Dielectric relaxations in copolymers of vinylidene fluoride

Autor:	Yoshiro Tajitsu, Takeo Furukawa, G. E. Johnson, X. Zhang
Rok vydání:	1992
Předmět:	Arrhenius equation Materials science Relaxation (NMR) Thermodynamics Dielectric Condensed Matter Physics Ferroelectricity Electronic Optical and Magnetic Materials Dielectric spectroscopy symbols.namesake Nuclear magnetic resonance Phase (matter) Melting point symbols Curie temperature
Zdroj:	Ferroelectrics. 135:401-417
ISSN:	1563-5112 0015-0193
DOI:	10.1080/00150199208230041
Popis:	Ferroelectric copolymers of vinylidene fluoride with trifluoroethylene and tetrafluoroethylene have been investigated by means of broad band dielectric spectroscopy (10 mHz-1 GHz) at temperatures covering the ferroelectric, paraelectric and molten phases as well as the glassy and rubbery states. The low-temperature relaxation spectra near Tg (∼ -40°C) consist of two processes; a WLF-type segmental mode and an Arrhenius type local mode. These processes are unified near room temperature to be transferred continuously to the high-temperature process. After showing a peak at the Curie point Tc (70–140°C), the relaxation strength decreases gradually in the paraelectric phase until the melting point Tm (∼ 150°C) is reached, where it decreases rapidly. It is found that the relaxation time in the molten phase lies on the Arrhenius line extended from the low-temperature local mode process. This implies that related molecular motions arise from a common elementary process. Departure from this Arrhenius lin...
Databáze:	OpenAIRE
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