Thermoplastic polyurethane is a linear segmented copolymer whose hard segments of diisocyanate and chain extender are joined to soft polyol segments by urethane linkages. The two segments separate into hard domains dispersed in a soft matrix, and the resulting physical crosslinks give elasticity without covalent network bonds [1]. Because the hard domains can be melted, the material can be processed by extrusion and injection molding and can be reprocessed, unlike a crosslinked polyurethane [2]. The hard-segment content sets the modulus and the softening temperature, while the polyol type sets the low-temperature flexibility and the hydrolysis resistance [3]. Polyester-based grades are stronger but hydrolyse more readily than polyether-based grades, so the choice is dictated by the service environment [4]. Bio-based polyols and non-isocyanate routes are being developed, though their property profiles do not yet match the conventional grades [5].
- segmented copolymer
- hard segment
- soft segment
- polyol
- phase separation
- chain extender
- reprocessing
Polymer Science and Applications·Mechanical Engineering·Engineering·Physical Sciences
References
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- Smorawska, J.; Włoch, M.; Głowińska, E. Structure–Property Relationship and Multiple Processing Studies of Novel Bio-Based Thermoplastic Polyurethane Elastomers. Materials 2023, 16, 6246. [CrossRef]