An explanation of anomalous dielectric relaxation properties of polypropylene glycol

Abstract

Dielectric measurements on low molecular weight poly(propylene glycol) over a wide frequency window of about 10 decades show that the relaxation times of the segmental relaxation and the normal modes have different temperature dependences. The segmental relaxation time, T s * , has a much stronger temperature dependence than that of the normal-mode relaxation time, T 2 * . As temperature is decreased, the shorter τ s * increases much faster than τ 2 * , with a tendency of τ s * to encroach τ 2 * resulting in a reduction of the dielectric strength of the normal mode. These dresults are explained quantitatively by the coupling model