Crystalization in the glass-forming materials: [KNO[sub 3]][sub X][Ca(NO[sub 3])[sub 2]][sub 1−X] and Brillouin scattering study of glass transition in X=0.64 mixture

Abstract Though the strong transformation in mechanical properties of glass-forming materials near the glass transition, Tg, has been recognized and exploited for millenia, efforts to understand and predict this phenomenon at a molecular level continue to this day. Close to Tg, where relaxation is considerably slower than predicted by the well-known Arrhenius equation, one of the most versatile and widely-used expressions to describe the dynamics or relaxation of glass formers is that of Vogel, Fulcher and Tammann (VFT). The VFT equation, introduced nearly 100 years ago, contains three adjustable fit parameters. In this work the dynamics of the polymer repeat units are related to macroscopic dynamics in polyelectrolyte complexes, which are hydrated amorphous blends of charged polymers. A simple expression, containing no freely adjustable fit parameters, is derived to quantitatively model relaxation from Tg to temperatures well into the Arrhenius region. The new expression, which also fits a selection of three common neutral polymers, will advance the understanding and use of the glass-forming phenomenon.

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Testing the paradigm of an ideal glass transition: Dynamics of an ultrastable polymeric glass

Science Advances ◽

10.1126/sciadv.aau5423 ◽

2018 ◽

Vol 4 (12) ◽

pp. eaau5423 ◽

Cited By ~ 11

Author(s):

Heedong Yoon ◽

Gregory B. McKenna

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Glassy State ◽

Relaxation Times ◽

Fictive Temperature ◽

Transition Dynamics ◽

Kauzmann Temperature ◽

Glass Forming ◽

Equilibrium Data ◽

Glass Forming Materials

A major challenge to understanding glass-forming materials is obtaining equilibrium data far below the laboratory glass transition temperatureTg. The challenge arises because it takes geologic aging times to achieve the equilibrium glassy state when temperatures are well belowTg. Here, we finesse this problem through measurements on an ultrastable amorphous Teflon with fictive temperatureTfnear to its Kauzmann temperatureTK. In the window betweenTfandTg, the material has a lower molecular mobility than the equilibrium state because of its low specific volume and enthalpy. Our measurements show that the determined scaled relaxation times deviate strongly from the classical expectation of divergence of time scales at a finite temperature. The results challenge the view of an ideal glass transition at or near toTK.

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Correlation Between Thermodynamic and Kinetic Properties of Glass-Forming Liquids

MRS Proceedings ◽

10.1557/proc-1048-z02-10 ◽

2007 ◽

Vol 1048 ◽

Author(s):

Oleg N. Senkov ◽

Daniel B. Miracle

Keyword(s):

Glass Transition ◽

Geometric Mean ◽

Configurational Entropy ◽

Excess Heat Capacity ◽

Kinetic Properties ◽

Vibrational Entropy ◽

Glass Forming ◽

Characteristic Temperatures ◽

Higher Temperature ◽

Glass Forming Materials

AbstractCorrelations between three characteristic temperatures: glass transition, Tg, Kauzmann, Tk, and Vogel-Fulcher-Tammann, To, were identified from the analysis of more than 60 metallic and non-metallic glass-forming materials. It was found that Tg ≥ Tk ≥ To and Tk is the geometric mean of Tg and To. The relation Tk ≥ To indicates that the excess total entropy of a super-cooled liquid ΔS approaches zero at a higher temperature than the configurational entropy ΔSconf, and such behavior was explained by the stronger temperature dependence of the excess vibrational entropy of the liquid, ΔSvib, than that of the corresponding glass, . A relationship between the fragility index m, reduced excess heat capacity ΔCp(Tg)/Sm, and reduced glass transition temperature, Trg, was identified using the found correlation between the characteristic temperatures.

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Brillouin scattering study on glass-forming ethanol

Journal of Non-Crystalline Solids ◽

10.1016/s0022-3093(02)01454-0 ◽

2002 ◽

Vol 307-310 ◽

pp. 154-160 ◽

Cited By ~ 12

Author(s):

Jae-Hyeon Ko ◽

Seiji Kojima

Keyword(s):

Brillouin Scattering ◽

Glass Forming ◽

Scattering Study

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Brillouin scattering study of inorganic glass-forming liquids

Philosophical Magazine B ◽

10.1080/13642810208221305 ◽

2002 ◽

Vol 82 (3) ◽

pp. 263-271 ◽

Cited By ~ 2

Author(s):

C. dreyfus ◽

S. Murugavel ◽

R. Gupta ◽

M. Massot ◽

R. M. Pick ◽

...

Keyword(s):

Brillouin Scattering ◽

Inorganic Glass ◽

Glass Forming ◽

Scattering Study

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