Jiang, S., An, L., Jiang, B., Wolf, B. A.

"Pressure Effects on the Thermodynamics of trans-decahydronaphthalene/polystyrene Polymer Solutions: Application of the Sanchez Lacombe Lattice Fluid Theory "

Macromolecular Chemistry and Physics 2003, 204, 692-703.

Abstract: The cloud-point temperatures (Tcl's) of poly-(ethylene oxide) (PEO) and poly(ethylene oxide)- block-polydimethylsiloxane (P(EO-b-DMS)) homopolymer and block-oligomer mixtures were determined by turbidity mea-surements over a range of temperatures (105 to 130 8C), pressures (1 to 800 bar), and compositions (10-40 wt.-% PEO). The system phase separates upon cooling and Tcl was found to decrease with an increase in pressure for a constant composition. In the absence of special effects, this finding indicates negative excess volumes. Special attention was paid to the demixing temperatures as a function of the pressure for the different polymer mixtures and the plots in the T-f plane (where f signifies volume fractions). The cloud-point curves of the polymer mixture under pressures were observed for different compositions. The Sanchez-Lacombe (SL) lattice fluid theory was used to calculate the spinodals, the binodals, the Flory-Huggins (FH) interaction parameter, the enthalpy of mixing, and the volume changes of mixing. The calculated results show that modified P(EO-b-DMS) scaling parameters with the new combining rules can describe the thermodynamics of the PEO/P(EO-b-DMS) system well with the SL theory. Cloud point curves for various PEO/P(EO-b-DMS) polymer mixtures at various pressures on the T-f PEO plane.

preprint number: 244