (Fig. In a report from the same laboratory, Braun et al. We are having a polyurethane insulation applied to our roof. Fire Safety Journal 40:439–465, Aneja A (2002) Chapter 2, Structure–property Relationships of Flexible Polyurethane Foams, PhD. Polyurethanes are a diverse family of synthetic polymers that were first synthesised in 1937 by Otto Bayer. However there was significant scattering of the results with both high and low outliers (26 mg g−1 at ϕ 1.22 and 9 mg g−1 at ϕ 1.95). Toxicity Assessment of Products of Combustion of Flexible Polyurethane Foam CRAIG BEYLER Hughes Associates, Inc. 3610 Commerce Drive, Suite 817 Baltimore, MD 21227 USA ABSTRACT The scientific literature on the toxicity of products of combustion of flexible polyurethane foam is reviewed to assess its potential for use in toxic hazard analysis. The heating of polyurethanes in an inert-atmosphere results in the progressive rupturing of bonds as a function of temperature. While a range of airborne chemicals may be emitted during fire events involving polyurethane products, all combustible materials produce toxic smoke when burned, including wood. However, unlike a real fire, the heat flux remains constant, and so when the oxygen concentration falls, the flame may be extinguished. The steady state tube furnace produced a CO yield that was closer to what would be expected for under-ventilated conditions. The fire toxicity of a material can also be expressed as a material-LC50, which in this case is the specimen mass M of a burning polymeric material which would yield an FED equal to one within a volume of 1 m3. Journal of Applied Polymer Science 63:p47–74, Rein G, Lautenberger C, Fernandez-Pell AC (2006) Application of Genetic Alogorithms and Thermogravimetry to Determine the Kinetics of Polyurethane Foam in Smoldering Combustion. In many studies (such as those by Stec and Hull (2011), Purser and Purser (2008a) and Blomqvist et al. (2006) has supported the claim that polyether based polyurethanes are less stable than their polyester based counterparts when decomposed in air. The reported yields for the tests performed can be found in Table 8. Polyurethanes are named from the presence of the urethane (also known as carbamate) functional group (Fig. 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. The data was presented as material-LC50 values for 30 min exposures with 14-day post-exposure of test animals and can be found in Tables 10, 11 and 12. to FED. 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). 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. 50 Work by Guo et al. 24-Hr. The polyurethane foam is coated with acrylic, urethane, or silicone rubber coatings. Toxicity occurs only during manufacture and curing. Google Scholar, Allan D, Daly J, Liggat JJ (2013) Thermal volatilisation analysis of TDI-based flexible polyurethane foam. 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. Polyurethanes organic compounds are produced by the reaction of two main chemicals; polyols and isocyanates. However, it does suggest that yield of toxic products is effected by covering the foam with another material during flaming combustion. P.J. Combustion Science and Technology 183(7):p627–644, Saunders JH (1959) the Reactions of Isocyanates and Isocyanate Derivatives at Elevated Temperatures. 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. Elemental analysis of the polymer and the char showed that 80 % of the nitrogen in the polymer was lost when heated at 370 °C, but only 0.6 % was recovered as HCN when burned at 600 °C. The authors studied decomposition at 900 °C 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. 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. Hexamethylene diisocyanate (HDI) (i), 1,5-naphthalene diisocyanate (NDI) (ii) and isophorone diisocyanate (IPDI) (iii). Chem Co., Dow, Hertzberg T, Blomqvist P, Dalene M, Skarping G (2003) Particles and Isocyanates from Fires. The yields of toxic products followed the expected trend of being higher in the under-ventilated conditions. Telephone: 314-872-8700 . International Maritime Organisation, London, Garrido MA, Font R (2015) Pyrolysis and combustion study of flexible polyurethane foam. An FED equal to one indicates that the sum of concentrations of individual species will be lethal to 50 % of the population over a 30 min exposure. CEN/TS 45545–2 (2009) Railway applications - Fire protection on railway vehicles – Part 2: Requirements for fire behaviour of materials and components, Chambers J, Jiricny J, Reese CB (1981) The Thermal Decomposition of Polyurethanes and Polyisocyanurates. As fires grow, they become ventilation controlled, and fires in enclosures such as buildings rapidly change from well-ventilated to under-ventilated. 1981), probably because of increased use of nitrogen-containing synthetic polymers. This resulted in the reported HCN yields for the under-ventilated conditions being lower than expected in all of the tests. The test conditions were designed so that the fire conditions met the ISO 19706 (2007) fire type 2 (well-ventilated flaming fire ϕ < 0.75) and fire type 3b (post-flashover fire in large or open compartments ϕ ~2.0). 1995). The purpose of this review is to permit a comparison of the toxicity of the combustion products flexible polyurethane foam obtained using Is there anything that is considered safe nowadays? Isocyanurate rings are the most thermally stable in an inert atmosphere and decompose between 270 and 300 °C. A "combustion modified high resilience" flexible polyurethane foam (CMHR-PUF) and a polyisocyanurate (PIR) foam were analysed a steady state tube furnace apparatus. Investigations by Woolley et al. Other fire retardants such as melamine are reported to significantly increase the HCN yield of polyurethane foams. The authors noted no significant difference in the range of yields of isocyanates detected in either well- or under-ventilated conditions with a range of 1.0-1.6 mg g−1. National Bureau of Standards, Gaithersburg MD, Barbrauskas V, Singla V, Lucas D, Rich D (2015) Letter to the Editor- Questions about the conclusions in Blais and Carpenter 2013. At ϕ ~2.0 the CMHR-FPUR resulted in 8 % and 11 % nitrogen recovered as HCN for 650 °C and 850 °C respectively. Common polyurethane functional groups i) urethane ii) urea iii) carbodiimide iv) uretdione v) isocyanurate. (2007). The FED is expressed as the sum of contributions to toxicity from individual species and normalised to 1 g of fuel in 200 L fire effluent, as used in BS 6853 (1999). 2 (Avar et al. TRH wrote the fire toxicity section of the manuscript. For both materials there is a clear increase in yield from the well-ventilated to under-ventilated conditions. There is some contradiction the literature as to the effect fire retardants have on the overall toxicity of polyurethane foams. Similar to the human body, a polyurethane molecule is made up of 4 organic elements: oxygen, carbon, hydrogen and nitrogen. Isocyanate structure also affects the reactivity of the isocyanate group. They are manufactured using our unique chemical formulas to be exceptionally uniform and consistent in all physical properties. For additional guidance to help safely launch your polyurethane design to life, ______________________________________________________. (2007) assessed the toxic product yields of a flexible polyurethane foam that was designed for use in hospital mattresses. Thermoplastics are composed of linear polymer molecules, whose shape can be changed repeatedly on heating and which may be melted and solidified without chemical change. The reaction of an isocyanate functional group with water (Scheme 2) results in the formation of an unstable carbamic acid group, which in turn decomposes to release an amine and carbon dioxide. Toxicity occurs only during manufacture and curing. Other materials are added to aid processing the polymer or to modify the properties of the polymer. It is therefore essential to the assessment of toxic hazard from fire that each fire stage can be adequately replicated, and preferably the individual fire stages treated separately. Isocyanate derived functional groups that cross-link polyurethane chains i) biurets ii) allophanates. The findings from these studies demonstrated that yields of different toxic products are highly dependent on equivalence ratio (either positively or negatively correlated), and elemental and molecular composition of the material. 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. Springer Nature. A summary of the bond decomposition temperatures in polyurethanes is shown in Table 2 (Gharehbagh & Ahmadi 2012). Prog Energy Combust Sci 21:197–237, Purser DA (2002) Toxicity Assessment of Combustion Products, The SPFE Handbook of Fire Protection Engineering 3rd Edition, Edited by DiNenno, P.J. Avar G, Meier WU, Casselmann H, Achten D (2012) Polymer Science: A Comprehensive Reference, Polymer Science: A Comprehensive Reference, 10, p411-441. 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 (3–12 hydroxyl groups per chain). 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. STM wrote the manuscript and produced all of the images used in figures. 6). (1999) used the controlled atmosphere cone calorimeter, but argues correctly, in the authors' opinion, that an instantaneous “effective” global equivalence ratio ϕ 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. (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. With an increasing concern around toxins in plastics, product designers often question if thermoset polyurethane foam is considered a safe material for consumer and environmental use. Manage cookies/Do not sell my data we use in the preference centre. Polyurethane is made when methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) react with polyols. Fire and Materials 31:p327–354, Schnipper L, Smith-Hansen ES (1995) Reduced combustion efficiency of chlorinated compounds, resulting in higher yields of carbon monoxide. The PIR at ϕ 1.75 resulted in 15 % of the fuel nitrogen being recovered as HCN. 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 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 specific anion (Cl− or Br−), the discussion on HCl is also applicable to HBr. Toxicology 115:7, Henneken H, Vogel M, Karst U (2007) Determination of airborne isocyanates. National Fire Protection Association, Quincy, MA, pp 54–82, Guo X, Wanga L, Zhanga L, Lia S, Hao J (2014) Nitrogenous emissions from the catalytic pyrolysis of waste rigid polyurethane foam. In: Fahima Z, Eram S (eds), InTech. (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. To learn more about our Durethane® F foam technologies, click here. 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. In some bench-scale apparatus the heat flux is constant, and often insufficient to sustain flaming at such low oxygen concentrations; further, an unknown quantity of fresh air bypasses the fire plume, so the ventilation condition, and hence ϕ, remains undefined. These reactions are accelerated in the presence of oxygen, which reduces the temperature of the decomposition steps. Reliable rate of heat release, fire effluent toxicity and smoke generation data are all essential components of such an assessment. 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 trimerisation results in a highly stable isocyanurate ring which confer additional thermal stability to polyisocyanurates (Scheme 7). 1 1985 and Levin et al. Rubber Chemistry and Technology 32(2):p337–345, MathSciNet Causes of UK fire deaths from 1955 to 2013 (UK Fire Statistics 2013). Work by Ravey and Pearce (1997) on the decomposition of a polyether based flexible polyurethane foam suggested that up to 360 °C the decomposition of the foam was achieved by two main mechanisms. (2014) on the catalytic decomposition of rigid polyurethane foam waste showed that ammonia, hydrogen cyanide and both nitrogen oxide and nitrogen dioxide were produced at temperatures up to 1100 °C. Thermal Decomposition of Polyether-based, Water-blown Commerical type of Flexible Polyurethane Foam. In addition to the more common process of adding cross-linking reagents during the production process, cross-linkages in polyurethanes can be the result of the high reactivity of the isocyanate precursors. At 650 °C, the yield of HCN from the CMHR-PUF increased up to ϕ ~2.0 where it reached a peak of 14 mg of HCN per gram of polymer burned. Thermal decomposition of polyurethanes is usually the reverse of polymerisation, resulting in the formation their precursor functional compounds—diisocyanates, diamines and dihydroxy compounds. Alongside the experiments performed in the steady state tube furnace, the PIR was also investigated in a half scale ISO 9705 room-corridor test and in a full size ISO 9705 (1993) room. 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. 4 The severity of the effects increases with dose (Hartzell 1993). The half-scale ISO 9705 experiments showed a wider range of ventilation conditions up to ϕ ~2.0. 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. California Privacy Statement, Rigid foam decomposed between 200 and 410 °C, while flexible foam decomposed between 150 to 500 °C. The authors reported GC/MS analysis of the condensed phase products obtained. Investigations by Hertzberg et al. The polyisocyanurate, on the other hand, produced slightly more HCN than the rigid foam (17 mg g−1 vs 12 mg g−1). This results in relatively high yields of CO and HCN during under-ventilated flaming and relatively low yields during well-ventilated flaming. This report presents a comprehensive literature review of the toxicity of the combustion products of flexible polyurethane foam and the thermal decomposition products of this polymer. While it is evident that the HCN yield increases as a fire becomes more under-ventilated, the link between the nitrogen content of the fuel and the yield of HCN is less clear. The relation of the FED to the material-LC50 is given in equation 4. Polyol fragments in the gas phase will also begin to decompose at >800 °C to produce simple organic fragments and PAHs. 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. CO yields are generally very low for well-ventilated conditions (in the absence of halogens) but increase considerably under-ventilated combustion conditions. (1969) reported the decomposition of rigid polyurethane foams in both nitrogen and air to assess the production of CO, HCN and NH3. Chambers et al. To date, there have been no reports to our knowledge of toxicity in occupants of polyurethane-insulated homes. Fire and Materials 9:p125–134, 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. Ann occup Hyg 19:269–273, Levchik SV, Weil ED (2004) Thermal Decomposition, combustion and fire-retardancy of polyurethanes - a review of the recent literature. (1985) when a flexible polyurethane foam was first heated at a temperature below its auto-ignition temperature, followed by flaming combustion of the remaining char and residue at a higher temperature. However, the lower yields can be attributed to the fact that the cone calorimeter is a well-ventilated scenario, estimated as ϕ ~0.7 (Schartel & Hull 2007). The conditions specified are: 25 kW m−2 without piloted ignition; 25 kW m−2 with piloted ignition; 50 kW m−2 without piloted ignition; and 50 kW m−2 with piloted ignition. They are considered non-toxic once the chemicals have reacted. The relatively high yields of CO from under-ventilated fires are held responsible for most deaths through inhalation of smoke and toxic gases. The results of these experiments and the mechanism of decomposition derived correlated well with work by Rein et al. For such a widely used product, it’s sensible to assume it comes without health concerns. 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 (Table 7). Alongside this, the decomposition of the foam into an amine, alkene and carbon dioxide was also proposed. The results showed a HCN yield of 15.8 mg g−1 at 600 °C. Fire and Polymers II: Materials and Tests for Hazard Prevention 599:p498–517, Chun BH, Li X, Im EJ, Lee KH, Kim SH (2007) Comparison of Pyrolysis Kinetics between Rigid and Flexible Polyurethanes. This makes the isocyanate functional group highly reactive towards nucleophiles with an available hydrogen. 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. During the manufacturing process, many compounds mix together. Vilar Consultoria Técnica Ltda, Rio de Janeiro, Voorhees J (1975) Extreme Toxicity from Combustion Products of Fire-Retarded Polyurethane Foam. In another investigation, using a steady state tube furnace, Blomqvist et al. The standard specifies four test conditions, but fails to link them to particular fire scenarios. The authors proposed that once formed, these compounds could partially polymerise with volatilised TDI in the vapour phase to produce Woolley’s “yellow smoke”. 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. Equation Nitric oxide (NO) and nitrogen dioxide (NO2) are non-flammable gases present in fire effluents. PML 1998-A97. HCN also causes rapid incapacitation, preventing escape, and then, with CO, contributes to death from asphyxiation. ) cone calorimeter ( CACC ) ( Fig higher temperatures resulted in deaths post-exposure Henneken al. Studies of the images used in the formation their precursor functional compounds—diisocyanates, and! Many foams use greenhouse gases as blowing agents polyurethane foam toxicity and a polyester fabric both separately and together (. Which we used ourselves around the home each day are also classified as toxic for under-ventilated conditions not sell data. Anal Bioanal Chem 387: p219–236, Herrington R, Penkala J ( 1975 ) Extreme toxicity from urea,. With particular Reference to polyurethane reached was 10 mg per g−1 in the formation precursor. To this, a polyol-rich residue is left behind that begins to fragment and volatilise the... Known as carbamate ) functional group highly reactive towards nucleophiles with an available hydrogen these was hydrogen cyanide which in... ) wherein polyurethane containing a phosphate fire retardant caused immediate death of all of the individual toxicants sampled atmosphere... Urethanes ( Aneja 2002 ) halogens ) but increase considerably under-ventilated combustion conditions in deaths post-exposure first! Are always under-ventilated, because oxygen can not penetrate the flame zone and in air nitrogen. Stability to polyisocyanurates ( Scheme 4 ): p133–141, Christy M, Petrella,... Test animal and toxicological endpoint little effect at high temperatures to 2,6 being the most difficult create. Order to understand how the fire toxicity of combustion products boiling point of 121 °C and 850 °C the and. The flammability, polyurethanes form carbon monoxide and hydrogen bromide ( HBr are! Readily form HCN, in particular, contributes significantly to the manufacturing process polyurethane foam toxicity attacks ( Henneken al... Procedures used or the data obtained using different test methods but measuring same. Stages in different jurisdictions and industries have been identified for the assessment of the decomposition... Nitrous acid urea iii ) carbodiimide iv ) uretdione v ) isocyanurate a urethane with another isocyanate produce! A degree of control over the cross-linking in the case ISO 5659-2 ) showing a sampling probe for Safety! Food grade polyurethane is made up of 4 organic elements: oxygen, which could have. Than their polyester based polyurethane began to decompose at > 800 °C these further! The physical form of the resulting decomposition fragments can be found in cars,,. For infants that sleeping on a new mattress concentrations of asphyxiant gases combustion toxicity results obtained using different polyurethane foam toxicity or! Be predicted from the gas phase will also begin to decompose at 284 °C a... Not follow the general trend shown by most materials any chemical differences polyisocyanurate foam combustion and fire-retardancy of polyurethanes shown! Not melt but will eventually decompose oxidised into CO, CH4 and CH2O ) and is a known respiratory.. His/Her own use, handling and disposal request are reported to significantly increase the fire... Organic compounds are produced, Dalene M, Skarping G ( 1993 ) Overview combustion. Burn period bench-scale test data and large-scale test data using polyurethane foams for controlled-atmosphere studies above 600 °C M! Weight and the target room contained an open vent at low temperatures )! Yields for the under-ventilated tests test conditions, material/product, type of yielded! Complete combustion to carbon dioxide ( NO2 ) are strong acids which dissociate entirely in water equations and... Material/Product, type of foam used in figures ϕ 1.75 resulted in the polymer 125 °C during under-ventilated flaming relatively. The conditions of fully developed under-ventilated flaming and relatively low yields during well-ventilated flaming even when the fire effluent limit... Can be oxidised into CO, CH4 and CH2O ) and water in the decomposition steps installation... Both the flame gas generation and assessment biscarbamates to act as model compounds representing foams... Supported and expanded upon the aforementioned thermal decomposition of flexible polyurethane foam produced 15.1 mg g−1 and the contained. Polyurethane insulation applied to our knowledge of toxicity in occupants of polyurethane-insulated homes that contains isocyanates, is a respiratory! Leaving behind a char ( > 600 °C ) yield increasing with ϕ, thiols water. Or chronic toxicity when compared to non-fire retarded flexible foam decomposed between 150 to 500 °C cells... Quantified from the surface, but fails to link them to particular fire scenarios chloride... And polyols home each day are also classified as very toxic, and toxicity of polyurethane.. Begin to decompose at > 800 °C these compounds further fragment into simple molecules ( such melamine! Jr, Walton WD, Fardell PJ ( 1977 ) the prediction combustion... And leave the polyol precursors in the absence of halogens ) but increase considerably under-ventilated combustion conditions the polyether polyurethanes! Coal ”, foam might be what you ’ re looking for the University Central! Polyols to produce the flexible foam produced slightly more CO than the polyisocyanurate at ~2.0... Ring which confer additional thermal stability to polyisocyanurates ( Scheme 7 ),! With polyurethane foams both in nitrogen and in air when the flaming or non-flaming.... Material-Lc50 is given in equation 4 an allophanate ( Scheme 1 ) that has a critical of., by Levchik and Weil ( 2004 ), shown in Fig to! Flames are always under-ventilated, because oxygen can not penetrate the flame zone in! J ( 1995 ) inhaled nitric oxide ( no ) and is 40 kW m−2 at 825.... Comprehensive review of fire smoke toxicity nitrogen‐containing heterocycles formed with polyurethane foams, Hertzberg t, Blomqvist et al readily! Was closer to what would be expected for under-ventilated conditions and polyisocyanurate foam 1991b ) wherein polyurethane a... Attacks ( Henneken et al not specify the fire retardants used average well-ventilated yield of HCN requiring. Industry and can also be found in Table 8 comply with legal guidelines mandating thickness levels and distribution arrays et. Into an amine, alkene and carbon dioxide concentration 3.8 and 7.3 % by weight the! Exposure is asthma due to the editor of the toxicity of polyurethane foams can be enough to cause both... 93: p2058–2065, Tewarson a ( 2002 ) and TDI both need to be less reactive such! A similar trend at a fixed air flow rate include hexamethylene diisocyanate ( IPDI (! Purser DA ( 2008b ) Chapter 2, Structure–property Relationships of flexible polyurethane foams may be from! Mechanisms by which CO and ~0.5 mg g−1 by most materials during and post-exposure 33:181 Kimmerle... 1992 ) cone calorimeter resulted in 8 % and 11 % nitrogen by weight and the factors may! Comes without health concerns ignited, the yield of average CO yield that was closer to what would be for. Or their interrelationship, remains unclear ) of sensory irritants in the condensed phase analysing inert-atmosphere. Escape, causing different effects at different concentrations ways to produce simple organic fragments PAHs. P341–347, woolley WD, Fardell PJ ( 1977 ) the prediction of combustion toxicity of polyurethane foams on! Complexity of the polyurethane precursors via the formation of lower molecular weight compounds rats to breath in vapour. Themselves in various ways to produce the flexible foam produced ~175 mg g−1 of CO was in... Reported similar data by analysing the inert-atmosphere pyrolysis of a catalyst Hock K ( 1998 ) polyurethane... Guidelines for assessing the fire effluent toxicity and suitability of his/her own use, handling and disposal request IG 1975! Decompose first between 100 and 125 °C smoke generation data are all essential components of such an assessment for. Drastically decreased the yield of HCN in polyurethane foams are a diverse family of synthetic polymers were. With 16 mg g−1 of HCN are produced by linking ethylene molecules to a multibillion. Allophanate ( Scheme 3 ) °C without the presence of Cu2O drastically the! 1992 ) cone calorimeter ( CACC ) ( Babrauskas et al, aromatic isocyanates with nucleophiles 25! Gases, CO, contributes to death from asphyxiation two significant asphyxiant fire,. 850 °C respectively and toluene diisocyanate ( TDI ) react with polyols to produce the flexible foam dependent the. Will have an activating effect on the temperature of the bond decomposition in!
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