Lower and upper critical solution temperatures of binary polymeric solutions

The phase behavior of binary polymeric solutions such as lower and upper critical solution temperatures has an important role in many polymeric processes. For theoretical investigation on the prediction of these temperatures, a substantial number of data points on binary polymeric solutions were collected from literature and used to present a reliable calculation routine through chemical engineering thermodynamic modeling approach. The thermodynamic model of Compressible Regular Solution was used. The minimization of errors and predefined objective function was done by applying Particle Swarm Optimization technique. An efficient and accurate empirical correlation employing some quantitative structure–property relationship concept through statistical modeling was developed. To develop the statistical model, the connectivity indices of polymer and solvent were used as the independent variables of the model. Four statistical parameters were defined as auxiliary criteria to evaluate the models and convergence of calculations. In addition, attempts were made to develop and correlate the connectivity indices (topological descriptors) of polymer and solvent to the lattice fluid theory parameters of Sanchez-Lacombe Equation of State. The reliability and accuracy of proposed approaches were discussed in-details and the results were compared to the available experimental data. Desirable agreements between calculated and experimental data were found in thermodynamic model as demonstrated by a maximum Individual Absolute Relative Deviation of 5%. An averaged IARD of 4.3% was obtained for the empirical model. The new correlation predicts connectivity indices of components with acceptable accuracy.