TY - JOUR

T1 - Dynamic properties of Span-80 adsorbed layers at paraffin-oil/water interface

T2 - Capillary pressure experiments under low gravity conditions

AU - Pandolfini, P.

AU - Loglio, G.

AU - Ravera, F.

AU - Liggieri, L.

AU - Kovalchuk, V. I.

AU - Javadi, A.

AU - Karbaschi, M.

AU - Krägel, J.

AU - Miller, R.

AU - Noskov, B. A.

AU - Bykov, A. G.

N1 - Publisher Copyright: © 2017 Elsevier B.V. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2017/11/5

Y1 - 2017/11/5

N2 - Measurements by capillary pressure tensiometry, under microgravity conditions aboard the International Space Station, supplied a consistent set of reliable results for the dynamic interfacial tension and for the interfacial dilational viscoelastic modulus, quantitatively characterizing the dynamics of Span-80 adsorbed layers at the paraffin-oil/water interface. The experiments were executed at three different temperatures, i.e., 20, 30 and 40 °C, according to a pre-established built-in time-line in the orbiting facility. The interfacial area was subjected to perturbations with various functional forms (square pulses, ramps and harmonic oscillations), at three consecutive amplitudes (5%, 10% and 20%). Each experiment was performed in three successive repetitions, in view of an advantageous telemetered data redundancy. The interfacial responses to imposed perturbations, for the studied minimal surfactant concentration of Span-80 in paraffin-oil (that is (2 ÷ 3) × 10−5 mol/dm3) revealed a diffusion-controlled adsorption mechanism, definitely matching the Lucassen & Van den Tempel model in the frequency-domain representation. The interfacial responses also showed a linearity range up to the 20% amplitude. Interfacial relaxation responses to transient interfacial perturbations substantially validated the diffusion-controlled model for the adsorption mechanism, in the time-domain representation.

AB - Measurements by capillary pressure tensiometry, under microgravity conditions aboard the International Space Station, supplied a consistent set of reliable results for the dynamic interfacial tension and for the interfacial dilational viscoelastic modulus, quantitatively characterizing the dynamics of Span-80 adsorbed layers at the paraffin-oil/water interface. The experiments were executed at three different temperatures, i.e., 20, 30 and 40 °C, according to a pre-established built-in time-line in the orbiting facility. The interfacial area was subjected to perturbations with various functional forms (square pulses, ramps and harmonic oscillations), at three consecutive amplitudes (5%, 10% and 20%). Each experiment was performed in three successive repetitions, in view of an advantageous telemetered data redundancy. The interfacial responses to imposed perturbations, for the studied minimal surfactant concentration of Span-80 in paraffin-oil (that is (2 ÷ 3) × 10−5 mol/dm3) revealed a diffusion-controlled adsorption mechanism, definitely matching the Lucassen & Van den Tempel model in the frequency-domain representation. The interfacial responses also showed a linearity range up to the 20% amplitude. Interfacial relaxation responses to transient interfacial perturbations substantially validated the diffusion-controlled model for the adsorption mechanism, in the time-domain representation.

KW - Adsorption layer

KW - Diffusion-controlled adsorption

KW - Dynamic interfacial tension

KW - Interfacial dilational viscoelasticity

KW - Sorbitan monooleate

KW - Span-80

KW - Water/paraffin-oil interface

UR - http://www.scopus.com/inward/record.url?scp=85019203617&partnerID=8YFLogxK

U2 - 10.1016/j.colsurfa.2017.05.012

DO - 10.1016/j.colsurfa.2017.05.012

M3 - Article

VL - 532

SP - 228

EP - 243

JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects

JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects

SN - 0927-7757

ER -