1. Sessile Drop Method (Static Contact Angle)

In Sessile drop technique a small drop of water is placed on the surface of the substrate.
A microscope or CCD camera with a built-in zoom lens allows close inspection and
measurement of the angle of contact between the droplet and the surface of the substrate.

The contact angle between a liquid and a solid is a measure of the interaction between the
solid and the liquid. This is usually determined using the sessile droplet method.

This contact angle represents the surface energy, or wettability of the surface of the
substrate.

The SEO Phoenix series offers a cost effective and accurate contact angle & surface
energy on the surface.

SEO Phx'es series

(Goniometer Type)



(CCD camera w/frame Grabber Type)



2. Captive Method (Dynamic Contact Angle)

To determine the advancing / receding contact angle, the measurements are performed
while the volume of the droplet is being increased, thus increasing the liquid-solid interface
area. This angle is generally larger than the receding contact angle, which is measured
when the size of the droplet is being reduced. The difference between the advancing
contact angle and the receding contact angle is referred to as the contact angle
hysteresis.

Its magnitude is dependent on the roughness, morphology and chemical homogeneity of
the solid surface, and also on the molecular reorganization processes at the interface.
SEO Equipment available measuring the Captive method.





3. Tilt Method

SEO Contact angle Analyzer which uses the sessile drop technique with an available
tilt stage for measuring dynamic Contact angle (advancing and receding Contact Angle).

further added work of adhesion between liquid and solid



4. Wilhelmy (Plate) Method (Dynamic Contact Angle)

The Wilhelmy plate technique provides the most accurate and repeatable measurements.
In the wilhelmy method, the Plate is hanged perpendicular to the liquid's surface.
It consists of putting a thin Pt plate or Clean glass in the test liquid and measure the force
acting on the plate when the system is at equilibrium.




 

The contact angle is a tangent angle between the interfaces formed when a phase contacts
tothe other immiscible phase. As the interfaces are equilibrated, the contact angle is called
to the equilibrated (or static) contact angle. The contact angle is applied to adhesive
materials, coating technology, polymer area, thin film technology, and surface treatment as
well as the interface science and technology.



As shown in Figure 1, when a liquid drop is settled on a solid surface, the contact angle of
the drop on the solid surface is defined by the mechanical equilibrium, of the drop under the
action of three interfacial tensions. The equilibrium relation is known as Young’sequation:




where qYis the Young contact angle, which is suited in the Young’s equation. The Young’s
equation represents that the contact angle measured in the field should be Young contact
angle if one used the Young equation or any other equation connect to the Young equation.