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Fractionation of poly(vinyl methyl ether) / Simona Morariu in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6943–6948 Titre : Fractionation of poly(vinyl methyl ether) : comparison of two large-scale fractionation techniques Type de document : texte imprimé Auteurs : Simona Morariu, Auteur ; John Eckelt, Auteur ; Bernhard A. Wolf, Auteur Année de publication : 2009 Article en page(s) : pp. 6943–6948 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Continuous  polymer  fractionation  Continuous  spin  fractionation  Poly(vinyl  methyl  ether) Résumé : The efficiencies of two large-scale fractionation techniques namely continuous polymer fractionation (CPF) and continuous spin fractionation (CSF) are compared. To this end, we used a commercially available sample of poly(vinyl methyl ether). Both methods are suitable to reduce the nonuniformity of the sample below 0.6. The results demonstrate that CSF has a better fractionation performance than the progenitor method, CPF. A further advantage is the three times higher throughput of CSF. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900484g [article] Fractionation of poly(vinyl methyl ether) : comparison of two large-scale fractionation techniques [texte imprimé] / Simona Morariu, Auteur ; John Eckelt, Auteur ; Bernhard A. Wolf, Auteur . - 2009 . - pp. 6943–6948. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6943–6948 Mots-clés : Continuous  polymer  fractionation  Continuous  spin  fractionation  Poly(vinyl  methyl  ether) Résumé : The efficiencies of two large-scale fractionation techniques namely continuous polymer fractionation (CPF) and continuous spin fractionation (CSF) are compared. To this end, we used a commercially available sample of poly(vinyl methyl ether). Both methods are suitable to reduce the nonuniformity of the sample below 0.6. The results demonstrate that CSF has a better fractionation performance than the progenitor method, CPF. A further advantage is the three times higher throughput of CSF. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900484g

Influence of temperature on the rheological behavior of polymer mixtures in solution / Simona Morariu in Industrial & engineering chemistry research, Vol. 50 N° 15 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 9451–9455 Titre : Influence of temperature on the rheological behavior of polymer mixtures in solution Type de document : texte imprimé Auteurs : Simona Morariu, Auteur ; Cristina-Eliza Brunchi, Auteur ; Camelia Hulubei, Auteur Année de publication : 2011 Article en page(s) : pp. 9451–9455 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Rheological  behavior  of  polymer Résumé : This article investigates the viscoelastic behavior of poly(acrylonitrile) (PAN) and poly[N-(4-carboxyphenyl)maleimide] (PMI) solutions in dimethylformamide (DMF) in comparison with PMI/PAN/DMF ternary mixtures. Some rheological characteristics, such as viscosity and relaxation time, were investigated as functions of the polymer mixture composition at different temperatures in the range of 0–60 °C. The solutions of each polymer and their mixtures exhibit a Newtonian behavior throughout the studied frequency range. At low temperatures, the behavior of the solutions having high PAN contents in the polymer mixture is influenced by physical gelation of the solution. The activation energy of the flow gives indications about the intensity of polymer–polymer interactions as a function of the polymer mixture composition. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200736e [article] Influence of temperature on the rheological behavior of polymer mixtures in solution [texte imprimé] / Simona Morariu, Auteur ; Cristina-Eliza Brunchi, Auteur ; Camelia Hulubei, Auteur . - 2011 . - pp. 9451–9455. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 15 (Août 2011) . - pp. 9451–9455 Mots-clés : Rheological  behavior  of  polymer Résumé : This article investigates the viscoelastic behavior of poly(acrylonitrile) (PAN) and poly[N-(4-carboxyphenyl)maleimide] (PMI) solutions in dimethylformamide (DMF) in comparison with PMI/PAN/DMF ternary mixtures. Some rheological characteristics, such as viscosity and relaxation time, were investigated as functions of the polymer mixture composition at different temperatures in the range of 0–60 °C. The solutions of each polymer and their mixtures exhibit a Newtonian behavior throughout the studied frequency range. At low temperatures, the behavior of the solutions having high PAN contents in the polymer mixture is influenced by physical gelation of the solution. The activation energy of the flow gives indications about the intensity of polymer–polymer interactions as a function of the polymer mixture composition. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200736e

Influence of the Solvent Quality on the Thermodynamic Behavior of Polymethylphenylsiloxane Solutions / Cristina-Eliza Brunchi in Industrial & engineering chemistry research, Vol. 49 N° 24 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12740–12746 Titre : Influence of the Solvent Quality on the Thermodynamic Behavior of Polymethylphenylsiloxane Solutions Type de document : texte imprimé Auteurs : Cristina-Eliza Brunchi, Auteur ; Simona Morariu, Auteur ; Maria Cazacu, Auteur Année de publication : 2011 Article en page(s) : pp. 12740–12746 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Solvent  quality  Thermodynamic Résumé : In this work we investigate the effect of the solvent quality on the thermodynamic behavior of the polydimethyldiphenylsiloxane copolymer by using turbidimetry and viscosimetry. The turbidimetric method was used for the determination of the composition of the solvent mixture at the theta point. The experimental data obtained by using the capillary viscometry both in good and theta solvent conditions have been processed by using classical Huggins equation and new Wolf model (2007), which allows the calculation of intrinsic viscosities and other hydrodynamic parameters. The results obtained by using the two approaches were discussed comparatively. The conformational properties of copolymer in solution depend on their molecular structure, which is essentially dominated by the solvent quality, reflecting the balance of the interactions between the polymer chains and each solvent and that between solvent molecules. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1015238 [article] Influence of the Solvent Quality on the Thermodynamic Behavior of Polymethylphenylsiloxane Solutions [texte imprimé] / Cristina-Eliza Brunchi, Auteur ; Simona Morariu, Auteur ; Maria Cazacu, Auteur . - 2011 . - pp. 12740–12746. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12740–12746 Mots-clés : Solvent  quality  Thermodynamic Résumé : In this work we investigate the effect of the solvent quality on the thermodynamic behavior of the polydimethyldiphenylsiloxane copolymer by using turbidimetry and viscosimetry. The turbidimetric method was used for the determination of the composition of the solvent mixture at the theta point. The experimental data obtained by using the capillary viscometry both in good and theta solvent conditions have been processed by using classical Huggins equation and new Wolf model (2007), which allows the calculation of intrinsic viscosities and other hydrodynamic parameters. The results obtained by using the two approaches were discussed comparatively. The conformational properties of copolymer in solution depend on their molecular structure, which is essentially dominated by the solvent quality, reflecting the balance of the interactions between the polymer chains and each solvent and that between solvent molecules. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1015238

The Behavior of chitosan in solvents with different ionic strengths / Simona Morariu in Industrial & engineering chemistry research, Vol. 51 N° 39 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 39 (Octobre 2012) . - pp. 12959–12966 Titre : The Behavior of chitosan in solvents with different ionic strengths Type de document : texte imprimé Auteurs : Simona Morariu, Auteur ; Cristina-Eliza Brunchi, Auteur ; Maria Bercea, Auteur Année de publication : 2012 Article en page(s) : pp. 12959–12966 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Solvents  Ionic  strengths Résumé : The thermodynamic behavior of chitosan in acidic aqueous solutions with ionic strengths between 0.04 × 10–2 and 24.30 × 10–2 M was investigated at 25 °C. The intrinsic viscosity and other thermodynamic parameters of chitosan with the molecular weight and the degree of acetylation of 7.14 × 105 g mol–1 and 26%, respectively, were determined and discussed by using both classical equations (Huggins and Fedors) and a new model (Wolf). At low ionic strengths of the solvent, the highest values of the intrinsic viscosity were obtained due to the expansion of the chitosan chains. Two critical concentrations, c* (which separates the dilute-semidilute regimes) and c+ (at which the dimensions of the polymer coils are considered to have shrunk to their unperturbed dimensions), were estimated, and the effect of the solvent ionic strength on their values was discussed. By increasing of the solvent ionic strength from 0.04 × 10–2 to 24.30 × 10–2 M, the persistence length decreased from 17.14 to 4.60 nm, suggesting an increase of the chitosan flexibility due to the decrease of repulsive potential between the polymer chains. The radius of gyration and the persistence length in the unperturbed state were determined as being 52.50 and 3.90 nm, respectively. The viscometric data were corroborated with those obtained by the zeta potential, conductivity, and turbidity measurements for the ionic strength of the solvent between 0.04 × 10–2 and 42.25 × 10–2 M. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301309g [article] The Behavior of chitosan in solvents with different ionic strengths [texte imprimé] / Simona Morariu, Auteur ; Cristina-Eliza Brunchi, Auteur ; Maria Bercea, Auteur . - 2012 . - pp. 12959–12966. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 39 (Octobre 2012) . - pp. 12959–12966 Mots-clés : Solvents  Ionic  strengths Résumé : The thermodynamic behavior of chitosan in acidic aqueous solutions with ionic strengths between 0.04 × 10–2 and 24.30 × 10–2 M was investigated at 25 °C. The intrinsic viscosity and other thermodynamic parameters of chitosan with the molecular weight and the degree of acetylation of 7.14 × 105 g mol–1 and 26%, respectively, were determined and discussed by using both classical equations (Huggins and Fedors) and a new model (Wolf). At low ionic strengths of the solvent, the highest values of the intrinsic viscosity were obtained due to the expansion of the chitosan chains. Two critical concentrations, c* (which separates the dilute-semidilute regimes) and c+ (at which the dimensions of the polymer coils are considered to have shrunk to their unperturbed dimensions), were estimated, and the effect of the solvent ionic strength on their values was discussed. By increasing of the solvent ionic strength from 0.04 × 10–2 to 24.30 × 10–2 M, the persistence length decreased from 17.14 to 4.60 nm, suggesting an increase of the chitosan flexibility due to the decrease of repulsive potential between the polymer chains. The radius of gyration and the persistence length in the unperturbed state were determined as being 52.50 and 3.90 nm, respectively. The viscometric data were corroborated with those obtained by the zeta potential, conductivity, and turbidity measurements for the ionic strength of the solvent between 0.04 × 10–2 and 42.25 × 10–2 M. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301309g