Elevated Temperature and Humidity Effects on Urea-Formaldehyde Foam Insulations Observed by Scanning Electron Microscopy

Abstract

Exposure of urea-formaldehyde foam insulation to elevated temperature and relative humidities may result in its deterioration, as evidenced by shrinkage, mass loss, and, under severe conditions, disintegration. This paper describes the results of a scanning electron microscope (SEM) study undertaken to determine the effect on the cellular microstructure of urea-formaldehyde foam insulations from exposure to elevated temperature and relative humidity conditions. Recommendations for a temperature humidity exposure test for these insulations are given. Four commercially available foam samples, typical of those installed in residences, were prepared in wooden boxes. The percent linear shrinkage in the boxes was determined at various time intervals after filling. Specimens of each foam sample (after drying) were exposed to a variety of elevated temperature and humidity conditions. Changes in mass and volume of the specimens were periodically recorded during exposure. Three foam samples showed slight changes in volume under all exposure conditions. One sample was more susceptible to the exposures at the elevated conditions. Scanning electron microscopy was used to investigate changes in cellular structure upon exposure. Results indicated that samples which underwent slight changes in volume during exposure had cellular structures which were not apparently altered. Conversely, SEM photomicrographs indicated cellular degradation in themore » sample which was affected by the elevated exposure conditions.« less