The interaction parameter for solutions of nitrocellulose in acetone

Vapor pressures of solutions of nitrocellulose in acetone were measured in all‐glass systems over the complete range of concentration, at temperatures from 20 to 60°C. Applying Flory's theory, the interaction parameter, χ1, was calculated. From its temperature‐dependence, the free energy of interaction between polymer and solvent was separated into interaction heat and interaction entropy components. A graph in which the heat terms are plotted against the corresponding entropy terms shows a straightline relation, with the line going through the origin.