Scientists led by CEE Professor Oscar Lopez-Pamies have derived the governing equations that explain and describe the macroscopic mechanical behavior of elastomers filled with liquid inclusions directly related to their microscopic behavior.
Oscar Lopez-Pamies. Image Credit: University of Illinois Urbana-Champaign
The study is explained in an article by Lopez-Pamies and Ph.D. Student Kamalendu Ghosh recently reported in the Journal of the Mechanics and Physics of Solids.
This work was done as part of the Lopez-Pamies grant from the National Science Foundation (NSF) program, Designing Materials to Revolutionize and Engineer our Future (DMREF).
DMREF is known as part of the Multi-Agency Materials Genome Initiative, which aims to prepare the stage for the advancement, manufacture, and deployment of advanced materials.
Since the discovery in the early 1900s that the addition of carbon black and silica nanoparticles to rubber gave rise to a composite material with drastically improved properties, efforts have been continuously made to understand when and how the addition of fillers to elastomers leads to new materials. physical and mechanical properties. The focus has been almost exclusively on solid fill inclusions.
Oscar Lopez-Pamies, lead author of the study, Department of Civil and Environmental Engineering, University of Illinois Urbana – Champaign
Recent experimental and theoretical results have shown that instead of adding solid inclusions to elastomers, liquid inclusions could lead to a new class of even more exciting materials. This has the ability to enable a number of new technologies.
For example, elastomers filled with liquid metals, ferrofluids and ionic liquids thus show special combinations of physical and mechanical properties.
The reason for these new properties is twofold. On the one hand, the addition of liquid inclusions to elastomers increases the overall deformability. This contrasts with the addition of conventional fillers which, being made of rigid solids, decrease the deformability.
Oscar Lopez-Pamies, lead author of the study, Department of Civil and Environmental Engineering, University of Illinois Urbana – Champaign
Lopez added: “In addition, the mechanics and physics of interfaces that separate a solid elastomer from embedded liquid inclusions, although insignificant when inclusions are large, can have a significant and even dominant impact on the macroscopic response of the material when the particles are small. ”
“Surprisingly, the equations state that these materials behave as solids, although solids with a macroscopic behavior that depends directly on the size of the liquid inclusions and the behavior of the elastomer / liquid interfaces,” López-Pamies continued.
Lopez-Pamies concluded: “This allows access to an incredibly wide range of fascinating behaviors by properly adjusting the size of the inclusions and the chemistry of the elastomer / liquid interfaces. One of those notable behaviors is the effect of inclusions can be made to disappear. “
Magazine reference:
Ghosh, K. & Lopez-Pamies, O. (2022) Elastomers full of liquid inclusions: theory, numerical implementation and some basic results. Journal of Solid Mechanics and Physics. doi.org/10.1016/j.jmps.2022.104930.
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