Aging glass

Shortland, A., N. Rogers, and K. Eremin (2007), Trace element discriminants between Egyptian and Mesopotamian late Bronze Age glasses, ]. Archaeol. Sci. 34, 823-829. 

As shown in Fig. 25, the aged glass typically has a lesser volume in the glassy state compared to the as-quenched state. It is obvious from the data that the longer the aging time, the larger is the amount of volume lost due to sub-Tg annealing. This observation also fits well into the free-volume collapse model discussed earlier. 

The C-F approach treats AH(°o, T ) as an adjustable parameter as it is considered that the linear C extrapolation is inaccurate. Thus a direct measure of the area (A - A ) is used to calculate AH(t, T ). The data are then analyzed by curve fitting plots of AH(t, T ) against log t, to assess the thermodynamic aspects from the AH(°o, T) parameter, and the kinetic aspects, embodied in (t), both of which are obtainable from this approach. Also considered in the C-F approach is the prediction of t, which is the time to reach 99.9% of the thermodynamic equilibrium state of the infinitely aged glass. This can be predicted from short-term experiments and is illustrated in Section 14.3.2.1. 

As shown In Figure 18, the aged glass typically has a lesser volume In the glassy state as compared to the as-quenched state. 

Differentiation between Egyptian and Mesopotamian Late Bronze Age glasses... 

WAXS measurement of crystallinity involves taking the ratio of the areas under the individual diffraction peaks to the total area under the peaks. However, it implies that the amorphous polymer should be devoid of significant order and this has been the subject of much speculation. Pechhold and Grossman invoked a cubic mesophase for the parallel packing of chains in the melt, justifying it by a cluster-entropy hypothesis. Nodular structures, of 5—10 nm in diameter, have been observed particularly in physical aged glasses (these have been reviewed by... 

Degryse, P., Boyce, A., Erb-Satullo, N., Eremin, K., Kirk, S., Scott, R., Shortland, A.J., Schneider, J., and Walton, M. (2010) Isotopic discriminants between late Bronze Age glasses from Egypt and the Near East. Archaeometry, 52, 380-388. 

Henderson, J., Evans, J., and Nikita, K. (2010) Isotopic evidence for the primary production, provenance and trade of late Bronze Age glass in the Mediterranean. Mediterranean Archaeol. Archaeom., 10 (1), 1-24. 

Figure 7.7 Schematic enthalpy changes through the glass-transition region, showing dependence on glass-formation conditions and origin of endothermic relaxation peak in aged glasses.

N. M. Cameron, The effect of environment and temperature on the strength of E-glass fibres. Part 2. Heating and ageing. Glass TechnoL, 9 14,21,1968. 

Yunker, P. et al. 2009. Irreversible rearrangements, correlated domains, and local structure in aging glasses. Phys. Rev. Lett. 103 115701-115704. 

The objective of the Rheomolding process is to structuralize the final nonequilibrium state of the system "at will" in order to implement desired performance improvements. Notice that Glass I of Fig. 1 has been described as an "aging glass." The reason is that the system will, in theory, try to relax to an equilibrium state. However, the time to return to equilibrium is kinetically controlled, and in practice, the temperature of use renders the time to relax extremely long. 

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