Thermal Stability of Polyester vs. Polyether-Based Urethans

It has been shown, by means of continuous and intermittent stress relaxation measurements and oven aging studies, that polyester-based urethans are more resistant to thermal degradation than the corresponding polyether-based urethans at temperatures in the range of 50° to 150° C. It has also been shown that this difference in thermal stability is due to irreversible, oxidative cleavage of polyether chain segments. Addition of representative antioxidants of the hindered phenolic and amine types to the polyether-based prepolymers prior to curing was found to be ineffective in improving the thermal stability of the resultant polyurethan elastomer. And, finally, the practical significance of these thermal stability studies has been demonstrated through heat buildup measurements.