Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 558302
Title Interfacial rheology and relaxation behavior of adsorption layers of the triterpenoid saponin Escin
Author(s) Giménez-Ribes, Gerard; Habibi, Mehdi; Sagis, Leonard M.C.
Source Journal of Colloid and Interface Science 563 (2020). - ISSN 0021-9797 - p. 281 - 290.
DOI https://doi.org/10.1016/j.jcis.2019.12.053
Department(s) Physics and Physical Chemistry of Foods
VLAG
Publication type Refereed Article in a scientific journal
Publication year 2020
Keyword(s) Dilatational - Escin - Interfacial rheology - Non-linear Viscoelastic (NLVE) regime - Relaxation - Saponin - Shear - Stretched exponential
Abstract

Hypothesis: Escin, a monodesmosidic triterpenoid saponin, was shown previously to form viscoelastic interfaces with a very high dilatational and surface shear storage modulus. This is expected to be due to the arrangement of Escin into 2D disordered soft viscoelastic solid interfacial structures, which results in turn in a distribution of relaxation times. Experiments: The responses to dilatational and surface shear deformations of Escin-stabilized air-water interfaces were studied, both in the linear viscoelastic (LVE) and non-linear (NLVE) regime. Step relaxation and amplitude sweeps were performed in dilatation experiments. For surface shear, amplitude sweeps and creep recovery experiments were performed. Findings: Escin stabilized-interfaces displayed a highly non-linear behavior in dilatation as seen in the Lissajous plots. In large oscillatory shear the Lissajous curves had a rhomboidal shape, indicating intracycle yielding and recovery, typical of glassy systems. The relaxation of the interface showed stretched exponential behavior, with stretched exponents typical of disordered solids with dynamic heterogeneity. The use of surface rheological measurements beyond the commonly measured LVE regime clearly has provided new insights into the behavior of these interfaces and their microstructure. These results highlight the need to reconsider other complex interfaces as disordered solids and not as 2D homogenous viscoelastic fluids.

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