DSpace Repository :: Browsing by Author "Casis, Natalia"

Browsing by Author "Casis, Natalia"

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Cellulose nanoﬁbrils as a replacement for xanthan gum (XGD) in water based muds (WBMs) to be used in shale formations
(2018-12) Villada, Yurany; Iglesias, María Celeste; Casis, Natalia; Erdmann, Eleonora; Peresin, María Soledad; Estenoz, Diana
"In this work, the potential replacement of xanthan gum (XGD) by cellulose nanofibrils in the composition of water based muds (WBMs) was studied. Bleached (B-CNF) and unbleached (L-CNF) cellulose nanofibrils, mainly differentiated by their lignin content, were tested and their performances were compared with that of XGD. The effects of cellulose nanofibrils on the rheological and filtration properties of WBMs were investigated. Rheometric analysis showed a shear-thinning behavior more noticeable for fluids containing B-CNF and XGD, while filtration properties were improved using L-CNF. The Sisko model was used to determine rheological parameters. Finally, it was found that by replacing XGD by double concentration of L-CNF in a WBM for Argentina shale, similar rheological properties were obtained. Structural changes were assessed by using Scanning Electron Microscopy (SEM). Particles agglomeration and good film formability were observed. Furthermore, WBMs with lignin-containing cellulose nanofibrils exhibited a better thermal stability after aging."
Functional characterization on colloidal suspensions containing xanthan gum (XGD) and polyanionic cellulose (PAC) used in drilling fluids for a shale formation
(2016) Villada, Yurany; Gallardo, Felipe Eusebio; Erdmann, Eleonora; Casis, Natalia; Olivares, Laura; Estenoz, Diana
"Drilling fluids are employed in the operation of hydrocarbon exploitation. Two kinds of drilling fluids are commonly used: water based muds and oil based muds. The oil based muds are characterized by their high performance in unconventional reservoirs due to the very low interaction with the reactive formation. Their environmental impact promotes the design of water based muds that present low toxicity. In this paper a water based mud for shale formation with similar rheological characteristics to the oil based mud used in the oil industry of Argentina was designed and the effect of xanthan gum and polyanionic cellulose on the main functional characteristics was studied. Rheometric analysis showed a shear-thinning behavior with notable effect on the concentration of polymers. After dynamic aging test, fluids with composition of PAC=8.00 g/L and XGD =3.00 g/L exhibited rheological properties very close to oil base mud. Structural changes were assessed from optical microscopy and scanning electron microscopy. Particles agglomeration due to the presence of polymers was observed. Furthermore, mud filtration essays allowed to evaluate the performance of PAC as control agent. The Carreau model and statistical analysis were used to determine rheological parameters."
Homogeneous hydrolytic degradation of poly(lactic-co-glycolic acid) microspheres: Mathematical modeling
(2015-12) Busatto, Carlos; Berkenwald, Emilio; Nicolás, Mariano; Casis, Natalia; Luna, Julio; Estenoz, Diana
"The homogeneous hydrolytic degradation of poly(lactic-co-glycolic acid) (PLGA) microspheres was investigated. A mathematical model was developed that estimates the evolutions of ester bonds concentrations and average molecular weights along the degradation process. The model is based on a detailed kinetic mechanism that includes the hydrolysis of the different types of ester bonds by random chain scission and considers the effect of polymer chemical composition and molecular structure. Novel and published experimental data were used to adjust and validate the model. The experimental work consisted of homogeneous hydrolytic degradation of PLGA microspheres. The predictions are in very good agreement with the experimental results."
Mechanisms and conditions that affect phase inversion processes. The case of high-impact polystyrene
(2019) Maffi, Juan M.; Casis, Natalia; Acuña, Pablo; Morales Balado, Graciela Elizabeth; Estenoz, Diana
"The phase inversion during the bulk polymerization of the styrene-polybutadiene system (HIPS manufacturing process) is empirically and theoretically studied in this article. In the experimental work, a series of reactions were performed with benzoyl peroxide as initiator and at temperatures considered of industrial interest (80ºC and 90ºC), varying also the reactor stirring level. Phase inversion was determined by offline viscosity measurements and verified by scanning electron micrography in transmission mode (STEM). The rheological behavior of each reacting system was analyzed and an empirical correlation to predict its apparent viscosity from fundamental reaction parameters was derived. This was achieved successfully for bothbefore and after the phase inversion point."
On the use of espina corona gum as a polymeric additive in water-based drilling fluid
(2022-10) Villada, Yurany; Taverna, María Eugenia; Maffi, Juan M.; Giletta, Sebastián; Casis, Natalia; Estenoz, Diana
"The aim of this work is to evaluate the espina corona gum (ECG) as a sustainable viscosifier or filtration reducer additive in water-based drilling fluids (WBMs) as a potential replacement of guar gum (GG). ECG is a galactomannan isolated from leguminous seeds of Gleditsia amorphoides, trees that grow in South America with viscosifier properties and applications in the food area. ECG was characterized by FTIR, Z potential, intrinsic viscometry, TGA, and steady and oscillatory shear rheological analysis. Moreover, its effect on the main functional properties of WBMs was studied. Fluids containing bentonite (BT), polyanionic cellulose (PAC), GG or ECG were prepared, and rheological, filtration, thermal and structural properties were determined. In order to study the theoretical rheological behavior, several models such as power law, Sisko and Herschel-Bulkley were evaluated. The rheological studies revealed that WBMs containing ECG exhibit higher viscosities in comparison with those with GG. Herschel-Bulkley parameters indicated that the WBMs with high ECG concentration showed higher yield stress. In addition, the presence of ECG improves the thermal stability and filtration properties. The results indicate that ECG can be considered as an innovative, renewable and non-toxic alternative to partially or totally replace GG in WBMs."
Polymeric Membranes from Colloidal Templates with Tunable Morphology
(2010-07) Casis, Natalia; Ravaine, Serge; Reculusa, Stéphane; Colvin, Vicki L.; Wiesner, Mark R.; Estenoz, Diana; Fidalgo de Cortalezzi, María Marta
"Polymeric porous membranes were fabricated from templates made from silica particles. The templates were obtained by self-assembly and by the Langmuir-Blodgett (L-B) technique. For the self-assembly technique, suspensions of silica particles in ethanol were used to create the deposits. L-B deposition was employed to produce templates of different particle sizes for the fabrication of asymmetric membranes. Two different polymers were tested to fabricate membranes: polystyrene (PS) and the diethyleneglycol dimethacrylate (DEGDMA)/urethane dimethacrylate (UDMA) copolymer. Templates and porous films were observed by SEM in order to analyze the pore morphology. Permeability of the poly(DEGDMA/UDMA) films was comparable to commercially available membranes. Proposed applications for these ordered porous structures include, sensors, filters, and catalytic materials."

Browsing by Author "Casis, Natalia"

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