Symmetrization poly segmental

Although being qualitatively in agreement with experimental results, disagreements between experiment and theory remain. Besides the composition, /a, and the total degree of polymerization, N, all theoretical works refer to the segmental interaction parameter x This parameter can be estimated from a relationship to the solubility parameters. The ODT as a thermodynamic measure of the incompatibility was used to compare a set of symmetrically composed diblock copolymers from different hydrocarbons, polydimethyl-siloxane and poly(ethylene oxide) (PEO) [33]. While the behaviour of hydrocarbon diblock copolymers was successfully described by a consistent set of solubility parameters, this procedure failed for systems containing PEO. The... 

It is known for a long time (Wetton et al. 1978) that the relaxation function measured for a miscible blend is considerably broadened compared to the spectra of the pure polymers (Colmenero and Arbe 2007). To be more precise the broadening is more or less symmetric. As an example this is shown for a miscible blend of polystyrene (PS) and poly(vinyl methylether) (PVME) in Fig. 12.15 (Colmenero and Arbe 2007 Katana et al. 1992 Zetsche and Fischer 1994). Compared to PVME the dipole moment of PS is weak, and therefore, the contribution of PS to the dielectric loss of the blend is negligible. In other words the fluctuations of PVME are selectively monitored by dielectric spectroscopy, whereas the fluctuations of the PS segments are dielectrically invisible. For the blend (see Fig. 12.15b), the loss peak is much broader than that for the single component PVME (see Fig. 12.15a). Moreover, the loss peak narrows as temperature increases. For the PVME/PS blend system, it was proven by a combination... 

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