The tubes melt-extruded of a commercially-available segmented polyurethane block copolymer based on the soft segment chemistry of poly(1,6-hexyl 1,2-ethyl carbonate) diol (namely Bionate TM 75D) were found to exhibit structural relaxation and phase demixing (or "cold crystallization") phenomena upon thermal exposure at low temperatures. To prevent these phenomena for practical engineering applications, a series of post- extrusion annealing experiments were conducted at temperatures from 50 to 150 °C within durations from 15 to 240 min. To reveal the correlative process-structure- property relationships, the annealed tube samples were then analyzed using differential scanning calorimetry (DSC) methods. It was observed that despite initial morphological states of the extruded tubes, their thermal properties are largely tunable via solid-state annealing processes. Dependent of annealing conditions, the extruded tubes could be renewed to a desirable phase- separated morphology exhibiting the desirable thermal properties that are deemed to be thermally stable.
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