Shear response of Langmuir monolayers of heneicosanoic ([Formula Presented]) acid studied using a torsion pendulum

R. S. Ghaskadvi, T. M. Bohanon, P. Dutta, J. B. Ketterson

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

We have studied the shear relaxation of heneicosanoic ([Formula Presented]) acid monolayers on the surface of water at different temperatures and pressures, in the CS, [Formula Presented], [Formula Presented], and S phases. A torsion pendulum was displaced from its equilibrium position by an angle θ(0) and the relaxation θ(t) was measured. Only the CS phase sustains a static shear (∼160 dyn/cm) at the time scales studied (≊[Formula Presented] s). The data fit well to a stretched exponential form θ(t)=θ(∞)+θ(0)-θ(∞)exp-(t/τ[Formula Presented]. We find that k[Formula Presented]/n is independent of the torsion constant k; this implies that the viscosity is time dependent. k[Formula Presented]/n is a strong function of pressure and temperature. At phase boundaries there is a discontinuity in either k[Formula Presented]/n or its slope.

Original languageEnglish (US)
Pages (from-to)1770-1773
Number of pages4
JournalPhysical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
Volume54
Issue number2
DOIs
StatePublished - 1996

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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