Microindentation for Characterization of Interactions in Liquid Metal Composites

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Virginia Tech


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.



Materials Characterization, Soft Matter, Liquid-Metal, Microindentation