FRSFCO - Producción de Investigación

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Author: search.filters.author.Meira, Gregorio

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    Decorative laminates based on phenolic resins modified with sodium lignosulfonate and kraft lignin: Evaluation of mechanical properties
    (2014-03) Taverna, María E.; Nicolau, Verónica V.; Ollearo, Rocío; Morán, Juan; Frontini, Patricia; Meira, Gregorio; Estenoz, Diana
    The substitution of phenol in the production of resol-type phenolic resins by environmentally-friendly compounds such as lignin and its derivatives is of great technological and academic interest, due to the similarity between resols and the aromatic structure of lignins. However, lignins must be chemically-modified in order to increase their reactivity toward formaldehyde. In this work, the addition of commercial lignins (sodium lignosulfonate and Kraft-type) as partial replacement of phenol in the resols used for decorative laminates production is experimentally studied. The work involved: the characterization and reactivation of commercial lignins, the industrial synthesis of traditional and modified resols by replacement of 10 and 20% w/w of phenol, the industrial impregnation of Kraft-type papers with the produced resins and the production of laminates at laboratory and industrial scales. The mechanical performance of the laminates was deeply assesed by determining tensile modulus, bending strengh, biaxial flexural impact strenght and Mode- I Interlaminar Fracture Toughness in both processing directions. Modified laminates exhibited mechanical properties comparable with those of traditional laminates, indicating a negligible depreciation of them. Industrial tests were carried out at Centro S.A, San Francisco, Córdoba.
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    Estudio experimental de la hidroximetilación del lignosulfonato de sodio proveniente de Eucalyptus grandis destinado a la modificación de resoles
    (2015-10-20) Taverna, María E.; Nicolau, Verónica V.; Estenoz, Diana; Meira, Gregorio; XI Simposio Argentino de Polímeros - SAP 2015
    Las ligninas son polímeros naturales renovables que provienen en su mayoría de desechos de la industria papelera. Debido a sus características estructurales similares al fenol (derivado del petróleo, de importación en Argentina, de costo elevado y alta toxicidad) constituye una muy buena alternativa para su reemplazo en la síntesis de resinas de fenol-formaldehído. Sin embargo, las ligninas presentan baja reactividad, reportándose porcentajes de reemplazo de hasta el 20%m/m en resinas de fenol-formaldehído.1,2 A fin de incrementar la reactividad, se han estudiado varios métodos siendo la metilolación la más importante en resoles.3 En este trabajo, se buscaron las mejores condiciones de reacción (relación inicial %m/m de formaldehído/lignina, temperatura, pH) para la hidroximetilación de un lignosulfonato de sodio comercial. El seguimiento de la reacción se realizó mediante una técnica espectroscópica modificada. Los resultados mostraron muy buena concordancia con el consumo de formaldehído medido volumétricamente.
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    Microparticles based on ionic and organosolv lignins for the controlled release of atrazine
    (Journal of Hazaourdos Materials, 2018-07-02) Taverna, María E.; Busatto, Carlos Alberto; Lescano, Maia Raquel; Nicolau, Verónica V.; Zalazar, Cristina; Meira, Gregorio; Estenoz, Diana
    Lignins are natural polymers of the lignocellulosic biomass. Nowadays, there is a growing interest in developing value-added products based on lignins due to their renewability, low cost and abundance. In this work, lignin microspheres from organosolv and ionic isolation processes were prepared for the controlled release of atrazine. Microspheres were prepared by the solvent extraction/evaporation technique. The controlled release of atrazine from organosolv and ionic lignins microparticles was studied in water. Mobility experiments were performed in an agricultural soil from Argentina. The results showed that microparticles prepared using dichloromethane as the dispersed phase were spherical, while lignins dispersed in ethyl acetate produce irregular microparticles. Organosolv lignin microparticles presented higher encapsulation efficiency for all herbicide loads. About 98% and 95% of atrazine was released in 24 and 48h approximately from organosolv and ionic lignin microparticles, respectively. The release profiles of atrazine from both lignin microparticles were not affected by the herbicide load. Atrazine mobility experiments in soil showed that about 80% of free atrazine was leached in 37 days, while 65.0% and 59.7% of the herbicide was leached from ionic and organosolv lignin microparticles, respectively. Thus, atrazine-loaded microparticles could reduce leaching compared to a commercial formulation of free atrazine.