Liquid Metal (LM) Composites are a rapidly expanding field within function materials research. Composed of isolated LM droplets dispersed in an elastomer, these composites can exhibit properties that include electrical conductivity, thermal conductivity, and programmable and anisotropic mechanical properties. Microindentation is a material characterization technique that can be used to study the micron-scale droplet-droplet interactions between the inclusions in these composites. Because most microindentation systems are incapable of producing plastic/elastic deformation volumes large enough to measure the interaction between inclusion and matrix or inclusion and inclusion in these systems, a specialized microindenter is designed and detailed here. The indenter is then used to test various droplet size, spacings, and matrix material combinations to view the mechanical and electrical implications of these variables. These materials were analyzed with a basic fracture energy scaling formula. It was also found that resistivity can decrease by up to seven orders of magnitude after droplet rupture, with as little as a 20μm elastomer film separating droplets before rupture. Continued studies of these phenomena will allow us to exploit the properties of these materials in new and interesting ways. / Master of Science / When a metal which is a liquid at room temperature (eutectic gallium-indium) is dispersed inside a soft, stretchable material such as a silicone rubber, it creates a unique functional material. These materials go beyond their typical uses by having new and exciting properties such as the ability to conduct heat and electricity. Not only do these materials have these properties, but we can also control them through specific manufacturing steps. These materials are called liquid metal composites or liquid metal embedded elastomers. These materials can be used to create flexible wiring for soft electronics and robots which can bend and stretch to suit their environment. One component of the interactions that lead to these properties is the interaction between pairs of droplets of liquid metal inside of the silicone.
To study these interactions, we utilize micro-indentation which produces very small and precise deformations in a material. By slowly pressing on the material, and measuring forces, displacements, and electrical resistance, we can gain a closer insight into how the interactions of droplets and rubber produce these properties. These materials can be modeled using an analysis of fracture energy, and pairs of droplets decrease electrical resistance by over 10 million times when droplets combine. By studying these interactions, we gain a greater sense of how to control the properties of these materials, and can create new wearable devices that can bend and stretch with the human body's movements.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/119213 |
| Date | 31 May 2024 |
| Creators | Albacarys, Daniel Alexander |
| Contributors | Mechanical Engineering, Bartlett, Michael David, Behkam, Bahareh, West, Robert L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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