Linear-limit aging times of three monoalcohols

TL;DR

This study investigates the physical aging behavior of three monoalcohols by analyzing dielectric loss after temperature jumps, revealing that aging responses follow the alpha relaxation rather than the Debye process for most of these alcohols.

Contribution

The paper introduces a method to identify linear-limit aging relaxation functions and compares aging timescales with dielectric relaxation times in monoalcohols.

Findings

Aging follows alpha relaxation for 5-methyl-2-hexanol and 2-ethyl-1-butanol.

No definitive conclusion for 1-phenyl-1-propanol due to overlapping processes.

Single-parameter aging describes all data well.

Abstract

This paper presents data for the physical aging of the three monoalcohols 2-ethyl-1-butanol, 5-methyl-2-hexanol, and 1-phenyl-1-propanol. Aging is studied by monitoring the dielectric loss at a fixed frequency in the kHz range following temperature jumps of a few Kelvin's magnitude, starting from states of equilibrium. The three alcohols differ in the Debye relaxation strength and how much the Debye process is separated from the $\alpha$ process. We first demonstrate that single-parameter aging describes all data well and proceed to utilize this fact to identify the linear-limit normalized aging relaxation functions. From the Laplace transform of these functions, the linear-limit aging loss-peak angular frequency defines the inverse of the linear aging relaxation time. This allows for a comparison to the temperature dependence of the Debye and $\alpha$ dielectric relaxation times of the three monoalcohols. We conclude that the aging response for 5-methyl-2-hexanol and 2-ethyl-1-butanol follows the $\alpha$ relaxation, not the Debye process, while no firm conclusion can be reached for 1-phenyl-1-propanol because its Debye and $\alpha$ processes are too close to be reliably distinguished.