The effect of hard-segment content, temperature, and thermal history on the morphology of polyurethane block copolymers

Polyurethane block copolymers are an industrially important class of polymers for which it is difficult to formulate consistent structure-property relationships because of the sensitivity of microscopic morphology, and therefore resultant end-use properties, on composition and processing history. This thesis includes two separate but related studies, the first of which develops structure-property relations for a particular polyurethane as a function of block copolymer composition, and the second of which investigates the changes in morphology and resultant physical properties of a class of these polymers as a function of two processing variables: temperature and thermal history.;A series of compression molded specimens were examined by differential scanning calorimetry (DSC), thermal-mechanical analysis (TMA), including flexure and penetration probe testing, and simultaneous small- or wide-angle X-ray scattering/DSC, in order to correlate transitions observed by the various techniques with microstructural changes occurring in each material as a function of polymer hard-segment content and temperature.;The dependence of microscopic morphology on thermal history was examined by performing isothermal annealing experiments on specimens of 60% hard-segment content as they were quenched from the homogeneous melt state at 240;The materials examined in this study were based on copolymers of 4-4...