Measuring contact angle of immiscible liquids

In summary, the contact angle of immiscible liquids is measured using a goniometer, which calculates the angle between the solid surface and the tangent line of the liquid interface. This measurement is significant in understanding the wetting behavior of a solid surface and can provide information on its surface energy, roughness, and chemistry. The surface tension of the liquids can affect the contact angle measurement, with higher tension resulting in a smaller angle and lower tension resulting in a larger angle. The contact angle can also change over time due to factors such as evaporation, adsorption, and surface roughness changes. However, there are limitations to this measurement, such as surface roughness, impurities, and surfactants, which can affect its accuracy.
  • #1
AqibH
16
0
I am looking for sources which describe how to measure the contact angle between immiscible liquids in a tube. The literature seems to be extremely lacking so if anyone has any knowledge I would appreciate the help.
 
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  • #2
A profile projector (aka optical comparator) perhaps?
 
  • #3
You might use an optical or an ultrasonic sensor. As you advance the sensor along the axis of the tube there will be a point where the conical surface of the contact annulus reflects directly back to the sensor. Block the direct axial reflection. Measure the sensor position with a micrometer or an LVDT.
 

1. How is the contact angle of immiscible liquids measured?

The contact angle of immiscible liquids is typically measured using a goniometer. This instrument measures the angle between the solid surface and the tangent line of the liquid interface. The contact angle is then calculated using the Young-Laplace equation.

2. What is the significance of measuring the contact angle of immiscible liquids?

The contact angle of immiscible liquids is an important parameter in understanding the wetting behavior of a solid surface. It can provide information on the surface energy, surface roughness, and surface chemistry of a material.

3. How does the surface tension of the liquids affect the contact angle measurement?

The surface tension of the liquids can greatly influence the contact angle measurement. Higher surface tension typically results in a smaller contact angle, while lower surface tension can lead to a larger contact angle. This is due to the balance of forces at the liquid-solid interface.

4. Can the contact angle of immiscible liquids change over time?

Yes, the contact angle of immiscible liquids can change over time due to various factors such as evaporation, adsorption, and surface roughness changes. It is important to measure the contact angle at a consistent time interval to ensure accurate results.

5. Are there any limitations to measuring the contact angle of immiscible liquids?

Yes, there are some limitations to measuring the contact angle of immiscible liquids. The surface roughness of the solid surface, impurities on the surface, and the presence of surfactants can all affect the accuracy of the measurement. It is important to carefully prepare the sample and consider these factors when conducting the measurement.

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