Discontinuous phase domain

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. 

Phase coexistence in lipid bilayers may be an important physical property for membranes of cells. When two phases coexist in a bilayer, depending upon the relative mass fractions of the phases and the shapes of their domains, one of the phases is percolative (physically continuous) and the other is nonpercola-tive (physically discontinuous or dispersed as isolated domains). Changes in the physico-chemical properties of the membrane (lateral pressure, temperature, and chemical composition are the most relevant for biological membranes) result in interconversion between the two phases—one phase grows at the expense of the other. In phase-separated systems of this type, a critical mass ratio of phases called the percolation threshold, at which the previously continuous phase becomes discontinuous and the previously discontinuous phase becomes continuous, becomes... 

In the jump-condition formulation the physical problem is generally decomposed into k bulk phase domains where the continuity and momentum equations for isothermal incompressible flows holds, and at the interface between these domains boundary conditions are specified using the interface jump conditions. That is, across the interface some quantities are required to be continuous, while others are required to have specific jumps. The discontinuous (singular) momentum jump condition can be derived by use of the surface divergence theorem (see e.g., [63] p 51 [26]). A rigorous derivation of the jump balances for the multi-fluid model is given in sect 3.3. 

X-ray diffraction analysis reveals two different vacancy distributions without the detection of a two-phase domain in every system. For low values of y S 0.25, the symmetry of the perovskite remains which indicates that the vacancies are apparently disordered. At higher values of y = 0.25 X-ray patterns give evidence of a distortion. For y = 0.25, they can be indexed with the theoretical parameters (orthorhombic symmetry) deduced from the vacancy ordering previously described. As a consequence, an order-disorder transition takes place around y 0.25. This phenomenon is illustrated in Fig. 4, which shows a discontinuity of the unit cell volume Vm around this value for each system. 

The properties of a two-phase system consisting of a continuous "matrix" phase and a discontinuous "filler" phase are calculated in tenns of the component properties and volume fractions. It is assumed that the thennoelastic properties within each phase domain are homogeneous and isotropic, and that there is perfect adhesion between adjacent phase domains. The shapes of the filler particles are assumed to have biaxial symmetry. If a filler particle is anisotropic (as in fibers or platelets), it is oriented uniaxially at this stage of the calculation. Particle shape is described by the aspect ratio Af (defined as the ratio of the largest dimension of the filler divided by its smallest dimension), and if Af l then also by... 

Properties of mixed polymer compositions are determined by many factors, among which in the first place should be allocated phase sfructure (ratio and the size of the phase domains). Therefore, at the first stage of the research attention has been paid to study the stmcture of formed compositions. In the investigation of samples with a low content of PHB (10-30% by weight) has been found that it forms a discontinuous phase, i. e., distributed in a continuous matrix PIB as separate inclusions of the order of 1-2 pm. The results of atomic force microscopy for the composition ratio of PHB-PIB 20 80 were shown in Figure 2.1. 

In the model presented by Hammond, the HS, tied together by a polydiacetylene backbone, are oriented laterally in lameUar-like hard domains oriented in random directions before stress is applied, and possibly forming spherulitic type superstructures. The SS are randomly coiled macromolecules spaced between the hard domains. At low moderate strains, when the material is stretched, stress is transferred to the hard domains. The HS orient perpendicular to the stress direction. Upon removal of the stress, the SS relaxation allows the hard domains to return in a random orientation. This results in a small residual hard domain orientation. Therefore, the two-phase microstructure of the material is not highly interconnected. It consists of discontinuous hard domains dispersed throughout a continuous SS phase [364]. 

The AB crosslinked copolymers of Bamford et are not strictly IPNs, since the polymer II chains are part of the same network as the polymer I chains. However, like graft copolymers and IPNs, they do phase separate into distinct domains. The polymer II chains usually form the discontinuous phase, because, similarly to the sequential IPNs, they are not stirred during polymerization. 

In the final state, the two polymers are considered to be completely phase separated. Polymer I forms the continuous phase, and polymer II forms the discontinuous phase. Nd domains of polymer II are formed with a total of N2 polymer II molecules occupying the domains. If a particular polymer II molecule is able to enter any of the Nd domains during phase separation, the number of complexions is... 

If phase separation occurs before the polyurethane gelation, phase domains greater than 40/xm are common, i.e., gross phase separation occurs. However, proper control of the polymerization rates yields phases less than 2 xm in dimension, with the polyurethane forming the continuous phase and the vinyl polymer the discontinuous phase. 

The adhesion of conductive polymers can be improved by mixing heterogeneous phases. The mixing of a non-polar polymeric adhesive phase with a polar conductive aqueous phase comprised of a wato receptive polymer humectant and an electrolyte has been disclosed (22,23). The two phase composite consists of a continuous phase of ionically conductive, hydrophilic pressure-sensitive adhesive (PSA) composition and a discontinuous phase of domains of hydrophobic PSA and provides for enhanced adhesion to manunalian skin, while retaining the critical alternating current impedance. 

In the presence of water, surfactants and lipids give rise to a variety of phases referred to as lyotropic phases or mesophases.i The most important of these phases are the lamellar, hexagonal, cubic micellar, and cubic bicontinuous phases denoted by L, H and V, and Q, respectively (see Figure 1.11 in Chapter 1). The subscripts 1 or 2 attached to these phase symbols indicate that the phase is direct (water continuous) or inverse (discontinuous water domains). Many other lyotropic phases have been identified that differ from the main ones by the state of the alkyl chain (crystalline or disordered) and of the head group arrangement (ordered or disordered). In the particular case of the lamellar phase, additional variations come from the possible different orientations adopted by the alkyl chains with respect to the plane of the lamellae (angle of tilt of the chain) and also from the state of the surface of the lamellae that can be planar or rippled. Numerous detailed descriptions have been given for the equilibrium state of the various phases that surfactants and lipids can form in the presence of water. 

When water activity is low, foods behave more like mbbery polymers than crystalline stmctures having defined domains of carbohydrates, Hpids, or proteins. Water may be trapped in these mbbery stmctures and be more or less active than predicted from equiUbrium measurements. As foods change temperature the mobiUty of the water may change. A plot of chemical activity vs temperature yields a curve having distinct discontinuities indicating phase... 

Figure 10.4 STM images19 of the c(2 x 2)S phase on Cu(110). (a) Islands of c(2 x 2) already showing the discontinuities that characterise this structure, (b) Complete c(2 x 2) phase at a sulfur concentration of 4.4 x 1014cm 2. (c) Model structure for the c(2 x 2) phase showing domain boundaries.

Now again, a state of inhomogeneity in polymers, so especially interesting in films and interfaces, occur when discontinuities are built into the main valence chains and networks. Block polymers are the classic embodiments of this. Many periodic distances separating domains in such alternating or rhymthic copolymers have been reported. These indicate existence of phases in laminar domains and, in other cases, of spherical domains.(51) Cases are shown experimentally for styrene/isoprene copolymers and also for styrene/butadiene.(52,53,54)... 

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