Off equilibrium fluctuations in a polymer glass

TL;DR

This study measures dielectric fluctuations in a polymer glass, revealing strong violations of the fluctuation-dissipation relation after rapid quenching, with violations diminishing at higher frequencies and slower cooling rates.

Contribution

It provides experimental evidence of FDR violation in polymer glasses and links the violation to intermittent, non-Gaussian dynamics influenced by quenching rate.

Findings

FDR is strongly violated after rapid quench.

Violation amplitude decreases with frequency.

Slow quenching reduces the violation.

Abstract

The fluctuation-dissipation relation (FDR) is measured on the dielectric properties a polymer glass (polycarbonate). It is observed that the fluctuation dissipation theorem is strongly violated for a quench from above to below the glass transition temperature. The amplitude and the persistence time of this violation are decreasing functions of frequency. Around $1Hz$ it may persist for several hours. The origin of this violation is a highly intermittent dynamics characterized by large fluctuations a strongly non-Gaussian statistics. The intermittent dynamics depends on the quenching rate and it disappears after slow quenches. The relevance of these results for recent models of aging are discussed.