Nonlinear effects in mass transfer of liquid media through polymeric materials.

Transport properties of several aromatic polyamides among which there exist fairly subtle structural differences were examined in perva-poration of water-isopropanol solutions. The dependences of the flux density on the membrane area and the oscillatory kinetics of permeability were established, and an unstable steady state arising via predominant permeation of an organic solvent through a highly hydrophilic polymeric membrane was revealed. Conductometric examination of the swelling kinetics showed that chitosan swelling in water gives rise to instabilities in the form of macrofluctuations of local sorbate concentration distribution in the polymer. The wavelet analysis of the time series of the stochastic oscillations was carried out. [ABSTRACT FROM AUTHOR]