Low frequency ac conduction and dielectric relaxation behavior of solution grown and uniaxially stretched poly(vinylidene fluoride) films

The measurements of ac conductivity [σm(ω)], dielectric constant [ɛ′(ω)] and loss [ɛ″(ω)] have been performed on solution grown (thickness ∼85μm) and uniaxially stretched (thickness ∼25, 45 and 80μm) films of poly(vinylidene fluoride) (PVDF) in the frequency range 0.1kHz–10MHz and in the temperature...

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Bibliographic Details
Published in:Polymer (Guilford) 2006-07, Vol.47 (16), p.5919-5928
Main Authors: Singh, Ramadhar, Kumar, Jitendra, Singh, Rajiv K., Kaur, Amarjeet, Sinha, R.D.P., Gupta, N.P.
Format: Article
Language:English
Subjects:
ac Conductivity
Applied sciences
Dielectric relaxation
Electrical, magnetic and optical properties
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Properties and characterization
Uniaxially stretched poly(vinylidene fluoride) films
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Summary:The measurements of ac conductivity [σm(ω)], dielectric constant [ɛ′(ω)] and loss [ɛ″(ω)] have been performed on solution grown (thickness ∼85μm) and uniaxially stretched (thickness ∼25, 45 and 80μm) films of poly(vinylidene fluoride) (PVDF) in the frequency range 0.1kHz–10MHz and in the temperature range 77–400K. The σm(ω) can be described by the relation σ(ω)=Aωs, where s is close to unity and decreases with increase in temperature. Three relaxations, observed in the present investigation, have been designated as the αc-, the αa- and the β-relaxations appearing from high temperature side to the low temperature side. The αc-relaxation could not be observed in the case of uniaxially stretched poly(vinylidene fluoride) films. The αc- and αa-relaxations are associated with the molecular motions in the crystalline regions and micro-Brownian motion in the amorphous regions of the main polymer chain, respectively, whereas the β-relaxation is attributed to the rotation of side group dipoles or to the local oscillations of the frozen main polymer chain.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2006.06.023