Physical aging in PMMA/silica nanocomposites: Enthalpy and dielectric relaxation

Relaxed enthalpy and volume during physical aging: Their interrelation

Several papers have recently presented results of measurements of physical aging by studying the behavior of glassy materials quenched from temperatures above their glass transition temperature g T . The evolution of the aging process is usually followed by plotting the relaxed enthalpy versus the accompanying decrease in volume. Here, we focus on the slope of such plots, which are found to be ...

Anomalous Enthalpy Relaxation in Vitreous Silica

It is a challenge to calorimetrically determine the glass transition temperature (Tg) of vitreous silica. Here, we demonstrate that this challenge mainly arises from the extremely high sensitivity of the Tg to the hydroxyl content, but also from decrease of the Tg with repeating the calorimetric scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercoo...

Time dependence of the segmental relaxation time of poly(vinyl acetate)-silica nanocomposites.

The aging-time dependence of the segmental relaxation time of poly(vinyl acetate) (PVAc) in the glassy state is investigated in the bulk polymer and its nanocomposites with silica (SiO(2)). These systems present identical segmental dynamics, when this is probed in the equilibrium supercooled liquid by broadband dielectric spectroscopy. An acceleration of the physical aging process of PVAc with ...

Dielectric Properties of Graphite Nanocomposites

enthalpy relaxation of gelatin in the glassy state

the glass transition temperature (tg) and the melting temperature (tm) of gelatin at water contents between 7 and 14% were measured using differential scanning calorimetry.  the plasticisation of the polymer by water led to a decrease in tg and tm. the tg of partially crystalline gelatin was higher than that of the amorphous one obtained by quenching from the melt. the enthalpy relaxation occur...