Miscibility pressure, definition

This is termed the a rent miscibility pressure because there is a considerable amount of evidence that asphaltenes, which are colloidally dispersed in most crude oils, will aggregate under appropriate dilution conditions and precipitate, so that the physicochemical definition of miscibility (single-phase for all proportions of the fluids in question) is not realized. There are also conditions, particularly found in oil reservoirs at temperatures below about 135 F, at which two liquid phases, or two liquid phases plus a gas phase, appear in addition to an asphaltene precipitate (11-13). In general, however, this does not prevent the attainment of 95 % oil recovery or more in slim-tube tests at the same pressures at which these multiple phases appear. Hence, the process is deemed "miscible," for all practical purposes. 

The case in which two layers are formed, with its accompanying maximum of pressure, leads to the third, in which completely miscible liquids, such as propyl alcohol and water, give a maximum of pressure for a definite composition as shown by he d. From this consideration it is... 

The 90% soln is a colorless liq. Prone to explode on contact with metals, their oxides, reducing substances, or on distillation. Has lower vapor pressure than formic acid. Miscible with water, ale, ether. Sol in benzene, chloroform. Solns are unstable, gassing being noticeable after a few hours, and the effective concn showing a definite decline in 2 hrs. 

By definition, miscible polymer blends are singlephase mixtures. Miscibility depends on the molecular weight, concentration, temperature, pressure, deformation rate, etc. Flow of these systems can be compared to that of solutions of low molecular weight, miscible components, or to flow of mixtures of polymeric fractions. Both models are far from perfect, but they serve to illustrate the basic behavior of miscible systems. 

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