Time dependence of small-angle x-ray measurements on segmented polyurethanes following thermal treatment

Using the method of small-angle x-ray scattering (SAXS), the time-dependent structural changes in some linear-segmented urethanes have been investigated. The results directly support the time- and temprature-dependent morphological model proposed earlier by one of the authors. Specifically, upon heating of many linear urethanes, the degree of domain structure is decreased. Upon quenching to ambient temperature, there is a significant period of time required to reestablish the domain structure which, in turn, strongly influences the time-dependent mechanical behavior.