ISSN:
0959-8103
Keywords:
poly(tetrafluoroethylene-perfluorovinyl ether)
;
dielectric constant
;
dielectric loss
;
activation energy
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Dielectric constant and dielectric loss have been studied for poly(tetrafluoroethylene-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 (αa-relaxation) and the other in the range 170-140 K (β-relaxation), with activation energies of 143·2 and 16·4 kcal/mol, respectively. The β-absorption is attributed to the short segmental local mode motion of the main chains. The αa-relaxation can be interpreted as due to large-scale conformational rearrangement. The Cole-Cole diagrams are given at different temperatures and the distribution parameters (∊0-∊∞) and (1-α) 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.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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