Factors affecting phase behavior

Heifetz, Y., Voet, H. and Appelbaum, S. W. (1996). Factors affecting behavioral phase transition in the desert locust, Schistocerca gregaria (Forskal)... 

Variables identified as important in the achievement of the low IFT in a W/O/S/electrolyte system are the surfactant average MW and MW distribution, surfactant molecular structure, surfactant concentration, electrolyte concentration and type, oil phase average MW and structure, temperature, and the age of the system. Salager et al. (1979b) classified the variables that affect surfactant phase behavior in three groups (1) formulation variables those factors related to the components of the system-surfactant structure, oil carbon number, salinity, and alcohol type and concentration (2) external variables temperature and pressure (3) two-position variables surfactant concentration and water/oil ratio. Some of the factors affecting IFT-related parameters are briefly discussed in this section. Some other factors, such as cosolvent, salinity, and divalent, are discussed in Section 7.4 on phase behavior. Healy et al. (1976) presented experimental results on the effects of a number of parameters. 

Ionic strength is particularly important for ion-exchange HPLC methods. Other factors affecting mobile phase, such as pH, must also be controlled. If the injected sample overwhelms the buffering capacity, then retention behavior will be affected if it is dependent on pH. 

Proper understanding of solute behavior in sub-H20 systems requires evaluation of both solute-sub H2O phase behavior (particularly in engineering scale systems where solute concentrations are finite), solute solubility trends in hot pressurized water, the diffusion coefficients of solutes in water as a function of temperature and their role in facilitating mass transport, and the potential effect of pressure - often trivialized as a major factor in SWE 16) - in affecting analyte extractions fi om sample matrices via sub-H20. All of these factors ultimately impact the resultant SWE, SWF, and SWR process, reinforcing one another fortuitously as temperature is increased, leading to an increase in solute flux into the sub-H20 medium. 

The thermodynamic analyses described provide an important quantitative understanding of impurity incorporation from solution, namely, the factors affecting the separation can be broken into two parts related to (1) the relative liquid phase behavior of solute and impurities and (2) the relative solid-state host-guest complementarity. This can be more generally stated, as... 

In view of their importance to process design, fundamental aspects of SCF technology are described in this section. Basic physical properties of SCFs are presented initially, followed by a consideration of phase behavior in high pressure systems. Lastly, the factors affecting the solubility of components in SCFs are described. 

Flame-retardant textiles are textiles or textile-based materials that inhibit or resist the spread of fire. Factors affecting flammability and thermal behavior of textile include fiber type, fabric construction, thermal behavior of textile polymer and its composition as well as the presence or absence of flame additives. On the other hand, flame-retardant additives can be classified by their chemical composition or by mode of action, i.e., gas phase action or by the formation of protective barrier [49, 50]. Moreover, flame-retardant functional finishes of cellulose-based textiles can be accomplished by [i] using inorganic phosphates, (ii) with organophosphorous compounds, [iii) with sulfur-derivatives or (iv) by grafting flame retardants monomers [49,50]. 

For demulsifiers of crude W/0 emulsions, a low EO content is preferred, at low molecular weights of 1500-3500. The random copolymers are usually of lower molecular weights. However, factors such as the concentration, solvent, and temperature affect the phase behaviors of these demulsifiers. Because of the wide applications and versatility of these compounds fliere have been extensive studies... 

A hypothetical lyotropic phase diagram, which exhibits the phase transitions that can be induced by varying the composition (water content) or the temperature, is displayed in Figure 4.1 [12, 14-17]. This phase diagram qualitatively condenses the major factors affecting the mesophase behavior and transitions, for example, the molecular shape of the surfactant, the composition (water content), and temperature [12, 15-17]. 

The data listed in Tables 5.3-5.6 are simply observations concerning the effect of eluent concentration and resin exchange capacity on the retention factors of metal cations. A more fundamental approach is to examine the effect of physical and chemical variations in both the mobile and stationary phases on chromatographic behavior of ions. The factors affecting selectivity of ion chromatography have been reviewed in a recent publication [11]. 

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