Physical and chemical network effects in polyurethane elastomers

摘要: The effects of the physical and chemical networks on relaxation processes morphology polyester-based polyurethane elastomers were studied by thermal, thermomechanical, dielectric methods. Two series prepared varying NCO/OH ratio during second step polymerization while hard segment content was maintained almost constant, at about 30% in first 39% second. Differential Scanning Calorimetry (DSC), ac Thermally Stimulated Depolarization Current (TSDC) measurements Dynamic Mechanical Analysis show a main related to glass transition soft parts copolymers. results all techniques used have shown that increase produces an temperature more homogeneous morphology. Dielectric TSDC spectroscopy provided information dynamics transition.