Crossover of aging dynamics in polymer glass: from cumulative aging to non-cumulative aging

TL;DR

This study investigates the aging dynamics of polymer glass, revealing a transition from cumulative to non-cumulative aging with temperature shifts, and discusses the potential for temperature chaos in these materials.

Contribution

It demonstrates a crossover in aging behavior in polymer glass and introduces a growth law of a dynamical coherent length based on activated dynamics.

Findings

Observed crossover from cumulative to non-cumulative aging with increasing temperature shift

Derived a unique coherent length for positive and negative temperature shifts

Discussed the potential existence of temperature chaos in polymer glasses

Abstract

The aging behavior of polymer glass, poly(methyl methacrylate), has been investigated through the measurement of ac dielectric susceptibility ata fixed frequency after a temperature shift $\Delta T$ ($\le $ 20 K)between two temperatures, $T_1$ and $T_2$. A crossover from cumulative aging to non-cumulative aging could be observed with increasing $\Delta T$ using a twin temperature ($T$-) shift measurement. Based on a growth law of a dynamical coherent length given by activated dynamics, we obtained a unique coherent length for positive and negative $T$-shifts. The possibility of the existence of temperature chaos in polymer glasses is discussed.