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). Science 187:p742744, Wisnewski AV, Lemus R, Karol MH, Redlich CA (1999) Isocyanate-conjugated human lung epithelial cell proteins: A link between exposure and asthma? The authors suggested that the presence of oxygen does not affect the mechanisms by which CO and HCN are produced. At a CO concentration of 10 ppm, impairment of judgement and visual perception occur; exposure to 100 ppm causes dizziness, headache, and weariness; loss of consciousness occurs at 250 ppm; and 1000 ppm results in rapid death. Routes of entry in this case are inhalation, ingestion (saliva), and skin absorption. 1992), shown in Fig. Appropriate formulation affords a degree of control over the cross-linking in the polymer without the need for additional cross-linking agents. Fire and Polymers II: Materials and Tests for Hazard Prevention 599:p498517, Chun BH, Li X, Im EJ, Lee KH, Kim SH (2007) Comparison of Pyrolysis Kinetics between Rigid and Flexible Polyurethanes. Thermosets are cross-linked polymer molecules which, on heating, do not melt but will eventually decompose. Fire and Materials 11:p129, Paul KT, Hull TR, Lebek K, Stec AA (2008) Fire smoke toxicity: The effect of nitrogen oxides. This suggests that any amines formed would have reacted with isocyanates in the vapour phase to form ureas, some of which would have condensed to produce the observed waxy white substance. Stec and Hull (2011) presented material-LC50 data for rigid polyurethane foam and polyisocyanurate foam, calculated using rat lethality data from ISO 13344 (1996). (2007)), the sample is raised to a fixed furnace temperature, which is further increased in the gas phase during flaming combustion. The authors noted that the yields of CO during the well-ventilated testing were higher than expected for both materials, and attributed this to the possible presence of gas phase free radical quenchers, such as halogens or phosphorous containing flame retardants, which would reduce the conversion of CO to CO2 (Schnipper & Smith-Hansen 1995). It has been designed to generate data for input to fire hazard assessments, using the methodology in ISO 13344 (1996) and ISO 13571 (2012), particularly in relation to the ISO fire stages. 5-step decomposition mechanism for flexible polyurethane foam (Rogaume et al. Fire Technology 51:p213217, Blais M, Carpenter K (2015) Flexible Polyurethane Foams: A comparative measurement of toxic vapors and other toxic emissions in controlled combustion environments of foams with and without fire retardants. Apparatus where changes rapidly allow little time for sampling and measurement of mass loss and effluent compositionat a specific value of, with resultant errors and uncertainties. These fumes could lead to irritation of the eyes, throat, and lungs, and could cause more severe allergic reactions for individuals with chemical sensitivities. The FED value is calculated using the exposed dose relationship (concentration-time product, Ct) for CO.
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