Dielectric relaxation of poly(vinyl acetate)

Abstract

Dielectric relaxation measurements of undiluted and diluted poly(vinyl acetate) PVAc have been made at temperatures 288<T<366 K over an extremely wide frequency range from 1 μHz to 150 MHz. The complex permittivity can be described quantitatively by the Havriliak–Negami equation ε*=ε∞+Δε[1+(jωτ0)β]−α, 0<α, β≤1. It has been found that the parameter α is given by a linear equation of dipole moment ratio g as α=1.09–0.91g. This observation suggests that α is connected closely with local chain conformations. On the other hand, β is nearly constant ∼0.87 above the glass transition temperature and is independent of effect of the diluent. This suggests that the constant value of β is an inherent characteristic of the relaxation spectrum of PVAc.