Q&A: Research improves understanding of particle interactions for better material design
Toothpaste has a hard job. Not only does it have to perform essential functions like scrubbing that coffee residue from your pearly whites, but it also must stay in the tube, exit smoothly under pressure and balance on a bunch of bristles without running all over the bathroom sink. And every user, everywhere, appreciates it when any excess paste extruded, but not needed on the toothbrush, slides seamlessly back into the tube. This is an example of a thixotropic elastoplastic suspension made from many different particles. Now that's a mouthful. According to Norman Wagner, Unidel Robert L. Pigford Chair in Chemical and Biomolecular Engineering at the University of Delaware, these types of suspensions are found in everything from lotions to 3D-printing inks to building block materials for items, including rubber tires, clays, cements and more.
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