The Polymorphism and Transitions of Anhydrous and Hydrous Sodium Stearate

Phase Boundaries in Concentrated Systems of Sodium Oleate and Water.

“…in about an hour). The times at room temperature before calorimetric study were also recorded, since specification of both rate of cooling and aging period may well be necessary to permit subsequent identification of what phase or mixture of phases is likely to have been present initially in each case (28). Most runs were made at a heating rate of 1.5°C.…”

“…The present data are of interest and will be discussed in terms of the possible existence of critical compositions at which other methods have indicated marked changes in the properties of similar systems (10,11,18,30), the problem of whether the various water-containing phases are mixtures of stoichiometric hydrates or contain the water in a solid-solution phase, essentially free in capillary spaces or adsorbed on the surface of the crystallites (5,9,12,16,18,28,29), their relation to previously suggested phase diagrams for the system (16,26), and conflicting views derived from x-ray investigation as to what crystalline phases may be present (5,6,9,10,11,21). The implications of the various transitions detected thermally, shoivn graphical!…”

“…This method is based on measurement of the temperature difference between two similar cells, one containing the sample and the other a thermally inert material, as both are uniformly heated at a slow rate. Its application to anhydrous soaps in the present apparatus has already been described ( 27), and its use further illustrated by application to a series of anhydrous alkali metal palmitates (34) and to low-moisture systems of sodium stearate (28). With pure anhydrous soaps transitions must occur sharply at a single temperature, causing a sharp peak in the curve of differential temperature vs. time.…”

“…With pure anhydrous soaps transitions must occur sharply at a single temperature, causing a sharp peak in the curve of differential temperature vs. time. Changes of slope in this curve have no phase significance unless the rate of transition is slow relative to the rate of rise of temperature, or on occurrence of a transition of the second kind (28). Application of this method to aqueous systems is considerably more complicated, since here changes of slope in the differential temperature curve are generally of phase significance.…”

Colloidal Structures in Binary Soap Systems

“…Since there is still no general experimental agreement on the nature of the curd phases (3,6,18,32), no attempt will be made to discuss them in this paper.…”