Mechanical behaviour of micro-capsules and their rupture under compression

Research output: Contribution to journalResearch articleContributedpeer-review


  • Ali Ghaemi - , University of Bayreuth (Author)
  • Alexandra Philipp - , University of Bayreuth (Author)
  • Andreas Bauer - , Henkel KGaA (Author)
  • Klaus Last - , Follmann GmbH and Co. KG (Author)
  • Andreas Fery - , Chair of Physical Chemistry of Polymeric Materials, University of Bayreuth, Leibniz Institute of Polymer Research Dresden (Author)
  • Stephan Gekle - , University of Bayreuth (Author)


Understanding the deformation of micro-capsules (MCs) and especially the mechanism of their rupture is of crucial importance for their performance in various applications. Mechanical instability can on the one hand be a failure mechanism, resulting in undesired release, but can on the other hand be used as a release trigger. In this work, finite element analysis together with nano-indentation experiments is applied to characterize the deformation of single filled MCs made of melamin-formaldehyde. The simulations reveal that the capsules undergo different deformation regimes: starting from linear elastic deformation, upon further compression the MCs yield and are plastically deformed. The final step is a strain hardening regime, where the maximum stress rapidly increases till the MCs rupture. Finally, we describe the MCs rupture mechanism obtained from numerical simulation and experimental results. We show that the axial and radial stresses cause significant thinning of the shell at the MC's equator, and that the circumferential stress leads to rupture along the meridians of the MC.


Original languageEnglish
Pages (from-to)236-243
Number of pages8
JournalChemical engineering science
Publication statusPublished - 13 Mar 2016



  • Finite element analysis, Microcapsule, Nanoindentation, Plasticity, Rupture, Simulations