Abstract
A flexible polyurethane foam consists of soft and hard segments. The soft segment mainly made from polyols is mobile, while the hard segment mainly made from urethane and/or urea is rigid. The balance of these two components decides the property of the polyurethane foam. In this research, water-blown flexible polyurethane foams were prepared by varying the content of water, on which the structure of hard segment depended. The solid-state NMR technique was applied to characterize the segment distribution in the flexible foam.
Results of13C spinlattice relaxation time showed that moleculer mobility was about 109Hz at room temperature. Broad-line NMR and spin diffusion data showed that the amount of hard segment increased with increasing the content of water. It is considered that, using much water, more reacting points are generated, thus resulting in an increase in the amount of hard segment. As a result, the hard segment domains are more finely distributed, and this lowers the resilience of the foam.
