Overflowing cylinder method

Various experimental methods for dynamic surface tension measurements are available. Their operational timescales cover different time intervals. - Methods with a shorter characteristic operational time are the oscillating jet method, the oscillating bubble method, the fast-formed drop technique,the surface wave techniques, and the maximum bubble pressure method. Methods of longer characteristic operational time are the inclined plate method, the drop-weight/volume techniques, the funnel and overflowing cylinder methods, and the axisym-metric drop shape analysis (ADSA) " see References 54, 55, and 85 for a more detailed review. 

Although many other experimental set-ups were developed to study the dynamics of adsorption, mainly via surface and interfacial tensions, of solutions of surface active compounds and polymers, they cannot all be described in detail here. More are given in textbooks of surface chemistry, e.g. by Adamson (1990) or Edwards et al. (1991). The last original technique, briefly discussed in this chapter, is the overflowing cylinder method used for example by Bergink-Martens et al. (1990). 

The case of adsorption at an interface that is subjected to stationary expansion needs a special theoretical description. This case is experimentally realized with the strip method [95,116], and the overflowing cylinder method [60,92]. It could be realized also by a Fangmuir trough. The interfacial expansion is characterized by the quantity d = dAI(Adt), which represents the relative rate of... 

This special case of interfacial dynamics is realized with the strip method [95,147] and the overflowing cylinder method [60,92]. Because the adsorption process is stationary, the time, t, is not a parameter of state of the system. For this reason, in the kinetic diagrams (like Figure 4.10) we plot the perturbations versus the dimensionless rate of surface expansion, 0 = (h /Di)(dA/dt)/A, where A is the interfacial area, and dA/dt = constant is the interfacial expansion rate. In Figure 4.10, the total perturbations, 4i,t> 4c,r, plotted, which represent the local perturbations, 4i(z), 4<.(z),... 

Future developments will also focus on the combination of different techniques, such as drop pressure and drop shape methods. A more efficient approach would be to combine macroscopic with microscopic or molecular methods, for example drop shape or pressure experiments with ellipsometric or spectroscopic techniques. Another useful possibility involves linking, for example, the inclinded plate or overflowing cylinder technique with scattering experiments, which would allow studies of structure formation under dynamic conditions and at freshly formed surfaces (Howe et al. 1993). 

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