Phase discontinuous

Phase transitions at which the entropy and enthalpy are discontinuous are called first-order transitions because it is the first derivatives of the free energy that are disconthuious. (The molar volume V= (d(i/d p) j is also discontinuous.) Phase transitions at which these derivatives are continuous but second derivatives of G... 

Although numerous mud additives aid in obtaining the desired drilling fluid properties, water-based muds have three basic components water, reactive soHds, and inert soHds. The water forming the continuous phase may be fresh water, seawater, or salt water. The reactive soHds are composed of commercial clays, incorporated hydratable clays and shales from drilled formations, and polymeric materials, which may be suspended or dissolved in the water phase. SoHds, such as barite and hematite, are chemically inactive in most mud systems. Oil and synthetic muds contain, in addition, an organic Hquid as the continuous phase plus water as the discontinuous phase. 

Immiscible Blends. When two polymers are blended, the most common result is a two-phase composite. The most interesting blends have good adhesion between the phases, either naturally or with the help of an additive. The barrier properties of an immiscible blend depend on the permeabihties of the polymers, the volume fraction of each, phase continuity, and the aspect ratio of the discontinuous phase. Phase continuity refers to which phase is continuous in the composite. Continuous for barrier appHcations means that a phase connects the two surfaces of the composite. Typically, only one of the two polymer phases is continuous, with the other polymer phase existing as islands. It is possible to have both polymers be continuous. 

The aspect ratio E/IE refers to the shape of the particles in the discontinuous phase. It is the average dimension of this phase parallel to the plane of the film E divided by the average dimension perpendicular to the film W. Plates in the plane of the film would have a high aspect ratio. Spheres or cubes would have an aspect ratio equal to 1. 

Pig. 11. Calculated permeabihties for a two-phase blend using Maxwell s result. Discontinuous phase has aspect ratio of 1.0. See Table 1 for unit... 

I. Single liquid drop in immiscible liquid. Free rise or fall, discontinuous phase coefficient, circulating drops... 

I>D Average volume fraction of discontinuous phase Dimensionless Dimensionless... 

Emulsions. Emulsions are formed when one liquid is dispersed as small droplets in another liquid with which the dispersed liquid is immiscible. Mutually immiscible fluids, such as water and oil, can be emulsified by stirring. The suspending liquid is called the continuous phase, and the droplets are called the dispersed (or discontinuous) phase. There are two types of emulsions used in drilling fluids oil-in-water emulsions that have water as the continuous phase and oil as the dispersed phase, and water-in-oil emulsions that have oil as the continuous phase and water as the dispersed phase (invert emulsions). 

Foam is gas-liquid dispersion in which the liquid is the continuous phase and the gas is the discontinuous phase. The first use of foam in drilling was reported in 1964. 

A disperse system is defined as a heterogenous, two-phase system in which the internal (dispersed, discontinuous) phase is distributed or dispersed within the continuous (external) phase or vehicle. Various pharmaceutical systems are included in this definition, the internal and external phases being gases, liquids, or solids. Disperse systems are also important in other fields of application, e.g., processing and manufacturing of household and industrial products such as cosmetics, foods, and paints. 

An emulsion separation method using hydrocyclones. The emulsion comprises a continuous phase, a discontinuous phase and fine solid particles. In the first step, the original emulsion is separated into an overflow emulsion and an underflow emulsion, in a first hydrocyclone. The overflow emulsion comprises portions of the continuous phase, the discontinuous phase and the fine solid particles. The overflow emulsion is inverted in which the continuous phase of the overflow emulsion is now a second discontinuous phase and the original discontinuous phase becomes a second continuous phase. Then, the inverted emulsion is directed to one or more subsequent hydrocyclones and the second continuous and discontinuous phases are collected. The fine solid particles remain in the second discontinuous phase. 

Flat Sheets. Generally, the interface between a liquid sheet and air can be perturbed by aerodynamic, turbulent, inertial, surface tension, viscous, acoustic, or electrical forces. The stability of the sheet and the growth rate of unstable disturbances are determined by the relative magnitude of these forces. Theoretical and experimental studies 255112561 on disintegration mechanisms of flat sheets showed that the instability and wave formation at the interface between the continuous and discontinuous phases are the maj or factors leading to... 

In addition to the cubic and/or inverse cubic forms described above, further transitional forms exist between the lamellar phase and the hexagonal mesophase (cubic, type II) or inverse hexagonal mesophase (cubic, type III) [6]. In contrast to the discontinuous phases of types I and IV, cubic mesophases of type II and III belong to the bieontinuous phases (Fig. 4f). A range of lyotropic mesophases are possible, depending on the mesogen concentration, the lipophilic or hydrophilic characteristics of the solvent, and the molecule itself [6]. 

Note 3 The finely divided domains are called the dispersed or discontinuous phase domains. 

Note The discontinuous phase domain is sometimes referred to as the guest polymer. 

Essentially aggregative fluidization is a two-phase system there is a dense phase (sometimes reterred to as the emulsion phase), which is continuous, and a discontinuous phase called the lean or bubble phase. The simplitied assumption that all the gas over and above that required tor minimum fluidization flows up through the bed in the form ot bubbles is known as the two-phase theory. It the total volumetric flow ot gas is Q then... 

The discontinuous phase generally takes the rough shape of a sphere to minimize surface area exposure to the other phase. The size of the spheres influences the overall properties and varies with concentration. In general, because of the affinity of like polymer chains, spheres tend to grow. Larger sphere sizes are promoted because they give less relative contact area with the other phase. 

Blends are physical mixtures of polymers. Depending on the extent and type of blend the properties may be characteristic of each blend member or may be some blend of properties. Immiscible blends are phase-separated with the phases sometimes chemically connected. They are generally composed of a continuous and discontinuous phase. HIPS is an example of an immiscible blend. Miscible blends occur when the two blended materials are compatible. Often the properties are a mixture of the two blended materials. The plastic automotive panels and bumpers are generally made from a miscible blend of PE and a copolymer of PE and PP. 

FIGURE 8.8 General forms for discontinuous phase materials, from left, are continuous or long fibers, short fibers, whiskers, and particulates. 

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