Adhesion force measurement of the solid-liquid interface

• Author / Creator

  Jain, Palak

• Wetting is the process where solid surfaces attempt to create a common interface when they come in contact with the liquid droplets. To characterize the wetting and spreading between a liquid droplet and a solid surface, various techniques have been established. The most common technique have been used past over two decades is the measurement of contact angle, defined as the angle formed at the interface where all three phases (solid, liquid, surrounding medium) meet. Although contact angle measurements have been studied for over 200 years, the authentic procedure or guidelines to measure contact angle is still in debate. Some authors prefer to quantify surface wettability using dynamic contact angles, whereas some authors report static contact angles measured between a liquid drop sitting on a solid surface. This study discusses the alternative and reliable method for quantification of wettability and adhesion, \textit{i.e,} adhesion force-based measurements using a micro-electronic mechanical balance system. In this technique, a drop holder is suspended and a liquid drop of the desired volume is generated at the tip of the holder facing toward the characterizing substrate. A series of commands has been initialized such as interaction and formation of solid-liquid interface, compression, retraction, and drop detachment, while continuously recording the interactive vertical forces, experienced by the force sensor. There are various parameters/variables involved in this study, which resulted in the variation of droplet base diameter and eventually affect adhesion force. These parameters such as drop volume, retracting speed, and compression allow to maneuver the adhesion force to obtain the required adherence or attachment between two surfaces. After establishing the guidelines to record reproducible and repeatable ( R \& R) results and studying the effect of these commonly operating parameters on adhesion force, we have also discussed the effect of the surrounding medium and performed experiments in the liquid medium. Unlike the air medium, we observed that the force sensor experienced other forces as well along with interactive forces underwater. Forces such as buoyancy and hydrostatic pressure must be subtracted from total vertical force to get absolute adhesion force. Lastly, components of adhesion force; surface tension, and Laplace pressure force are also critically analyzed with respect to drop volume and compression. This study also introduces the normalization of total adhesion force and its components to negate the influence of varied droplet base diameter.

• Subjects / Keywords

  • Adhesion force measurement
  • wetting
  • surface wettability
  • force tensiometer

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-xygd-zq04

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.