ワンショット法により重合した熱可塑性ポリウレタンエラストマーの構造と物性への重合温度の影響

抄録

Effects of polymerization temperature on the molecular aggregation structure and the mechanical and melting properties of thermoplastic polyurethane elastomers (TPUs) were investigated. The TPUs were prepared from poly(ethylene adipate)glycol, 4, 4'-diphenylmethane diisocyanate, and 1, 4-butanediol by a one-shot method in bulk at various polymerization temperatures from 140 to 230°C. Glass transition temperature of the soft segment and melting point of the hard segment increased and decreased with increasing polymerization temperature, respectively. The pulsed NMR analyses of the TPUs indicated that the relative proton contents in the interfacial phase between hard and soft phases and its spin-spin relaxation time increased with increasing polymerization temperature. It is conceivable that the degree of microphase-separation of the TPUs became weaker with increasing polymerization temperature. Dynamic storage modulus for the rubbery plateau region of the TPUs prepared at 140 and 170°C were much higher than those at 190 and 230°C. Also, viscosity measurement revealed that the TPUs prepared at lower polymerization temperature bare the non-Newtonian behavior for wide shear rate region owing to the residual hard segment domains at an operated temperature. These results can be attributed to the degree of microphase-separation and melting temperature of the hard segment domain in the TPUs.