Scientists led by Professor Oscar Lopez-Pamis of CEE have derived control equations that explain and describe the macroscopic mechanical behavior of elastomers filled with liquid inclusions directly on 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 carried out as part of the Lopez-Pamies grant from the National Science Foundation (NSF) program, Design of Materials for Revolution and Engineering of Our Future (DMREF).
DMREF is known as part of the multi-agency Materials Genome Initiative, which aims to lay the foundation for the breakthrough, production and implementation of modern materials.
Ever since the discovery in the early 1900s that the addition of carbon black and nanoparticles to rubber resulted in a composite material with drastically improved properties, efforts have been made to understand when and how adding fillers to elastomers leads to materials with new mechanical properties. and physical properties. The focus is almost exclusively on the inclusion of solid fillers.
Oscar Lopez-Pamis, Corresponding Author, Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign
Recent experimental and theoretical results show that instead of adding solid inclusions to elastomers, liquid inclusions can lead to even a very exciting new class of materials. This has the ability to allow a range of new technologies.
For example, elastomers filled with liquid metals, ferrofluids and ionic liquids, thus showing special combinations of physical and mechanical properties.
The reason for such 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, because they are made from solids, reduce deformability.
Oscar Lopez-Pamis, Corresponding Author, Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign
Lopez-Pamis added: “Furthermore, the mechanics and physics of the interfaces separating the rigid elastomer from the embedded liquid inclusions, although insignificant when the inclusions are large, can have a significant and even dominant effect on the macroscopic response of the material when the particles are small. . ”
“Surprisingly, the equations show that these materials behave like solids, albeit solid, with macroscopic behavior that depends directly on the size of the liquid inclusions and the behavior of the elastomer / liquid interfaces,” Lopez-Pamis continued.
Lopez-Pamis concluded: “This allows access to an incredibly wide range of captivating behaviors by properly adjusting the size of the inclusions and the chemistry of the elastomer / fluid interfaces. One such remarkable behavior is “cover-up”, when the effect of inclusions may disappear.
Journal reference:
Ghosh, K. & Lopez-Pamies, O. (2022) Elastomers filled with liquid inclusions: theory, numerical performance, and some key findings. Journal of Mechanics and Physics of Solids. doi.org/10.1016/j.jmps.2022.104930.
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