THERMAL AND MECHANICAL-PROPERTIES OF POLYURETHANE DIACETYLENE SEGMENTED COPOLYMERS .1. MOLECULAR-WEIGHT AND ANNEALING EFFECTS

The thermal transitions and mechanical properties of a number of segmented polyurethanes containing diacetylene groups within their hard segments were evaluated. The ultimate tensile properties of these materials were found to be strongly dependent on their overall molecular weight and thermal history. In all cases, increased molecular weight resulted in improved mechanical properties. Annealing treatments were also found to dramatically improve the mechanical properties of these elastomers. Thermal analysis revealed that annealing increased the cohesive forces of the hard domains, thereby increasing their mechanical integrity. The effect that annealing had on the mechanical behavior was found to be highly dependent on the particular mechanism of deformation active in these segmented copolymers. Two distinctly different modes of deformation were observed in the polyurethane-diacetylene elastomers. © 1990, American Chemical Society. All rights reserved.