Continuous-phase composition

I. Polystyrene (Dispersed Phase)-Polyacrylamide (Continuous Phase) Composite (Table 6), and... 

Single-step preparations of composite polymers have been examined in previous sections. The volume fraction of the continuous phase was, however, relatively small in those cases. In contrast, the present method allows us to prepare composites with larger volume fractions of the continuous phase. Composites with large volume fractions of the continuous phase can also be obtained in a single-step by polymerizing an emulsion or a microemulsion [24]. An emulsion of a hydrophobic (hydrophilic) monomer in another hydrophilic (hydrophobic) monomer can be extremely stable (even thermodynamically stable, and then it is called a microemulsion) if a sufficiently large amount of surfactant is introduced into the system. For an emulsion to be thermodynamically stable, a cosurfactant is in most cases needed besides the surfactant. The latter method was used to prepare composites by employing acrylamide... 

Continuous Phase Composition Emulsion liquid membrane properties can be significantly influenced by changing the composition of the external aqueous phase. Emulsion stability can be improved by an increase in the viscosity as a result of the decrease in the rate of fluid drainage between the liquid films [88]. An increase in ionic strength of the external phase has been shown to cause a decrease in entrainment phenomena during permeation. This has been attributed to an alteration of the stmcture of the interface between the emulsion and the external phase promoted by the presence of electrolytes in the external phase. A reduction in osmosis also occurs due to a reduction in the chemical potential difference between both sides of the membrane [94,98]. 

Effect of Continuous-Phase Composition. In order to determine the temperature range in which acrylamide mlcroemulslon polymerization could be conducted within a supercritical alkane continuous phase, the phase behavior of the Brlj mixture/water/acrylamide system in mixtures of propane (T - 97 C) and ethane (T, 32 C) was Investigated. In addition, extqploylng a mixture of ethane and propane allows us to examine the effect of the continuous-phase... 

Effect of Continuous Phase Composition. With increasing concentration of Shellsol T in the continuous phase and therefore decreasing bulk phase viscosity (as shown in Figure 13), the emulsion breaking efficiency increases (Figure 14). As expected, the mutual approach of the water droplets will be facilitated in lower viscous continuous phases. 

Figure 13. Effect of continuous phase composition on viscosity and emulsion viscosity. Experimental data Oemulsion, o organic phase fitted data —lnrj0 = exp -K (vol%)+K2] lnrj = lnri0 + K3.

Figure 14. Effect of continuous phase composition on emulsion breaking efficiency.

Detection and Measurement of Ostwald Ripening Influenced by Continuous Phase Composition... 

At first, the surfactant and thickener were well mixed into the continuous phase (compositions, see Table 23.1). Then the dispersed phase was introduced slowly and dispersed using an impeller type stirrer to prepare the pre-emulsion. Afterwards a rotor-stator device (Polytron PT6000, Kinematica AG, Luzem, CH) was used for further dispersion of the pre-emulsion droplets to produce stable emulsions. Rotational speeds from 1000 to 10,000 rpm were applied within fixed constant time periods, and secondary drop size distributions were measured over time after representative sampling to achieve desired-size secondary droplets of the model emulsions. These model emulsions were stable for several days. However, the model SE was in general used at the same day of preparation for spray characterization employing air-assisted nozzles and rotary atomizers RA. 

A hypothetical moving-bed system and a Hquid-phase composition profile are shown in Figure 7. The adsorbent circulates continuously as a dense bed in a closed cycle and moves up the adsorbent chamber from bottom to top. Liquid streams flow down through the bed countercurrently to the soHd. The feed is assumed to be a binary mixture of A and B, with component A being adsorbed selectively. Feed is introduced to the bed as shown. 

A composite material (1) is a material consisting of two or more physically and/or chemically distinct, suitably arranged or distributed phases, generally having characteristics different from those of any components in isolation. Usually one component acts as a matrix in which the reinforcing phase is distributed. When the continuous phase or matrix is a metal, the composite is a metal-matrix composite (MMC). The reinforcement can be in the form of particles, whiskers, short fibers, or continuous fibers (see Composite materials). 

Drilling fluids are classified as to the nature of the continuous phase gas, water, oil, or synthetic. Within each classification are divisions based on composition or chemistry of the fluid or the dispersed phase. 

The dominance of distiHation-based methods for the separation of Hquid mixtures makes a number of points about RCM and DRD significant. Residue curves trace the Hquid-phase composition of a simple single-stage batch stiHpot as a function of time. Residue curves also approximate the Hquid composition profiles in continuous staged or packed distillation columns operating at infinite reflux and reboil ratios, and are also indicative of many aspects of the behavior of continuous columns operating at practical reflux ratios (12). 

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. 

Recalciilate the , and continue this iterative procedure until it converges to a fixed value for X, yi- This sum is appropriate to the pressure P for which the calculations have been made. Unless the sum is unity, the pressure is adjusted and the iteration process is repeated. Systematic adjustment of pressure P continues until X, yi = 1- The pressure and vapor compositions so found are the equilibrium values for the given temperature and hquid-phase composition as predicted by the equation of state. 

The mass spectrometer sampling capillary or the dispersive infra-red analyzers used for continuous analysis and monitoring of the gas phase composition are situated between the reactor and the sampling valve, as close to the reactor as possible, in order to avoid any delay in the recording of changes in the composition of reactants or products. This delay should be taken into account when plotting simultaneously the time dependence of catalyst potential or current and gas phase concentration of the reactants or products. 

In either case the resulting material Is a composite, with the polymer as the continuous phase or matrix, binding together the pieces of the discontinuous filler phase. The presence of filler can have a profound effect on the properties of the polymer composite, as Illustrated In Table 7.1. From this Table, It can be seen that the nature of the filler Is Important, with different effects being obtained with different fillers. 

TPEs prepared from rubber-plastic blends usually show poor high-temperature properties. This problem could be solved by using high-melting plastics like polyamides and polyesters. But, often they impart processing problems to the blends. Jha and Bhowmick [49] and Jha et al. [50] have reported the development and properties of novel heat and oil-resistant TPEs from reactive blends of nylon-6 and acrylate rubber (ACM). The properties of various thermoplastic compositions are shown in Table 5.4. In this kind of blend, the plastic phase forms the continuous phase, whereas... 

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