The slow molecular mobility in the amorphous solid and supercooled liquid phases of brucine, an anti-cancer drug. A study by differential scanning calorimetry (DSC), thermostimulated currents (TSC) and dielectric relaxation spectroscopy (DRS)

Diogo, Hermı́nio P.; Ramos, Joaquim J. Moura; Viciosa, María Teresa

doi:10.1016/j.molliq.2023.122423

Cited by 2 publications

(1 citation statement)

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“…Schick et al 79 showed that aging glassy poly(vinyl chloride) (PVC) significantly below T g occurred with a time scale deviating from the VFT behavior towards Arrhenius temperature dependence. A similar behavior was found by others in a wealth of glassy polymers [80][81][82][83][84][85][86][87][88] and other glasses 89,90 although, at least in some cases, this could have been attributed to the fact that the time scale of aging was determined in nonequilibrated glasses. Indeed the time scale of the α relaxation in aging experiments conducted close to T g was found to depend on the glass thermodynamic state; specifically an increase of τ with the glass density was observed.…”

Section: Complex Physical Aging Behaviorsupporting

confidence: 83%

Physical aging and vitrification in polymers and other glasses: Complex behavior and size effects

Cangialosi

2024

Journal of Polymer Science

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The paradigmatic view on the transformation of a supercooled liquid into a glass, so‐called vitrification or glass transition, and the subsequent time evolution of the non‐equilibrium glass, addressed as physical aging, relies on the exclusive role of the main relaxation with super‐Arrhenius temperature dependence. The aim of the present review is to carefully scrutinize the wealth of recent experimental results, above all in polymeric glasses, showing the relevance of other relaxational mechanisms in both vitrification and physical aging. While the relaxation bears dominant role in both phenomena in proximity of the glass transition temperature, , a broad view on a much wider temperature range indicates that vitrification and physical aging are mediated by non‐ mechanisms of equilibration. This review also shows that a reduction of the typical time scale of equilibration can be achieved in glasses with large free interface, namely with reduced sample size. In this way, fast non‐ mechanisms of equilibration can be exploited to convey glasses to low energy states in experimentally feasible time scales, thereby attaining information on the existence of the so‐called “ideal glass” in small sized samples.

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