Hydrocarbon and fluorocarbon solubility and dilation in poly(dimethylsiloxane): comparison of experimental data with predictions of the Sanchez-Lacombe equation of state

M.G. De Angelis, T.C. Merkel, V.I. Bondar, B.D. Freeman, F. Doghieri, G.C. Sarti

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Sorption and dilation isotherms are reported for a series of gases (N2, O2, CO2), hydrocarbon vapors (CH4, C2H6, C3H8), and their fluorocarbon analogs (CF4, C2F6, C3F8) in poly(dimethylsiloxane) (PDMS) at 35°C and pressures up to 27 atmospheres. The hydrocarbons are significantly more soluble in hydrocarbon-based PDMS that their fluorocarbon analogs. Infinite dilution partial molar volumes of both hydrocarbons and fluorocarbons in PDMS were similar to their partial molar volumes in other hydrocarbon polymers and in organic liquids. Except for C2H6 and C3H8, partial molar volume was independent of penetrant concentration. For these penetrants, partial molar volume increased with increasing concentration. The Sanchez-Lacombe equation of state is used to predict gas solubility and polymer dilation. If the Sanchez-Lacombe model is used with no adjustable parameters, solubility is always overpredicted. The extent of overprediction is more substantial for fluorocarbon penetrants than for hydrocarbons. Very good fits of the model to the experimental sorption and dilation data are obtained when the mixture interaction parameter is treated as an adjustable parameter. For the hydrocarbons, the interaction parameter is approximately 0.96, and for the fluorocarbons, it is approximately 0.87. These values suggest less favorable interactions between the hydrocarbon-based PDMS matrix and the fluorocarbon penetrants than between PDMS and hydrocarbons.
Original languageEnglish
Pages (from-to)3011-3026
Number of pages16
JournalJournal of Polymer Science Part B: Polymer Physics
Volume37
Issue number21
DOIs
Publication statusPublished - 1999

Keywords / Materials (for Non-textual outputs)

  • Equations of state
  • Fluorocarbons
  • Hydrocarbons
  • Isotherms
  • Liquids
  • Mathematical models
  • Pressure
  • Solubility
  • Sorption
  • Dilation
  • Infinite dilution partial molar volumes
  • Polydimethylsiloxane
  • Sanchez-Lacombe equation of state
  • Silicones

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