The Permanence Properties of Flexible Urethan Foams

The acceptance of urethan foam as a commercial product has hinged to an important extent on its permanence as a foam under all conditions of actual end use. Customer experience with commercial flexible urethan foams has confirmed the satisfactory service life of these materials. However, in the development of this industry, it was necessary to be able to predict the performance of experimental systems which later were to become fully commercial. Most often, this prediction had to be made very early, long before the materials were allowed to be put into end service. The common way to do this is by accelerated testing, wherein the time axis is condensed by stepping up the aging process well beyond any normal conditions. Considerable time and expense are saved in this kind of test; however, there is always the question that such an accelerated step-up of test conditions is not representative of actual use, and/or causes reactions in the sample which do not occur in normal use. It is important that these questionable features be reconciled before the intercomparability of accelerated and shelf-life testing is accepted.