Microbial degradation of polyurethane foams and isocyanate based polyureas in different media

To assess the possibilities of the liberation of toxic aromatic amines under different conditions of disposal, the degradation of different¹⁴C-labelled polyurethane foams was investigated in the leachate of a refuse tip, in composted municipal waste and in an agricultural soil. With unlabelled foam cubes experiments were run under the environmental conditions of a refuse tip. The degradation of¹⁴C-labelled polyureas was studied in different agricultural soils. In the laboratory tests the criteria of degradation were the liberation of aromatic amines and the production of¹⁴CO₂. The degradation in the refuse tip was estimated on the basis of weight loss. From the results it can be assumed that the polyether based polyurethane foams are largely resistant to microbial as well as chemical attack under all practical conditions of disposal. Polyester based polyurethane foams are susceptible to chemical hydrolysis favored by extreme environmental conditions such as high temperature and/or low or high pH values. Under these circumstances an accumulation of aromatic amines can occur if their further microbial degradation is impeded by the lack of suitable conditions for the growth of microorganisms. No indication of any degradation of the isocyanate based polyureas was found.