Measuring contact angles inside of capillary tubes with a tensiometer

Area of Science:

• Materials Science
• Surface Chemistry
• Fluid Dynamics

Background:

• Accurate measurement of liquid-solid interactions is crucial for understanding material wettability.
• Traditional tensiometry methods are often limited in analyzing wettability within confined geometries like small tubes or hollow fibers.

Purpose of the Study:

• To introduce and validate a new tensiometry method for determining wetting and advancing contact angles in small diameter tubes.
• To demonstrate the applicability of this method for both transparent and opaque tube materials.

Main Methods:

• A novel tensiometry technique was developed, utilizing the maximum force from liquid rise height to estimate advancing contact angles.
• The method was validated using transparent tubes made of glass, poly(carbonate) (PC), and poly(tetrafluoroethylene) (PTFE) with various liquids.
• The technique was further demonstrated with opaque poly(ether ether ketone) (PEEK) tubes.

Main Results:

• The tensiometry method accurately determined advancing contact angles in small tubes, showing good agreement with estimations from final liquid rise height.
• The technique successfully measured wettability within opaque PEEK tubes, highlighting its versatility.
• Validation with multiple materials and liquids confirmed the reliability of the new method.

Conclusions:

• The developed tensiometry method provides a robust and versatile approach for quantifying wettability and contact angles in small diameter tubes.
• Its ability to analyze opaque materials overcomes limitations of visual methods, broadening its application in material science and engineering.