Journal ArticleDOI
Temperature and pressure study of Brillouin transverse modes in the organic glass-forming liquid orthoterphenyl.
TLDR
It is shown that in the range of the experiment, the orientational time is depending on a unique parameter built on temperature and density, and this parameter appears to be always of the same order of magnitude.Abstract:
Transverse Brillouin spectra of orthoterphenyl are measured in the (250-305 K; 0.1-100 MPa) temperature-pressure range, which corresponds to the supercooled phase of this organic glass former. We show that the analysis of these spectra combined with an extrapolation of the reorientation times under pressure leads to an estimate of the static shear viscosity in a pressure range whose validity extends beyond the range of the Brillouin measurements. The relative contributions of temperature and of density to the change of this reorientation time measured along an isobar are extracted from our results in a large temperature range extending from the liquid to the low temperature supercooled state. They appear to be always of the same order of magnitude. It is also shown that in the range of the experiment, the orientational time is depending on a unique parameter built on temperature and density.read more
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Supercooled dynamics of glass-forming liquids and polymers under hydrostatic pressure
TL;DR: In this paper, a review of the mechanisms underlying the relaxation properties of glass-forming liquids and polymers is provided, with an emphasis in the insight provided into the mechanism underlying the glass relaxation properties.
Journal ArticleDOI
Thermodynamical scaling of the glass transition dynamics.
TL;DR: It is shown that a generalized scaling, log (tau) proportional, variant T-1 V-gamma, where gamma is a material constant, yields superpositioning for ten glass formers, encompassing van der Waals molecules, associated liquids, and polymers.
Journal ArticleDOI
Thermodynamic scaling of the viscosity of van der Waals, H-bonded, and ionic liquids
TL;DR: It is shown that the superpositioning of relaxation times for various glass-forming materials when expressed as a function of TV(gamma), where the exponent gamma is a material constant, can be extended to the viscosity.
Journal ArticleDOI
Scaling out the density dependence of the α relaxation in glass-forming polymers
TL;DR: In this paper, it was shown that the density and temperature dependences of α-relaxation time of several glass-forming polymers can be described through a single scaling variable X = e(ρ)/T, where e(α) is well fitted by a power law ρx, x being a species-specific parameter.
Journal ArticleDOI
Thermodynamic interpretation of the scaling of the dynamics of supercooled liquids.
TL;DR: The recently discovered scaling law for the relaxation times, tau(T,upsilon) = I(Tupsilon(gamma), where T is temperature and upsilon the specific volume, is derived by a revision of the entropy model of the glass transition dynamics originally proposed by Avramov.
References
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Book
Neural Networks: A Comprehensive Foundation
TL;DR: Thorough, well-organized, and completely up to date, this book examines all the important aspects of this emerging technology, including the learning process, back-propagation learning, radial-basis function networks, self-organizing systems, modular networks, temporal processing and neurodynamics, and VLSI implementation of neural networks.
Journal ArticleDOI
Formation of glasses from liquids and biopolymers.
TL;DR: The onset of a sharp change in ddT( is the Debye-Waller factor and T is temperature) in proteins, which is controversially indentified with the glass transition in liquids, is shown to be general for glass formers and observable in computer simulations of strong and fragile ionic liquids, where it proves to be close to the experimental glass transition temperature.
Journal ArticleDOI
Relaxation processes in supercooled liquids
TL;DR: The characteristic features of alpha and beta relaxation in the supercooled state of non-network forming liquids and polymers are reviewed in this paper, where a crossover temperature Tc, located above the calorimetric glass transition temperature Tg, where the transport properties change from those typical for a strongly coupled liquid to those characteristic for a glass.
Journal ArticleDOI
Detailed comparison of the Williams–Watts and Cole–Davidson functions
C. P. Lindsey,G. D. Patterson +1 more
TL;DR: In this paper, the distribution function of relaxation times underlying the nonexponential relaxation function of Williams and Watts is derived and compared with the analogous Cole-Davidson distribution function, and several useful relations between relaxation and distribution functions are summarized or derived, and the limitations of deriving distribution functions from relaxation functions are discussed.