Dynamic Mechanical Properties of Urea-Urethane Block Polymers
Segmented polyurethanes containing different molecular weight glycols and urea-urethane block polymers have been the subject of numerous investigations in the past decade (1–16). The results of these investigations indicate clearly that these polymers form highly aggregated structures. If the aggregation occurs preferentially between certain segments in the macromolecule , concentration gradients arise in the polymer which should eventually lead to the formation of domains of the type observed in ABA-type block polymers (17). Only recently has a domain structure been directly observed in these systems (10,19,20). The domains are much smaller than those observed in the styrene-butadiene block polymers and, therefore, are more poorly defined. This probably occurs because the block lengths are shorter and more dispersed in size in the urethane system than they are in the styrene-butadiene system.
KeywordsBlock Length Dynamic Mechanical Property Domain Formation Cyclohexyl Amine Block Polymer
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