Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

Browse

Filters

2000 - 20074

Settings

Scopus Q: search.filters.scopusQuartile.N/ASubject: search.filters.subject.Diffusion

Search Results

Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Phase Equilibrium and Diffusion of Solvents in Polybutadiene: a Capillary-Column Inverse Gas Chromatography Study
    (John Wiley and Sons Inc., 2002) Cai, W. D.; Ramesh, N.; Tıhmınlıoğlu, Funda; Danner, Ronald P.; Duda, John Larry; De Haan, A.
    The capillary-column inverse gas chromatography method was used to measure the diffusion and partition coefficients of ethylbenzene, styrene, and acrylonitrile in polybutadiene (PBD) at infinite dilution of the solvents. Experiments were performed over a temperature range of 50-125°C. At temperatures well above the glass-transition temperature of PBD, the diffusivities were correlated using an Arrhenius expression. The Arrhenius parameters in turn were intercorrelated and shown to be a function of the occupied volume, thus providing a method for predicting the diffusion of other solvents in the same polymer. Further, the activation energy was predicted using the Duda-Vrentas free-volume approach. The activation energy thus obtained was compared with the activation energy of the Arrhenius approach. The weight-fraction activity coefficient data were compared to the predictions of the group contribution, lattice-fluid equation-of-state, and the UNIquac Functional-group Activity Coefficient (UNIFAC) free-volume models.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Solubility and Diffusivity of Methylmethacrylate and Butylacrylate Monomers in a Mma-Ba Copolymer
    (John Wiley and Sons Inc., 2007) Yürekli, Yılmaz; Alsoy Altınkaya, Sacide; Zielinski, John M.
    Mutual diffusion coefficients and sorption isotherms of methyl methacrylate (MMA) and butyl acrylate (BA) monomers in methyl methacrylate-butyl acrylate copolymer (MMA-BA) have been measured by gravimetric sorption. MMA is found to have higher solubility and diffusion rates in the copolymer than BA. Sorption data for MMA were interpreted using classical Flory-Huggins thermodynamic theory with a constant interaction parameter (χ). A modified version of this theory has been applied to correlate the sorption data of BA, which exhibit a temperature and concentration-dependent χ parameter. For MMA, the isotherm data reveal enhanced polymer-solvent interactions with increasing temperature, while for BA the data indicate a drive toward phase separation with increasing temperature. Despite the difference in thermodynamic behavior, both monomers are found to exhibit Fickian diffusion and the diffusivity data are correlated reasonably well with the Vrentas-Duda free volume theory. Some deviation between the free-volume correlation and the experimental data is observed at the lowest temperature and BA concentration examined.
  • Article
    Citation - WoS: 17
    Citation - Scopus: 18
    Solvent Diffusion in Amorphous Polymers: Polystyrene-Solvent Systems
    (John Wiley and Sons Inc., 2000) Tıhmınlıoğlu, Funda; Danner, Ronald P.
    The inverse gas chromatography (IGC) technique was used to obtain the partition and diffusion coefficients of solvents in polystyrene over a wide range of temperatures. Infinite dilution experiments were performed with three solvents: toluene, benzene, and hexane. Finite concentration data were measured for the polystyrene-toluene system at various concentrations from 110 to 180 °C. For the finite concentration region, the modified capillary column model used by Tihminlioglu and Danner (J Chromatogr A 1999, 845, 93-101) was used to calculate diffusion and thermodynamic data. Finite concentration thermodynamic data were also calculated with the retention theory approach and compared with the capillary column model. The experimental IGC results are in good agreement with data from other experimental techniques.
  • Article
    Citation - WoS: 19
    Citation - Scopus: 20
    Solvent Diffusion in Amorphous Polymers: Polyvinyl Acetate-Toluene System
    (John Wiley and Sons Inc., 2000) Tıhmınlıoğlu, Funda; Danner, Ronald P.; Lützow, Norbert; Duda, John Larry
    In a previous publication (Tihminlioglu et al., J Polym Sci Part B: Polym Phys 1997, 35, 1279), we presented an extensive analysis of the polyvinyl acetate-toluene system. The inverse gas chromatography (IGC) technique was used to measure phase equilibria and diffusion coefficients above and near the glass-transition temperature of a polymer. At temperatures above the glass transition, the capillary column model developed by Pawlisch et al. (Macromolecules 1987, 20, 1564) was used. For the finite concentration region, the modified model of Tihminlioglu and Danner (J Chromatogr A 1999, 845, 93) was applied. Data obtained with the IGC method were in agreement with data measured with the gravimetric and piezoelectric sorption techniques. In this work, we revisit the partition coefficient issue and provide some new data at lower temperatures. At temperatures near the glass-transition temperature, the modification of the capillary column model proposed by Vrentas et al. (Macromolecules 1993, 26, 6670) was used for the infinite dilution region. The diffusion data correlated well with the Vrentas-Duda free-volume model.