Preparation and physical properties of polyurethane modified with poly(4,4′‐diphenylsulfone terephthalamide)

Three conventional polyurethane (PU) elastomers were blended physically with various ratios of high molecular weight of poly(4,4′‐diphenylsulfone terephthalamide) (PSA) to form 12 PU/PSA polyblends in order to modify their physical properties. Also three new polyurethanes were synthesized with a low‐molecular‐weight PSA prepolymer as a hydrogen donor for chain extending. From dynamic properties, it showed that both the blends and the new polyurethanes (or polyurethane‐ureas) exhibited a glass transition temperature (Tg) below 0°C and had a higher modulus E′ than those of the conventional PU. Based on the analysis of X‐ray diffraction of the conventional and the new PU, it was shown that the degree of stress‐induced crystallization was dependent on the segmental composition of the soft and hard segments and also the degree of its stretching. On the morphological observation, it was revealed that both the blends and the new polyurethanes were in a dispersed phase structure, although new PU exhibited a better compatible state. For tensile properties, it was found that both tensile strength and elongation of the new polyurethanes were better than those of the blends and conventional PU.