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Papers by peyman memari
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2013
Cinétique de diffusion et comportement diffuso-mécanique du système dioxide de carbone / polyfluo... more Cinétique de diffusion et comportement diffuso-mécanique du système dioxide de carbone / polyfluorure de vinylidène sous décompression explosive de gaz : identification des couplages diffuso-élastiques majeurs par confrontation numérique et expérimentale
Journal of Membrane Science, 2015
ABSTRACT The sorption of methane, carbon dioxide and hydrogen sulphide in polyethylene (PE) was i... more ABSTRACT The sorption of methane, carbon dioxide and hydrogen sulphide in polyethylene (PE) was investigated. Data were obtained in a large range of pressures from both experiments and molecular simulation. Monte Carlo (MC) simulations in the osmotic ensemble were used to predict gas concentrations in the amorphous polymer phase. An ad hoc constraint in the osmotic simulations was used to mimic the effect of the crystalline phase. The results obtained from MC simulation compared favourably to experimental results and data from literature. Different sorption mechanisms were evidenced in the low to middle gas pressure range as a function of the gas nature. However, the decrease of gas solubility was evidenced at high pressure. It was assigned to a hydrostatic effect and the bulk modulus of the PE amorphous phase was determined. A simple model allowing the accurate description of gas solubility from low to high gas pressure range was proposed. It was shown to accurately describe the different sorption isotherm shapes obtained for PE and the characteristic parameters of the model were determined for each gas.
Polymer, 2010
ABSTRACT We have employed Monte Carlo simulations in the osmotic ensemble to study the solubility... more ABSTRACT We have employed Monte Carlo simulations in the osmotic ensemble to study the solubility of three different gases (N2, CH4, CO2) in polyethylene. The simulations are performed at temperatures below the polymer melting point. Although under such conditions, polyethylene is in a semicrystalline state, we have used simulation boxes containing only a purely amorphous material. We show that under such circumstances, computed solubilities are 4–5 times larger than experimental data. We therefore introduce an original use of the osmotic ensemble to implicitly account for the effects of the complex morphology of semicrystalline materials on gas solubility. We have made the assumption that i) the network formed by polymer chains trapped between different crystallites and ii) the changes in local density from crystalline regions to purely amorphous regions, may be both represented by an ad-hoc constraint exerted on the amorphous phase. A single constraint value emerges, independent of the gas nature, characteristic of the crystalline degree of the polymer. It is concluded that the role of this constraint is mostly to reproduce the effective density of the permeable phase of the real material, indirectly giving insights into the morphology of a semicrystalline polymer.Graphical abstract
Journal of Membrane Science, 2012
ABSTRACT We present solubility values of gas mixtures (CH4 + CO2 and CH4 + H2) in polyethylene be... more ABSTRACT We present solubility values of gas mixtures (CH4 + CO2 and CH4 + H2) in polyethylene below its melting temperature. The objective of such studies is to assess the existence of specific interactions between the matrix and one type of penetrant molecule. Data were acquired using both experiments and molecular simulations. Experiments were performed on a medium density polyethylene with pure and mixed gases for temperatures in the range 308–313 K. Hence, the solubility coefficient of each component of a gas mixture was determined. Monte Carlo simulations in the osmotic ensemble were also used to predict gas concentrations in the polymer phase. A good agreement with experimental data is observed. This is a significant validation of the use of an ad hoc constraint in the osmotic ensemble simulations to mimic the overall effect of the crystalline regions and to predict quantitatively solubility data in this semicrystalline system.
Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 2013
Cinétique de diffusion et comportement diffuso-mécanique du système dioxide de carbone / polyfluo... more Cinétique de diffusion et comportement diffuso-mécanique du système dioxide de carbone / polyfluorure de vinylidène sous décompression explosive de gaz : identification des couplages diffuso-élastiques majeurs par confrontation numérique et expérimentale
Journal of Membrane Science, 2015
ABSTRACT The sorption of methane, carbon dioxide and hydrogen sulphide in polyethylene (PE) was i... more ABSTRACT The sorption of methane, carbon dioxide and hydrogen sulphide in polyethylene (PE) was investigated. Data were obtained in a large range of pressures from both experiments and molecular simulation. Monte Carlo (MC) simulations in the osmotic ensemble were used to predict gas concentrations in the amorphous polymer phase. An ad hoc constraint in the osmotic simulations was used to mimic the effect of the crystalline phase. The results obtained from MC simulation compared favourably to experimental results and data from literature. Different sorption mechanisms were evidenced in the low to middle gas pressure range as a function of the gas nature. However, the decrease of gas solubility was evidenced at high pressure. It was assigned to a hydrostatic effect and the bulk modulus of the PE amorphous phase was determined. A simple model allowing the accurate description of gas solubility from low to high gas pressure range was proposed. It was shown to accurately describe the different sorption isotherm shapes obtained for PE and the characteristic parameters of the model were determined for each gas.
Polymer, 2010
ABSTRACT We have employed Monte Carlo simulations in the osmotic ensemble to study the solubility... more ABSTRACT We have employed Monte Carlo simulations in the osmotic ensemble to study the solubility of three different gases (N2, CH4, CO2) in polyethylene. The simulations are performed at temperatures below the polymer melting point. Although under such conditions, polyethylene is in a semicrystalline state, we have used simulation boxes containing only a purely amorphous material. We show that under such circumstances, computed solubilities are 4–5 times larger than experimental data. We therefore introduce an original use of the osmotic ensemble to implicitly account for the effects of the complex morphology of semicrystalline materials on gas solubility. We have made the assumption that i) the network formed by polymer chains trapped between different crystallites and ii) the changes in local density from crystalline regions to purely amorphous regions, may be both represented by an ad-hoc constraint exerted on the amorphous phase. A single constraint value emerges, independent of the gas nature, characteristic of the crystalline degree of the polymer. It is concluded that the role of this constraint is mostly to reproduce the effective density of the permeable phase of the real material, indirectly giving insights into the morphology of a semicrystalline polymer.Graphical abstract
Journal of Membrane Science, 2012
ABSTRACT We present solubility values of gas mixtures (CH4 + CO2 and CH4 + H2) in polyethylene be... more ABSTRACT We present solubility values of gas mixtures (CH4 + CO2 and CH4 + H2) in polyethylene below its melting temperature. The objective of such studies is to assess the existence of specific interactions between the matrix and one type of penetrant molecule. Data were acquired using both experiments and molecular simulations. Experiments were performed on a medium density polyethylene with pure and mixed gases for temperatures in the range 308–313 K. Hence, the solubility coefficient of each component of a gas mixture was determined. Monte Carlo simulations in the osmotic ensemble were also used to predict gas concentrations in the polymer phase. A good agreement with experimental data is observed. This is a significant validation of the use of an ad hoc constraint in the osmotic ensemble simulations to mimic the overall effect of the crystalline regions and to predict quantitatively solubility data in this semicrystalline system.