Three-phase interline

While the surface tension of the adhesive, is easily measured in the laboratory, the other terms in Wa, by themselves, are not. A second easily measurable property associated with the solid-liquid-air system, however, is the contact angle, 9, the angle, drawn in the liquid, between the solid-liquid and the liquid-air interfaces, drawn in the plane perpendicular to the three-phase interline, as shown in Fig. 4. Minimization of the free energy of the solid-liquid-air... 

Fig. 4. Definition of contact angle showing the derivation of Young s equation, Eq.. 8, using a balance of horizontal forces at the three-phase interline.

Figure 5, A and B, shows in sequence the behavior of a water drop at pH 14. In Figure 5, A, the abscissas are the successive volumes of the drop, but in Figure 5, B, the abscissas represent the diameter of the three-phase interline. The ordinates in both A and B are the observed contact angles. Figure 5, B, shows that the drop expands with constant 0 = to an interfacial diameter of approximately 1.0 mm. At this point the volume increase is stopped. During the 18 seconds that elapsed before the drop volume reduction was started, the system showed a slight relaxation phenomenon, which increased the three-phase interline diameter, and slightly decreased 0, while the drop volume remained constant (square dots in 5, B). When the drop volume was reduced, steadily decreased to zero while the interfacial area, Hg-H20, remained constant. When 0 reached zero, a thin film remained on the mercury surface.

B. Contact angle vs. diameter of three-phase interline... 

Speed Dependence. All experiments done with the controlled drop volume method are inherently accompanied by a steadily varying speed of lateral movement of the three-phase interline. As the rate of volume change remains constant throughout each experiment, the lateral movement of the three-phase interline decreases with increasing drop volume and increases with decreasing drop volume. For our experiments with a maximal drop volume of 3.4 cu. mm., a drop volume change of 0.0189 cu. mm. per second, and a 0 of 119°, the speed (computed over 6 seconds) varied from0.3 x lO to 0.1 mm. per second. 

In these experiments 6j is independent of the rate of movement of the three-phase interline over the whole speed range. Not so with 0. The maximum hysteresis depends not only on the velocity of movement of the interline when the drop is shrinking, but also on the duration of contact at maximal diameter, and the magnitude of the maximal drop volume. Table III, for example, illustrates the effect of changing the duration of contact at maximal diameter. 

Electrochemically driven three-phase interlines into insulator compounds electroreduction of solid SiQ2 in moltrm CaQ2. Chemphyschem 7 1750-1758... 

Hu, X. and Chen, G.Z. (2005) Electrochemistry at conductor/insulator/ electrolyte three-phase interlines a thin layer model. Journal of Physical Chemistry B, 109,14043-51. 

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