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Ebulliometric and Static Measurement of Total Pressure in the in the Binary Water + Poly(Ethylene Glycol) System.
Pavlíček, Jan ; Bogdanić, Grozdana ; Wichterle, Ivan ; Izák, Pavel
The total pressure of the systems containing water and three different poly(ethylene glycol)s with nominal molecular weights of 1000, 3000 and 6000 g mol-1 was measured isothermally at 303.15, 308.15, 313.15, 323.15, 333.15, 343.15, 353.15 and 363.15, using the improved static apparatus for lower temperatures and ebulliometrically for higher temperatures, covering the concentration range up to 50 wt % of the polymer. The 343.15 K isotherm was measured by both experimental methods, and both showed good continuity and performance. A lot of additional data have been measured but not yet published, which are integrated here together with our recent measurement.
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Simple Equipment for Measurement of Total Pressure Tested on Poly(ethylene glycol) + Water System.
Pavlíček, Jan ; Bogdanić, Grozdana ; Wichterle, Ivan
In this work, new equipment designed for total pressure determination in mixtures where one of component is not volatile, such as polymer + solvent systems, is presented. It enables measurement of pressure above solutions in a wider concentration range. The equipment has been tested and calibrated using vapour pressure of pure water. It consist of thermostat with temperature measurement (AΣΛ, model F250), 100 ml vessel for solution with magnetic stirrer with a very strong driver, and of heated manifold for charging, degassing and for pressure measurement. Pressure is measured with use of absolute heated capacitance unit MKS Baratron (pressure range 1000 Torr = 133 kPa). Mixtures were prepared by weighing to obtain volume of 50 ml, approx.
Plný tet: SKMBT_C22016090211390 -  PDF
Plný text: content.csg - PDF
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Additive Group-Contribution Methods for Predicting Properties of Polymer Systems
Bogdanić, Grozdana
This overview presents group-contribution models for predicting properties of pure polymers, polymer/solvent and polymer/polymer mixtures. The state of art can be easily considered taking into account that polymer solutions and blends are complicated systems, with frequent occurrence of LLE in many forms (UCST, LCST, closed loop), significant effect of temperature and polymer molar mass in phase equilibrium, the free-volume effects, and other factors causing these difficulties. The choice of a suitable model depends on the actual problem and demands, especially on the following: type of mixture (solution or blend, binary or multicomponent), type of phase equilibrium (VLE, LLE, SLE), conditions (temperature, pressure, concentration), type of calculation (accuracy, speed, yes/no answer, or complete design). The performance of various models and their range of application will be discussed.
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Experiments and Modelling of Liquid–Liquid Equilibria in the Mineral Oil + N,N-dimethylformamide System
Sedláková, Zuzana ; Andresová, Adéla ; Morávková, Lenka ; Bogdanić, Grozdana
Description of phase behaviour of a highly nonideal system mineral oil + DMF is a rather complex task, because hydrocarbon feed, which has to be separated into aromatic and nonaromatic fractions, consists of large number of compounds that differ significantly in molecular weight and chemical structure. Such a complex mixture was substituted by two pseudo-components, aromatic and nonaromatic in order to simplify the procedure. They were represented by adequate model compounds, whose thermodynamic behaviour was similar to the original one. The chosen model system simulates properly the real one in the sense of the mutual solubility of aromatic and nonaromatic components. However, this simplification of description of strongly nonideal mixtures should be considered as the first approximation.
Plný tet: SKMBT_C22012102413410 - PDF
Plný text: content.csg - PDF
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Theoretical Background for Predicting the Properties of Petroleum Fluids via Group Contribution Methods
Bogdanić, Grozdana ; Pavlíček, Jan ; Wichterle, Ivan
The major problem encountered in the petroleum industry lies in the proper thermodynamic representation of rather complex fluids. In this work, the UNIFAC group contribution method for predicting the properties of such fluids has been exploited as a basis for their description in terms of model compounds. Standard thermodynamic procedures are used to estimate the critical properties, acentric factors, and molecular weights for the model compounds. In such a way, the already available generalized methods can be used for calculations of the phase equilibrium in complex petroleum mixtures.
Plný tet: SKMBT_C22012102413400 - PDF
Plný text: content.csg - PDF
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Vapor–Liquid Equilibrium in Diluted Polymer + Toluene Systems
Bogdanić, Grozdana ; Wichterle, Ivan
Vapor–liquid equilibrium data were determined for five polymer plus toluene systems at isothermal conditions between 60 and 100 oC. Polymers comprise copolymers and terpolymers of octadecyl acrylate, acrylic acid, styrene, and 1-vinyl-2-pyrrolidone because of their practical importance as flow improvers for crude oil and/or derivatives. All-glass micro-ebulliometer with circulation of liquid phase was used for measurement of total pressure over polymer + toluene mixtures. Two predictive group contribution models (the Entropic–Free Volume and the Group Contribution–Flory) were applied to estimate phase behavior of two polymer solutions; good agreement with experimental data was achieved.
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