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3. THE GLASS STATE AND THE GLASS TRANSITION: THERMODYNAMIC and KINETIC ASPECTS.

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Presentation on theme: "3. THE GLASS STATE AND THE GLASS TRANSITION: THERMODYNAMIC and KINETIC ASPECTS."— Presentation transcript:

1 3. THE GLASS STATE AND THE GLASS TRANSITION: THERMODYNAMIC and KINETIC ASPECTS

2 Differential Scanning Calorimetry Differential Thermal Analysis

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4 Is the glass transition a true thermodynamic phase transition ?  T g depends on the cooling rate  T g depends on the thermal history

5 Ehrenfest relations Prigogine-Defay ratio must be = 1 if it were a phase transition with a single order parameter

6 sub-T g aging and annealing T anneal.

7 using Differential Scanning Calorimetry (DSC, TMDSC…) [J. M. Hutchinson, Thermochimica Acta 324 (1998) 165-174

8 using Differential Scanning Calorimetry

9 the fictive temperature T f B2O3B2O3

10 Ethanol

11 the fictive temperature T f  phenomenological Tool-Narayanaswamy-Moynihan (TNM) approach [ Tool, J. Am. Ceram. Soc. 29 (1946) 240. Narayanaswamy, J. Am. Ceram. Soc. 54 (1971) 491. Moynihan et al., J. Am. Ceram. Soc. 59 (1976) 12. ]  curve fitting method: [I. M. Hodge, J. Non-Cryst. Solids 169 (1994) 211]

12 THE KAUZMANN PARADOX EXCESS OF ENTROPY: TKTK

13 W. Kauzmann, Chem. Rev. 43, 219 (1948)

14 THE KAUZMANN PARADOXNN 1.0

15 STRONG AND FRAGILE GLASS-FORMING LIQUIDS 01

16 Vogel-Tamman-Fulcher equation: (D: strength) fragility index m:

17 STRONG AND FRAGILE GLASS-FORMING LIQUIDS C. A. Angell, J. Non-Cryst. Solids 102, 205 (1988)

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21 [I. Chang and H. Sillescu] Ecuación de Stokes-Einstein: [A. Einstein, Annalen der Physik 17, 549 (1905)]

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