Abstract
A topological theory has been introduced to extend the theory of Balsara and Nauman to evaluate the entropy of in homogeneous polymer solutions. Previous theories have considered only the terms about the displacement of junction points, while the present theory has obtained a more complete expression for the entropy by adding the topological interaction terms between strands. There have been predicted the characteristics of the spinodal decomposition and the interfacial tension of polymer solutions from the resultant expression. It is exposed that the theoretically predictive values show good agreement with the experimental data for polymer solutions.