# Nonlinear Viscoelasticity of Sorbitan Tristearate Monolayers at Liquid/Gas Interface

Krishnaswamy, Rema and Majumdar, Sayantan and Sood, AK (2007) Nonlinear Viscoelasticity of Sorbitan Tristearate Monolayers at Liquid/Gas Interface. In: Langmuir, 23 (26). pp. 12951-12958.

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## Abstract

The interfacial rheology of sorbitan tristearate monolayers formed at the liquid/air interface reveal a distinct onlinear viscoelastic behavior under oscillatory shear sually observed in many 3D metastable complex fluids with large structural relaxation times. At large strain amplitudes $(\gamma)$, the storage modulus (G') decreases monotonically whereas the loss modulus (G'') exhibits a peak above a critical strain amplitude before it decreases at higher strain amplitudes. The power law decay exponents of G' and G'' are in the ratio 2:1. The peak in G'' is absent at high temperatures and low concentration of sorbitan tristearate. Strain-rate frequency sweep measurements on the monolayers do indicate a strain-rate dependence on the structural relaxation time. The present study on sorbitan tristearate monolayers clearly indicates that the nonlinear viscoelastic behavior in 2D Langmuir monolayers is more general and exhibits many of the features observed in 3D complex fluids.

Item Type: Journal Article Langmuir American Chemical Society Copyright of this article belongs to American Chemical Society. Division of Physical & Mathematical Sciences > Physics 05 Jun 2008 19 Sep 2010 04:45 http://eprints.iisc.ac.in/id/eprint/14205