Slow rheological mode in glycerol and glycerol–water mixtures

Jensen, Mikkel H.; Gainaru, C.; Alba‐Simionesco, Christiane; Hecksher, Tina; Niss, Kristine

doi:10.1039/c7cp06482a

Cited by 51 publications

(52 citation statements)

References 62 publications

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“…This likely indicates that the water molecules have faster dynamics like in bulk water. The dynamical change of water molecules is likely coupled with aggregated water domains (Jensen et al, 2018). Furthermore, a negligible EISF means that water molecules are not restricted in confined space at the pico-second time scale.…”

Section: Resultsmentioning

confidence: 99%

Molecular Basis of Water Activity in Glycerol–Water Mixtures

Oyama¹

2019

Front. Chem.

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Water activity (Aw) is a reliable indication of the microbial growth, enzymatic activity, preservation, and quality of foods. However, a molecular basis of Aw is still under debate in multiple related disciplines. Glycerol–water mixtures can provide a variation of Aws by controlling the ratio of glycerol and water. In this study, the molecular basis of Aw was examined by using differential scanning calorimetry (DSC), attenuated total reflection Fourier-transform infrared spectroscopy (ATR-IR), and incoherent quasi-elastic neutron scattering (IQENS) based on moisture sorption isotherms of glycerol–water mixtures. Three regions were identified and classified based on DSC results. DSC showed that bulk-like water existed at Aw > ≈ 0.7 at 27°C. Hydrogen bonding related molecular vibrations were analyzed by ATR-IR, which indicated that the OH stretching in water molecules is significantly different for Aw > ≈ 0.7. Translational diffusive and/or rotational motions in time and space analyzed by IQENS appeared when Aw > ≈ 0.7, and are correlated with hydrogen bonding related local vibrational dynamics in the glycerol–water mixtures. More importantly, Aw values of glycerol–water mixtures can be explained by the hydrogen bonding network and molecular dynamics of water in the solution. We discuss the implications of Aw in the preservation of food at the molecular level.

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Section: Resultsmentioning

confidence: 99%

Molecular Basis of Water Activity in Glycerol–Water Mixtures

Oyama¹

2019

Front. Chem.

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“…In this experiment, a constant temperature bath is utilized to raise the temperature to between 10 and 100 o C. More descriptions about the working principle and specifications of LVDV-2T Brookfield Viscometer are reported by Lahari et al [27]. [29] observed that "water acts as a lubricant, softening the hydrogen bonding which contributed to the macroscopic viscosity of the glycerol-water mixture". Takamura et al [30] observed that "the increase in viscosity of glycerol-water mixtures with the addition of glycerol is highly non-linear" and the variation in the aqueous phase was over three orders of magnitude.…”

Section: B Measurement Of Viscositymentioning

confidence: 99%

“…Fig. 7 Comparison of Viscosity of GW70 and SiO2 nanofluids Jensen et al[29] observed that "water acts as a lubricant, softening the hydrogen bonding which contributed to the macroscopic viscosity of the glycerol-water mixture". Takamura et al[30] observed that "the increase in viscosity of glycerol-water mixtures with the addition of glycerol is highly non-linear" and the variation in the aqueous phase was over three orders of magnitude.…”

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confidence: 99%

Effect of Temperature and Nanoparticle Concentration on the Viscosity of Glycerine-water based SiO2 Nanofluids

Lahari¹,

Bee²,

Sai³

et al. 2021

IJRTE

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Dynamic viscosity of SiO2/22nm nanofluids prepared in a glycerine-water (30:70 by volume) mixture base liquid, referred to as GW70, is measured experimentally. Nanofluids with concentrations of 0.2, 0.6, and 1.0 percent are produced, and viscosity measurements are carried out at temperatures ranging from 20 to 80 oC using a LVDV-2T model Brookfield Viscometer. The particle size and elemental composition of nanoparticles are determined using FESEM and EDX. XRD images confirm the SiO2 peaks in the crystalline structure. The rheology of nanofluids is influenced by the nanoparticle’s concentration. In the experimental temperature and concentration range, nanofluids show Newtonian behavior. The viscosity of nanofluids enhanced as particle concentration increased and reduced as temperature increased. For 1.0 percent vol. concentration at 20oC, the maximum viscosity value is achieved, and for 0.2 percent vol. concentration at 80oC, the lowest viscosity value is observed. The viscosity of the glycerine-water base fluid was also determined at 20, 40, 60, and 80 degrees Celsius. The viscosity ratio of nanofluids to the base liquid is found to be more than one for all the nanofluids. This viscosity data is useful to estimate HTC of glycerine-water-based silica nanofluids.

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“…If one applies the model description of the preceding Section II to different glass formers, one learns many things. and of glycerol at 196 K [18]. The continuous lines are fits in terms of the model with the parameters given in Table I and II.…”

Section: A Overviewmentioning

confidence: 99%

“…This is illustrated in Fig. 1, which compares the normalized shear relaxation curves of the metallic glass Zr 65 Al 7.5 Cu 17.5 Ni 10 [17] with those of the hydrogen bonding molecular glass former glycerol [18].…”

Section: A Overviewmentioning

confidence: 99%

Eshelby description of highly viscous flow—Half model, half theory

Buchenau

2018

The Journal of Chemical Physics

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A recent description of the highly viscous flow ascribes it to irreversible thermally activated Eshelby transitions, which transform a region of the undercooled liquid to a different structure with a different elastic misfit to the viscoelastic surroundings. The description is extended to include reversible Eshelby transitions, with the Kohlrausch exponent β as a free parameter. The model answers several open questions in the field.

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Slow rheological mode in glycerol and glycerol–water mixtures

Cited by 51 publications

References 62 publications

Molecular Basis of Water Activity in Glycerol–Water Mixtures

Molecular Basis of Water Activity in Glycerol–Water Mixtures

Effect of Temperature and Nanoparticle Concentration on the Viscosity of Glycerine-water based SiO2 Nanofluids

Eshelby description of highly viscous flow—Half model, half theory

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