Relaxation dynamics of poly(vinylidene fluoride) studied by dynamical mechanical measurements and dielectric spectroscopy
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Otros documentos de la autoría: Andrio, Andreu; Sencadas, V.; lanceros-mendez, senentxu; Sabater Serra, Roser; Gomez Ribelles, Jose Luis
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Título
Relaxation dynamics of poly(vinylidene fluoride) studied by dynamical mechanical measurements and dielectric spectroscopyAutoría
Fecha de publicación
2012Editor
EDP Sciences; Società Italiana di Fisica; SpringerISSN
1292-8941; 1292-895XTipo de documento
info:eu-repo/semantics/articleVersión de la editorial
http://link.springer.com/content/pdf/10.1140%2Fepje%2Fi2012-12041-x.pdfVersión
info:eu-repo/semantics/publishedVersionResumen
The aim of this study is to analyze the mobility of polymer chains in semicrystalline poly(vinylidene fluoride) (PVDF). PVDF crystallizes from the melt in the α crystalline phase. The transformation
from the α phase ... [+]
The aim of this study is to analyze the mobility of polymer chains in semicrystalline poly(vinylidene fluoride) (PVDF). PVDF crystallizes from the melt in the α crystalline phase. The transformation
from the α phase to the electroactive β phase can be induced by stretching at temperatures in the range
between 80 and 140 ◦
C. The spherulitic structure of the crystalline phase is deformed during stretching to
form fibrils oriented in the direction of the strain. The amorphous phase confined among the crystalline
lamellae is distorted as well and some degree of orientation of the polymer chains is expected. Dynamicmechanical and dielectric spectroscopy measurements were performed in PVDF films stretched to strain
ratios up to 5 at temperatures between 80 and 140 ◦
C. Dynamic-mechanical measurements were conducted
between −60 ◦
C and melting and in this temperature range the relaxation spectra show the main relaxation
of the amorphous phase (called β-relaxation) and at higher temperatures a relaxation related to crystallites
motions (αc-relaxation). Although the mean relaxation times of the β-relaxation are nearly equal in PVDF
before and after crystal phase transformation, a significant change of shape of the relaxation spectrum
proves the effect of chain distortion due to crystal reorganization. In stretched PVDF the elastic modulus
of the polymer in the direction of deformation is significantly higher than in the transversal one, as expected
by chain and crystals fibril orientation. The recovery of the deformation when the sample is heated is related
with the appearance of the αc-relaxation. Dielectric spectroscopy spectrum shows the main relaxation of
the amorphous phase and a secondary process (γ-relaxation) at lower temperatures. Stretching produces
significant changes in the relaxation processes, mainly in the strength and shape of the main relaxation β.
The Havriliak-Negami function has been applied to analyze the dielectric response. [-]
Publicado en
Eur. Phys. J. E (2012) 35: 41Derechos de acceso
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag 2012. "The final publication is available at link.springer.com"
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