The Mathematical Institute, University of Oxford, Eprints Archive

Elastometry of deflated capsules elastic moduli from shape and wrinkle analysis

Knoche, S. and Vella, D. and Aumaitre, E. and Degen, P. and Rehage, H. and Cicuta, P. and Kierfeld, J. (2013) Elastometry of deflated capsules elastic moduli from shape and wrinkle analysis. Physical Review Letters . (Submitted)



Elastic capsules, prepared from droplets or bubbles attached to a capillary (as in a pendant drop tensiometer), can be deflated by suction through the capillary. We study this deflation and show that a combined analysis of the shape and wrinkling characteristics enables us to determine the elastic properties in situ. Shape contours are analyzed and fitted using shape equations derived from nonlinear membrane-shell theory to give the elastic modulus, Poisson ratio and stress distribution of the membrane. We include wrinkles, which generically form upon deflation, within the shape analysis. Measuring the wavelength of wrinkles and using the calculated stress distribution gives the bending stiffness of the membrane. We illustrate this method on two very different capsule materials: polymerized octadecyltrichlorosilane (OTS) capsules and hydrophobin (HFBII) coated bubbles. Our results are in agreement with the available rheological data. For hydrophobin coated bubbles the method reveals an interesting nonlinear behavior consistent with the hydrophobin molecules having
a rigid core surrounded by a softer shell.

Item Type:Article
Subjects:D - G > General
Research Groups:Oxford Centre for Collaborative Applied Mathematics
ID Code:1716
Deposited By: Peter Hudston
Deposited On:30 Jul 2013 13:16
Last Modified:29 May 2015 19:24

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