It is believed that the mechanism for removing acid build up in car engine oils involves low water phase volume, water-in-oil (w/o) microemulsions. However, examples of relatively stable microemulsions can be found. high or low temperature or addition of surface tension modifying agents. Since these systems can be in equilibrium with other phases, many systems, especially those with high volume fractions of both the two imiscible phases, can be easily destabilised by anything that changes this equilibrium e.g. the apparently clear heptane/AOT/water microemulsions consist multiple phases). Apparently clear single phase formulations can still consist of multiple iso-tropic phases (e.g. The Gibbs phase diagram, however, is an empirical visual observation of the state of the system and may, or may not express the true number of phases within a given composition. These points combine to form regions with boundaries between them, which represent the "phase behavior" of the system at constant temperature and pressure. Each point within the triangle represents a possible composition of a mixture of the three components or pseudo-components, which may consist (ideally, according to the Gibbs' phase rule) of one, two or three phases. Moving away from that corner reduces the volume fraction of that specific component and increases the volume fraction of one or both of the two other components.
The three components composing the system are each found at an apex of the triangle, where their corresponding volume fraction is 100%. Gibbs phase diagrams can be used to show the influence of changes in the volume fractions of the different phases on the phase behavior of the system. The relative amounts of these three components can be represented in a ternary phase diagram. If a cosurfactant is used, it may sometimes be represented at a fixed ratio to surfactant as a single component, and treated as a single "pseudo-component". Three components are the basic requirement to form a microemulsion: an oil phase, an aqueous phase and a surfactant. The microemulsion region is usually characterized by constructing ternary-phase diagrams.
0 kommentar(er)
