화학공학소재연구정보센터
Thermochimica Acta, Vol.532, 172-175, 2012
Structural and vibrational relaxations at spontaneous aging in glass
The entropy change of intermediate-range orders (IROs) through the glass transition is discussed on the basis of the theories developed by Adam-Gibbs and Prigogine. It is estimated that the time dependence of the configurational entropy of glass is zero, but that of its vibrational entropy shows a constant decrease with the smallest change, while maintaining a constant fictive temperature and an isostructural state. It is shown that the spontaneous aging of well annealed glass shows a vibrational relaxation with a long relaxation time, while the annealing and physical aging of glass show a structural relaxation with a short relaxation time. The results indicate that the volume of glass decreases at a constant time rate through spontaneous aging at a constant temperature. It is emphasized that the existence of the constant configurational entropy below the glass transition temperature is the basic feature of glass forming. The nanoorder-size of the IROs in glass determines the residual entropy. The time symmetry in glass is spontaneously violated. The glass transition is a nano-emergence through the abrupt decrease in the fluctuations in the supercooled liquid state. (C) 2011 Elsevier B.V. All rights reserved.