From the contact angle θ determined with one liquid of known surface tension only it is possible to obtain the values of the surface tensions γ sv and γ sl via the equation of state 1.
Contact angle surface energy conversion.
Is contact angle h is the height of a droplet and r is the radius of droplet s base see fig.
Static contact angle offers a quick easy and quantitative measurement of wettability.
The contact angle is measured as the inward angle between the base and the tangent at the point of contact between the liquid and the surface.
A more general approach to understanding a surface s wettability is through surface free energy analysis.
The angle between the droplet outline and the solid surface is the contact angle.
It is most suitable for relatively smooth and homogenous surfaces.
By measuring the contact angle formed by probe liquids with known surface tensions values the surface free energy components are calculated using analysis models.
2 arc tan h r where.
Static contact angles are by far the most measured wettability values.
The two last mentioned quantities are.
Where the subscripts s and l stand for the solid s and the liquid l whilst the subscript v stands for vapor.
This value corresponds to the surface energy level in the equilibrium.
In this method the contact angle of the surface is measured with several liquids usually water and diiodomethane.
I would like to calculate the surface free energy of solid by using contact angle measurement of liquid by the relation of young s equation.
Static contact angles are also used to define the surface free energy i e.
Tantec s half angle method is based on the formula for determining contact angles from the droplet dimensions.
ϒ s ϒ sl ϒ l cos θ where the inter facial.
Contact angle ca measurements provide quantitative data on the interfacial energy between a liquid drop and a solid surface.
This may raise the question of how we equate surface energy density units j m 2 with surface tension units n m.
This can occur with a low surface energy solid or a high surface tension liquid such as water.
Based on the contact angle results and knowing the surface tension of the liquids the surface energy can be calculated.
For complete data the advancing receding and static contact angles must be measured.
This is commonly referred to as a contact angle measurement using the sessile drop method.
In practice this analysis is done automatically by a contact angle meter.
The most common way to measure surface energy is through contact angle experiments.
