Development of polyurethane engineering thermoplastics. II. Structure and properties

Rigid, tough thermoplastic polyurethanes were synthesized by a two–step technique. These materials presented a complex structure consisting of a continuous, rigid, amorphous, or semicrystalline matrix with a dispersed soft phase. The influence of soft–segment content upon rigidity modulus, heat–distortion temperature, and fracture behavior has been deter‐mined on model amorphous polyurethanes. The influence of crystallinity upon final prop‐erties has been studied on two materials: a preparation of ours and a commercial product. Various degrees of crystallinity have been induced in the samples by annealing. Phase structure was characterized by differential scanning calorimetry and wide–angle X–ray scat‐tering. Some of the polyurethane samples assayed in this paper exhibited similar properties to those reported in respect of more conventional engineering thermoplastics, such as ABS or nylon.