Examinando por Materia "POLIMEROS"
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Capítulo de libroChitosan: from organic pollutants to high-value polymeric materials(2017) Errea, María Inés; Rossi, Ezequiel; Goyanes, Silvia Nair; D'Accorso, Norma Beatriz"...chitosan has proved to be versatile for so many industrial applications and its versatility is the main value of this polymer. However, the lability at acidic pH of chitosan is a limiting factor that affects mainly its industrial implementation for the removal of metallic anions from water. In addition, the physical and mechanical properties may vary between two manufacturing batches due to the characteristic polydispersity of chitosan with respect to molecular weight and degree of acetylation. This variation could affect the industrial process and in some cases, when strict specifications are requested (e.g., drug delivery), increase the final cost of the product because a purification step prior to use is required. Briefly, despite of the disadvantages mentioned before, due to its great versatility, its nontoxicity, its biodegradability, and the fact that it has a renewable resource, the industrial interest in chitosan and its application has been increasing remarkably in the last years." Artículo de Publicación PeriódicaCuring process of benzoxazine systems. An experimental and theoretical study(2019-09) Gilbert, E.; Forchetti, A.; Pesoa, Juan I.; Berkenwald, Emilio; Spontón, Marisa E.; Estenoz, Diana"A mathematical model that simulates the curing process of benzoxazine (Bz) systems is presented. The model predicts the conversion, gel point and Tg along the curing process, and considers the diffusional limitations to mass transfer due to the increase in the system viscosity along the process. This model can be used to select an appropriate combination of time and temperature in order to obtain a material with pre-specified properties. The theoretical parameters were adjusted with experimental data: conversion, weight-average molecular weight, weight fraction of solubles and Tg. The Bz based on bisphenol A and aniline (BzBA) was used to adjust the model. The curing kinetic of this Bz was followed by FTIR, SEC and DSC, considering five different curing conditions. A very good agreement between experimental and simulated values was observed, even when curing is carried out under different temperatures profiles." Proyecto final de GradoDesarrollo integral de un dispositivo médico implantable de fijación cortical para reparación de ligamento cruzado anterior en PEEK(2018) Fayad, Cecilia; Klausner, Santiago; Franco, Germán; Beducci, Lucio"Este trabajo se basa en la incorporación de un nuevo producto para plásticas ligamentarias, dentro de la familia de los ya existentes en la empresa Micromed System S.A." Artículo de Publicación PeriódicaDetection of chlorantraniliprole residues in tomato using field-deployable MIP photonic sensors(2021-02) Rossi, Ezequiel; Salahshoor, Zahra; Ho, Khanh-Van; Lin, Chung-Ho; Errea, María Inés; Fidalgo de Cortalezzi, María Marta"A photonic sensor based on inversed opal molecular imprinted polymer (MIP) film to detect the presence of chlorantraniliprole (CHL) residue in tomatoes was developed. Acrylic acid was polymerized in the presence of CHL inside the structure of a colloidal crystal, followed by etching of the colloids and CHL elution. Colloidal crystals and MIP films were characterized by scanning electron microscopy and FT-IR, confirming the inner structure and chemical structure of the material. MIP films supported on polymethylmethacrylate (PMMA) slides were incubated in aqueous solutions of the pesticide and in blended tomato samples. The MIP sensor displayed shifts of the peak wavelength of the reflection spectra in the visible range when incubated in CHL concentrations between 0.5 and 10 μg L−1, while almost no peak displacement was observed for non-imprinted (NIP) films. Whole tomatoes were blended into a liquid and spiked with CHL; the sensor was able to detect CHL residues down to 0.5 μg kg−1, significantly below the tolerance level established by the US Environmental Protection Agency of 1.4 mg kg−1. Stable values were reached after about 30-min incubation in test samples. Control samples (unspiked processed tomatoes) produced peak shifts both in MIP and NIP films; however, this matrix effect did not affect the detection of CHL in the spiked samples. These promising results support the application of photonic MIP sensors as an economical and field-deployable screening tool for the detection of CHL in crops." Artículo de Publicación PeriódicaDetection of progesterone in aqueous samples by molecularly imprinted photonic polymers(2022-04) Qasim, Sally; Hsu, Shu-Yu; Rossi, Ezequiel; Lin, Chung-Ho; Polo Parada, Luis; Fidalgo de Cortalezzi, María Marta; Salahshoor, Zahra"A label-free molecular imprinted polymer (MIP) sensor was fabricated for the detection of progesterone in aqueous solutions, by polymerization inside the void spaces of colloidal crystals, which gave them photonic properties. The prepolymerization mixture was prepared from acrylic acid as the functional monomer, ethylene glycol as the cross-linker agent, ethanol as solvent, and progesterone as the imprinted template. After polymerization, the colloidal crystal was removed by acid etching and the target eluted with a solvent. Material characterization included as follows: attenuated total reflectance-Fourier-transform infrared spectroscopy, dynamic light scattering, swelling experiments, and environmental scanning electron microscopy. MIPs were investigated by equilibrium binding, kinetics experiments, and UV–visible spectra to investigate Bragg diffraction peak shift that occurs with the rebinding at different progesterone concentrations in deionized water and 150-mM NaCl solutions. The MIP response was investigated with progesterone concentration in the 1–100 μg L−1 range, with LOD of 0.5 μg L−1, reaching the detected range of hormone in natural waters. Furthermore, hydrogel MIP films were successfully tested in various real water matrices with satisfactory results. Moreover, the MIP film exhibited good selectivity toward the progesterone hormone evidenced by a larger response than when exposed to structurally similar molecules. Computational studies suggested that size along with surface potential influenced the binding of analog compounds. Due to their ease of use and low cost, the sensors are promising as screening tools for the presence of progesterone in aqueous samples." Artículo de Publicación PeriódicaEnhancement of the fouling resistance of zwitterion coated ceramic membranes(2020-08) Storms, Max; Kadhem, Abbas J.; Xiang, Shuting; Bernards, Matthew; Gentile, Guillermina José; Fidalgo de Cortalezzi, María Marta"Ceramic membranes suffer from rapid permeability loss during filtration of organic matter due to their fouling propensity. To address this problem, iron oxide ultrafiltration membranes were coated with poly(sulfobetaine methacrylate) (polySBMA), a superhydrophilic zwitterionic polymer. The ceramic-organic hybrid membrane was characterized by scanning electron microscopy (SEM) and optical profilometry (OP). Membranes with and without polySBMA coating were subjected to fouling with bovine serum albumin solution. Hydraulic cleaning was significantly more effective for the coated membrane than for the non-coated one, as 56%, 66%, and 100% of the fouling was removed for the first, second, and third filtration cycle, respectively. Therefore, we can highlight the improved cleaning due to an increased fouling reversibility. Although some loss of polymer during operation was detected, it did not affect the improved behavior of the tested membranes." Artículo de Publicación PeriódicaMechanisms and conditions that affect phase inversion processes. A review.(2020-07) Maffi, Juan M.; Meira, Gregorio R.; Estenoz, Diana"The phenomenon of phase inversion occurs in liquid-liquid dispersions found in a variety of chemical engineering fields. From simple oil-water mixtures to complex polymeric systems, the operating variables that affect this physical phenomenon are discussed in this work. The contribution on this matter by a large number of researchers is critically assessed, outlining both coherent and conflicting results. A detailed review of the mechanisms by which phase inversion takes place is also provided. While this subject has been studied for the past fifty years, this multivariate nonlinear process is not yet comprehensively understood, and this review article aims to describe the conclusions so far reached to provide insight for future research." Tesis de doctoradoNuevos desarrollos en el modelado matemático del proceso continuo para la producción en masa de polímeros de estireno en presencia de elastómeros =(2022-07) Laganá, María Laura; Estenoz, Diana; Stripeikis, Jorge"El objetivo general de esta tesis es investigar aspectos aún no dilucidados en el área de la ingeniería del proceso de polimerización en masa de estireno (St) en presencia de elastómeros para la producción de Poliestireno de alto impacto (HIPS). La investigación se enfoca en el entendimiento y modelado matemático de los fenómenos fisicoquímicos involucrados, en el estudio y empleo de nuevas técnicas de modelado para la simulación de sistemas complejos, y en la optimización de los procesos. Se pretende lograr desarrollos que contribuyan a diseñar y operar los procesos industriales continuos con alto grado de comprensión, y optimizados desde el punto de vista de la productividad y de la calidad del producto final." Trabajo final de especializaciónOptimización de la recuperación de petróleo mediante polímeros y surfactantes(2019) Nahum, Maximiliano Ariel; Tomasone, Gonzalo Martín; Shiratori, Julio Tesis de doctoradoPolímeros modificados químicamente como agentes de captura de metales en agua(2020-04-21) Rossi, Ezequiel; Errea, María Inés; Fidalgo de Cortalezzi, María Marta"En el marco del interés por el tratamiento de aguas contaminadas, el objetivo general de este Trabajo de Tesis fue obtener materiales para la remoción de metales pesados de sistemas acuosas, mediante la modificación química de polímeros. Específicamente, se presentan los productos obtenidos al modificar celulosa, quitosano y poli (cloruro de vinilbencilo) (PCVB), la caracterización de los nuevos materiales y los estudios de captura de metales a los que fueron sometidos." Ponencia en CongresoPolymer viscosity: understanding of changes through time in the reservoir and a way to predict them(2019-09) Katz Marquez, Román E.Polymer rheological behavior in an Enhanced Oil Recovery (EOR) project is one of the critical factors to determine whether the polymer injection would be effective to increase the oil production in a field. Due to complications on the measurement of this parameter and its variation within the reservoir, the challenge of understanding viscosity behavior relies on lab and field tests that become key factors to solve this issue. This study was conducted during an injectivity test for an EOR project in Los Perales field (Santa Cruz, Argentina) in three wells with different operational and subsurface conditions, and tests were performed twice a day for 30 days each in order to obtain sufficient time span of data. From lab rheology tests performed at reservoir conditions, where the main objective was to analyze viscosity changes through time, two different tendencies were observed: one that affects in early times and another that becomes preeminent at late times. With these results, a describing equation was developed to predict viscosity evolution over time. The equation consists of three terms including thermal variation, chemical degradation and the final viscosity towards which the polymer tends. Although the equation properly describes both lab and field polymer solution, there is a considerable difference, especially when the effects mentioned become preponderant. This difference is attributed to both the water used for the mixture and the possible impurities that may be incorporated during the maturation or transfer of the polymer. Since most of the data used was obtained from field tests, this emphasizes the appliance of the equation on the field. Impurities turn out to be crucial, specially oxygen (O2) and hydrogen sulfide (H2S) combined. Their presence highly impacts the asymptotic viscosity, so a correlation between H2S content and final viscosity was also developed. Finally, an analysis of the temperature influence on the viscosity was conducted. A correlation between the final viscosity and temperature was found and used to incorporate temperature variations in the predictions and therefore to relate measurements performed at different conditions. The primary advantage of this study is that the equation and correlations enable the prediction of the polymer solution viscosity at any time. This allows the estimation of actual polymer viscosity in the reservoir from a routine measurement at any temperature and impurities content. The versatility of this equation is what makes it novel and useful in an industry going towards EOR projects. Trabajo final de especializaciónSurfactant and polymer retention in chemical enhanced oil recovery processes(2017) De la Cruz Vivanco, Carlos Alberto; Voirin, Jean-Marie"Chemical Enhanced Oil Recovery by alkali, surfactant and/or polymer flooding could be o good option to produce remaining oil from brown fields. One parameter that affects performance and economics of a CEOR process is how much of the injected chemicals is adsorbed or retained by the porous medium. There may be significant interactions between transported molecules and the porous medium which cause the chemical to be retained and lead to the formation of a bank of injection fluid wholly or partially denuded of chemical. Clearly, this can lead to a reduction in the efficiency of the chemical flood. Therefore, the level of chemical retention can be considered as one of the key factors in determining the economic viability of a chemical flood. Thus, it is of great importance to establish the correct retention levels for a given proposed field chemical EOR process. The conditions under which such laboratory measurements should be made are extremely important so that relevant figures for retention are available for the simulation assessment of the chemical flood. In order to obtain relevant data for surfactant and polymer retention, reliable analytical methods must be available to determine their concentration. This is necessary to calculate retention by material balance in laboratory experiments or in the field. In this work, a bibliographic search was done to find analytical methods for surfactant and polymer determination. Several methods were found with good potential. Careful analysis of each methodology, equipment availability at BASF and previous experience, led to the conclusion that determination by Total Organic Carbon (TOC) and Total Nitrogen (TN) content was the most convenient option. It has the advantage that one single piece of equipment can analyze both TOC and TN and an autosampler can be used for automatic measurement. This makes it very convenient for retention determination experiments and coreflood tests in which many samples need to be analyzed. Therefore, this method was successfully implemented for determination of two surfactants and two polymers and calibration curves were obtained in the range from 0 to 200 ppm. Two calculation approaches were proposed for concentration determination, based on single- and two-variable linear regression. It was found that error is approximately 50% lower by using two-variable regression. Once a reliable analytical method was implemented, experiments were carried out to determine surfactant and polymer retention onto Bentheimer sand in static no-flow conditions and in dynamic conditions in a sandpack, at 23 °C. One sulfate surfactant and one HPAM polymer from BASF were studied in synthetic sea water brine, with 3.5% TDS. Adsorption isotherms obtained in static conditions showed that the surfactant was adsorbed in two layers, with maximum adsorption of 760 μg/g. For the polymer, a maximum adsorption of 426 μg/g was observed and possibly a two-layer adsorption behavior but further experiments are needed to confirm this. When both chemicals were mixed, competitive adsorption occurred and adsorption values decreased. Moreover, polymer prevented the adsorption of the second surfactant layer, reducing its adsorption by 80%. Dynamic retention experiments were carried out with a 0.2-mL/min flowrate. Maximum amounts of 206 and 132 μg/g were retained at 1500 ppm. This is only approximately 30% of the amount adsorbed in static conditions. After water flooding, only 16.4% of previously adsorbed surfactant was desorbed, reaching a residual retention of 172 μg/g. Regarding polymer, 31.7% was desorbed by water flooding, with a residual retention of 90 μg/g. It can be said that retention is largely irreversible." Proyecto final de GradoThe effect of neutralization of a cationic polymeric vaccine delivery system via addition of an anionic polymer on protein expression(2023-07-17) Dadi, Sabrina MikaNext generation vaccines have arisen as a quick response to the SARS-Cov-2 pandemic. This technology uses genetic material for immunization and allows a cost effective and adaptive method in comparison to classic vaccine platforms. Nevertheless, said genetic sequence needs an appropriate method in order to be delivered to host cells efficiently, promote cellular uptake and prevent degradation. In this study, the delivery of self-amplifying RNA (saRNA) using a cationic polymer is analysed. Nanoparticles were formulated via self assembly, using the polymer poly (cystamine bisacrylamide-co-4-amino-1-butanol) (pABOL) as well as saRNA coding for the gene of interest, firefly luciferase. Surface charge is one of the main differences seen when comparing the encapsulation of these nanoparticles to the FDA approved lipid nanoparticles (LNPs), LNPs are neutral, whereas pABOL nanoparticles are cationic. And although LNP delivery has led to an overall higher immune response, pABOL delivery has induced 100x higher intramuscular protein expression. Therefore, the surface charge of pABOL nanoparticles was modified in order to study characteristics such as size, polydispersity index and protein expression in vitro. The anionic polymer polyglutamic acid (PGA) was used and a series of formulations using different weight to weight ratios of PGA to pABOL were prepared. This polymer has been previously added to cationic lipoparticles so as to modify its surface charge and study the effect on the biodistribution. Increasing levels of PGA led to anionic particles, as expected, and protein expression levels comparable to that of cationic particles formulated without PGA. It was also seen that neutral particles showed particle sizes of approximately 1000 nm and a significantly lower protein expression when tested in vitro. The formulation technique was also studied. We found that for 50 μL doses prepared for in vitro experiments, there were no significant differences in the particle characteristics when formulation methods varied, but this was not the case for in vivo formulations. Overall, PGA showed itself to be a promising polymer to complement pABOL characteristics when used as a delivery system for genetic material and we hypothesize that this has the potential to alter cellular tropism.