Surface tension tensiometer

Recently, a very practical bubble pressure tensiometer was developed using elegant pressure transducer mechanics which only needs one capillary made from a high-tech polymer [51, 52]. The tensiometer is able to measure at different immersion depths but needs calibration in order to make the resulting data comparable to surface tension values from other sources. It was shown in a series of measure-... 

Surface Tension Measurement. Surface tension was determined with a Rosano Tensiometer (Arenberg-Sage Inc., Jamaica Plain, Mass.) utilizing a sand-blasted platinum blade. 

The surface tension measurements were obtained with a Precision Cenco-du-Nouy Tensiometer, No. 70540. The solvents and saturated solutions were prethermostatted to 25.0°C prior to each measurement. The temperature of the solutions was determined subsequent to the measurements, and adjustments were made to coincide with a temperature deviation from 25.0°C. Only reproducible values were retained. R/r and L for the platinum ring used for the surface tension measurements were 53.6 and 5.997 cm, respectively. The factor F, which corrects for liquid elevated above the free surface of the liquid by the ring in the relationship y = Mg/2L X F, was determined (37) for each particular solvent. 

R = mean radius of the tensiometer ring used in the surface tension studies,... 

The monolayer was compressed manually and in stages for this part of the study, and the surface viscosity was determined at every stage of the compression. Surface tensions were monitored with a Rosano tensiometer (Federal Pacific Electric Co., Newark, N. J.). The time required for determining surface viscosity at a single surface concentration was 2 to 3 minutes. 

The maximum surface tension recorded is proportional to the force needed to remove the ring from the liquid interface and is directly proportional to the surface tension of the liquid. Figure D3.6.2 shows a plot of the recorded force as a function of the experimental time. Modern tensiometers that are connected to a computer not only record the entire experiment but also automatically compute the surface tension. 

Modem drop volume tensiometers are connected to a computer with sophisticated software that can be used to automatically record the surface tension as a function of the true interfacial age. Adsorption kinetics experiments with the drop volume technique can be conducted using either the constant drop formation method or the quasistatic method (for details, see Commentary). The choice of the dynamic measurement method depends primarily on the time range over which the adsorption kinetics needs to be measured. 

Important techniques to measure the surface tension of liquids are the sessile drop method, the pendant or sessile bubble method, the Du-Notiy ring tensiometer, and the Wilhelmy-plate method. 

Viscosity and density of the component phases can be measured with confidence by conventional methods, as can the interfacial tension between a pure liquid and a gas. The interfacial tension of a system involving a solution or micellar dispersion becomes less satisfactory, because the interfacial free energy depends on the concentration of solute at the interface. Dynamic methods and even some of the so-called static methods involve the creation of new surfaces. Since the establishment of equilibrium between this surface and the solute in the body of the solution requires a finite amount of time, the value measured will be in error if the measurement is made more rapidly than the solute can diffuse to the fresh surface. Eckenfelder and Barnhart (Am. Inst. Chem. Engrs., 42d national meeting, Repr. 30, Atlanta, 1960) found that measurements of the surface tension of sodium lauryl sulfate solutions by maximum bubble pressure were higher than those by DuNuoy tensiometer by 40 to 90 percent, the larger factor corresponding to a concentration of about 100 ppm, and the smaller to a concentration of 2500 ppm of sulfate. 

It is apparent from Eq.(30) that the higher the temperature of the first stage reactor and the value of r, the smaller the value of %ax This may be the reason why Degraff and Poehlein could not find 8max in their experiments. Equation(31) suggests that one can estimate the value of max simply by determing tc by measuring surface tension with the use of, for example, a du-Nouy tensiometer. ... 

Figure 2.56 Schematic diagram of a tensiometer used to measure surface tension of liquids.

For liquids of low viscosity, a useful measurement technique is the tensiometer, schematically represented in Fig. 2.56. Here, the surface tension is related to the force it takes to pull a platinum ring from a solution. Surface tension for selected polymers are listed in Table 2.12 [71 ], for some solvents in Table 2.13 [58] and between polymer-polymer systems in Table 2.14 [71],... 

The changes in the culture s surface tension were evaluated by the ring Du Nouy method (29) using a SIGMA70 system unit (KSV Instruments, Trumbull, CT) tensiometer. Measurements were performed at 25°C. The decrease in surface tension was used as a qualitative measurement of surfactant concentration and a quantitative indicator of efficiency. 

In some cases the surface tension also was measured by the ring method using a du Noiiy tensiometer. 

Experimental Procedure -- The surface tensions of Triton X-100 solutions, with or without other additives, were measured using a du Nouy ring tensiometer (Fisher Scientific Company) at 25°C. 

The initial concentration (0.001 wt% active) was selected from the measurement of surface and interfacial tensions. It lies in the range of CMC value for these measurements, which were performed by using the Wilhelmy plate method in a Rosano surface tensiometer. The standard procedure described in the manual was carefully followed. Surface tension was measured against the air, whereas the interfacial tension was measured against isooctane, which was used to simulate dense CO2. It is well known fact that good foamers are most effective well above the CMC range and in subsequent tests the concentrations were increased well above that range. 

Surface Tension Measurements. The surface tension of each HA or FA solution was measured using a du Nouy ring tensiometer as previously described (13). 

Equilibrium surface pressure (TTg) values were calculated as TTg = ct-q — (Te, where (a-g) is the equilibrium surface tension and oq is the solvent surface tension. They were measured by the Wilhelmy plate method, using a platinum plate attached to a Sigma digital tensiometer. The range of concentrations studied were 5 X 10 to 2% wt. 

Static and dynamic surface tension of marine water onshore or platform-based measurements by the oscillating bubble tensiometer... 

Figure 6.7 Liquid surface tension determination by the spinning drop tensiometer method. A liquid drop (7) is suspended in an immiscible denser liquid (2) in a horizontal transparent tube which can be spun about its longitudinal axis, and the drop (7) elongates from a spherical shape to a prolate ellipsoid with increasing speed of revolution. Later, the drop becomes approximately cylindrical, at very high rotational velocities. A camera with a frame grabber captures the images of the drop inside the transparent tube.

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