Vapor−liquid equilibrium data were determined for five polymer + methylbenzene systems under isothermal conditions between (333.15 and 373.15) K. The polymers studied include copolymers and ...terpolymers of octadecyl propenoate, propenoic acid, ethenylbenzene, and 1-vinyl-2-pyrrolidone because of their practical importance as flow improvers for crude oil and/or derivatives. An all-glass microebulliometer with circulation of the liquid phase was used for measurements of total pressure over polymer + methylbenzene mixtures. Two predictive group-contribution models (entropic−free volume and group contribution−Flory) were applied to estimate the phase behaviors of two polymer solutions; good agreement with the experimental data was achieved.
► We have measured new experimental data on vapour–liquid equilibria in systems with reacting components. ► Six binary and one quaternary systems consisting of ethanol, propanol, ethyl and propyl ...ethanoate were investigated. ► Correlation of data with use of the NRTL equation. ► Prediction of phase equilibria in quaternary transesterification system is based on binary data.
Phase and chemical equilibria in the quaternary ethyl ethanoate+ethanol+propyl ethanoate+propanol system and in all six binary subsystems have been investigated at two isotherms, namely at 323.15 and 348.15K. In total, 116 quaternary experimental points were determined. The binary data were correlated by means of the NRTL model using a robust approach and the maximum likelihood procedure. The binary parameters obtained were used for prediction of vapour–liquid equilibria in the quaternary system and results show a good agreement of calculated and experimental data. The three-dimensional phase diagrams for the quaternary system have been constructed with use of transformed compositions.
•Vapor-liquid equilibrium in the 2-propanol + water + ionic liquid system.•New method for thermodynamic description of the system containing azeotrope.•Only a few experimental data points are ...needed.•Calculation of azeotropic composition and pressure vs. ionic liquid concentration.
Vapor-liquid equilibrium data were measured isothermally in the vicinity of azeotropic points of the title system at 333.15, 343.15, and 353.15 K. Data were processed using a newly-developed method based on relatively small amounts of input data, which provides thermodynamic description of azeotropic behavior. The regular two-parameter Redlich-Kister equation was used for this purpose. The parameters obtained were correlated with ionic liquid concentrations to express the smooth analytical dependence of both the azeotropic composition and pressure.
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Recently we designed an apparatus for total pressure measurement in binary polymer + solvent systems. Accurate as it is, the apparatus is limited by its direct capacitance pressure sensor that can ...operate only at 318.15 K. In this study we tested a new setup that overcomes this limitation with a pressure transducer (MKS Baratron), which can be heated up to 430 K. The main improvement is that the new setup has eliminated solvent vapour condensation in the pressure measurement unit. Other parts of the equipment can easily be kept at temperatures higher than the system temperature with heating tapes. Unlike the ebulliometric method, which is limited by problems arising from the boiling of viscous mixtures, now we can study solutions with higher polymer concentrations. We tested the new setup by measuring the total pressure of binary poly(ethylene glycol) + water mixtures at six isotherms in the (308.15–343.15) K range. Additionally we determined new data for three isotherms (343.15, 353.15, and 363.15) K using ebulliometric method. We then correlated our measurements with both methods using the UNIQUAC–free volume model and compared them with available published data for isotherms 313.15 K and 333.15 K. The agreement with our static measurement results was excellent.
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Dependences of total pressure on the composition of water + poly(ethylene glycol) systems were measured with both the ebulliometric and static method. New data on vapour-liquid equilibria cover the ...temperature range 303.15–363.15 K and the range of the weight fraction of solvent 0.5–1.0 for polymers of nominal molecular weight 1000, 3000, and 6000 g mol−1. These data together with those determined earlier were correlated using the UNIQUAC free-volume (FV) model to be consistent with previous studies. In addition, all available literature data on this system were processed in the same way. As a result, the obtained average deviations were used as indicators of data quality. Average deviation of experimental and calculated solvent activity was about 0.0004 for all our data. The evaluated adjustable parameters were proportional to molecular weight, which ensures reliable interpolation and even extrapolation beyond the investigated temperature and molecular weight ranges.
A new apparatus for determining the total pressure in binary systems with one nonvolatile component, such as polymer‐solvent mixtures, was designed. In contrast to the ebulliometric method, it ...enables measurement of the pressure above solutions across wider concentration ranges. The apparatus was tested on mixtures of water and poly(ethylene glycol). The tested polymers had three nominal molar weights. The measurements were correlated with the UNIQUAC‐free volume model described earlier and compared with the published data. The applicability of known predictive models on the measurements was also tested and it was found that the entropic free‐volume model yielded the best prediction of vapor‐liquid equilibria for the studied systems.
Determination of the vapor pressure of solutions with high polymer concentrations by conventional methods is challenging. A simple new setup to determine phase equilibria in systems containing one nonvolatile component was designed and applied to measure the pressure above three different water‐poly(ethylene glycol) systems and these data were compared with published and predicted data.
This study investigated the efficiency of 22 polymer additives of defined and controlled structural characteristics in improving the flow properties of crude oil. The additives were synthesized by ...the solution polymerization of alkyl acrylates of various alkyl chain lengths with styrene, acrylic acid and 1-vinyl-2-pyrrolidone as copolymers or terpolymers. Polymerization was performed by
tert-butylperoxy-2-ethylhexanoate as initiator in xylene at 92
°C, up to high conversion. The influence of polymerization conditions on additive composition and properties, and their effect on the pour point and rheological properties of crude oil samples from the fields of Števkovica, Obod and Đeletovci located in the northern Croatia were studied. Additive efficiency was dominantly influenced by the alkyl acrylate chain length. The influence of component with carboxyl functional group or heterocyclic-nitrogen compound on additive quality was less obvious. Additive efficiency significantly depended on the properties of crude oil, and
n-paraffin content and distribution. The main advantage of the process is that additives can be directly used without purification.
Vapour–liquid equilibria have been determined in the polymer+solvent systems, namely the poly(acrylic acid)+water, and poly(methyl methacrylate)+acetone system. Each system has been measured at three ...isothermal conditions. An all-glass microebulliometer with circulation of the liquid phase was used for dynamic measurements of total pressure over liquid mixtures. The determined data were correlated with the UNIQUAC equation.
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