| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Hecksher, Tina
Roskilde University
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (13/13 displayed)
- 2024RUSC (Roskilde University Shear Code)
- 2022Piezoelectric shear rheometrycitations
- 2022Rheological model for the alpha relaxation of glass-forming liquids and its comparison to data for DC704 and DC705citations
- 2021Identity of the local and macroscopic dynamic elastic responses in supercooled 1-propanolcitations
- 2019Fast contribution to the activation energy of a glass-forming liquidcitations
- 2017Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane datacitations
- 2017Connection between fragility, mean-squared displacement and shear modulus in two van der Waals bonded glass-forming liquidscitations
- 2016Communicationcitations
- 2015Communication: Direct tests of single-parameter agingcitations
- 2015A review of experiments testing the shoving modelcitations
- 2014The dynamic bulk modulus of three glass-forming liquidscitations
- 2013Mechanical spectra of glass-forming liquids. I. Low-frequency bulk and shear moduli of DC704 and 5-PPE measured by piezoceramic transducerscitations
- 2013Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scatteringcitations
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article
Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane data
Abstract
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. 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 each 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 the angular frequency as ω−1/2ω−1/2, has seven parameters. Assuming time-temperature superposition for the alpha and beta processes separately, the number of parameters varying with temperature is reduced to four. The model provides a better fit to the data than an equally parametrized 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 from 172 K to 200 K. The data are qualitatively similar to the shear modulus data by having a significant beta process. A single-order-parameter framework is suggested to rationalize these similarities.