| 摘要 |
<p>The device provided is a tensiometer, it is an experimental device that allows the surface tension of liquids to be measured. It consists of: an electromagnetic force sensor, to which a rectangular strip of glass is attached by way of a rod that is securely fastened to it; a scissor lift; and a beaker that contains the liquid to be studied. Using the lift the beaker is gradually raised until the free surface of the liquid and the lower part of the strip, the width and thickness of which are known, make contact. Next, the beaker is gradually lowered using the scissor lift, the tension measured by the force sensor gradually increases as the beaker is lowered until the strip tearing limit, where the tension reaches its maximum value. Prior calibration of the sensor allows the tearing force of the strip to be calculated, and the surface tension of the liquid to be deduced therefrom. The measurement range of the electromagnetic force sensor (electromagnetic dynamometer) is comprised between 0 mN and 30 mN, and returns measurements with a precision of DeltaF = 10-2 mN. By attaching an attachment to the electromagnetic force sensor, the surface tension of liquids may be measured simply by weighing N droplets of a given drop count, knowing its capillary diameter. In this case, the force sensor is used as an electromagnetic weighing scale the measurement range of which is between 0 g and 3 g, and returns values with a precision Deltam = 1 mg. Surface tension measurements were carried out on water/ethanol mixtures using both techniques (strip tearing method and falling droplets of a drop count method), the results obtained by these two techniques were in very good agreement. Surface tension measurements were also carried out on pure liquids (distilled water, methanol and acetic acids) the results obtained were in very good agreement with results from the literature.</p> |
