Long-Term Stability Of Urea-Formaldehyde Foam Insulation

Abstract

The long-term breakdown of urea-formaldehyde (UF) foam was investigated by monitoring the changes in the content of hot-water-soluble, low-molecular-weight components. At 90% relative humidity and 40-90 °C, diffusion-controlled “postcuring” processes (activation energy, 20 kJ/mol) in the UF foam initially led to the formation of high-molecular-weight insoluble products. On further aging, degradation of the UF polymer (activation energy, 50 kJ/mol) is manifested by a decrease in the magnitude of the insoluble fraction. By comparison of acidic and “acid-free” foams, the inherent residual acidity is shown to be a critical factor affecting the hydrolytic breakdown of UF foams. In acid-free, in contrast to acidic, foams no formation of low-molecular-weight material was observed when foam was heated (40-100 °C) at 0% relative humidity. Formaldehyde emission, which accompanies the degradation of acidic UF foam, is characterized by an initial burst of release followed by a slow continuous evolution. The total amount of formaldehyde emitted from acidic UF foam (30 days, 55 °C, 90% relative humidity) was reduced by a factor of 6 when the acidic components were removed from the foam before testing. © 1980, American Chemical Society. All rights reserved.