The molecular chains of TPU form a linear block structure consisting of soft segments-oligomeric polyols (with a molecular weight of 1,000–6,000)-and hard segments composed of diisocyanates and chain extenders. The soft segments constitute 60% to 95% of the composition to ensure elasticity, while the hard segments form physical cross-linking points through hydrogen bonding.
Polyester-based TPU utilizes raw materials such as polyethylene adipate (PEA-2000), whereas polyether-based TPU employs polytetrahydrofuran ether glycol (PTMG). The difference in the degree of phase separation between these two systems results in the polyester-based type exhibiting a tensile strength that is 30% to 50% higher than that of the polyether-based type.