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Vapor-liquid equilibria of carbon dioxide and nonionic surfactant system at elevated pressures
김화용,신문삼,Jungin Shinand 한국화학공학회 2006 Korean Journal of Chemical Engineering Vol.23 No.3
solutions of the polyoxyethylene nonionic amphiphiles have been extensively investigated atatmospheric presure, but only a few data of nonionic amphiphile - carbon dioxide system are available at elevatedpressures. Isothermal vapor-liquid equilibrium data for the binary ethylene glycol propyl ether (C3E1) - carbon dioxidesystem at 313.15 K, 323.15 K were measured at elevated pressures. We used two-phase circulating type equipmentwith a view cell. Modeling of the experimental data has been performed using the Peng-Robinson equation of state, sta-
An empirical near-critical correction for a quasi-chemical nonrandom lattice fluid
김화용,이주호,Gap Su Han,Alexander Breitholz,유기풍,신문삼 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.1
This paper proposes a simple empirical correction to improve the near-critical volumetric behavior of a classical equation of state (EOS) which overpredicts the critical point. The focus is on the alternative representation of long-range density fluctuation, an effect neglected in classical EOS, in terms of molecular clustering. To formulate the molecular clustering of interest, the Veytsman statistics is extended and fluctuation parameter is explicitly obtained as a solution to the quadratic equation. The proposed contribution was combined with a quasi-chemical nonrandom lattice fluid (QLF), which overpredicts the critical point. The combined model was found to require three clustering parameters besides three classical parameters and tested against vapor-liquid equilibrium data consisting of 43 nonpolar and polar components. The calculation results showed that the combined model satisfactorily represents the flattened part of the critical isotherm curve for methane as well as the top of the coexistence curve for the tested components.
Dispersion polymerization of N-vinyl caprolactam in supercritical carbon dioxide
김화용,Jungin Shin,조동우,Won Bae 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.5
Dispersion polymerization of N-vinyl caprolactam (NVCL) was carried out in supercritical carbon dioxide (scCO2) using three surfactants. The polymerization was performed in the presence of fluorine-based poly(heptadecafluorodecyl acrylate) (PHDFDA), poly(heptadecafluorodecyl methacrylate) (PHDFDMA) or siloxane-based PDMSg-pyrrolidonecarboxylic acid (Monasil PCA) as a surfactant. FE-SEM and image analyzer were used to characterize particle morphology, size, and size distribution. When fluorine-based surfactants were used, spherical PVCL particles were obtained. Using Monasil PCA resulted in agglomerated and irregular polymer particles. The effect of concentration of surfactants, initiators, and monomer, and reaction pressure on the particle morphology, average particle size and particle size distribution (PSD) was also investigated with fluorine-based surfactant, PHDFDA or PHDFDMA.