Effect of molecular weight of sulfanilic acid-phenol-formaldehyde condensate on the properties of cementitious system / Xinping Ouyang in Cement and concrete research, Vol. 39 N° 4 (Avril 2009)  

Public ISBD [article]  inCement and concrete research > Vol. 39 N° 4 (Avril 2009) . - pp. 283–288 Titre : Effect of molecular weight of sulfanilic acid-phenol-formaldehyde condensate on the properties of cementitious system Type de document : texte imprimé Auteurs : Xinping Ouyang, Auteur ; Xinyuan Jiang, Auteur ; Xueqing Qiu, Auteur Année de publication : 2009 Article en page(s) : pp. 283–288 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Bleeding  Dispersion  Retardation  Workability  Admixture Résumé : The effect of the molecular weight of sulfanilic acid-phenol-formaldehyde condensate (SPF) on the properties of cementitious system was investigated. It is found that SPF with the molecular weight of 35,000 Dalton (Da) gives a good adsorption capacity on the surface of the cement particles, hence a larger zeta potential to cement particles and a good fluidity to the cement paste. In addition, this fraction has a high chelating capacity to calcium in the cement slurry, causing a long retardation of the cementitious system. However, the fractions of a high molecular weight (42,000 Da, and 45,000 Da) exhibit lower bleed water as a percentage of total mix water (BWP). It can be deduced that there is an ideal molecular weight for the best performances of the superplasticizer investigated, which can be used for optimizing the technical parameters in the preparation. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000064 [article] Effect of molecular weight of sulfanilic acid-phenol-formaldehyde condensate on the properties of cementitious system [texte imprimé] / Xinping Ouyang, Auteur ; Xinyuan Jiang, Auteur ; Xueqing Qiu, Auteur . - 2009 . - pp. 283–288. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 4 (Avril 2009) . - pp. 283–288 Mots-clés : Bleeding  Dispersion  Retardation  Workability  Admixture Résumé : The effect of the molecular weight of sulfanilic acid-phenol-formaldehyde condensate (SPF) on the properties of cementitious system was investigated. It is found that SPF with the molecular weight of 35,000 Dalton (Da) gives a good adsorption capacity on the surface of the cement particles, hence a larger zeta potential to cement particles and a good fluidity to the cement paste. In addition, this fraction has a high chelating capacity to calcium in the cement slurry, causing a long retardation of the cementitious system. However, the fractions of a high molecular weight (42,000 Da, and 45,000 Da) exhibit lower bleed water as a percentage of total mix water (BWP). It can be deduced that there is an ideal molecular weight for the best performances of the superplasticizer investigated, which can be used for optimizing the technical parameters in the preparation. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000064

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Lignosulfonate separation using preparative column chromatography / Xinping Ouyang in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10792-10799 Titre : Lignosulfonate separation using preparative column chromatography Type de document : texte imprimé Auteurs : Xinping Ouyang, Auteur ; Pan Zhang, Auteur ; Xueqing Qiu, Auteur Année de publication : 2011 Article en page(s) : pp. 10792-10799 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Column chromatography Résumé : A two-step chromatographic process was developed for the fractionation of lignosulfonate (LS), a main component of sulfite effluence. LS fractions with low polydispersity were obtained, which enables detailed investigation into the relationship between structure and property of LS with different molecular weight (Mw). Sephacryl S-100 was used for LS separation in the first step, and then Sephadex LH-20 and Sephacryl S-100 were chosen for further separation of LS fractions with Mw below and above 6000 Da, respectively. Although the mechanism of column chromatographic separation of LS was mainly dependent on its molecular size, 0.20 mol/L of NaCl or NaNO3 solution was needed in the mobile phase at pH 5.7 to mirtimize electrostatic interaction and polyelectrolyte effect. Compared with the polyelectrolyte effect, the electrostatic interaction was more important in the LS separation. Because the LS fractions of higher Mw had a characteristic of low negative charge, a mobile phase with high flow rate and high pH value was suitable for separating LS fractions with high Mw. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523896 [article] Lignosulfonate separation using preparative column chromatography [texte imprimé] / Xinping Ouyang, Auteur ; Pan Zhang, Auteur ; Xueqing Qiu, Auteur . - 2011 . - pp. 10792-10799. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10792-10799 Mots-clés : Column chromatography Résumé : A two-step chromatographic process was developed for the fractionation of lignosulfonate (LS), a main component of sulfite effluence. LS fractions with low polydispersity were obtained, which enables detailed investigation into the relationship between structure and property of LS with different molecular weight (Mw). Sephacryl S-100 was used for LS separation in the first step, and then Sephadex LH-20 and Sephacryl S-100 were chosen for further separation of LS fractions with Mw below and above 6000 Da, respectively. Although the mechanism of column chromatographic separation of LS was mainly dependent on its molecular size, 0.20 mol/L of NaCl or NaNO3 solution was needed in the mobile phase at pH 5.7 to mirtimize electrostatic interaction and polyelectrolyte effect. Compared with the polyelectrolyte effect, the electrostatic interaction was more important in the LS separation. Because the LS fractions of higher Mw had a characteristic of low negative charge, a mobile phase with high flow rate and high pH value was suitable for separating LS fractions with high Mw. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523896

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