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Compositional polydispersity in linear low density polyethylene / Aleksandra Dominik in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4127–4135 Titre : Compositional polydispersity in linear low density polyethylene Type de document : texte imprimé Auteurs : Aleksandra Dominik, Auteur ; Walter G. Chapman, Auteur ; Robert D. Swindoll, Auteur Année de publication : 2009 Article en page(s) : pp. 4127–4135 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Linear  low  density  polyethylene  Short-chain  branching  distribution  Linear  polymers Résumé : A study of the effect of a short-chain branching distribution (SCBD) on the phase behavior of linear low density polyethylene (LLDPE) was conducted. The perturbed chain-SAFT equation of state was the underlying thermodynamic model chosen for the study; the branched polyolefins were described using a simple modeling concept previously proposed by Dominik and Chapman.(1) To isolate the effect of the SCBD on phase behavior, the copolymer systems were considered monodisperse in molecular weight. The study revealed that, in the case of low to moderate values of the polydispersity index of the SCBD, the compositional polydispersity affected the phase behavior at low polymer concentrations only. When the polydispersity index of the SCBD is high, or, in other words, when the difference in branch content between the components of the distribution is significant, additional phases appear. The formation of multiple phases results from the incompatibility of branched and linear polymers. Similar observations were made on the basis of experimental studies in the case of polymer blends. The SCBD of LLDPE was determined by the chemistry of the polymerization reaction. A broad SCBD was found to significantly affect the phase behavior of LLDPE solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800982z [article] Compositional polydispersity in linear low density polyethylene [texte imprimé] / Aleksandra Dominik, Auteur ; Walter G. Chapman, Auteur ; Robert D. Swindoll, Auteur . - 2009 . - pp. 4127–4135. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4127–4135 Mots-clés : Linear  low  density  polyethylene  Short-chain  branching  distribution  Linear  polymers Résumé : A study of the effect of a short-chain branching distribution (SCBD) on the phase behavior of linear low density polyethylene (LLDPE) was conducted. The perturbed chain-SAFT equation of state was the underlying thermodynamic model chosen for the study; the branched polyolefins were described using a simple modeling concept previously proposed by Dominik and Chapman.(1) To isolate the effect of the SCBD on phase behavior, the copolymer systems were considered monodisperse in molecular weight. The study revealed that, in the case of low to moderate values of the polydispersity index of the SCBD, the compositional polydispersity affected the phase behavior at low polymer concentrations only. When the polydispersity index of the SCBD is high, or, in other words, when the difference in branch content between the components of the distribution is significant, additional phases appear. The formation of multiple phases results from the incompatibility of branched and linear polymers. Similar observations were made on the basis of experimental studies in the case of polymer blends. The SCBD of LLDPE was determined by the chemistry of the polymerization reaction. A broad SCBD was found to significantly affect the phase behavior of LLDPE solutions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800982z

Correlation and prediction of water content in alkanes using a molecular theory / Christopher P. Emborsky in Industrial & engineering chemistry research, Vol. 50 N° 13 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 7791–7799 Titre : Correlation and prediction of water content in alkanes using a molecular theory Type de document : texte imprimé Auteurs : Christopher P. Emborsky, Auteur ; Kenneth R. Cox, Auteur ; Walter G. Chapman, Auteur Année de publication : 2011 Article en page(s) : pp. 7791–7799 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Phase  equilibriums  Chemical  equilibriums  solutions Résumé : We present a predictive model for the saturated water concentration in n-alkanes based on a theoretical equation of state for the hydrocarbon rich phase and a water equation of state for the aqueous phase. By considering a polar or associating component at low concentration in a nonpolar solvent, we can neglect polar or hydrogen bonding interactions in the hydrocarbon rich phase, thus reducing the number of fitted parameters. The approach allows us to determine the intrinsic pure component equation of state parameters independent of polar and associating interactions. As an example, the nonpolar, non-associating equation of state parameters for water are determined by fitting water solubility data in liquid hydrocarbons (carbon numbers (CN) = 4–13, 16) at ambient conditions. Using the PC-SAFT equation of state, a predictive model for the solubility of water in n-alkanes is produced. Comparisons of the model are presented with binary mixture experimental data for methane to decane across a wide range of conditions. Excellent qualitative and good quantitative agreement is exhibited without fitting a binary interaction parameter. The model is then extrapolated to predict water solubility in n-alkanes as a function of temperature, pressure, and carbon number for conditions where experimental data is of questionable validity or unavailable. Implications on the potential model used in molecular simulations are also discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200296e [article] Correlation and prediction of water content in alkanes using a molecular theory [texte imprimé] / Christopher P. Emborsky, Auteur ; Kenneth R. Cox, Auteur ; Walter G. Chapman, Auteur . - 2011 . - pp. 7791–7799. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 7791–7799 Mots-clés : Phase  equilibriums  Chemical  equilibriums  solutions Résumé : We present a predictive model for the saturated water concentration in n-alkanes based on a theoretical equation of state for the hydrocarbon rich phase and a water equation of state for the aqueous phase. By considering a polar or associating component at low concentration in a nonpolar solvent, we can neglect polar or hydrogen bonding interactions in the hydrocarbon rich phase, thus reducing the number of fitted parameters. The approach allows us to determine the intrinsic pure component equation of state parameters independent of polar and associating interactions. As an example, the nonpolar, non-associating equation of state parameters for water are determined by fitting water solubility data in liquid hydrocarbons (carbon numbers (CN) = 4–13, 16) at ambient conditions. Using the PC-SAFT equation of state, a predictive model for the solubility of water in n-alkanes is produced. Comparisons of the model are presented with binary mixture experimental data for methane to decane across a wide range of conditions. Excellent qualitative and good quantitative agreement is exhibited without fitting a binary interaction parameter. The model is then extrapolated to predict water solubility in n-alkanes as a function of temperature, pressure, and carbon number for conditions where experimental data is of questionable validity or unavailable. Implications on the potential model used in molecular simulations are also discussed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200296e