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

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Ali, Nabila

Contributors dc:contributor

• Dunn, Alison C.

• Surface Topography
• Fractured Surface
• Elastomers
• Entangled Hydrogels.

Statement dc:rights

• Copyright 2023 Nabila Ali

Language dc:language

en, eng

Handle dc:identifier

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

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F122168