A comparative study on thermodynamic phase behavior analysis of cellulose acetate, cellulose acetate propionate and cellulose acetate butyrate-DMF-water ternary systems

In the present study, the ternary phase diagrams in three non-solvent/solvent/polymer systems [water/DMF/cellulose acetate (CA), water/DMF/cellulose acetate propionate (CAP) and water/DMF/ cellulose acetate butyrate (CAB)] were constructed by theoretical calculation and experimental measurement. Cloud point curves were calculated by using the Flory-Huggins theory for three-component systems and measured by titration of the CA, CAP and CAB solutions with water until the onset of turbidity. The results indicated that with an increase in the hydrophobic nature of polymers from CA to CAB, the water/polymer interaction parameters (chi (water/polymer)) increased, while the solvent/polymer interaction parameter (chi (solvent/polymer)) decreased. Moreover, the area of homogeneous region of the investigated systems decreased in the following order: water/DMF/CA>water/DMF/CAP>water/DMF/CAB. The tie-lines in all of the investigated systems were calculated and discussed.