Centro‐symmetric technique for measuring shear modulus, viscosity, and surface tension of spread monolayers
作者:
B. M. Abraham,
K. Miyano,
S. Q. Xu,
J. B. Ketterson,
期刊:
Review of Scientific Instruments
(AIP Available online 1983)
卷期:
Volume 54,
issue 2
页码: 213-219
ISSN:0034-6748
年代: 1983
DOI:10.1063/1.1137348
出版商: AIP
数据来源: AIP
摘要:
We have constructed an apparatus which enables one to measure, simultaneously, the shear modulus, the viscosity, and the surface pressure of a monomolecular film on water under a hydrostatic compression. It is particularly suitable for measurements of the static shear modulus of insoluble monolayers. A capillary wave generator/detector system was also incorporated to determine the surface pressure. The trough is a Teflon cup 12.7 cm (5.4 in.) in inner diameter with sloping interior sides. As the cup is raised, while maintaining the water elevation fixed, the film is uniformly compressed. A rotor suspended at the center from a fine torsion fiber is used to measure the mechanical properties (surface viscosity and/or surface shear modulus). To measure the quasistatic shear properties, the cup is rotated through a small angle and the residual deflection of the rotor determined. Dynamic shear response is probed by studying transient torsional oscillations following a sudden angular displacement of the torsion fiber. There are no barrier seals and circular symmetry is maintained at all times. The apparatus has a resolution of 5×10−4surface poise of shear viscosity and 1×10−4dyn/cm of static shear modulus.
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