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

Jakobsen, Bo; Hecksher, Tina; Christensen, Tage Emil; Olsen, Niels Boye; Dyre, Jeppe C.; Niss, Kristine

doi:10.1063/1.3690083

Cited by 57 publications

(74 citation statements)

References 56 publications

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“…We use and discuss the data in relation to other response functions in Refs. [34] and [35]. The time scale is about half a decade slower than that of the dielectric response, but its temperature dependence is the same.…”

Section: The Shape Of the Relaxation Curvementioning

confidence: 93%

Dynamic thermal expansivity of liquids near the glass transition

et al. 2012

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Based on previous works on polymers by Bauer et al. [Phys. Rev. E 61, 1755 (2000)], this paper describes a capacitative method for measuring the dynamical expansion coefficient of a viscous liquid. Data are presented for the glass-forming liquid tetramethyl tetraphenyl trisiloxane (DC704) in the ultraviscous regime. Compared to the method of Bauer et al., the dynamical range has been extended by making time-domain experiments and by making very small and fast temperature steps. The modeling of the experiment presented in this paper includes the situation in which the capacitor is not full because the liquid contracts when cooling from room temperature down to around the glass-transition temperature, which is relevant when measuring on a molecular liquid rather than a polymer.

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Section: The Shape Of the Relaxation Curvementioning

confidence: 93%

Dynamic thermal expansivity of liquids near the glass transition

et al. 2012

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“…From the VFT equations for toluene [115] and ethylbenzene [129] the corresponding temperatures can be determined under the assumption that dielectric and calorimetric responses give the same glass transition temperatures [130]. The inset in Figure 45 shows the cyclopentane calibration together with the two additional calibrations of toluene and ethylbenzene.…”

Section: Secondary Calibration With the Dynamic Glass Transition Of Tmentioning

confidence: 99%

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

Ahrenberg

Chua

Whitaker

et al. 2013

The Journal of Chemical Physics

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Vapor-deposited glasses of toluene and ethylbenzene have been characterized by in situ ac chip-nanocalorimetry. The high sensitivity of this method allows the detection of small changes in the heat capacity of nanogram size samples. We observe that vapor-deposited glasses have up to 4% lower heat capacities than the ordinary glass. The largest heat capacity decrease and the most kinetically stable glasses of toluene and ethylbenzene are observed in a range of deposition temperatures between 0.75 Tg and 0.96 Tg. Compared to larger molecules, deposition rate has a minor influence on the kinetic stability of these glasses. For both toluene and ethylbenzene, the kinetic stability is strongly correlated with the heat capacity decrease for deposition temperatures above 0.8 Tg. In addition, ac-nanocalorimetry was used to follow the isothermal transformation of the stable glasses into the supercooled liquid at temperatures slightly above Tg. Toluene and ethylbenzene stable glasses exhibit a constant transformation rate which is consistent with the growth front mechanism recently demonstrated for tris-naphthylbenzene and indomethacin. The kinetic stability of the most stable toluene and ethylbenzene glasses is comparable to that observed for other stable glasses formed by vapor deposition.

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“…The thermal and dielectric data usually exhibits a systematic shift, as previously found for different homopolymers, 41,42 and also for low molecular compounds. 62 The inset B of Fig. 6 compares dielectric data measured for thin films of P2VP with the VFT fit line extracted from the specific heat spectroscopy data.…”

Section: Conventional Analysis Of Specific Heat Spectroscopy Datamentioning

confidence: 99%

Calorimetric evidence for a mobile surface layer in ultrathin polymeric films: poly(2-vinyl pyridine)

et al. 2015

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Specific heat spectroscopy was used to study the dynamic glass transition of ultrathin poly(2-vinyl pyridine) films (thicknesses: 405-10 nm). The amplitude and the phase angle of the differential voltage were obtained as a measure of the complex heat capacity. In a traditional data analysis, the dynamic glass transition temperature T g is estimated from the phase angle. These data showed no thickness dependency on T g down to 22 nm (error of the measurement of AE3 K). A derivative-based method was established, evidencing a decrease in T g with decreasing thickness up to 7 K, which can be explained by a surface layer. For ultrathin films, data showed broadening at the lower temperature side of the spectra, supporting the existence of a surface layer. Finally, temperature dependence of the heat capacity in the glassy and liquid states changes with film thickness, which can be considered as a confinement effect.

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

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

Cited by 57 publications

References 56 publications

Dynamic thermal expansivity of liquids near the glass transition

Dynamic thermal expansivity of liquids near the glass transition

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

Calorimetric evidence for a mobile surface layer in ultrathin polymeric films: poly(2-vinyl pyridine)

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