Spinning drop method

When the shape of the drop approximates a cylinder, the interfadal tension is 

Bashforth, J. C. Adams An Attempt to Test the Theories of Capillary Action, University Press, Cambridge, 1883. 

Nierderhauser, F. E. Bartelk Report of Progress, Fundamental Research on Occurence of Petroleum, American Petroleum Institute, Lord Baltimore Press, Baltimore, 1950, 114. 

Adsorption of Surfactants and Polymeric Surfactants at the Solid/Liquid Interface 

The key to understanding how surfactants and polymers (to be referred to as polymeric surfactants) function as stabilisers is to know their adsorption and conformation at the solid/liquid interface. This is the objective of the present chapter, which is a survey of the general trends observed and some of the theoretical treatments. 

The spinning drop method is commonly used in petroleum-related applications for determining the interfacial tension at the crude oil/aqueous solution interface in the presence of different surfactants. 

Physical-Chemical Mechanics of Disperse Systems and Materials 

FIGURE 1.14 Schematic illustration of spinning drop method the equilibrium shape of the rotating drop. 

All of the methods described earlier can be classified as static, because all of the measurements are conducted under conditions of stable equilibrium. This condition corresponds to the minimum in potential energy, which in turn corresponds to the balance between the total surface energy and the energy in a field of gravitational or centrifugal force. There are also methods in which the measurements of surface tension are conducted under conditions of metastable equilibrium, corresponding to the maximum of the free energy of the system. Such methods can be classified as semistatic. 

FIGURE 1.15 Schematic illustration of maximum bubble pressure method change in the curvature radius 

There is an upper limit to the values of y that can be measured and is determined by the upper hmit of rotational speeds available to elongate the drop or bubble (see References [11, 16]). 

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The AOS and IOS surfactants discussed in this section are laboratory-prepared samples. The experiments were carried out by Borchardt [40] who used the spinning drop method throughout. Experimental details are given in the footnotes of the tables that follow. 

The pendant drop method was satisfactory for low Yqw values,. e. 0.02 mN/m. Typical data are given in Table III. In the systems where ultra-low yij values have been reported by other methods (like spinning drop), the pendant drop needs further investigations before it can be applied, since this would require syringes with much smaller diameters (J. e. 10 mm). As regards the theoretical analyses, we cannot find any concern why pendant drop should have any limitations for such studies. (Same is valid for spinning drop method). 

Figure 13.15 Spinning drop method to measure the interfacial tension between two liquids.

The Young-Laplace equation forms the basis for some important methods for measuring surface and interfacial tensions, such as the pendant and sessile drop methods, the spinning drop method, and the maximum bubble pressure method (see Section 3.2.3). Liquid flow in response to the pressure difference expressed by Eqs. (3.6) or (3.7) is known as Laplace flow, or capillary flow. 

In the spinning drop method, an oil droplet of approximately 1 fxL is placed in a glass capillary (2 mm i.d.) full of aqueous solution. The glass tube is sealed and spun horizontally around its axis at 5000 to 10,000 rpm. Centrifugal force will cause the lighter phase (usually the oil) to form an... 

The spinning drop method was first proposed by Vonnegut in 1942 and... 

The measurement of interfacial tension (IFT) was performed through the spinning drop method as described by Cayias (11). 

Spinning Drop Method A method for determining surface or, more commonly, interfadal tension based on measuring the shape of a droplet (or bubble) suspended in the center of a horizontal, cylindrical tube filled with a liquid, as the tube is spinning about its long axis. This method is particularly suited to the determination of very low interfadal tensions. 

Figure 4.9. Schematic representation of the inteifacial tension measurements by the spinning drop method ffi is the angular velocity, and d the deformed drop diameter.

In the spinning drop method, a droplet of polymer-1 immersed in polymer-2 is submitted to extensional deformation through the use of centrifugal forces [Elmendorp and De Vos, 1986]. The extent of deformation is controlled by the rotational speed imposed on the system contained... 

The pendant and spinning drop methods were used to determine Vj for different polymer pairs as well as the effect of temperature and compati-bilizer [Garmabi and Kamal, 1998]. The authors... 

Interfacial tension, - Spinning drop method 311 Interference microscopy 547, 548... 

Noiiy Ring methods, pendant and spinning drop methods, for surface and interfacial dilational elasticity, thin-film techniques, and surface lateral diffusion when using fluorescence recovery after photobleaching (FRAP) methods. 

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