Intermittent origin of the large violations of the fluctuation dissipation relations in an aging polymer glass

TL;DR

This study investigates the violation of the fluctuation-dissipation relation in aging polymer glasses, revealing intermittent dynamics with violations that depend on frequency and persist for hours at low frequencies.

Contribution

It provides new experimental evidence of intermittent violations of FDR in polymer glasses and discusses their implications for aging models.

Findings

FDR is strongly violated after quenching below glass transition.

Violations decrease with increasing frequency and duration.

Violations persist for about 3 hours at frequencies above 1Hz.

Abstract

The fluctuation-dissipation relation (FDR) is measured on the dielectric properties of a polymer glass (polycarbonate)in the range $20mHz - 100Hz$. It is found that after a quench below the glass transition temperature the fluctuation dissipation theorem is strongly violated. The amplitude and the persistence time of this violation are decreasing functions of frequency. At frequencies larger than 1Hz it persists for about $3h$. The origin of this violation is a highly intermittent dynamics characterized by large fluctuations. The relevance of these results for recent models of aging dynamics are discussed.