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Dielectric Relaxation of Poly(tetrafluoroethylene-perfluorovinyl ether) Films

✍ Scribed by Abd El Aal, M. M.; Mokhtar, S. M.; Osman, M. B. S.

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
401 KB
Volume
39
Category
Article
ISSN
0959-8103

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✦ Synopsis

Dielectric constant and dielectric loss have been studied for poly(tetrafluoroethy1ene-perfluorovinyl ether) (PFA) films over a wide temperature range in the frequency range 0.1-100 kHz. Two relaxation peaks were observed, one at room temperature (a,-relaxation) and the other in the range 170-140 K (/?-relaxation), with activation energies of 143.2 and 16.4 kcal/mol, respectively. The /?-absorption is attributed to the short segmental local mode motion of the main chains. The a,-relaxation can be interpreted as due to largescale conformational rearrangement. The Cole-Cole diagrams are given at different temperatures and the distribution parameters ( E ~ -and (1 -a) of the relaxation times were calculated.

The X-ray diffraction pattern of PFA shows both a diffuse halo and sharp reflections, characteristic of amorphous and crystalline phases of conventional semicrystalline polymers. Also, no evidence of crystallinity in the films due to thermal treatment during dielectric measurements was observed. IR spectra revealed the absence of any new peaks after the heat treatment.

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