Study the Behavior of π-A Isotherm with Increasing Amount of Octadecanoic acid at Air–Water Interface

R. S. Bhande, Y. A. Landge and

Abstract

The surface pressure-mean molecular area (π-A) isotherm of surfactant was obtained by using Langmuir balance technique. Characterization of 2-D Langmuir film of Octadecanoic acid (OA) was carried out in term of π –A isotherm and surface pressure–compressibility (π–CS) curve. There has been plenty of work reported on the studies for Langmuir monolayer and Langmuir Blodgett film monolayer or multilayer sampled on solid substrates. However, effect of increasing in amount of surfactant with respect to initial and final surface pressure of on π -A isotherm not been investigated at the air-water interface. Surface pressure–compressibility (π–CS) curves of OA monolayer obtained from the surface pressure area data. The compressibility characterized the phase transition of film more clearly during the monolayer compression and is deemed to be more sensitive for intermolecular interactions especially for their changes. The phase transition point of OA monolayer was shown clearly by a peak in π–CS curve.

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