Characterization of thermally generated aerosols from polyurethane foam

Isocyanates constitute a group of highly reactive chemicals used on a large scale for the production of flexible polyurethane (PUR) foam. Exposure to isocyanates is known to produce irritation of the mucous membranes and the eyes. Isocyanates also have strong sensitizing properties and may cause occ upational asthma. It is therefore important to monitor isocyanate emissions at workplaces. To obtain information for the improvement of isocyanate sam plers and for health risk assessments of exposure, the emitted aerosol from two types of flexible PUR foam subjected to thermal degradation was charac terized. Particle size distribution and toluene diisocyanate (TDI) concentr ation in the emitted aerosols were measured. Thermal degradation of flexibl e PUR foam at temperatures from 250 to 300 degreesC produced an aerosol wit h a geometric mean particle diameter of 30-50 nm. Between 5% and 9% of the PUR foam was emitted as TDI, and 2% to 6% of TDI monomers were found in the particle phase under the experimental conditions used. The 2,6-TDI isomer was more abundant in the gas phase than in the particle phase.