Mechanical properties of microcapsules used in a self-healing polymer

M. W. Keller, N. R. Sottos

Research output: Contribution to journalArticlepeer-review


The elastic modulus and failure behavior of poly(urea-formaldehyde) shelled microcapsules were determined through single-capsule compression tests. Capsules were tested both dry and immersed in a fluid isotonic with the encapsulent. The testing of capsules immersed in a fluid had little influence on mechanical behavior in the elastic regime. Elastic modulus of the capsule shell wall was extracted by comparison with a shell theory model for the compression of a fluid filled microcapsule. Average capsule shell wall modulus was 3.7 GPa, regardless of whether the capsule was tested immersed or dry. Microcapsule diameter was found to have a significant effect on failure strength, with smaller capsules sustaining higher loads before failure. Capsule size had no effect on the modulus value determined from comparison with theory.

Original languageEnglish (US)
Pages (from-to)725-733
Number of pages9
JournalExperimental Mechanics
Issue number6
StatePublished - Dec 2006


  • Compression
  • Microcapsule
  • Modulus
  • Self-healing composite
  • Strength
  • Urea-formaldehyde

ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics


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