2005 Volume 78 Issue 12 Pages 447-452
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 prepolymer method in bulk at various polymerization temperatures from 140 to 230°C. The molecular weight distribution of hard segment components, the glass transition temperature of soft segments, and the melting point of hard segment domains of the TPUs had very little dependence on the polymerization temperature. On the other hand, the heat of fusion and the relative proton contents of hard segment domains for the TPUs prepared above 170°C were slightly less than those for the TPU prepared at 140°C. It is conceivable that the degree of aggregation of hard segments in the TPUs became weaker with increasing polymerization temperature. The dynamic storage modulus of the rubbery plateau region and apparent shear viscosity for the TPUs prepared above 170°C were slightly less than those for the TPU prepared at 140°C. It was revealed that the aggregation structure formed at various polymerization temperatures influences not only the mechanical properties but also the melting properties of the TPUs.
