Simultaneous determination of three Flory-Huggins interaction parameters in polymer/solvent/nonsolvent systems by viscosity and cloud point measurements

We propose an integral procedure to simultaneously obtain the three Flory- Huggins interaction parameters in polymer(3)/solvent(2)/nonsolvent(1) systems by carrying out only viscosity and cloud point measurements. First, the interaction parameter between polymer and solvent, chi(23), is obtained by applying the Rudin's model which has been well established for various polymer solutions. Then the solvent/nonsolvent interaction parameter chi(12) and polyrner/nonsolvent interaction parameter chi(13) are calculated by combining the Rudin's model and the modified Flory Huggins free energy for the ternary system, which leads to a group of candidate values of chi(12) and chi(13). Finally, these values are selected by the best agreement between the calculated binodal curves and the measured cloud points of the ternary system. This procedure has been successfully applied to PES/NMP/H2O, PAN/DMSO/H2O, and PAN/DMF/H2O systems. All the values obtained are comparable to those reported previously. The procedure is simple and easy to follow, with no requirement of complex equipments. (C) 2014 Elsevier Ltd. All rights reserved.