ANALYSIS OF POLYMER MEMBRANE FORMATION THROUGH SPINODAL DECOMPOSITION

A phenomenological model used in a previous work for spinodal decomposition of polymer-solvent systems is further analyzed. From the dimensionless form of the nonlinear Cahn-Hilliard equation, the dimensionless induction time is found to be a constant number for suddenly quenched systems. Computer simulation is carried out for prediction of early stage behavior with thermal history corresponding to a linear temperature drop followed by a constant temperature vs. time. In the areas of polymer membrane formation and phase separation studies, the universality of the constant dimensionless induction time for suddenly quenched systems allows the determination of the minimum time needed for phase separation via spinodal decomposition. Also, simulation results for the double linear temperature history allows the convenient prediction of early stage spinodal decomposition behavior at every point of a membrane cross section undergoing thermal inversion phase separation.