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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.zeige mehrzeige weniger

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Metadaten
Autor*innen:P. Frübing, H. Krüger, Harald Goering, R. Gerhard-Multhaupt
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
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