Artículos de publicaciones periódicas

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Development of poly(lactic acid) nanocomposites reinforced with hydrophobized bacterial cellulose
(2020-01) Ávila Ramírez, Jhon Alejandro; Bovi, Jimena; Bernal, Celina; Foresti, María Laura; Errea, María Inés
"Poly(lactic acid)/bacterial cellulose nanocomposites were prepared by solvent casting. Aiming to reduce the incompatibility between polar bacterial cellulose (BC) and the nonpolar poly(lactic acid) (PLA) matrix which induces filler aggregation and poor reinforcement dispersion, BC was acetylated by the use of a non-conventional route catalyzed by citric acid. The derivatized BC (AcBC) was incorporated into de PLA matrix at varying filler loadings, and optical, morphological, structural, thermal, tensile and barrier (water vapor) properties of PLA/AcBC in comparison with PLA/BC were evaluated. Noticeable changes in the nanocomposite properties were ascribed to the success of the route proposed to surface hydrophobize BC, which significantly improved its dispersibility within the PLA matrix and the matrix-filler interaction. By the way, the variation of filler loading allowed attaining remarkable increases in the nanocomposite films stiffness without significant reductions in tensile strength and water vapor permeability."
Highly functional lactic acid ring-opened soybean polyols applied to rigid polyurethane foams
(2019-10) Herrán, Rodrigo; Amalvy, Javier Ignacio; Chiacchiarelli, Leonel Matías
"We synthesized polyols with high hydroxyl functionalities (FOHs), between 9.0 and 12.6, and characterized them with differential scanning calorimetry, thermogravimetric analysis, and size exclusion chromatography after we parametrically studied the ring-opening reaction of epoxidized soybean oil with lactic acid (LA) as a function of the reaction temperature and lactic acid equivalent frac-tion (fLA). An increase of only 20C in the reaction temperature (from 80 to 100C) caused changes in the hydroxyl number (+17.8%), FOH (–25%), viscosity (–14.0%), and oligomeric content (–24.1%). fLA mostly affected the ring-opening yield, and only for fLA values above 0.4 was possible to achieve values higher than 80%. Rigid polyurethane foams (rPUFs) were synthesized and characterized with scanning electron microscopy, dynamic mechanical analysis (DMA), and compressive mechanical tests. rPUFs with a very high specific compres-sive strength (7.8 kPa kg–1 m3) were synthesized solely with biobased soybean oil. DMA revealed a compromised relationship between the specific compressive strength and its temperature dependence. To increase the first one, the most relevant method was to increase FOH. Instead, to increase the latter one, the OH number had to be maximized."
Nanocomposites based on poly(lactic acid) and bacterial cellulose acetylated by an α-hydroxyacid catalyzed route
(2019-01) Ávila Ramírez, Jhon Alejandro; Cerrutti, Patricia; Bernal, Celina; Errea, María Inés; Foresti, María Laura
"Poly(lactic acid) (PLA) nanocomposite films reinforced with acetylated bacterial cellulose nanoribbons were prepared by solvent casting. Acetylation of bacterial cellulose (BC) was performed by an innovative and sustainable direct solventfree route catalyzed by citric acid. The effect of derivatization and its extent on the morphological, optical, thermal and mechani-cal properties of the nanocomposites was analyzed. Data collected from the above studies showed that acetylation of BC nanoribbons clearly improved the nanofibers dispersion in the PLA matrix with respect to unmodified BC, which in turn resulted in increased transparency and mechanical properties of the nanocomposites produced."

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