General Observations Concerning Structures and Properties of Phase Inversion Membranes

General Observations Concerning Structures and Properties of Phase Inversion Membranes. Before going into any detailed discussion of the formation mechanism of microporous membranes, several general observations concerning the membrane structure, preparation procedures, and mass transport properties are described. 

The flux and retention properties, the membrane porosity and the rate of precipitation change in a corresponding pattern, as shown in Table 1.4. With increasing polymer concentration, the permeability decreases and the retention increases. The overall porosity also decreases and the gelation time increases with increasing polymer concentration. 

Polymer- Precipitant Porosity Filtration Rejection Structure 

The Effect of the Polymer-Solvent-Precipitant System on Membrane Structure and Properties. The effect of the polymer on membrane structure and properties is closely related to the solvent used in the casting solution and the precipitant. The solvent and the precipitant used in membrane preparation determine both the activity coefficient of the polymer in the solvent-precipitant mixture and the concentration of the polymer at the point of precipitation and solidification. The polymer-solvent-precipitant interaction can be approximately correlated in terms of the disparity of the solubility parameter of polymer and solvent. 

During precipitation, the casting solution can be divided into three layers. Traveling from the glass plate towards the precipitation bath these layers are  

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