Deformation-induced mechanical anisotropy of gelatin films

Weibing Teng, Xiangming Zhang, Valerie Merkle, Xiaoyi Wu

Research output: Contribution to journalArticle

Abstract

Deformation-induced mechanical and structural anisotropy has been analyzed using a gelatin film model. Specifically, gelatin films cast from water and 2,2,2-trifluoroethanol (TFE) are stretched at various draw ratios, locked-in the extended conformations, crosslinked by glutaraldehyde, and then mechanically analyzed in the longitudinal and transverse directions. Notably, the longitudinal modulus of the gelatin films that are cast from water or TFE linearly increases with draw ratio λ, accompanied by a substantial reduction in transverse modulus. When normalized by the Young's modulus of undrawn films, the transverse moduli as a function of draw ratio follow a power-law relationship E/E0∝λα, where α≈-2.5 for the water-cast films and α≈-1.5 for the TFE-cast films. A Scanning Electron Microscopic analysis of the water- and TFE-cast films shows the formation of wrinkles and microcracks oriented in the drawing direction due to large deformations. Fourier Transform Infrared spectroscopy reveals the dominance of aggregated strands and β-sheets in the secondary structures of the gelatin films and the deformation-induced renaturation of triple-helical structures in the films. A model is thus proposed relate the observed mechanical anisotropy of drawn gelatin films to deformation-induced structural anisotropy.

Original languageEnglish (US)
Pages (from-to)18-26
Number of pages9
JournalExtreme Mechanics Letters
Volume7
DOIs
StatePublished - Jun 1 2016

Fingerprint

Trifluoroethanol
Anisotropy
Water
Glutaral
Microcracks
Conformations
Elastic moduli
gelatin film
Scanning
Electrons
Fourier transform infrared spectroscopy
Direction compound

Keywords

  • Gelatin films
  • Large deformation
  • Longitudinal modulus
  • Mechanical anisotropy
  • Transverse modulus

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Bioengineering
  • Engineering (miscellaneous)
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

Deformation-induced mechanical anisotropy of gelatin films. / Teng, Weibing; Zhang, Xiangming; Merkle, Valerie; Wu, Xiaoyi.

In: Extreme Mechanics Letters, Vol. 7, 01.06.2016, p. 18-26.

Research output: Contribution to journalArticle

Teng, Weibing ; Zhang, Xiangming ; Merkle, Valerie ; Wu, Xiaoyi. / Deformation-induced mechanical anisotropy of gelatin films. In: Extreme Mechanics Letters. 2016 ; Vol. 7. pp. 18-26.
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