Relaxation behaviour of thermoplastic polyurethanes with covalently attached nitroaniline dipoles
- Thermoplastic polyurethanes with covalently attached nitroaniline chromophores exhibit a strong high-temperature relaxation associated with a glass transition rather than the typical frequency-independent loss due to the aggregation of polymer chains via hydrogen bonds. This relaxation behaviour suggests the formation of an amorphous structure without separation into soft-segment and hard-segment phases. In such a structure, a field-induced orientation of molecular dipoles is stabilised by the high viscosity of the material below its glass transition. The dipole orientation yields a pyroelectric effect caused by dipole-density changes upon thermal expansion and contraction. The changes in phase separation are investigated by varying the chain length of the soft-phase component and studying its influence on the calorimetric, dynamic-mechanical, and dielectrical properties. Good correlation was found between differential scanning calorimetry, dynamic-mechanical analysis and dielectricThermoplastic polyurethanes with covalently attached nitroaniline chromophores exhibit a strong high-temperature relaxation associated with a glass transition rather than the typical frequency-independent loss due to the aggregation of polymer chains via hydrogen bonds. This relaxation behaviour suggests the formation of an amorphous structure without separation into soft-segment and hard-segment phases. In such a structure, a field-induced orientation of molecular dipoles is stabilised by the high viscosity of the material below its glass transition. The dipole orientation yields a pyroelectric effect caused by dipole-density changes upon thermal expansion and contraction. The changes in phase separation are investigated by varying the chain length of the soft-phase component and studying its influence on the calorimetric, dynamic-mechanical, and dielectrical properties. Good correlation was found between differential scanning calorimetry, dynamic-mechanical analysis and dielectric spectroscopy as well as measured and calculated pyroelectric coefficients. This leads to a uniform picture of the structural changes caused by the incorporation of nitroaniline chromophores into the polyurethane structure.…
Autor*innen: | P. Frübing, H. Krüger, Harald Goering, R. Gerhard-Multhaupt |
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Dokumenttyp: | Zeitschriftenartikel |
Veröffentlichungsform: | Verlagsliteratur |
Sprache: | Englisch |
Titel des übergeordneten Werkes (Englisch): | Polymer |
Jahr der Erstveröffentlichung: | 2002 |
Verlag: | Springer |
Verlagsort: | Berlin |
Jahrgang/Band: | 43 |
Ausgabe/Heft: | 9 |
Erste Seite: | 2787 |
Letzte Seite: | 2794 |
Freie Schlagwörter: | Dielectric relaxation; Nitroaniline chromophore; Thermoplastic polyurethane |
DOI: | 10.1016/S0032-3861(02)00075-7 |
ISSN: | 0032-3861 |
ISSN: | 1873-2291 |
Verfügbarkeit des Dokuments: | Physisches Exemplar in der Bibliothek der BAM vorhanden ("Hardcopy Access") |
Bibliotheksstandort: | Sonderstandort: Publica-Schrank |
Bibliotheksstandort: | ZP 23 |
Datum der Freischaltung: | 19.02.2016 |
Referierte Publikation: | Ja |
Datum der Eintragung als referierte Publikation: | 16.12.2002 |