Chemistry Reference
In-Depth Information
processes of "condensation/evaporation" of the drops when waves com-
press and dilate the film are insignificant and practically do not affect the
resulting film elasticity. The latter is expected to be as high as for the satu-
rated monolayer. We feel that this is the case for high-frequency gravity-
capillary waves. At very slow quasistatic film deformations the opposite
limiting case can be realized and the film elasticity at concentrations ex-
ceeding the saturated monolayer concentrations is nearly zero. Another ar-
gument in favour of choosing the high root values at high concentrations
for the ordinary surfactants is that the relative damping coefficients slight-
ly decrease with frequency in this concentration range. This, according to
theory occurs for large elasticity values.
100
(b)
100
(a)
10 Hz
15 Hz
25 Hz
20 Hz
10
10
1
1
1.0
10.0
0.1
1.0 10.0 100.0
Concentration, mg/m
2
Concentration, mg/m
2
100
(c)
10
1
0.1
1.0 10.0
Concentrat ion, mg/m
2
Fig. 6.
Elasticity roots of oleyl alcohol (a), oleic acid (b) and Emkarox (c) films,
retrieved from the damping coefficient values
