Flexible Polyurethane Foam: A Literature Review of Thermal Decomposition Products and Toxicity

Abstract

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. Combustion toxicity results obtained using different test methods but measuring the same toxicologic endpoints were compared. That is, time to incapacitation and time to death using the USF and FAA test methods were compared. Also, LC50 values using the DIN, NBS, and University of Pittsburgh tests were compared. The results indicate that despite the use of different test methods, foam densities, formulations, fire retardants, and other additives, combustion toxicity data were generally considered comparable when similar endpoints were compared. Neither CO nor HCN appeared to be the primary cause of death due to the combustion products of flexible polyurethane foam, although they were probably contributory factors. Under conditions of oxidation and pyrolysis, polyurethane foams decomposed into a liquid polyol component and a “yellow smoke.” The polyol decomposed into CO, CO2, and low-molecular-weight hydrocarbons including ketones, ethers, and/or esters. At high temperatures (greater than 800°C), the “yellow smoke” decomposed into HCN and other nitrogen-containing compounds such as acetonitrile, acrylonitrile, and benzonitrile. Twice as much HCN was produced under pyrolytic conditions as in oxygen-rich atmospheres. Various amounts and types of other combustion compounds were produced, depending on the temperature and oxygen availability.