This work uses high-speed video imaging to study the formation of filaments,
during impact and rebounding of drops with polymer additives. We use PEO of
different concentrations from 10 to 1000 ppm and study how drops rebound from
various different surfaces: superhydrophilic, hydrophilic, hydrophobic, and
superhydrophobic. Bouncing occurs for all surfaces at low impact velocities. We
specifically focus on the phenomenon of the generation of polymer filaments, which are
pulled out of the free surface of the drop during its rebounding from micro-pillared or
rough substrates. We map the parameter regime, in terms of polymer concentration
and impact Weber number, where the filaments are generated in the most repeatable
manner. This occurs for regularly pillared surfaces and drops of 100 ppm PEO
concentrations, where numerous separated filaments are observed. In contrast, for
superhydrophobic coatings with random roughness the filaments tend to merge forming
a branching structure. Impacts on inclined surfaces are used to deposit the filaments on
top of the pillars for detailed study.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/668998 |
| Date | 04 1900 |
| Creators | Al Julaih, Ali |
| Contributors | Thoroddsen, Sigurdur T, Physical Science and Engineering (PSE) Division, Lacoste, Deanna, Mishra, Himanshu |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | 2022-04-28, At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis will become available to the public after the expiration of the embargo on 2022-04-28. |
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