Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

doi:10.1063/1.4936867

Cited by 7 publications

(6 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Constant time-scale indices have also been reported for shearand bulk-mechanical data on 5PPE, tetramethyl-tetraphenyltrisiloxolane (DC704), 1,2,6-hexanetriol, and more [15][16][17] . Other studies report dynamic response data that exhibit not only temperature-but also pressure-independent time-scale indices 18,19 .…”

Section: Introductionmentioning

confidence: 99%

Time-scale ordering in hydrogen- and van der Waals-bonded liquids

Roed

Dyre

Niss

et al. 2021

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

The coupling behavior of time scales of structural relaxation is investigated on the basis of five different response functions for 1,2,6-hexanetriol, a hydrogen-bonded liquid with a minor secondary contribution, and 2,6,10,15,19,23hexamethyl-tetracosane (squalane), a van der Waals bonded liquid with a prominent secondary relaxation process. Time scales of structural relaxation are derived as inverse peak frequencies for each investigated response function. For 1,2,6-hexanetriol, the time-scale indices are temperature-independent, while a decoupling of time scales is observed for squalane in accordance with literature. An alternative evaluation approach is made on the squalane data, extracting time scales from the terminal relaxation mode instead of the peak position, and in this case temperature-independent coupling is also found for squalane, despite its strong secondary relaxation contribution. Interestingly, the very same ordering of response-function-specific time scales is observed for these two liquids, which is also consistent with the observation made for simple van der Waals bonded liquids reported previously [Jakobsen et al., J. Chem. Phys. 136, 081102 (2012)]. This time-scale ordering is based on the following response functions, from fast to slow dynamics: shear modulus, bulk modulus, dielectric permittivity, longitudinal thermal expansivity coefficient, and longitudinal specific heat. These findings indicate a general relation between the time scales of different response functions and, as inter-molecuar interactions apparently play a subordinate role, suggest a rather generic nature of the process of structural relaxation.

show abstract

Section: Introductionmentioning

confidence: 99%

Time-scale ordering in hydrogen- and van der Waals-bonded liquids

Roed

Dyre

Niss

et al. 2021

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…Due to its relatively high glass transition temperature (T g ) at atmospheric pressure, 245 K, 5PPE suits the technical specifications of our high-pressure dielectric setup. Furthermore, 5PPE fulfils several prerequisites to be considered an R-simple liquid [9,[32][33][34], just like tetramethyl-tetraphenyl-siloxane studied in Ref. [16].…”

Section: Experimental Details and Measuring Principlementioning

confidence: 94%

“…[16]. In 5PPE we thus expect the existence of isomorphs, that is, lines in the phase diagram along which several structural, dynamic and thermodynamic properties are invariant [9,23,[32][33][34]. Isomorphs are also isochrones, which are curves in the phase diagram with constant relaxation time.…”

Section: Experimental Details and Measuring Principlementioning

confidence: 99%

Challenges of interpreting dielectric dilatometry for the study of pressure densification

Sanz¹,

Dyre²,

Niss³

2019

Preprint

Self Cite

View full text Add to dashboard Cite

We report an experimental study documenting the challenge of employing dielectric dilatometry for the study of pressure densification in glass-forming materials. An influence of the dielectric cell geometry on the resulting capacitance of 5-poly-phenyl-ether upon vitrification under different thermobaric pathways is documented. The capacitive response is studied for two different multilayer capacitors: one with, in principle, fixed plate distance and one with Kapton R spacers allowing for contraction/expansion. A combination of changes in the dielectric permittivity of the material and modifications of the capacitor geometry determines the final capacitance. We conclude that, in order to convert the measured capacitance to material density, it is of paramount importance to understand the geometry. The data presented do not make it possible to conclude on whether or not simple glass formers such as 5-poly-phenyl-ether can be pressure densified, but our work highlights the challenge of utilizing dielectric spectroscopy to tackle this problem effectively.

show abstract

“…5PPE has fragility of m ≈ 80, similar to that of cumene, and it has a similar behaviour with only a weak wing 54 . The glass transition temperature of 5PPE from shear modulus is 243 K. 5PPE has been shown to obey TTS 55 and is found to have very simple behaviour in the sense defined by isomorph theory 37,47 . The MSD shown in Fig.…”

Section: Testing For Another Liquidmentioning

confidence: 99%

“…IV C we also test the elastic models for another van der Waals bonding liquid, a 5-polyphenyl ether (5PPE), which is a large molecule but with behaviour and fragility similar to that of cumene 37,47 . For 5PPE we present new MSD data and compare to earlier published shear mechanical data.…”

Section: The Experiments and Datamentioning

confidence: 99%

Connection between fragility, mean-squared displacement, and shear modulus in two van der Waals bonded glass-forming liquids

Hansen¹,

Frick²,

Hecksher³

et al. 2017

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

The temperature dependence of the high-frequency shear modulus measured in the kHz range is compared to the mean-squared displacement measured in the nanosecond range for the two van der Waals bonded glass-forming liquids cumene and 5PPE. This provides an experimental test for the assumption connecting two versions of the shoving model for the non-Arrhenius temperature dependence of the relaxation time in glass formers. The two versions of the model are also tested directly and both are shown to work well for these liquids.

show abstract

Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

Cited by 7 publications

References 66 publications

Time-scale ordering in hydrogen- and van der Waals-bonded liquids

Time-scale ordering in hydrogen- and van der Waals-bonded liquids

Challenges of interpreting dielectric dilatometry for the study of pressure densification

Connection between fragility, mean-squared displacement, and shear modulus in two van der Waals bonded glass-forming liquids

Contact Info

Product

Resources

About