Chemistry Reference
In-Depth Information
1.0
(b)
1.0
(a)
0.9
0.9
0.8
0.8
0.7
0.7
0.1
1.0 10.0
Concentration, mg/m
0.1
1.0 10.0
Concentration, mg/cm
2
2
1.0
(c)
0.9
0.8
0.7
0.10
1.00 10.00
Concentration, mg/m
2
Fig. 2.
Wavelength of 25 Hz waves as a function of surfactant concentration of
oleyl alcohol (a), oleic acid (b) and Emkarox (c)
It follows from Figure 3 that the film pressure values increase with sur-
factant concentration tending to nearly constant values at large concentra-
tions, which correspond to monomolecular films reflecting complete
monomolecular coverage. The concentrations of the latter films are about
(1.5 - 2) mg m
-2
.
The behaviour of the pressure-concentration curves is analogous to the
pressure-concentration curves obtained with Langmuir trough technique.
Figure 4 gives examples of static isotherms for films of oleyl alcohol and
Emkarox, measured at the University of Southampton with a Langmuir-
Blodgett Trough “NIMA 611”. The static elasticity values shown in Figure
4 are calculated from the isotherms (the scale for the elasticity values in
Fig. 4 is the same as for the film pressure values).
