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Effect of valence electron spin polarization on the physical properties of CuCl 2 ‐filled poly(vinylidene fluoride) as a microwave modulator
Author(s) -
Tawansi A.,
Ayad M. I.,
AbdelRazek E. M.
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19990509)72:6<771::aid-app5>3.0.co;2-o
Subject(s) - electron paramagnetic resonance , condensed matter physics , materials science , polaron , hyperfine structure , bipolaron , chemistry , analytical chemistry (journal) , nuclear magnetic resonance , electron , atomic physics , physics , quantum mechanics , chromatography
Infrared and optical spectra, differential thermal analysis, dc electrical resistivity, magnetic susceptibility, electron spin resonance, and microwave response of CuCl 2 ‐filled poly(vinylidene fluoride) (PVDF) films, over the filler mass fraction range 0.05 ≤ W ≤ 0.4, were measured. The infrared spectra evidenced the presence of β‐phase, for all of the filler levels with main deformations of 20% (for W = 0.25) and 30% (for other filler levels) head‐to‐head and tail‐to‐tail units, which were considered as polaron and bipolaron defects. Optical activity was mainly influenced by PVDF structure. Differential thermal analysis revealed dipole relaxation and premelting endothermic peaks. A quasi–one‐dimensional interpolaron hopping was thought to proceed in the direct current electric conduction, with a hopping distance less than the distance between two successive head‐to‐head sites. A temperature‐independent Pauli paramagnetic behavior was observed, confirming the presence of induced energy bands due to CuCl 2 filling. Most of the observed electron spin resonance signals were antisymmetric, with superimposed repels due to the hyperfine interactions characterizing PVDF. The obtained linear dependence of the isotropic hyperfine coupling constant (Δ A ` ), for Cu(II), on average g ‐factor, implied that Δ A ` is a measure of the valence electron spin polarization. An octahedral or distorted octahedral configuration was suggested for Cu(II). The present system is a good microwave modulator. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 771–781, 1999