Liquid surface tension testing method based on mechanical vibration of liquid droplet

Abstract

The invention relates to a liquid surface tension testing method based on mechanical vibration of a liquid droplet. The method specifically comprises the following steps: placing a hydrophobic substrate on a Doppler ultrasonic probe, and generating a liquid droplet on the hydrophobic substrate; vibrating a triggering device to freely vibrate the liquid droplet; converting free vibration of capillary waves on the surface of the liquid droplet into an ultrasonic Doppler frequency shift signal through the ultrasonic probe by using a non-focusing continuous wave Doppler method, and amplifying theultrasonic Doppler frequency shift signal; acquiring a free vibration characteristic diagram of the liquid droplet from the ultrasonic Doppler frequency shift signal by using a computer signal processing module, performing Fourier transform so as to obtain a vibration frequency characteristic diagram, analyzing the vibration frequency characteristic diagram, and reading frequency of a second harmonic generation peak; by taking the reciprocal of the mass of the liquid droplet as a transverse coordinate, and the square of the frequency of the second harmonic generation peak as a longitudinal coordinate, drawing diagrams, fitting straight lines, calculating a straight slope, and further calculating the surface tension of the liquid droplet. The method based on ultrasonic Doppler frequency shifting is capable of carrying out frequency measurement on ultrasonic signals, and has the advantages of reagent conservation, high performance cost ratios and portability.

Description

Technical field [0001] The invention belongs to the technical field of liquid physical and chemical properties measurement, and specifically relates to a liquid surface tension test method based on droplet mechanical vibration. Background technique [0002] The surface tension of a liquid is an important property of a liquid. In a normal temperature system, it can be used to determine the surface activity and calculate the adsorption amount of the surfactant on the surface of the solution. There are many methods for measuring surface tension. According to the measurement principle, it can be divided into dynamic method and statics method. The dynamic method calculates the surface tension by measuring the value that determines a certain process, while the statics method measures the value under a certain state. Some specific values ​​are used to calculate the surface tension. The static drop method, which calculates the surface tension based on the natural shape of the droplet on...

AI Technical Summary

Problems solved by technology

The static drop method, which calculates the surface tension based on the natural shape of the droplet on a horizontal glass slide, is a static method. The traditional static drop method is based on the Laplace'sequation (Laplace's equation) in physics. The relationship between contour and surface tension is calculated, but the calculation is cumbersome, error-prone and time-consuming

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