| Title: |
Dielectric relaxation in vinylidene fluoride–hexafluoropropylene copolymers. |
| Authors: |
Valentin V. Kochervinskii; Inna A. Malyshkina; Grigory V. Markin; Nadezhda D. Gavrilova; Natalia P. Bessonova |
| Source: |
Journal of Applied Polymer Science; Aug2007, Vol. 105 Issue 3, p1101-1117, 17p |
| Subject Terms: |
DIELECTRICS; POLYMERS; COPOLYMERS; RELAXATION spectroscopy |
| Abstract: |
The molecular mobility in copolymers of vinylidene fluoride–hexafluoropropylene VDF/HFP of 93/7 and 86/14 ratios has been investigated by means of broadband dielectric relaxation spectroscopy (10−1–107 Hz), differential scanning calorimetry DSC (−100 to 150°C), and of wide angle X‐ray diffraction WAXS. Four relaxation processes and one ferroelectric‐paraelectric phase transition have been detected. The process of the local mobility β‐ (at temperatures below glass transition point) is not affected by chemical composition of the copolymer and the formed structure. Parameters of segmental mobility in the region of glass transition (αa‐relaxation) depend on the ratio of comonomer with lower kinetic flexibility. αc‐relaxation is clearly observed only in VDF/HFP 93/7 copolymer, which is characterized by a higher crystallinity and a higher perfection of crystals of α‐ (αp‐) phase. Diffuse order–disorder relaxor type ferroelectric transition connected with the destruction of the domains in low‐perfect ferroelectric phase in the amorphous regions has been detected for both copolymers. An intensive relaxation process (α‐process) was observed for both copolymers in high‐temperature region. DSC data shows that it falls on the broad temperature region of α‐phase crystals melting. It is considered to be connected with the space charge relaxation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [ABSTRACT FROM AUTHOR] |
| : |
Copyright of Journal of Applied Polymer Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) |
| Database: |
Complementary Index |