Viscosity soap solutions

Berkman and Egloff explain that some additives increase the flexi-bihty or toughness of bubble walls, rather than their viscosity, to render them more durable. They cite as illustrations the addition of small quantities of soap to saponin solutions or of glycerin to soap solution to yield much more stable foam. The increased stability with ionic additives is probably due to elec trostatic repulsion between charged, nearly parallel surfaces of the hquid film, which acts to retard draining and hence rupture. 

Kamei and Oishi (K4), 1956 Flow of films of water, soap solution, millet-jelly solutions inside tubes of diameter 5.09-1.9 cm. X 100 cm., with zero and countercurrent air flow. Kinematic viscosities 1.1-40 cs. As = 1-4200. Surface tension found to affect holdup. 

Again in the lubrication of moving metal parts oriented layers are produced, solidly anchored to the metal by carboxyl groups etc. Only the London interaction between the hydrocarbon tails then still acts between the two metal parts each with their layer of lubricating oil. A pure hydrocarbon (kerosene or paraffin oil) lubricates badly since this is forced away through inadequate adhesion to the metal. This is not only a consequence of too small a viscosity since a soap solution (potassium oleate etc.) is serviceable (drilling oil). 

Clark [21] has measured the shear stress at static and dynamic state of a foam from hydrolysed keratin, and soap. The maximum static shear stress Toji was 35.0 Pa and the dynamic T0d was 23.0 Pa at 1% keratin concentration and 225.0 Pa and 110.0 Pa, respectively, at 10% concentration. According to Clark s data the To,, value is directly proportional to the surface viscosity. For a foam from 5% soap solution T0ii, and to,d coincided and were equal to 32 Pa. Being in qualitative agreement with Eqs. (8.14) - (8.16), this shear stress increased with diminishing foam bubble size. 

Fig. 7.1. Schematic view of the light-scattering apparatus 1, stainless steel vessel 2, inlet for thennostatting fluid 3, windows to illuminate the film 4, film 5, ground glass frame 6, glass vessel with soap solution 7, mechanism to move vessel up and down 8, tumable part of the cover 9, tube 10, photomultiplier 11, prism 12, concentric grooves filled with high-viscosity paraffinic oil 13, concentric rims. (From Ref. 138, courtesy of American Institute of Physics.)...

Figure 2. Effect of KBr on reduced viscosity of 37.9% polysoap. Key , O, 1.00% poly soap solution at 25 and 45 °C, respectively , , 6.00% poly soap solution at 25 and 45 °C, respectively. Reproduced from ref. 7. Copyright 1956 American Chemical Society.)...

The difference between the viscosity of soap solutions in water and alcohol (Fig. 4) demonstrates clearly that it is only in water that association to larger aggregates takes place... 

There must be some kind of connection between the structure of the soap micelles and the mechanical properties of soap solutions. We have already seen that many soaps can form elastic or gelatinous systems and there is therefore every reason for establishing the connection between the properties and the X-ray observations. We have to thank Philippoff in particular for attempts in this direction. To what extent — he asks himself — will the viscosity depend on the aggregation Since the specific volume of the dissolved material will undergo little or no change through association of the particles, the shape factor must be influenced. In this connection various possibilities can be envisaged ... 

When we add KOH to a soap solution — of fairly high concentration — the viscosity falls and after a minimum rises very steeply (see Fig. 38). The X-ray interference of the long spacing remains the same, thus the thickness of the micelles does... 

The viscosity of many soap solutions exhibits anomalies which point to structure viscosity on addition of electrolytes (Philippoff ). It is obvious that nothing else could be expected with the picture we have given (Fig. 39). 

Fig. 43. Influence of electrolyte on the viscosity of a soap solution of low concentration. (Bungenberg de Jong and Van Alphen, 1947).

The viscosity of micellar soap solutions will first be discussed. Complete measurements of the viscosity of sodium octanoate solutions over the whole micellar composition range (0-40.5% (w/w)) have been reported by Ekwall and Holmberg (1965). In the premicellar solution the viscosity follows the relation... 

Soap solution admirably fulfils Plateau s second condition, its surface tension being only about 40 per cent, of that of water, while its cohesion is also very small and it is doubtless to this property that its emulsifying power is chiefly due. So far as viscosity is concei ned, this can have but little influence, for a 1 per cent, solution of sodium oleate, which has a viscosity very little different from tliat of pure water, is an excellent emulsifying agent. 

If one compares in the same way, from the point of view of their tensions and viscosities of their surface layers, the soap solution and that of albnmin, the values above show that the tension of the films of the second is double that of the films of the first but, in the soap caps, the colorless phase is only, at the maximnm, 20", while, in those of albumin, it is, as I have pointed out, several hours thus, while passing from the first liqnid to the second, the tension and the viscosity of the surface layers both increase considerably, so that their ratio remains snfQciently large. 

With the rosin soap solution (see the third note of 248), I found, at a temperature of 18° on the surface, 7.30" duration, angle beyond the magnetic meridian line 5° duration inside 4.48", angle 0° arc described by the gold sheet 26°. The rosin soap solution thus also has a surface viscosity with positive excess. 

In the third place, the liquid of the second table which presents the smallest ratio is the rosin soap solution, and it is also that which provided me the smallest bubbles I carried out several successive preparations of this liquid with the same substances, in the same proportions, and by employing the same process, but, 1 do not know why, these preparations appeared less and less good the solution with which the tests with the needle ( 277) were carried out, tests from which I deduced the number which, in the table, represents surface viscosity, gave me bubbles of only 9 centimetres at the maximum, while with the solutions of household soap and of household soap, 1 obtained 25 centimetres, and, with those of albumin and saponin, 13 centimetres. The results of our two tables thus agree well with the theory exposed in the 258 and 259. There is, moreover, a small uncertainty with regard to the rosin soap tension the 7.68 registered in the table was not measured with the same solution, but on an-... 

In the first place, let us seek the approximate value of the surface viscosity of the glyceric liquid. When one prepares this liquid with soap, the best proportions are those which I indicated ( 100), being 2.2 volumes of glycerin of Price for 3 of household soap solution at 1/40 however, one can claim that, in this mixture, surface viscosities are distributed in the ratio of volumes if thus one takes, in the tables of 296 the values of respective surface viscosities of the two ingredients, being 60.42 and 94.79, the surface viscosity of the mixture will be equal to = 80.25 it is, one... 

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