Artículos de publicaciones periódicas

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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."
Kinetic and chemorheological modeling of thermosetting polyurethanes obtained from an epoxidized soybean oil polyol crosslinked with glycerin
(2022-10) Armanasco, Franco; Chiacchiarelli, Leonel Matías; D'hers, Sebastián
"Thermosetting polyurethanes were obtained using an aromatic isocyanate and a hydrophobic polyol formulation obtained from epoxidized soybean oil (ESO) crosslinked with glycerin. A systematic DSC analysis of the effect of catalyst type, crosslinker concentration, isocyanate index and ESO crystallization on cure kinetics was conducted. The combination of a stannic catalyst at 0.2 wt% and glycerin at 20 wt% produced a cure kinetics governed by an autocatalytic heat flow where vitrification played a key role in the formation of chemical bonds. The evolution of Tg as a function of conversion, which followed Di-Benedetto's predictions, supported the hypothesis that vitrification was a preponderant phenomenon during cure. Dynamic Mechanical Analysis (DMA) of a post-cured sample revealed a Tg centered at 220°C, whereas quasi-static flexural mechanical tests shown a flexural modulus of 2.14 GPa and a flexural strength of 99.4 MPa. Rheological experiments at isothermal conditions supported the hypothesis that vitrification played a key role in the evolution of apparent viscosity. A master model using Kim-Macosko equations was obtained for the proposed formulation. The results presented in this work will serve to further extend the use of biobased polymers applied in the polymer composite industry."
Preparation and characterization of nanoencapsulated synthetic soybean oil derivative-an abundant and environmentally friendly phase change material-heat transfer analysis and applications
(2020-10) Bergamo, Jorge; Rossi, Ezequiel; Maffi, Juan M.; De Angelis, Laura; Errea, María Inés
"The thermal properties of a phase change material (PCM), together with its environmental health risks and natural abundance are important aspects to consider when choosing one for a domestic application. In this work, a soybean oil derivative, which comes from one of the most abundant crops on Earth, is proposed as PCM. A heat transfer model was developed to compare the performance of the proposed PCM, under the same boundary and initial conditions, with other materials reported in literature that have well-known disadvantages in terms of flammability, renewability, abundance and environmental care. Results showed that its performance was as good as theirs. Nanocapsules of the PCM coated with TiO2 were prepared and characterized physical, thermal and morphologically. Thermal studies were carried out in a device designed and constructed simulating a water heater, and a reduction of about 70% of the PCM phase thermal resistance due to the TiO2 shell was observed. Furthermore, the calculated thermal energy stored in the device filled with nanoencapsulated PCM was 10.6% higher with respect to the blank, and the total cooling time of the water was increased by over 18% thanks to the PCM."

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