Polyurethanes soft segment matrix

DSC, WAXS, electron diffraction, and electron microscopy support a phase-separated morphology for all five of the random copolymer PCP/MDI/BDO-segmented polyurethanes studied. The slight increase observed by Seefried et al. (9) in the lower temperature Tg with hard-segment concentration is therefore likely attributable to increased reinforcement of the soft-segment matrix by an increased number of dispersed hard-segment domains. 

Figure 1. Molecular schematics of some possible segmented polyurethane morphologies. For convenience, good phase separation is assumed, (a) Hard-segment domains dispersed within a soft-segment matrix (b) interconnected hard-segment phase giving rise to continuous phases of both hard and soft segments (c) soft-segment phase is dispersed within a continuous matrix of hard segments.

Figure 6.2 Polyurethane hard segment domains dispersed in a soft segment matrix.

Figure 8.4 Relationship between soft segment crystallinity and the extent of non-covalent filler-matrix interactions in shape memory polyurethane (SMPU) composites filled with organoclay, carbon nanofIber (CNF), oxidized carbon nanofiber (ox-CNF), silicon carbide (SiC), and carbon black (CB). The ratio A/Ai. determined from fluorescence emission spectroscopy experiments, is a measure of the...

Another strategy has been used to develop co-continuous nanocomposites by in situ formation of a chemical linkage between the matrix segments and the CN surface during synthesis of the polymer matrix. For example, in nanocomposites of waterborne polyurethane (WPU) with a PCL soft-segment and CNs, segments... 

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