Effect of Annealing on the Thermal and Dynamic Mechanical Properties of Para-Tetramethyl Xylene Diisocyanate-Based Polyurethanes. (Reannouncement with New Availability Information)
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Polyurethanes are linear segmented copolymers, which consist of alternating hard and soft segments. The soft segment is commonly a low molecular weight polyether or polyester chain. The hard segment is composed of diisocyanate molecules condensed with a low molecular weight diol or diamine. the properties of these materials are largely governed by the phase separation of the hard and soft segments of the polyurethane. This phase separation typically results in the formation of hard-segment domains, which are dispersed in a rubbery matrix. Compositional variables are known to affect the degree of phase segregation, hard-segment domain organization, and consequently the polyurethane's properties. In addition, it has been found that high-temperature thermal treatment (annealing) can induce significant changes in the thermal properties of polyurethane elastomers. These changes were attributed to an increase in the degree of order of the hard-segment domains and in some cases to a change in the extent of phase separation in the urethane.
Effect of Annealing on the Thermal and Dynamic Mechanical Properties of Para-Tetramethyl Xylene Diisocyanate-Based Polyurethanes. (Reannouncement with New Availability Information)