Thermodynamic properties of solutions of cellulose triacetate

Abstract

Abstract The lowering of vapor pressures of solutions containing 10–50% by weight of cellulose triacetate in chloroform and methylene chloride have been measured at several temperatures. Attempts made to obtain similar data for solutions in s ‐tetrachlorethane failed apparently because of decomposition of solvent. Solvent activities, free energies, heats and entropies of dilution are obtained. Both systems become increasingly exothermal as the polymer concentration is increased. In the triacetate‐chloroform system, T Δ S̄ 1 decreases from relatively large values at low concentrations as the concentration is increased resembling comparable secondary cellulose acetate systems with acetone and dioxan as solvents. In the methylene chloride system, T Δ S̄ 1 increases with concentration as in comparable cellulose nitrate‐solvent systems. These results are interpreted in terms of solvation and chain stiffness. Values of the polymer‐solvent interaction parameter x 1 increase with concentration and values of the entropy contribution to x 1 are greater than those suggested by lattice theories. Expression of volume fraction of polymer in terms of solvated rather than dry polymer should lead to values of x 1 and the entropy contribution which are more in keeping with the predictions of lattice theories.