α-Scale decoupling of the mechanical relaxation and diverging shear wave propagation length scale in triphenylphosphite

Torchinsky, Darius; Johnson, Jeremiah A.; Nelson, Keith A.

doi:10.1063/1.3700756

Cited by 10 publications

(11 citation statements)

References 53 publications

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“…Evidently, the dielectric -roughly equivalent to the rotational -relaxation time is slower than the Maxwell -roughly equivalent to the translational -relaxation time. Similar observations, slower rotational relaxation time and constant decoupling index, were reported by Dreyfus et al 53 for m-toluidine and more recently by Torchinsky et al 54 for triphenylphosphite and Jakobsen et al 55 for two other glass-forming liquids. Glycerol, however, is not a strongly correlating liquid, [56][57][58] and for this reason there are no theoretical arguments for the absence of a relaxation time decoupling.…”

Section: A Glycerolsupporting

confidence: 84%

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Klieber

Hecksher

Pézeril

et al. 2013

The Journal of Chemical Physics

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This paper presents and discusses the temperature and frequency dependence of the longitudinal and shear viscoelastic response at MHz and GHz frequencies of the intermediate glass former glycerol and the fragile glass former tetramethyl-tetraphenyl-trisiloxane (DC704). Measurements were performed using the recently developed time-domain Brillouin scattering technique, in which acoustic waves are generated optically, propagated through nm thin liquid layers of different thicknesses, and detected optically after transmission into a transparent detection substrate. This allows for a determination of the frequency dependence of the speed of sound and the sound-wave attenuation. When the data are converted into mechanical moduli, a linear relationship between longitudinal and shear acoustic moduli is revealed, which is consistent with the generalized Cauchy relation. In glycerol, the temperature dependence of the shear acoustic relaxation time agrees well with literature data for dielectric measurements. In DC704, combining the new data with data from measurements obtained previously by piezo-ceramic transducers yields figures showing the longitudinal and shear sound velocities at frequencies from mHz to GHz over an extended range of temperatures. The shoving model's prediction for the relaxation time's temperature dependence is fairly well obeyed for both liquids as demonstrated from a plot with no adjustable parameters. Finally, we show that for both liquids the instantaneous shear modulus follows an exponential temperature dependence to a good approximation, as predicted by Granato's interstitialcy model.

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Section: A Glycerolsupporting

confidence: 84%

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Klieber

Hecksher

Pézeril

et al. 2013

The Journal of Chemical Physics

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“…Studies of time scales of different response functions -such as dielectric constant and shear modulus -on the other hand often show weak or no decoupling, 20,25,26,[38][39][40][41][42] but examples exist where the opposite is observed. 43 The lack of generality in the literature and in the present results could well be due to differences in experimental conditions (especially the temperature calibration of different cryostats, but also different samples), which once again stresses the importance of having accurate and reproducible temperature control and only comparing response functions that are measured simultaneously or at least under identical experimental conditions.…”

Section: B Relaxation Timesmentioning

confidence: 73%

The dynamic bulk modulus of three glass-forming liquids

Gundermann

Niss

Christensen

et al. 2014

The Journal of Chemical Physics

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We present dynamic adiabatic bulk modulus data for three organic glass-forming liquids: two van der Waal's liquids, trimethyl-pentaphenyl-trisiloxane (DC705) and dibuthyl phtalate (DBP), and one hydrogen-bonded liquid, 1,2-propanediol (PD). All three liquids are found to obey time-temperature superposition within the uncertainty of the measurement in the adiabatic bulk modulus. The bulk modulus spectra are compared to the shear modulus spectra. The time scales of the two responses were found to be similar. The shapes of the shear and bulk modulus alpha loss peak are nearly identical for DBP and DC705, while the bulk modulus spectrum for PD is significantly broader than that of the shear modulus. The data further suggest that a "bulk modulus version of the shoving model" for the temperature dependence of the activation energy using the bulk modulus relaxation strength, ΔK(T), works well for DC705 and DBP, but not PD, while a formulation of the model using the high-frequency plateau value, K∞(T), gave a poor result for all three liquids.

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“…Like the final or Maxwell-relaxation time τ , a solidity length L should exist which diverges at the (idealized) glass transition. For the observation of transverse sound modes in transverse momentum fluctuations, such a length was found in mode-coupling theory calculations [59] and observed in forced Rayleigh scattering [60]. Yet it had been overlooked that it also determines the spatial pattern of strain fluctuations.…”

Section: Solidity Length Scalementioning

confidence: 94%

Nonlinear mechanical response of supercooled melts under applied forces

Cárdenas

Frahsa

Fritschi

et al. 2017

Eur. Phys. J. Spec. Top.

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We review recent progress on a microscopic theoretical approach to describe the nonlinear response of glass-forming colloidal dispersions under strong external forcing leading to homogeneous and inhomogeneous flow. Using mode-coupling theory (MCT), constitutive equations for the rheology of viscoelastic shear-thinning fluids are obtained. These are, in suitably simplified form, employed in continuum fluid dynamics, solved by a hybrid-Lattice Boltzmann (LB) algorithm that was developed to deal with long-lasting memory effects. The combined microscopic theoretical and mesoscopic numerical approach captures a number of phenomena far from equilibrium, including the yielding of metastable states, process-dependent mechanical properties, and inhomogeneous pressure-driven channel flow.

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α-Scale decoupling of the mechanical relaxation and diverging shear wave propagation length scale in triphenylphosphite

Cited by 10 publications

References 53 publications

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

The dynamic bulk modulus of three glass-forming liquids

Nonlinear mechanical response of supercooled melts under applied forces

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