TY - JOUR

T1 - Shear response of Langmuir monolayers of heneicosanoic ([Formula Presented]) acid studied using a torsion pendulum

AU - Ghaskadvi, R. S.

AU - Bohanon, T. M.

AU - Dutta, P.

AU - Ketterson, J. B.

PY - 1996

Y1 - 1996

N2 - 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.

AB - 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.

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U2 - 10.1103/PhysRevE.54.1770

DO - 10.1103/PhysRevE.54.1770

M3 - Article

AN - SCOPUS:0000864362

SN - 1063-651X

VL - 54

SP - 1770

EP - 1773

JO - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

JF - Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

IS - 2

ER -