Surface morphology of hydrogels and silicones correlates with conditions of controlled fracture

Ali, Nabila

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https://hdl.handle.net/2142/122168 Copy

Description

Title

Surface morphology of hydrogels and silicones correlates with conditions of controlled fracture

Author(s)

Ali, Nabila

Issue Date

2023-12-06

Director of Research (if dissertation) or Advisor (if thesis)

Dunn, Alison C.

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Surface topography
• fractured surface
• elastomers
• entangled hydrogels.

Abstract

Fracturing soft and hydrated materials is a complex task because of the varying energy dissipation within their unique soft networks. The Hutchens group has recently conducted research that involves controlled fracture to break down the energy required to create a new surface into tearing and cutting components based on experimental geometry. This approach allows them to separate the effects of material composition and blade geometry from the pre-stress near the fracture area. As an initial step, we put forth a hypothesis that the surface features resulting from planar cuts on soft materials can represent the energy dynamics of the fracture process. To put this hypothesis to the test, we employed a custom y-shaped cutting device to systematically alter the failure conditions while cutting highly entangled polylacrylamide hydrogel and oil-diluted silicone. We then analyzed the surface features on the cut surfaces, focusing on their morphological characteristics such as height, wedge angles concerning the cutting direction, and periodicity. Our findings indicate that samples with a more substantial tearing contribution to the fracture force exhibit more pronounced surface features, including increased periodicity and greater peak-to-valley distance, on average. This research is expected to provide insights into applications involving the insertion of needles into soft materials, where the process of fracturing at the needle tip and the friction along the needle shaft are intricately linked, particularly through the presence of damaged surface features.

Graduation Semester

2023-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/122168

Copyright and License Information

Copyright 2023 Nabila Ali

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