Thermodynamics of Phase Behavior in PEO/P(EO-b-DMS) Homopolymer and Block Co-Oligomer Mixtures under Pressure
✍ Scribed by Shichun Jiang; Lijia An; Bingzheng Jiang; Bernhard A. Wolf
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 199 KB
- Volume
- 204
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
The cloud‐point temperatures (T~cl~'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 measurements over a range of temperatures (105 to 130 °C), pressures (1 to 800 bar), and compositions (10–40 wt.‐% PEO). The system phase separates upon cooling and T~cl~ 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‐ϕ plane (where ϕ 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‐ϕ~PEO~ plane.
magnified imageCloud point curves for various PEO/P(EO‐b‐DMS) polymer mixtures at various pressures on the T‐ϕ~PEO~ plane.