DEVELOPMENT OF POLYURETHANE ENGINEERING THERMOPLASTICS .2. STRUCTURE AND PROPERTIES

Rigid, tough thermoplastic polyurethanes were synthesized by a two-ste p technique. These materials presented a complex structure consisting of a continuous, rigid, amorphous, or semicrystalline matrix with a di spersed soft phase. The influence of soft-segment content upon rigidit y modulus, heat-distortion temperature, and fracture behavior has been determined on model amorphous polyurethanes. The influence of crystal linity upon final properties has been studied on two materials: a prep aration of ours and a commercial product. Various degrees of crystalli nity have been induced in the samples by annealing. Phase structure wa s 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 con ventional engineering thermoplastics, such as ABS or nylon.