Method for measuring liquid surface tension based on two measurement points of liquid drop profile curve

Abstract

The invention relates to a method for measuring liquid surface tension based on two measurement points of a liquid drop profile curve. The method comprises the following steps: shooting a picture of a liquid drop spread on the upper surface of an auxiliary test platform or a picture of a liquid drop suspended below a horizontally-placed axial symmetric auxiliary bearing surface by an image acquisition device; processing the picture to draw a liquid drop profile curve; selecting two measurement points on the liquid drop profile curve to measure the vertical distance between the two measurement points, the distances between the intersection points between the horizontal lines across the measurement points and the liquid drop profile curve, and the angles between the tangent lines of the liquid drop profile curve at the two measurement points and the horizontal line; measuring the volume of the liquid between the horizontal planes where the two measurement points are located according to the liquid drop profile curve; and then directly measuring the interfacial tension of the liquid. The interfacial tension of the liquid calculated by directly measuring the liquid drop profile curve does not need the assistance of a complex numerical modeling process. The interfacial tension of the liquid can be measured in case of the absence of the vertex of the liquid drop profile curve or the absence of a local profile curve.

Description

technical field [0001] The invention relates to the technical field of liquid performance testing, in particular to a method for measuring the interfacial tension of a liquid by measuring geometric parameters at two selected measurement points on an axisymmetric droplet profile curve and calculating the liquid volume between the two measurement points. It is suitable for the situation that the small droplet formed by the liquid measured in the sessile drop method can have a contact angle greater than 90° on the surface of the auxiliary measurement platform or the maximum width of the droplet profile curve obtained by the pendant drop method (the droplet profile curve and The maximum value of the distance between two intersection points where a horizontal straight line intersects) The measurement of the interfacial tension of a liquid when the position is not on the axisymmetric auxiliary support surface, especially suitable for liquid interfacial tension with only a small volum...

AI Technical Summary

Problems solved by technology

However, the realization of these two methods depends on the clearly identifiable vertices of the droplet contour curve, which limits the scope of application of these two methods: on the one hand, due to the influence of light during the test, the contour of the droplet contour curve Missing phenomenon may occur, at this time it is difficult to obtain the radius of curvature of the droplet profile curve at the vertex and the height of the droplet, thus making the measurement method invalid; on the other hand, the radius of curvature of the droplet profile curve at the vertex is obtained by approximating The calculation method is obtained by assuming that the curved surface of the droplet in the local area near the vertex is an ideal spherical surface, but in fact, the droplet will be deformed under the action of gravity, so that the distance between the curved surface of the droplet and the ideal spherical surface There are deviations, which will affect the measurement results

Images