Homogeneous phase separation

The homogeneous phase separation process is influenced by pH and concentration of polymer reagent. Cleavage of the anionic species from the polymer was... 

Consider shifting from homogeneous phase separation to heterogeneous phase separation. 

Consider shifting from heterogeneous phase separation to homogeneous phase separation. 

In this chapter, we discuss the thermodynamic properties of surface phases. In the previous chapters we have assumed that heterogeneous systems consist of a number of completely homogeneous phases separated by sharply defined mathematical surfaces. It is clear from either molecular or macroscopic considerations that this assumption cannot rigorously apply. Molecules in the vicinity of the interface between any two phases experience a different environment from molecules in the bulk of the phases. Thus, the densities of the various components and the densities of energy and entropy in the vicinity of the interface will be different from the corresponding densities in the bulk phases. However, the influence of the interface does not extend for more than a few molecular dimensions (about 10 cm) into the phases, and the phases may therefore be assumed to be uniform except in the immediate neighborhood of the interfaces. The interface between two phases is in reality a thin region in which the physical properties vary continuously from the bulk properties of one phase to the bulk properties of the other phase. 

Kapnistos, M., Hinrichs, A., Vlassopoulos, D., Anastasiadis, S. H., Stammer, A., and Wolf, B. A., Rheology of a lower critical solution temperature binary polymer blend in the homogeneous, phase-separated, and transitional regimes. Macromolecules, 29, 7155-7163 (1996). 

Firstly, the upper phase and then the lower phase will be forced out through the valve and subsequent analysis enables the composition of co-existing phases to be determined. One of the disadvantages of this apparatus is that it depends on a homogeneous phase separating into two phases and there is no provision for... 

Thermoplastic elastomer (TPE) blends have been broadly studied as a new class of materials. TPEs offer various advantages and require no state-of-the-art processing machinery, while scrap and rejects are recyclable. Blends can be homogeneous, phase separated or both. TPEs are multi-phase polymer systems consisting of hard and soft domains that can be copolymers or mechanical blends. This phase separation leads to materials having unique and viable commercial physical properties. TPEs exhibit the thermoplastic characteristics of the hard thermoplastic phase, and resilience as a result of the rubbery domains. TPEs based on natural rubber (NR) and thermoplastic blends are known as thermoplastic natural rubber (TPNR) blends. There are two types of TPNR, namely thermoplastic polyolefin (TPO) and thermoplastic vulcanizate (TPV).3... 

Figure 2.2. Experimental cloud point curve (SAN/PMMA). The region below the line is homogeneous. Phase separation takes place above the line. ...

Figure 13 Pattern formation in the period-3 CML. Coexisting patches of three homogeneous phases separated by sharp, rough fronts, where z jumps between values of the homogeneous phases.

Some examples of the rich information provided by IR spectroscopy, described in this chapter, include the material structural evolution during the different stages of sol-gel processing, the detection of OH species and porosity, the analysis of structural homogeneity, phase separation and densification degree and the study of structural differences between thin films, thicker multilayer films and bulk sol-gel samples, as well as between purely inorganic and sol-gel derived hybrid materials. 

Separation of the different phases of a heterogeneous mixture should be carried out before homogeneous separation, taking advantage of what already exists. Phase separation tends to be easier and... 

In both cases the late stages of kinetics show power law domain growth, the nature of which does not depend on the mitial state it depends on the nature of the fluctuating variable(s) which is (are) driving the phase separation process. Such a fluctuating variable is called the order parameter for a binary mixture, tlie order parameter o(r,0 is tlie relative concentration of one of the two species and its fluctuation around the mean value is 5e(/,t) = c(r,t) - c. In the disordered phase, the system s concentration is homogeneous and the order... 

An example of heterogeneous-azeotrope formation is shown in Fig. 13-13 for the water-normal butanol system at 101.3 kPa. At liquid compositions between 0 and 3 mole percent butanol and between 40 and 100 mole percent butanol, the liquid phase is homogeneous. Phase sphtting into two separate liquid phases (one with 3 mole percent butanol and the other with 40 mole percent butanol) occurs for any overall hquid composition between 3 and 40 mole percent butanol. A miuimum-boihug heterogeneous azeotrope occurs at 92°C (198°F) when the vapor composition and the over l composition of the two liquid phases are 75 mole percent butanol. 

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