| mall-angle neutron scattering was used to investigate the poly(tetramethylene oxide) (PTMO) chain conformation as a function of temperature, PTMO molecular weight, and overall sample composition in a series of polyether-polyurethanes. The method of phase-contrast matching was used to eliminate the coherent neutron scattering due to the two-phase microstructure of these materials. The partial deuterolabelling necessary for this technique also provided a coherent neutron scattering contrast between labelled and unlabelled PTMO segments. In all of the materials examined, the PTMO conformation was found to be slightly extended relative to the unreacted PTMO conformation at room temperature, and was found to depend only on the PTMO molecular weight. Upon heating, the extended segments relaxed to a more compact conformation, though a higher temperature was required in the material with a higher hard segment content before this relaxation occurred, reflecting the fact that the hard-segment domains are more cohesive in this material.;The investigation of hard-segment length distributions was an attempt to determine the relationship between various methods of polyether-polyurethane synthesis and the distribution of lengths which resulted. This investigation met with limited success in achieving its goal. In general, the results of these experiments supported theoretical predictions. However, some of the results could not be explained. This analysis must be developed further if the results are to be truly reliable.;Castor oil was reacted in varying ratios with... |
