Interfacial tension Girifalco-Good theory

The Good-Girifalco theory [77-82] was originally formulated to make an attempt to correlate the solid-liquid interfacial tension to the solid surface energy and the liquid surface tension through an interaction parameter, basic formulation of the theory is ... 

Girifalco, L.A. and Good. R.J. A theory for the estimation of surface and interfacial energies I. Derivation and application to interfacial tension, J. Phys. Chem., 61(7) 904-909,1957. 

One of the major problems of the application of the theory to sohds is the determination of the interfacial tension. For such systems it cannot be determined by direct measurements, it is usually derived from thermodynamic calculations. Good and Girifalco [31] developed the first theory for the calculation of Yab> because it contained an adjustable parameter it did not gain practical use. The most widely accepted solution was suggested by Fowkes [32,33]. He assumed that surface tension can be divided as shown in Eq. 9 ... 

Many theories for estimating the interfacial tensions have been presented in Sections 3.5.1-3.5.3. The equations for the surface and interfacial tensions as well as for the work of adhesion are summarized in Table 3.6. Notice that the work of adhesion corresponds to the cross term of the interfacial tension expression (under the square roots), which reflects different contributions of intermolecular forces, according to the various theories (either the total surface tensions in Girifalco—Good and Neumann, only those contributions due to dispersion forces in Fowkes, due to both dispersion and specific forces in Owens-Wendt, separately dispersion, polar and hydrogen bonding ones in Hansen/Beerbower, or the van der Waals and as5mimetric acid/base effects in van Oss et ai). 

All theories have strengths and weaknesses and it may be difficult to decide a priori which theory is the best. Perhaps for this reason, several textbooks (Shaw, 1992 Hamley, 2000 Goodwin, 2004 Israelachvilli, 1985) present only the very simple theories of Fowkes and Girifalco-Good, possibly for illustration purposes, while others (Pashley and Karaman, 2004) do not present any theories at all for estimating the interfacial tension( ). 

Many theories have been proposed for the estimation of interfacial tensions, many more than just the Fowkes, Girifalco-Good and Hansen-Beerbower. These theories can be tested against experimental data for liquid—liquid interfaces but testing is more difficult for solid-liquid interfaces (where the interfacial tension cannot be measured directly). 

The Fowkes, Girifalco-Good and Hansen are all theories for estimating the interfacial tension of solid-liquid (and other) interfaces. Which statement is always correct ... 

A very simple theory for the interfacial tension that performs satisfactorily in some simple cases is given by a modified form of the Girifalco-Good equation (using a correction parameter equal to one) ... 

The authors postulate that a solid and a liquid of similar polarity will give a minimum value of y%. Kitazaki and Hata also discuss the ramifications of their postulates and experimeiital results on adhesion measurements. Overall their conclusion is that a maximum is achieved when the polarities of the solid surface and the adhesive are as similar as possible. From the Good and Girifalco theory, a maximum in would also be expected when the interparticle forces across the interface are at a maximum. Wu has also analyzed the separation of the force components of the interfacial and surface tensions. Wu, however, chooses to make an arithmetic mean approximation rather than the geometric mean approximation used by Good and by Fowkes. He bases this choice on an analogy with the form of the expressions for the interparticle forces, which are more closely mimicked by an arithmetic mean. Wu contends that his use of the arithmetic mean yields results closer to measured values. 

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