Maxwell equation and classical theories of glass transition as a basis for direct calculation of viscosity at glass transition temperture

Nemilov, S. V.

doi:10.1134/s1087659613060084

Cited by 36 publications

(18 citation statements)

References 31 publications

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“…Nemilov [15], the  g value depends on the cooling rate ( g  10 12.8 Pa s at -3 K/min) and is lower for weak glasses with low shear moduli (for organic glasses,  g can be as low as 10 10 Pa s).…”

Section: Mauro Et Al [9] Equationmentioning

confidence: 99%

High-temperature viscosity of many-component glass melts

Hrma

Kruger

2016

Journal of Non-Crystalline Solids

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In this article, we argue that 1) the activation energy for viscous flow becomes independent of temperature when the viscosity of molten glass is sufficiently low at high enough temperatures, such as those that exist in a glass-melting furnace, and 2) the intercept of the linear function ln versus T -1 ( is the viscosity and T is the temperature) is independent of glass composition. This hypothesis, which is hardly new and is well supported by experimental data, allows minimization of the number of fitting parameters. A new dataset of meticulously measured viscosities of a large composition region of simulated nuclear waste glasses that recently became available provided an excellent opportunity to test this hypothesis to verify it again. Also, we used this dataset to demonstrate that some popular functions designed for representing the high-viscosity segment (where the activation energy changes with temperature) are not recommendable for approximating the low-viscosity segment (where the activation energy is constant). Fitting such functions produces overparameterization and leads to physically meaningless (or at least aesthetically unsatisfactory) outcomes, or, if the functions are constrained by the glass-transition viscosity and the high-temperature asymptote, the result is a significant lack of fit.

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Section: Mauro Et Al [9] Equationmentioning

confidence: 99%

High-temperature viscosity of many-component glass melts

Hrma

Kruger

2016

Journal of Non-Crystalline Solids

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“…All modern theories of glass transition take this into account (both the theories describing this process with the linear temperature change in time and with a periodic change). For this reason, the kinetic theories of glass transition and the dynamic theory of liquids are in complete agreement with each other (see [ 3 , 13 ]). In the dynamic theory of liquids, a solid-like state arises at a certain definite ratio of the frequency of the periodic external action on a system and the time of its structural relaxation.…”

Section: Features Of the Vitreous Statementioning

confidence: 60%

“…The validity of the dynamic theory of liquids is currently not seen as a subject for revision. These questions are considered most consistently in [ 3 , 13 ], and here the details are omitted.…”

Section: Features Of the Vitreous Statementioning

confidence: 99%

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On the Possibility of Calculating Entropy, Free Energy, and Enthalpy of Vitreous Substances

Nemilov

2018

Entropy

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A critical analysis for the arguments in support of, and against, the traditional approach to thermodynamics of vitreous state is provided. In this approach one presumes that there is a continuous variation of the entropy in the glass-liquid transition temperature range, or a "continuous entropy approach" towards 0 K which produces a positive value of the entropy at T → 0 K. I find that arguments given against this traditional approach use a different understanding of the thermodynamics of glass transition on cooling a liquid, because it suggests a discontinuity or "entropy loss approach" in the variation of entropy in the glass-liquid transition range. That is based on: (1) an unjustifiable use of the classical Boltzmann statistics for interpreting the value of entropy at absolute zero; (2) the rejection of thermodynamic analysis of systems with broken ergodicity, even though the possibility of analogous analysis was proposed already by Gibbs; (3) the possibility of a finite change in entropy of a system without absorption or release of heat; and, (4) describing the thermodynamic properties of glasses in the framework of functions, instead of functionals. The last one is necessary because for glasses the entropy and enthalpy are not functions of the state, but functionals, as defined by Gibbs' in his classification.

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“…As we will demonstrate, restricting the analysis to moderate variations of T g and δT g , its dependence can be described by a linear correlation as suggested as a possibility in Ref. based on the analysis of different model approaches. However, in general, the ratio δT g / T g will be shown to be a function of an appropriately defined fragility index generalizing the definition proposed by Angell .…”

Section: Introductionmentioning

confidence: 89%

Correlation between glass transition temperature and the width of the glass transition interval

Schmelzer

Тропин

Fokin

et al. 2019

Int J of Appl Glass Sci

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The glass transition is a kinetic phenomenon. Its basic characteristics-the glass transition temperature, T g , and the width, δT g , of the glass transition interval-depend significantly on cooling and heating rates as it is observed experimentally by standard DSC and fast scanning calorimetry. The knowledge of these and related correlations is of outstanding importance both for a theoretical understanding of vitrification and devitrification processes and their control in a variety of technological applications. By these reasons, general kinetic criteria of vitrification and, based on them, theoretical expressions for the glass transition temperature and the width of the glass transition range in dependence on rates of change of temperature have been derived in previous papers. These results are advanced here by establishing a direct correlation between these two quantities, T g and δT g . The ratio δT g /T g is shown, for arbitrary cooling and heating rates, to be a function of an appropriately defined index being a straightforward generalization of the definition introduced by Angell. The theoretical results are tested and confirmed by experiment. The methods employed here can be utilized generally for the description of vitrification caused also by a variation of other external control parameters like pressure. K E Y W O R D S glass transition, glasses J E L C L A S S I F I C A T I O N 64.70.kj Glasses; 64.70.Q-Theory and modeling of the glass transition How to cite this article: Schmelzer JWP, Tropin TV, Fokin VM, et al. Correlation between glass transition temperature and the width of the glass transition interval. Int J Appl Glass Sci. 2019;10:502-513. https ://

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Maxwell equation and classical theories of glass transition as a basis for direct calculation of viscosity at glass transition temperture

Cited by 36 publications

References 31 publications

High-temperature viscosity of many-component glass melts

High-temperature viscosity of many-component glass melts

On the Possibility of Calculating Entropy, Free Energy, and Enthalpy of Vitreous Substances

Correlation between glass transition temperature and the width of the glass transition interval

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