Contact angle tensiometric

Considering Eq. (39), it can be noted that the major variable on the y-axis (in left-hand side) is yFH cos 0sfh which becomes identical with yH FFh/Fha using Eq. (43). In association of Eq. (39) with Eq. (43), the direct calculation of contact angle, 0sfh, is not required in this tensiometric method, as seen in Fig. 5. 

In this section, we have examined the characteristics of fiber surfaces obtained by two-liquid tensiometric technique which could allow the energetic study of cylindrical solids with very small diameter, comparing to the classical contact angle method. 

Dynamic contact angles are the angles which can be measured if the three-phase boundary (liquid/solid/vapor) is in actual motion. A Wilhelmy plate is used in dynamic contact angle measurements, and this method is also called the tensiometric contact angle method. It has been extensively applied to solid-liquid contact angle determinations in recent years. In practice, a solid substrate is cut as a thin rectangular plate, otherwise a solid material is... 

Considering curved surfaces, then the contact angles of various liquids on the cylindrical surfaces of fibres have been determined using the tensiometric (or Wilhelmy) plate method [13,14] or by calculating the value of 0 from measurements of drop size and fibre diameter [15,16]. 

The Wilhelmy plate or tensiometric method is widely used for measuring equilibrium, advancing and receding contact angles. This is described fully in the next section as it is one of the few techniques which are generally applicable to materials of cylindrical cross-section such as fibres. 

Figure 3 Techniques for measuring contact angles on fibres (a) and (b) tensiometric or Wilhelmy plate technique for measurement of advancing and receding angles (a) fibre touching liquid surface (b) fibre after immersion in liquid to depth d and (c) drop on fibre technique for measurement of equilibrium contact angle...

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