Viscosity of microemulsions

The viscosity of microemulsions has been studied several times in order to determine hydration and interactions between the dispersed droplets. It was found that an increase in hydration of the surfactant molecules resulted in rheological behavior more similar to that of suspensions containing solid particles in low concentrations. In any case, the microemulsions showed Newtonian flow characteristics. 

The viscosity of microemulsions was measured with a Rheotest 2 (Medingen, Germany) instrument in the range of shear rates 5 - 1800 s. ... 

One of the most easily observed macroscopic properties of colloidal systems is their flow behavior, and it may range anywhere between a low viscous fluid and a gel state. The rheological properties and, in particular, the viscosity of microemulsions are macroscopically observable parameters that characterize a given system. Of course, the viscosity is a relevant quantity for many practical applications of microemulsions. For instance, pumping such systems might be of interest in their application, and here viscosity plays an important role. 

As an example the viscosity of microemulsions is an important factor in their ability to recover oil [1], which means that knowledge of it and, even more so, the capability to control it are important in the process of tertiary oil recovery. Therefore, it has been studied experimentally in some detail with respect to surfactant systems that are of interest for the oil recovery process [2-10]. Furthermore, there also exists theoretical work that models microemulsion viscosity as a function of the phase composition and phase type in order to predict properties of microemulsions under realistic conditions [11,12]. 

Another possible application where the typically low viscosity of microemulsions is very useful is in the preparation of alternative fuels for diesel engines. Such hybrid fuel microemulsions containing vegetable oil [13] and alcohols, with 1-butanol [14] or a lower trialkylamine [15] acting as surfactant attracted interest some years ago, and such systems were tested for their practical application [16]. Similar systems containing triglyceride, aqueous ethanol, and 1-butanol [17] or long-chain fatty alcohols [18] were also studied for the same purpose. 

D. Modifying the Viscosity of Microemulsions by Admixing Other Substances... 

The changing of system composition affects the viscosity of microemulsions. An oil continuous system can change into a bicontinnons system and ultimately to a water continuous ensemble. Such changes yielding different structural organizations (states) become associated with distinct changes in... 

S. Ajith, A.C. Jhon, and A.K. Rakshit 1994 Physicochemical studies of microemulsions pure, Appl. Chem. 66, 509-514 Z. Saidi, C. Matthew, 1. Peyrelasse, and C. Boned 1990 Percolation and structural exponents for the viscosity of microemulsions, Phys. Rev. A 42, 872-876 S. Ray, S.R. Bisal, and S.P. Moulik 1992 Studies on structure and dynamics of microemulsion 11 Viscosity behavior of water-in-oil microemulsion, J. Surf. Sci. Technol. 8, 191-208. 

Measurement of viscosity of microemulsions provides information on the flow properties of the systans [86-89]. The study of the viscosity of microemulsions as a tool for the assessment of fluids circulations within the droplets was performed in early stage of microemulsions investigation [76]. The study of Ktistis [90] confirmed that the change in the mass ratio of different components of the microemulsions produced a systematic change in the viscosity of the system. The viscosity of the microemulsions plays a major role in their intended applications as reported by HaPe and Keipert [91] in their study on the development and characterization of microemulsions for ocular applications. Shia et al. [92,93] affirmed that the spacing between molecules at microemulsions interfaces is extremely... 

Saidi, Z. Mathew, C. Peyrelasse, J. Boned, C. (1990). Percolation and critical exponents for the viscosity of microemulsions. Physical Review A, 42(2), 872-876. 

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