6533b823fe1ef96bd127ea41

RESEARCH PRODUCT

Thermodynamics of pseudo-ternary systems as a tool to predict the morphologies of cellulose acetate/polystyrene blends cast from tetrahydrofuran solutions

Gislaine Aparecida Da SilvaBernhard A. WolfJohn EckeltMaria Do Carmo Gonçalves

subject

Ternary numeral systemPolymers and PlasticsSpinodal decompositionOrganic ChemistryThermodynamicsFlory–Huggins solution theoryGibbs free energychemistry.chemical_compoundsymbols.namesakechemistryPhase (matter)Materials ChemistrysymbolsPolystyreneTernary operationPhase diagram

description

Abstract The demixing behavior of the ternary system THF/CA/PS (tetrahydrofuran/cellulose acetate/polystyrene) was investigated at 25 °C. 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 ( χ CA/THF =0.442 and χ PS/THF =0.475) the polymer/polymer interaction parameter was adjusted (directly minimizing the Gibbs energy) to χ 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.

yearjournalcountryeditionlanguage
2003-02-01Polymer
https://doi.org/10.1016/s0032-3861(02)00869-8