Liquid-induced phase separation

All kinds of synthetic materials can be used for preparing membranes. The basic principle involved is to modify the material by means of an appropriate technique in such a way so as to obtain a membrane structure with morphology suitable for a specific (class) of separation or application. The choice of the material limits the preparation techniques employed, the membrane morphology obtained and the separation principle allowed. Several techniques are frequently applied to produce tissue engineering scaffolds, e.g., liquid-induced phase separation (LIPS), immersion precipitation. 

Much later, experiments on model colloids revealed tliat tire addition of polymer may eitlier induce a gas-liquid type phase separation or a fluid-solid transition [94, 95, 96 and 97]. Using perturbation tlieories, tliese observations could be accounted for quite well [97, 98]. 

Induced Phase Separation would work technically, but would be uneconomic relative to Liquid Recycle because of additional unit processes and increased energy requirements. 

Induced Phase Separation is also a good choice for octene hydroformylation. Octene can easily dissolve in the organic based catalyst solution, and with addition of small amounts of water, nonanal and its condensation products will readily separate from the sodium salt of a monosulfonated phosphine. To choose between Liquid Recycle and Induced Phase Separation would require a detailed technical and economic study that is outside the scope of this chapter. 

NAPS is also a possibility for octene hydroformylation, but again a detailed technical and economic comparison would be required in order to chose among it, Liquid Recycle and Induced Phase Separation. 

The final chapter on applications of optical rheometric methods brings together examples of their use to solve a wide variety of physical problems. A partial list includes the use of birefringence to measure spatially resolved stress fields in non-Newtonian flows, the isolation of component dynamics in polymer/polymer blends using spectroscopic methods, the measurement of the structure factor in systems subject to field-induced phase separation, the measurement of structure in dense colloidal dispersions, and the dynamics of liquid crystals under flow. 

Biopolymer incompatibility seems to provide phase-separated liquid and gel-like aqueous systems. In highly volume-occupied food systems aggregation, crystallisation and gelation of biopolymers and their adsorption at oil/water interfaces favour an increase in the free volume, which is accessible for other macromolecules. Denatura-tion of proteins during food processing decreases their solubility and co-solubility of proteins with one another and with polysaccharides and induces phase separation of the system. 

Thermally-Induced Phase Separation (TIPS). Thermally-induced phase separation (Tl PS) results from cooling a liquid crystal/ thermoplastic melt. The liquid crystal and thermoplastic are chosen to... 

The above results of phase behavior as summarized in Table I suggest that the observed macroscopic phase separation is directly related to the structure of the surfactant solution. There is no phase separation when the solutions are isotropic. But the added polymer induces phase separation only when a single liquid crystalline phase or a stable dispersion of liquid crystal particles in brine is present in the absence of polymer. The effect is the same for two different types of polymer and is independent of the polymer concentration over a fair range of composition. 

Polymer addition induces phase separation in liquid crystalline... 

Phase inversion is a process in which a polymer is transformed from a liquid to a solid state. There are a number of methods to achieve phase inversion. Among others, the dry-wet phase inversion technique and the temperature induced phase separation (TIPS) are most commonly used in the industrial membrane manufacturing. The dry-wet phase inversion technique was applied by Loeb and Sourirajan in their development... 

In this section, we describe and explain some aspects of a thermally induced phase separation of a binary mixture containing a nematic liquid crystal forming the continuous phase. The first three subsections deal with a detailed description of the experimental observations. The phase diagram of the mixture, the scenario of the phase separation as well as the structures obtained after long times after the temperature quench are presented. The fourth subsection is devoted to a discussion of the experimental results on the basis of the concepts described in Sect. 2. In the fifth subsection, we report on the kinetic aspects of the phase separation. 

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