Water system, sodium caprylate-decanol

Laser-Raman spectroscopy is a new method with considerable potential for providing an explanation of how the surroundings inside the aggregates influence the crystalline state of the hydrocarbon chains and other groups (25, 26). It seems probable, however, that an important area of research on the phase equilibria proper would concentrate on attempts to throw light on the exact thremodynamic criteria for the association processes. Ekwalls studies of the water activities of mesophases in the system water-decanol-sodium caprylate are an example of such research (4). However, thermodynamic treatment of the association processes presupposes measurements of the activities of several... 

Solyom and Ekwall (20) have studied rheology of the various pure liquid crystalline phases in the sodium caprylate-decanol-water system at 20 °C, for which a detailed phase diagram is available. Their experiments using a cone-and-plate viscometer show that, in general, apparent viscosity decreases with increasing shear rate (pseudo-plastic behavior). Values of apparent viscosity were a few poise for the lamellar phase (platelike micelles alternating with thin water layers), 10-20 poise for the reverse hexagonal phase (parallel cylindrical micelles with polar... 

Previous Investigations of Sodium Caprylate-Decanol-Water System... 

We first consider a model system of sodium caprylate, decanol, and water. In Figure 1 all the concentration areas in which any mesomorphous substance at all has been observed are included in one extensive region referred to as liquid crystal. Regions L and L2 consist of homogeneous,... 

Figure 1. Triangular diagram of three-component system sodium caprylate-decanol-water at 20°C.

Figure 18. Schematic picture of mesomorphous structures in phases E, D, and F in three-component system sodium caprylate-decanol-water (4, 20, 21)...

In the sodium caprylate-alcohol-water system the length of the alcohol chain was systematically varied from decanol down to ethanol, and in all the systems mesophases D and E with an intervening two-phase area were found 21). The same applies to the systems with potassium soaps it was notably the case also for the system potassium caprate-octanol-water (Figure 23), which has been described as containing only a single mesophase (1, 2, 3). 

Figure 21.32. Phase diagram of the sodium octanoate (caprylate)/decanol/water system B/mucous woven lamellar phase C, tetragonal phase F, reversed-phase G, isotropic phase other phases, etc. as for Figures 21.13, 21.16, 21.22 and 21.26 (reproduced from ref. (50) with permission of Academic Press)...

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