Thermodynamic compatibility of starch and carboxymethyl cellulose sodium

The thermodynamic functions of mixing of starch with carboxymethyl cellulose sodium in films obtained from aqueous solutions at different temperatures were studied. For compositions with different starch contents, the enthalpies of dissolution in water and the sorption isotherms of water vapor were determined by the calorimetric and sorption methods. The enthalpies, Gibbs energies, and entropies of mixing of starch with carboxymethyl cellulose sodium in the entire range of compositions were calculated from the thermodynamic cycle. It was shown that all the thermodynamic functions are negative, which is indicative of the thermodynamic compatibility the components, their strong intermolecular interactions, and high ordering in the course of mixing. The affinity of the components to each other, which is due largely to the entropy factor, increases with the temperature of film formation.