Silva, G. A., Eckelt, J., Gonçalves, Maria do Carmo, Wolf, B. A.

"Phase Diagram of the Ternary System Tetrahydrofuran/Cellulose Acetate/Polystyrene and Morphology of Cellulose Acetate/Polystyrene Blends" <

Polymer 2003, 4, 44, 1075-1080.

Abstract: The demixing behavior of the ternary system THF/CA/PS (tetrahydrofuran/ cellulose acetate/polystyrene) was investigated at 25degreesC. Cloud point measurements show that the system exhibits a large miscibility gap caused by the incompatibility of CA and PS. Both ends of the experimentally determined tie lines are located inside the two-phase area of the phase diagram. By means of the measured critical composition of the ternary system and the Flory- Huggins interaction parameters published for two of the binary subsystems (X-CA/(THF) = 0.442 and X-PS/(THF) = 0.475) the polymer/polymer interaction parameter was adjusted (directly minimizing the Gibbs energy) to X-CA/(PS) = 0.057. These thermodynamic data were used to calculate the extension of the metastable and the unstable regions of the phase diagram. This procedure permits a realistic prediction of the morphologies of the (solvent-free) blends from the location of the starting composition of the casting solutions in the Gibbs phase triangle, as demonstrated by means of optical micrographs and field emission scanning electron micrographs. (C) 2002 Published by Elsevier Science Ltd.

preprint number: 230