Physical aging and electrical properties of polymers

Merging of the α and β relaxations and aging via the Johari–Goldstein modes in rapidly quenched metallic glasses

“…10 Recent evidence suggests that this ␤-relaxation or, more precisely, the local cooperate dynamics of several ␤ relaxations, give rise to one shear transformation event, or one ␣ relaxation, 11,12 and is thought to be the driving process for enhanced diffusion. 19 In this paper, evidence is provided that this aging process observed well below T g can be associated with the slow Johari-Goldstein type ␤ relaxation, in the following denoted as ␤ relaxation. This effect has been repeatedly observed as an increase in Young's modulus 14,15 or decrease of the free volume, 16 at temperatures at which irreversible aging of the macroscropic structure, the partial restoration of equilibrium structure below T g , where complete equilibration is significantly longer than the experimental time window, is negligible on experimental timescales.…”

Nonequilibrium Dynamics in Amorphous Si3B3N7

“…The physical aging of polymers and other "soft" materials was studied experimentally almost three decades ago by Struik and co-workers. 1,2 The interest of a wider community for this area was then greatly stimulated by the work of Lundgren et al 3 on the magnetic properties of spin glasses, and aging has since remained a source of important questions and insights in nonequilibrium statistical physics. 4 The basic features of aging were mainly established during the 1980s in studies of the magnetic linear susceptibility and autocorrelation functions of spin glasses [5][6][7][8] but are shared by many other systems, including, to cite only a few examples, type II superconductors, 9 glasses, [10][11][12][13][14] granular materials, 15 and soft condensed matter.…”

“…To detect the onset of ergodicity breaking and characterize the behavior in both the ergodic and nonergodic regions, we consider a number of relevant dynamic and thermodynamic measures: (1) The physical movement of the particles, as statistically characterized by the mean-square displacement (MSD), is diffusive in the ergodic region and subdiffusive elsewhere. (2) The related bond survival probability (BSP) 41 drops to a finite average close to zero on a characteristic time scale at sufficiently high temperatures but becomes scale-free and age-dependent in the nonergodic region.…”

Mechanisms and modes for ignition of low-voltage, PVC-insulated electrotechnical products

“…In plastics, it manifests as a physical aging process, common to all amorphous polymers, which consists of an ongoing vitrification process. Numerous electrical properties are affected by this, but it has been studied only to a very limited extent [100]. Several studies on creep of PVC have been published [101,102] but none directly address electric failures.…”