Nonlinear Dielectric Relaxation Spectra of Polyvinyl Acetate

概要

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The frequency spectra of the linear and third nonlinear permittivities, ε^*_1 and ε^*_3, have been measured for polyvinyl acetate (PVAc) at temperatures above T_g. The Debye relaxation of ε^*_1 associated with the micro-Brownian motion of noncrystalline segments is found to be accompanied by the complex frequency dependence of ef due to combined contributions from the intrinsic nonlinear dielectricity and the electrostriction. Additional measurements for the elastic corn-pliance S^* allow subtraction of the latter contribution (∝S^*ε^<*2>_1) to yield the intrinsic nonlinear dielectric relaxation spectra in the form of ?ε_3/(1+iωτ_3)^3 in accordance with phenomenonogical prediction. The evaluated relaxation strengths ?ε_1 and ?ε_3, lead to estimates of equivalent Langevin dipoles consisting of eleven monomers and a saturation polarnzalion of 20 mC/m^2.
1992-03-15