Two-Step Aging of Highly Polar Glass

Abstract

Nonequilibrium processes, including physical aging, belong to the most challenging phenomena of glassy dynamics. One of the fundamental problems that needs clarification is the effect of material polarity on the time scale of the structural recovery of glass. The importance of this issue arises from practical applications and recent findings suggesting a substantial contribution of dipole–dipole interactions to the dielectric permittivity spectra of polar glass-formers. Herein, we use dielectric spectroscopy to investigate structural relaxation and aging dynamics of highly polar glass-former 4-[(4,4,5,5,5-pentafluoropentoxy)methyl]-1,3-dioxolan-2-one (FPC), a derivative of propylene carbonate with ε s = 180 and μ = 5.1. We show that ε″( t age ) data of FPC at T age < T g reveal complex behavior resulting from considerable cross-correlation effects. Namely, two characteristic aging time scales, reflecting the evolution of cross-correlation mode and generic structural relaxation toward equilibrium, are obtained at a given T age . Furthermore, a single stretched exponential behavior of ε″( t age ) has been received for weakly polar carvedilol with negligible dipole–dipole interactions.

Comment on “Anomalous structural recovery in the near glass transition range in a polymer glass: Data revisited in light of temperature variability in vacuum oven‐based experiments”

“…Another study, carried out closer to T g showed that the shape of equilibrium recovery behavior, though not showing any evident non‐monotonous pattern, was better fitted by two‐time scales. [ 30 ]…”

“…Another study, carried out closer to T g showed that the shape of equilibrium recovery behavior, though not showing any evident non-monotonous pattern, was better fitted by two-time scales. [30] The presence of multiple steps of equilibrium recovery underlines the presence of different mechanisms of equilibration. While, as previously explained, highlighting their simultaneous presence is a hard task in isothermal aging, isochronal measurements, for instance heating at a constant rate after aging way below T g , helps to unveil the existence of the fast mechanism of equilibration, that is, the one relevant for the first decay in isothermal experiments.…”

The Aging Effects of Ultraviolet Irradiation on the Optical Properties of Glass

“…In various industries such as construction, daily use, and healthcare, glass, as a direct interface between people and the environment, people and machinery, the development of glass materials and their performance has garnered more and more attention from both consumers and professionals [1][2][3]. In glass applications, glass is inevitably affected by factors such as temperature, humidity, and ultraviolet radiation, which can lead to a reduction in the mechanical properties and service life of the glass [4][5]. Therefore, studying the ultraviolet radiation performance of glass in comparison to normal environmental conditions is of paramount importance.…”

New Insights from Nonequilibrium Kinetics Studies on Highly Polar S-Methoxy-PC Infiltrated into Pores

“…It should be highlighted that, up to now, the vast majority of such annealing experiments were performed only in a limited range of temperatures ( T < T g,interfacial ), as above T g,interfacial , the effects of isothermal time-dependent measurements were hardly detectable. It is also worth mentioning that S -methoxy-PC (static permittivity, ε s ∼180) , was explicitly chosen due to strong dipole–dipole interactions and interesting effects (i.e., two-step aging) accompanying equilibration of this compound below T g . − …”

“…It is also worth mentioning that S -methoxy-PC (static permittivity, ε s ∼180) 24 , 25 was explicitly chosen due to strong dipole–dipole interactions and interesting effects (i.e., two-step aging) accompanying equilibration of this compound below T g . 26 − 28 …”