Dynamic thermal expansivity of liquids near the glass transition

Niss, Kristine; Gundermann, Ditte; Christensen, Tage Emil; Dyre, Jeppe C.

doi:10.1103/physreve.85.041501

Cited by 31 publications

(63 citation statements)

References 38 publications

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“…We have measured the complex, frequency-dependent dielectric constant ε(ω), shear modulus G(ω) 20,23 , adiabatic bulk modulus K S (ω) 23,24 , and longitudinal specific heat c l (ω) 25 liquids tetramethyl-tetraphenyl-trisiloxane (DC704) and 5-polyphenyl-4-ether (5PPE) (commercial vacuum-pump oils). For DC704 the time-dependent longitudinal thermal expansion coefficient α l (t) 26 was also measured (see appendix B for details). We note that both liquids have linear-response functions that to a good approximation obey time-temperature superposition (TTS) 23,28,29 , i.e., their loss-peak shapes are temperature independent in log-log plots.…”

Section: Resultsmentioning

confidence: 99%

Communication: Identical temperature dependence of the time scales of several linear-response functions of two glass-forming liquids

Jakobsen

Hecksher

Christensen

et al. 2012

The Journal of Chemical Physics

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Section: Resultsmentioning

confidence: 99%

Communication: Identical temperature dependence of the time scales of several linear-response functions of two glass-forming liquids

Jakobsen

Hecksher

Christensen

et al. 2012

The Journal of Chemical Physics

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“…4 via a single, internal energy bond. The predictions for the dynamic adiabatic/isothermal bulk moduli (or those of the dynamic expansion coefficient [77]) depend, of course, not just on the dynamic shear modulus (compliance), but also on the non-dissipative elements. For a system described by Fig.…”

Section: Data For the Dynamic Adiabatic Bulk Modulus Of Squalanementioning

confidence: 99%

Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane data

Hecksher

Olsen

Dyre

2017

The Journal of Chemical Physics

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This paper presents data for supercooled squalane's frequency-dependent shear modulus covering frequencies from 10 mHz to 30 kHz and temperatures from 168 K to 190 K; measurements are also reported for the glass phase down to 146 K. The data reveal a strong mechanical beta process, also above the glass transition. A model is proposed for the shear response of the metastable equilibrium liquid phase of supercooled liquids. The model is an electrical equivalent-circuit characterized by additivity of the dynamic shear compliances of the alpha and beta processes. The nontrivial parts of the alpha and beta processes are represented by a "Cole-Cole retardation element" defined as a series connection of a capacitor and a constant-phase element, resulting in the Cole-Cole compliance function well-known from dielectrics. The model, which assumes that the high-frequency decay of the alpha shear compliance loss varies with angular frequency as ω −1/2 , has seven parameters. Assuming time-temperature superposition for the alpha and the beta processes separately, the number of parameters varying with temperature is reduced to four. The model provides a better fit to data than a seven-parameter Havriliak-Negami type model. From the temperature dependence of the best-fit model parameters the following conclusions are drawn: 1) the alpha relaxation time conforms to the shoving model; 2) the beta relaxation loss-peak frequency is almost temperature independent; 3) the alpha compliance magnitude, which in the model equals the inverse of the instantaneous shear modulus, is only weakly temperature dependent; 4) the beta compliance magnitude decreases by a factor of three upon cooling in the temperature range studied. The final part of the paper briefly presents measurements of the dynamic adiabatic bulk modulus covering frequencies from 10 mHz to 10 kHz in the temperature range 172 K to 200 K. The data are qualitatively similar to the shear data by having a significant beta process. A single-order-parameter framework is suggested to rationalize these similarities. * dyre@ruc.dk arXiv:1701.05086v2 [cond-mat.soft]

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“…In this work we avoid the problem by determining the density, ρ, indirectly from measurement of the dielectric constant (relative permittivity) of the liquid [39,40]. The ClausiusMossotti equation relates the high frequency limiting value of the permittivity, ε∞, to the material…”

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Pressure densification of a simple liquid

Casalini

Roland

2017

Journal of Non-Crystalline Solids

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The magnitude of the high frequency, static dielectric permittivity is used to determine the density of tetramethyl tetraphenyl trisiloxane, a non-associated glass-forming liquid, as a function of temperature and pressure. We demonstrate that the properties in the glassy state are affected by the pressure applied to the liquid during vitrification. This behavior is normal for hydrogen-bonded liquids and polymers, but unanticipated by models of simple liquids.KEYWORDS: pressure densification, physical aging, glass formation, simple liquids _____________________________________________________ One of the curiosities regarding studies of the glass transition is the overriding focus on the properties of the liquid, rather than those of the glass. The main reasons for this are the equilibrium nature of the liquid state and the experimental inaccessibility of structural relaxation times, τ, below the glass transition temperature, Tg. These are, of course, the properties that define the glass transition -the material falls out of equilibrium as τα becomes very large. In response to this nonequilibrium structure, glass slowly reorganizes, a process known as physical aging [1,2,3,4,5,6]. Aging is an important technical aspect of glasses, affecting their stability and thus utility for many applications. A factor controlling the non-equilibrium structure is the condition of the liquid upon vitrification. For example, variation of the rate of cooling through Tg can be used to produce glasses with varying departures from equilibrium, and thus varying stability [7,8,9,10]. Another method, employed herein, is the application of pressure to the supercooled liquid. The glass transition is pressure-dependent, so that pressure affords a means to control the properties of the glass, including its physical aging behavior. Besides the material engineering value, understanding how the glass structure depends on the pressure during its formation is also important in discerning the principal control parameters and ultimately solving the "glass transition problem" [11,12,13,14,15,16,17].

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Dynamic thermal expansivity of liquids near the glass transition

Cited by 31 publications

References 38 publications

Communication: Identical temperature dependence of the time scales of several linear-response functions of two glass-forming liquids

Communication: Identical temperature dependence of the time scales of several linear-response functions of two glass-forming liquids

Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane data

Pressure densification of a simple liquid

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