Documents disponibles écrits par cet auteur

Effect of reagent addition rate and temperature on synthesis of gold nanoparticles in microemulsion route / Girish Muralidharan in Industrial & engineering chemistry research, Vol. 50 N° 14 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8786–8791 Titre : Effect of reagent addition rate and temperature on synthesis of gold nanoparticles in microemulsion route Type de document : texte imprimé Auteurs : Girish Muralidharan, Auteur ; Lakshmanan Subramanian, Auteur ; Sravan Kumar Nallamuthu, Auteur Année de publication : 2011 Article en page(s) : pp. 8786–8791 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gold  Nanoparticles  Microemulsion Résumé : Nanoparticle synthesis in a microemulsion route is typically controlled by changing the water to surfactant ratio, concentration of precursors, and/or concentration of micelles. The experiments carried out in this work with chloroauric acid and hydrazine hydrate as precursors in water/AOT-Brij30/isooctane microemulsions show that the reagent addition rate can also be used to tune the size of stable spherical gold nanoparticles to some extent. The particle size goes through a minimum with variation in feed addition rate. The increase in particle size with an increase in reaction temperature is in agreement with an earlier report. A population balance model is used to interpret the experimental findings. The reduced extent of nucleation at low feed addition rates and suppression of nucleation due to the finite rate of mixing at higher addition rates produce a minimum in particle size. The increase in particle size at higher reaction temperatures is explained through an increase in fusion efficiency of micelles which dissipates supersaturation; increase in solubility is shown to play an insignificant role. The moderate polydispersity of the synthesized particles is due to the continued nucleation and growth of particles. The polydispersity of micelle sizes by itself plays a minor role. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2002507 [article] Effect of reagent addition rate and temperature on synthesis of gold nanoparticles in microemulsion route [texte imprimé] / Girish Muralidharan, Auteur ; Lakshmanan Subramanian, Auteur ; Sravan Kumar Nallamuthu, Auteur . - 2011 . - pp. 8786–8791. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8786–8791 Mots-clés : Gold  Nanoparticles  Microemulsion Résumé : Nanoparticle synthesis in a microemulsion route is typically controlled by changing the water to surfactant ratio, concentration of precursors, and/or concentration of micelles. The experiments carried out in this work with chloroauric acid and hydrazine hydrate as precursors in water/AOT-Brij30/isooctane microemulsions show that the reagent addition rate can also be used to tune the size of stable spherical gold nanoparticles to some extent. The particle size goes through a minimum with variation in feed addition rate. The increase in particle size with an increase in reaction temperature is in agreement with an earlier report. A population balance model is used to interpret the experimental findings. The reduced extent of nucleation at low feed addition rates and suppression of nucleation due to the finite rate of mixing at higher addition rates produce a minimum in particle size. The increase in particle size at higher reaction temperatures is explained through an increase in fusion efficiency of micelles which dissipates supersaturation; increase in solubility is shown to play an insignificant role. The moderate polydispersity of the synthesized particles is due to the continued nucleation and growth of particles. The polydispersity of micelle sizes by itself plays a minor role. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2002507

Rheological modeling of spherical polymeric gels and dispersions incorporating the influence of particle size distribution and surface forces / Girish Muralidharan in Industrial & engineering chemistry research, Vol. 48 N° 19 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8805–8811 Titre : Rheological modeling of spherical polymeric gels and dispersions incorporating the influence of particle size distribution and surface forces Type de document : texte imprimé Auteurs : Girish Muralidharan, Auteur ; Venkataramana Runkana, Auteur Année de publication : 2009 Article en page(s) : pp. 8805–8811 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Spherical  polymeric  gels  Rheological  modeling  Dispersions  Krieger−Dougherty  equation Résumé : Polymer gels are cross-linked polymer particles that are finding applications in coatings, controlled drug delivery, consumer products, etc. A simple model for predicting the viscosity of spherical polymeric gels and dispersions which can help in the formulation of dispersions in terms of solids content, particle size distribution (PSD), pH, ionic strength, etc. is developed. The model is based on an extended Krieger−Dougherty (K−D) equation, which incorporates the influences of both PSD and interparticle surface forces. The two important parameters in the model are the maximum packing fraction and the interaction energy between the particles. Unlike previous models which treated them as adjustable parameters, they are computed as functions of particle, solvent, and suspension characteristics. The maximum packing fraction is calculated as a function of PSD using linear packing theory while the interaction energy is computed using well-established surface force theories. The hydrodynamic thickness of the polymer layer and the mean distance between the chain attachment points on the hard core particle surface are treated as adjustable parameters. The model predictions are in close agreement with the experimentally observed viscosity values for microgel and latex suspensions reported in the literature. The effect of PSD on the suspension viscosity was found to be more pronounced at high particle volume fractions than at low volume fractions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801736q [article] Rheological modeling of spherical polymeric gels and dispersions incorporating the influence of particle size distribution and surface forces [texte imprimé] / Girish Muralidharan, Auteur ; Venkataramana Runkana, Auteur . - 2009 . - pp. 8805–8811. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8805–8811 Mots-clés : Spherical  polymeric  gels  Rheological  modeling  Dispersions  Krieger−Dougherty  equation Résumé : Polymer gels are cross-linked polymer particles that are finding applications in coatings, controlled drug delivery, consumer products, etc. A simple model for predicting the viscosity of spherical polymeric gels and dispersions which can help in the formulation of dispersions in terms of solids content, particle size distribution (PSD), pH, ionic strength, etc. is developed. The model is based on an extended Krieger−Dougherty (K−D) equation, which incorporates the influences of both PSD and interparticle surface forces. The two important parameters in the model are the maximum packing fraction and the interaction energy between the particles. Unlike previous models which treated them as adjustable parameters, they are computed as functions of particle, solvent, and suspension characteristics. The maximum packing fraction is calculated as a function of PSD using linear packing theory while the interaction energy is computed using well-established surface force theories. The hydrodynamic thickness of the polymer layer and the mean distance between the chain attachment points on the hard core particle surface are treated as adjustable parameters. The model predictions are in close agreement with the experimentally observed viscosity values for microgel and latex suspensions reported in the literature. The effect of PSD on the suspension viscosity was found to be more pronounced at high particle volume fractions than at low volume fractions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801736q