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Acetone influence on glass transition of poly(methyl methacrylate) and polystyrene in compressed carbon dioxide / Jun He in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 5093–5097 Titre : Acetone influence on glass transition of poly(methyl methacrylate) and polystyrene in compressed carbon dioxide Type de document : texte imprimé Auteurs : Jun He, Auteur ; Bo Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 5093–5097 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Poly(methyl  methacrylate)  Polystyrene  Compressed  gaseous  acetone/carbon  dioxide  Glass  transition  pressure Résumé : In this work, the glass transitions of poly(methyl methacrylate) and polystyrene in compressed gaseous acetone/carbon dioxide were measured by an in situ creep compliance method at pressures lower than 7.0 MPa and at 318−338 K. When a small amount of acetone (x = 0.01−0.02) was added to a polymer-compressed carbon dioxide system, the glass transition pressure of polymer was further depressed by 1.0−4.0 MPa. The observed glass transition pressure depression increased with the acetone concentration in carbon dioxide and decreased with the temperature rise. A simple model was used to estimate the glass transition temperature depressions for the polymers in compressed gaseous acetone/carbon dioxide solution. The calculated results were in good agreement with the determined ones, except for the retrograde vitrification region. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801949g [article] Acetone influence on glass transition of poly(methyl methacrylate) and polystyrene in compressed carbon dioxide [texte imprimé] / Jun He, Auteur ; Bo Wang, Auteur . - 2009 . - pp. 5093–5097. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 5093–5097 Mots-clés : Poly(methyl  methacrylate)  Polystyrene  Compressed  gaseous  acetone/carbon  dioxide  Glass  transition  pressure Résumé : In this work, the glass transitions of poly(methyl methacrylate) and polystyrene in compressed gaseous acetone/carbon dioxide were measured by an in situ creep compliance method at pressures lower than 7.0 MPa and at 318−338 K. When a small amount of acetone (x = 0.01−0.02) was added to a polymer-compressed carbon dioxide system, the glass transition pressure of polymer was further depressed by 1.0−4.0 MPa. The observed glass transition pressure depression increased with the acetone concentration in carbon dioxide and decreased with the temperature rise. A simple model was used to estimate the glass transition temperature depressions for the polymers in compressed gaseous acetone/carbon dioxide solution. The calculated results were in good agreement with the determined ones, except for the retrograde vitrification region. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801949g

Partition coefficients of methyl methacrylate and acetone between polymer and compressed carbon dioxide phases by an in situ infrared spectroscopy method / Jun He 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. 7354–7358 Titre : Partition coefficients of methyl methacrylate and acetone between polymer and compressed carbon dioxide phases by an in situ infrared spectroscopy method Type de document : texte imprimé Auteurs : Jun He, Auteur ; Bo Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 7354–7358 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methyl  methacrylate  Acetone  Polymer  gaseous  carbon  dioxide  phase  Compressed  gaseous  carbon  dioxide  phase  Partition  coefficients  Fourier  transform  infrared  spectroscopy  method Résumé : Partition coefficients of methyl methacrylate and acetone between some polymer and compressed gaseous carbon dioxide phases were determined by an in situ Fourier transform infrared (FTIR) spectroscopy method with a special designed high pressure IR cell at 318.2 K and 2.0−7.0 MPa. At the same temperature and pressure, the partition coefficient for methyl methacrylate was higher than that for acetone between the same polymer and subcritical carbon dioxide. For most solute/polymer/CO2 systems, the partition coefficient of solute between the polymer and compressed gaseous carbon dioxide decreased with the pressure increase. Only for a methyl methacrylate/poly(methyl methacrylate)/CO2 system, the partiton coefficient was not sensitive to the pressure change at pressures lower than 3.9 MPa. A linear solvation free energy relationship was used to estimate the main tendency of the pressure dependency. With the pressure dependent polarizability−dipolarity parameter of carbon dioxide, the calculated results were in accord with some experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801824y [article] Partition coefficients of methyl methacrylate and acetone between polymer and compressed carbon dioxide phases by an in situ infrared spectroscopy method [texte imprimé] / Jun He, Auteur ; Bo Wang, Auteur . - 2009 . - pp. 7354–7358. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7354–7358 Mots-clés : Methyl  methacrylate  Acetone  Polymer  gaseous  carbon  dioxide  phase  Compressed  gaseous  carbon  dioxide  phase  Partition  coefficients  Fourier  transform  infrared  spectroscopy  method Résumé : Partition coefficients of methyl methacrylate and acetone between some polymer and compressed gaseous carbon dioxide phases were determined by an in situ Fourier transform infrared (FTIR) spectroscopy method with a special designed high pressure IR cell at 318.2 K and 2.0−7.0 MPa. At the same temperature and pressure, the partition coefficient for methyl methacrylate was higher than that for acetone between the same polymer and subcritical carbon dioxide. For most solute/polymer/CO2 systems, the partition coefficient of solute between the polymer and compressed gaseous carbon dioxide decreased with the pressure increase. Only for a methyl methacrylate/poly(methyl methacrylate)/CO2 system, the partiton coefficient was not sensitive to the pressure change at pressures lower than 3.9 MPa. A linear solvation free energy relationship was used to estimate the main tendency of the pressure dependency. With the pressure dependent polarizability−dipolarity parameter of carbon dioxide, the calculated results were in accord with some experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801824y

Response spectral characteristics and reliabilities of linear structures to both intensity and frequency content time-varying earthquake loads / Jun He in Journal of structural engineering, Vol. 138 N° 12 (Décembre 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 12 (Décembre 2012) . - pp. 1492–1504 Titre : Response spectral characteristics and reliabilities of linear structures to both intensity and frequency content time-varying earthquake loads Type de document : texte imprimé Auteurs : Jun He, Auteur Année de publication : 2013 Article en page(s) : pp. 1492–1504 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Random  earthquake  load  Yeh-Wen  model  Linear  elastic  structure  Spectral  characteristics  First-passage  probability Résumé : A numerical method for estimating the useful spectral characteristics of responses of classically damped linear elastic structures to the Yeh-Wen model of fully nonstationary random earthquake loads is developed. The derivation of the method is carried out in three steps. First, the stationary Gaussian white noise process in the space of a frequency modulation function is transformed to the uniformly modulated Gaussian white noise process in the time space. Second, the numerical computation procedure for the unit impulse response functions in the time domain of the Clough-Penzien filters modified in the space of a frequency modulation function is proposed. Finally, the numerical solutions for the useful spectral characteristics of responses of linear structures to the Yeh-Wen model are given, from which the first-passage reliability problem can be solved by using Vanmarcke’s approximation. Numerical investigation of a simple oscillator shows the effect of the frequency modulation functions on the numerical results and computational efficiency of the developed method. The numerical analysis of the spectral characteristics and first-passage probabilities of a response of a supertall television tower demonstrates how to implement the numerical method in practical applications. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000600 [article] Response spectral characteristics and reliabilities of linear structures to both intensity and frequency content time-varying earthquake loads [texte imprimé] / Jun He, Auteur . - 2013 . - pp. 1492–1504. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 12 (Décembre 2012) . - pp. 1492–1504 Mots-clés : Random  earthquake  load  Yeh-Wen  model  Linear  elastic  structure  Spectral  characteristics  First-passage  probability Résumé : A numerical method for estimating the useful spectral characteristics of responses of classically damped linear elastic structures to the Yeh-Wen model of fully nonstationary random earthquake loads is developed. The derivation of the method is carried out in three steps. First, the stationary Gaussian white noise process in the space of a frequency modulation function is transformed to the uniformly modulated Gaussian white noise process in the time space. Second, the numerical computation procedure for the unit impulse response functions in the time domain of the Clough-Penzien filters modified in the space of a frequency modulation function is proposed. Finally, the numerical solutions for the useful spectral characteristics of responses of linear structures to the Yeh-Wen model are given, from which the first-passage reliability problem can be solved by using Vanmarcke’s approximation. Numerical investigation of a simple oscillator shows the effect of the frequency modulation functions on the numerical results and computational efficiency of the developed method. The numerical analysis of the spectral characteristics and first-passage probabilities of a response of a supertall television tower demonstrates how to implement the numerical method in practical applications. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000600

The temperature, cosolvent, and blending effects on the partitions between polymer and compressed carbon dioxide / Jun He 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. 7359–7363 Titre : The temperature, cosolvent, and blending effects on the partitions between polymer and compressed carbon dioxide Type de document : texte imprimé Auteurs : Jun He, Auteur ; Bo Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 7359–7363 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Methyl  methacrylate  Poly(methyl  methacrylate)  Compressed  gaseous  carbon  dioxide  Cosolvent  effect Résumé : In this work, the temperature influence and blending effect on the partition of methyl methacrylate between poly(methyl methacrylate) and compressed gaseous carbon dioxide were investigated; the cosolvent effect of ethanol on the partition of acetone between poly(carbonate biphenol A) and compressed gaseous carbon dioxide was also studied by using an in situ IR spectroscopy method at fluid pressure lower than 7.0 MPa. The temperature increase and the cosolvent addition decreased the partition coefficient of solute between polymer and compressed gaseous carbon dioxide. Interestingly the blending of the polymers increased the partition coefficient, and the distribution of methyl methacrylate between the poly(methyl methacrylate)/poly(vinylidene fluoride) complex and compressed gaseous CO2 was not a simple additive of the distribution of the two separate at a pressure lower than 6.0 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801832v [article] The temperature, cosolvent, and blending effects on the partitions between polymer and compressed carbon dioxide [texte imprimé] / Jun He, Auteur ; Bo Wang, Auteur . - 2009 . - pp. 7359–7363. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7359–7363 Mots-clés : Methyl  methacrylate  Poly(methyl  methacrylate)  Compressed  gaseous  carbon  dioxide  Cosolvent  effect Résumé : In this work, the temperature influence and blending effect on the partition of methyl methacrylate between poly(methyl methacrylate) and compressed gaseous carbon dioxide were investigated; the cosolvent effect of ethanol on the partition of acetone between poly(carbonate biphenol A) and compressed gaseous carbon dioxide was also studied by using an in situ IR spectroscopy method at fluid pressure lower than 7.0 MPa. The temperature increase and the cosolvent addition decreased the partition coefficient of solute between polymer and compressed gaseous carbon dioxide. Interestingly the blending of the polymers increased the partition coefficient, and the distribution of methyl methacrylate between the poly(methyl methacrylate)/poly(vinylidene fluoride) complex and compressed gaseous CO2 was not a simple additive of the distribution of the two separate at a pressure lower than 6.0 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801832v