Foam structural parameters characteristics

The polyhedral foam consists of gas bubbles with a polyhedral shape the faces of which are flat or slightly bent liquid films, the edges are the Plateau borders and the edge cross-points are the vertexes (see Chapter 1). In the study of the physicochemical characteristics of foams there are several techniques that involve the analytical dependences of these characteristics and the structural parameters of foams. 

Relation between the Geometrical (Structural) Parameters of a Foam and its Physicochemical Characteristics... 

A detail analysis of Eqs. (10.21) and (10.22) and identification of the relationship between the characteristics of foam separation and the structural parameters of the foam are possible on the basis of the material balance equations for the substance in the foam and in the solution, including those taking into account the foam breakdown [51]. The material balance of a substance participating in foam separation is given by... 

The direct measurement of the various important parameters of foam films (thickness, capillary pressure, contact angles, etc.) makes it possible to derive information about the thermodynamic and kinetic properties of films (disjoining pressure isotherms, potential of the diffuse electric layer, molecular characteristics of foam bilayer, such as binding energy of molecules, linear tension, etc.). Along with it certain techniques employed to reveal foam film structure, being of particular importance for black foam films, are also considered here. These are FT-IR Spectroscopy, Fluorescence Recovery after Photobleaching (FRAP), X-ray reflectivity, measurement of the lateral electrical conductivity, measurement of foam film permeability, etc. 

In investigations of the structure and properties of disperse materials, particularly plastic foams, it is necessary to find out the distribution pattern of one phase in the material. It is simpler to consider the distribution of the gas phase in a solid body, i.e. the gas-filled cell distribution within a foam bulk] In their turn, the cells, as shown above, may be characterized by several parameters (size, shape, volume and surface area). The cell size distribution pattern is the most comprehensive characteristic of the dispersity of the gas structural elements of plastics. Furthermore, the cell size can, be determined by one of the methods which will be discussed below, and the foam dispersity is expressed in terms of the nominal cell diameter distribution function. 

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