Neat polyurethane thermoplastic elastomers

DRS and TSDC were systematically employed in a series of recent papers to investigate the molecular dynamics and ionic conductivity in neat PTE. In many cases, the results were combined with those of morphological characterization techniques, in particular SAXS and DSC, and of water sorption/diffusion 

Three sources of information are associated with each DRS loss peak (and TSDC peak), as already mentioned in Section 2.1 the frequency (temperature) position of the peak, which provides information on the time scale of the response, the magnitude of the peak, which provides information on the concentration of dipolar units contributing to the loss peak and on dipole moments, and the shape of the peak, which provides information about interactions on the molecular level [12,17,22,23]. In the case of DRS loss peaks, this information is rationalized in terms of the Havriliak-Negami (HN) expression (Eq. (5)) and other similar expressions discussed in Section 2.1. The values of the fitting parameters can then be discussed in terms of molecular dynamics in relation to structure and morphology. An interesting question is whether the evaluation of the a loss peak provides any information on the microphase separation and any measure of DMS in PTE [6,10,13]. In the case of TSDC measurements, the same question refers to the combination of the a and the MWS peak, as the latter clearly reflects properties of the phase-separated morphology [54]. 

In addition to DRS and TSDC, a variety of experimental techniques (DSC, WAXS, SAXS and water sorption/diffusion measurements) were employed to investigate the microphase separation and molecular dynamics in model PTE based on either PPG or PBAD and three different diisocyanates (100% t,t-HMDI, 20% t,t-HMDI and MDI, see Section 4) [6,34]. The samples investigated 

PPG = poly(propylene glycol) PBAD = poly(butylene adipate) 

DIG and CE, respectively. The materials prepared are listed in Table 2. Special attention was paid to the investigation of the a relaxation by DRS and TSDC and to the interfacial MWS relaxation by TSDC. Representative results of the DRS measurements (raw data in the frequency and temperature domain) were 

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