Direct tests of single-parameter aging

TL;DR

This study provides precise measurements of physical aging in organic glasses after temperature jumps, demonstrating a simplified aging model that predicts relaxation behavior without fitting to complex functions.

Contribution

Introduces a simplified version of the Tool-Narayanaswamy aging formalism enabling direct calculation of relaxation curves from experimental data.

Findings

Data conform to the new aging formalism

Accurate temperature control within 100 micro Kelvin

Rapid thermal equilibration after temperature jumps

Abstract

This paper presents accurate data for the physical aging of organic glasses just below the glass transition probed by monitoring the following quantities after temperature up and down jumps: the shear-mechanical resonance frequency (around 360 kHz), the dielectric loss at 1 Hz, the real part of the dielectric constant at 10 kHz, and the loss-peak frequency of the dielectric beta process (around 10 kHz). The setup used allows for keeping temperature constant within 100 micro Kelvin and for thermal equilibration within a few seconds after a temperature jump. The data conform to a new simplified version of the classical Tool-Narayanaswamy aging formalism, which makes it possible to calculate one relaxation curve directly from another without any fitting to analytical functions.