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A new method for evaluation of the isothermal conversion curves from the nonisothermal measurements. application in nickel axide reduction kinetics / Borivoj Adnadjevic in Industrial & engineering chemistry research, Vol. 48 N°3 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1420–1427 Titre : A new method for evaluation of the isothermal conversion curves from the nonisothermal measurements. application in nickel axide reduction kinetics Type de document : texte imprimé Auteurs : Borivoj Adnadjevic, Auteur ; Bojan Jankovic, Auteur Année de publication : 2009 Article en page(s) : p. 1420–1427 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Metal  oxide  Nickel  oxide  --  reduction  kinetics Résumé : A new method for evaluation of isothermal conversion curves from the experimentally determined nonisothermal conversion curves for the nickel oxide reduction process in hydrogen atmosphere was established. It was concluded that by applying the conventional and proposed prediction methods it was not possible (at Tiso ≤ 300 °C) to calculate the isothermal conversion curves using the experimentally obtained nonisothermal conversion curves for this reduction process. The dependence of the apparent activation energy on the degree of conversion shows that the investigated reduction process is complex under isothermal or nonisothermal conditions. By applying Miura’s procedure, the shape of density distribution functions of the apparent activation energies was determined for the isothermal and nonisothermal reduction processes. It was concluded that the existence of different distributions of internal energy of the NiO reduction centers is a consequence of different reduction kinetics under isothermal and nonisothermal experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801074j [article] A new method for evaluation of the isothermal conversion curves from the nonisothermal measurements. application in nickel axide reduction kinetics [texte imprimé] / Borivoj Adnadjevic, Auteur ; Bojan Jankovic, Auteur . - 2009 . - p. 1420–1427. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1420–1427 Mots-clés : Metal  oxide  Nickel  oxide  --  reduction  kinetics Résumé : A new method for evaluation of isothermal conversion curves from the experimentally determined nonisothermal conversion curves for the nickel oxide reduction process in hydrogen atmosphere was established. It was concluded that by applying the conventional and proposed prediction methods it was not possible (at Tiso ≤ 300 °C) to calculate the isothermal conversion curves using the experimentally obtained nonisothermal conversion curves for this reduction process. The dependence of the apparent activation energy on the degree of conversion shows that the investigated reduction process is complex under isothermal or nonisothermal conditions. By applying Miura’s procedure, the shape of density distribution functions of the apparent activation energies was determined for the isothermal and nonisothermal reduction processes. It was concluded that the existence of different distributions of internal energy of the NiO reduction centers is a consequence of different reduction kinetics under isothermal and nonisothermal experimental conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801074j

Nonisothermal degradation of Zetaplus impression material / Bojan Jankovic 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. 7044–7053 Titre : Nonisothermal degradation of Zetaplus impression material : kinetic aspects Type de document : texte imprimé Auteurs : Bojan Jankovic, Auteur Année de publication : 2009 Article en page(s) : pp. 7044–7053 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonisothermal  degradation  process  Zetaplus  impression  material  Thermogravimetric  measurements  Differential  thermal  analysis  measurements Résumé : Kinetic analysis of the nonisothermal degradation process of Zetaplus impression material has been performed. Kinetic data for the investigated degradation process were obtained from the thermogravimetric (TG) and differential thermal analysis (DTA) measurements conducted at the three different heating rates (β = 10, 20, and 25 °C min−1) in an air atmosphere. For determination of the kinetic model function (f(α) or g(α)), the isoconversional and Master-plot methods were used. It was found that the first degradation stage of Zetaplus impression material can be described by the three-dimensional diffusion (D3) and with the following values of kinetic parameters: Ea = 99.5 kJ mol−1 and A = 1.05 × 108 min−1. Kinetic analysis shows that the first degradation stage corresponds to the bond cleavages and polydimethylsiloxane thermal volatilization, which is contolled by the rate of diffusion and evaporation of oligomers produced on decomposition. The observed second degradation step is more complex; it includes two parallel independent reactions with different values of the apparent activation energy. By applying the nonlinear regression (NLR) method, it was found that the second degradation stage can be described by two independent parallel first-order reactions (nth-order reaction model). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900104b [article] Nonisothermal degradation of Zetaplus impression material : kinetic aspects [texte imprimé] / Bojan Jankovic, Auteur . - 2009 . - pp. 7044–7053. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7044–7053 Mots-clés : Nonisothermal  degradation  process  Zetaplus  impression  material  Thermogravimetric  measurements  Differential  thermal  analysis  measurements Résumé : Kinetic analysis of the nonisothermal degradation process of Zetaplus impression material has been performed. Kinetic data for the investigated degradation process were obtained from the thermogravimetric (TG) and differential thermal analysis (DTA) measurements conducted at the three different heating rates (β = 10, 20, and 25 °C min−1) in an air atmosphere. For determination of the kinetic model function (f(α) or g(α)), the isoconversional and Master-plot methods were used. It was found that the first degradation stage of Zetaplus impression material can be described by the three-dimensional diffusion (D3) and with the following values of kinetic parameters: Ea = 99.5 kJ mol−1 and A = 1.05 × 108 min−1. Kinetic analysis shows that the first degradation stage corresponds to the bond cleavages and polydimethylsiloxane thermal volatilization, which is contolled by the rate of diffusion and evaporation of oligomers produced on decomposition. The observed second degradation step is more complex; it includes two parallel independent reactions with different values of the apparent activation energy. By applying the nonlinear regression (NLR) method, it was found that the second degradation stage can be described by two independent parallel first-order reactions (nth-order reaction model). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900104b