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Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
Wasan and his research group focused on the field of interfacial rheology during the past three decades [15]. They developed novel instruments, such as oscillatory deepchannel interfacial viscometer [20,21,28] and biconical bob oscillatory interfacial rheometer [29] for interfacial shear measurement and the maximum bubble-pressure method [15,29,30] and the controlled drop tensiometer [1,31] for interfacial dilatational measurement, to resolve complex interfacial flow behavior in dynamic stress conditions [1,15,27,32-35]. Their research has clearly demonstrated the importance of interfacial rheology in the coalescence process of emulsions and foams. In connection with the maximum bubble-pressure method, it has been used in the BLM system to access the properties of lipid bilayers formed from a variety of surfactants [17,28,36].
Polymeric Surfactants
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
Interfacial rheology deals with the response of mobile interfaces to deformation (24). Emulsions contain a molecular or macromolecular surfactant film at the fluid interface, which, apart from being necessary for the stabilization of the dispersion, also initiates additional interfacial stresses beyond that stress already contributed by a homogeneous interfacial tension, γ. If a nonuniformity of surfactant concentration develops within the fluid interface, an interfacial tension gradient dγ/dA, where A is the interfacial area, is produced. This gradient is sometimes defined by the Gibbs elasticity, ε, which is simply equal to dγ/dlnA, which induces both areal and volumetric liquid motion. The gradient-driven flow is the basis of the so-called “Marangoni effect.” In addition to the possible existence of these interfacial tension gradients, other interfacial rheological stresses of a viscous nature may arise, such as those relating to interfacial shear and dilational viscosities (25). Many surfactant and polymer films also exhibit non-Newtonian interfacial rheological behavior that may be characterized by Bingham plastic models and interfacial viscoelasticity. Below a summary of the basic equations needed to describe the above-mentioned interfacial rheological parameters is given, followed by a brief description of some of the essential techniques required to measure interfacial rheology. Finally, some results will be given to correlate interfacial rheology with emulsion stability. Basic Equations for Interfacial Rheology
Complex study of acid-in-oil emulsions, their formation, stabilization and breakdown
Published in Journal of Dispersion Science and Technology, 2023
Mikhail A. Silin, Lyubov A. Magadova, Lyutsia F. Davletshina, Timur I. Yunusov, Konstantin K. Merzlyakov, Viktoria D. Kotekhova
The possibility of emulsion formation and stabilization depends on interfacial interactions between the water and hydrocarbon phases. The main parameters of the interfacial interactions are interfacial tension and interfacial rheology. The study of the interfacial tension between oil and acid and its influence on emulsion formation can be found in several articles.[15–17] The relationship between interfacial rheology and emulsion stability is reported in several other papers.[18–21] According to these studies, the low interfacial tension and high elastic modulus of the interfacial film favor emulsion stability at low-pH. The data showed thermodynamic reasons for high emulsion stability and the occurrence of structural barriers at low-pH values.
The role of adsorption of a natural surfactant at oil–water interface in enhanced oil recovery: interfacial rheology, and structural, and emulsifying analyses
Published in Chemical Engineering Communications, 2023
Jinesh Machale, Subrata Kumar Majumder, Pallab Ghosh, Tushar Kanti Sen, Ali Saeedi
The performance of the aforesaid natural surfactants for EOR has been evaluated mainly with the help of numerous analyses such as the measurement of IFT, wettability, adsorption, rheological characteristics, phase behavior, and core flooding (Anghel 1990; Sheng 2010; Elakneswaran et al. 2021). However, the surfactant injected in the oil reservoir interacts with the crude oil and adsorbs on its surface, forming a complex interfacial film. Therefore, explicit knowledge of the film characteristics is essential for interpreting the displacement of entrapped oil from the reservoir (Sun et al. 2011). This depends on the interfacial properties of the rock–oil–water system, controlled by the composition of the aqueous phase, rock wettability, and physicochemical properties of the crude oil (Borwankar and Wasan 1986; Dong et al. 2009; Alvarado and Manrique 2010). Generally, the surfactant adsorbs spontaneously from the bulk phase at the oil–water interface, where the resultant free energy is lesser than that in the solution. The adsorbed surfactant not only changes the IFT but also develops an interfacial film with viscoelastic properties (Krägel and Derkatch 2010). Interfacial rheology is a potential tool employed to examine the interfacial film structure and its stability (Roth et al. 2000; Lyu et al. 2018). It illustrates the functional association between the stress applied at the interface and its deformation.
Viscosity Variation During Evaporation of a Vegetable Oil Emulsion Stabilized by Tween 80R
Published in Journal of Dispersion Science and Technology, 2011
Duo Wei, Lingling Ge, Stig E. Friberg, Rong Guo
The seminal paper in the general area of rheology of two-phase emulsions was early published by Tadros,[9] who reviewed the factors that affect the flow characteristics of emulsions, such as the volume fraction of the dispersed phase, the viscosity of the drops and their interfacial rheology. The basic equations and principles of the interfacial rheology measurement and their correlation with emulsion stability were illustrated by the results from investigations of bulk rheology of emulsion systems. Viscosity-volume fraction relationship for O/W and W/O emulsions and viscoelastic properties of concentrated O/W and W/O emulsions and of weakly flocculated emulsions were compared to basic aspects.