Du Noüy ring method

Abstract: For aqueous solutions of sodium oleate, the dynamic surface tension (using the maximum bubble pressure technique) and the equilibrium surface tensions (using the du Nouy ring method) were studied ...

Abstract: Air−liquid interfacial surface tension measurements were performed on four 1-alkyl-3-methylimidazolium-based ([Cnmim], n = 3, 4, 6, 8) ionic liquids at 15 temperatures from (287 to 353) K at atmospheric pressure. To validate the accuracy of the results, the Wilhelmy plate method and the du Nouy ring method were employed in parallel using the Krűss K100MK2 tensiometer. At each temperature, from 33 to 55 Wilhelmy plate and from 10 to 30 du Nouy ring individual readings were taken in most cases. The surface tension average values at particular temperatures are presented with estimated overall standard uncertainty of 0.05 mN·m−1. An empirical surface tension−temperature equation has been developed describing the temperature dependence of each ionic liquid surface tension. To the 69 up-to-now published surface tension values of the above-mentioned four ionic liquids, the present study adds an additional 102 data points representing means calculated from about 3000 individual surface tension readings that altog...

Abstract: This work aims at studying the surface tension of some linear, cyclic, aromatic, and α-substituted perfluorocarbons. Despite its fundamental interest, information about this property for these compounds is scarce, and the available data are old and present strong discrepancies among each other. The measurements were carried out in the temperature range (283 to 327) K with the Du Nouy ring method. The analysis of the experimental data shows that the molecular structure is an important factor in the surface behavior of the studied compounds since the aromatic fluorocompounds present the highest surface tensions, followed by the cyclic and substituted fluorocompounds. The linear n-perfluoroalkanes exhibit the lowest surface tension values, slightly increasing with the carbon number. The surface thermodynamic functions such as surface entropy and enthalpy were derived from surface tension values and are also reported. The experimental data were compared against the Faizullin correlation, and it is shown that ...

Abstract: Air entraining admixtures (AEA) are generally used for increasing the workability and resistance to freezing and thawing in concrete. These admixtures generate air bubbles with diameters ranging from 10 μm to 1 mm, providing spaces for the expansion of ice, and therefore facilitate frost protection. In this study, performances of AEAs were investigated based on surface tension measurements, accounting for the effect of AEAs on surface tension. For this purpose, a new test method was developed which depends on surface tension measurements according to the Du Nouy ring method. All types of AEAs used in the scope of this research presented a substantial influence on the surface tension. It was observed that a significant relationship between the air void system and surface tension exists. The surface tension method was found as a useful tool to determine the AEA type and content to obtain the desired air void system in concrete.