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 determined on model amorphous polyurethanes. The influence of crystallinity upon final properties 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 scattering. 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.