Determination of Isocyanate and Aromatic Amine Emissions from Thermally Degraded Polyurethanes in Foundries

Abstract

Thermal degradation of polyurethanes can cause emissions of isocyanates and aromatic amines into work atmospheres. Results from laboratory studies on the use of 4,4′-methylenediphenyl isocyanate (MDI)-based polyurethane bound foundry core materials showed that anilines and phenyl isocyanates are major degradation products, but the possibility for emissions of MDI and its corresponding diamine, 4,4′-methylenedianiline, also was demonstrated. Results from field investigations in two different foundries showed that of these degradation products, mainly anilines and phenyl isocyanates are found in foundry work atmospheres, whereas MDI and methylenedianiline concentrations were negligible. The selection of air sampling and analytical procedures for, as well as interpretation of results from, simultaneous determination of isocyanates and their corresponding amines are discussed.