Viscoelastic retardation spectra of interfaces formed by water/glycerol monostearate crystals in canola oil dispersions

• Viscoelastic retardation spectrum of water/oil interfaces with particles was studied.
• Creep compliance data was fitted using regularization method.
• Dominant retardation times increase with decreasing particle content.

The applicability of a phenomenological theory of viscoelasticity for processing and analyzing mechanical data of adsorption interfaces is explored in this work. Based on this theory, a retardation spectrum was generated by the application of Tikhonov regularization techniques to data obtained from creep compliance experiments. To this end, 2% or 3% (w/w) glycerol monostearate (GMS) was put into canola oil (CO) at 70 °C, and the dispersions were cooled down to 30 °C (cooling rate of 1 or 10 °C/min), for obtaining GMS crystals in CO dispersions (CDx,y). The viscoelastic retardation spectrum was estimated from creep compliance mechanical tests of the formed interfaces. The interpretation of the results in terms the distribution of retardation modes λ and their relative intensity L(λ) was found to reflect the main features of the viscoelastic properties of water/oil adsorption layers. In particular, the creep dynamics were dominated by relatively slow (400–700 s) dynamics, which can be related to the reconfiguration of the adsorption layer, induced by diffusion and adsorption/desorption mechanisms in the vicinity of the water/oil interface. Reconfiguration of the adsorption layer as a consequence of applied shear was more pronounced for relatively small concentrations of dispersed particles, suggesting that a saturation of the adsorption layer contributes to its stability.

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