Desarrollo de sistemas ligantes para la obtención de piezas metálicas y cerámicas mediante la tecnología de moldeo por inyección de polvos

El Grupo de Síntesis y Procesado de Materiales de la Universidad Carlos III de Madrid tiene una experiencia dilatada en la tecnología de Moldeo por Inyección de Polvos (PIM). La ventaja fundamental de la tecnología es la fabricación de piezas de pequeño tamaño y forma complicada que no se pueden obtener mediante tecnologías convencionales de fabricación. Nuestro grupo ha desarrollado de forma satisfactoria, y en colaboración con diversas empresas, varios sistemas ligantes para la obtención de piezas metálicas y cerámicas, a partir de polvos desde escala nano a micrométrica. Se busca colaboración con empresas de fabricación de piezas metálicas, cerámicas o plásticas, de sectores diferentes sectores industriales (automóvil, aeronáutico, electrónico, ….) que deseen incorporar esta tecnología de producción

Evaluation of polyolefin-based macroporous separators for high temperature Li-ion batteries

Macroporous separators are critical components in liquid electrolyte batteries. Besides preventing physical contact between electrodes, they enable free ionic transport, electronic isolation and thermal shutdown. Nevertheless, separators also increase electrical resistance and takes up limited space inside the battery, affecting ionic conductivity. Widely used in lithium-ion batteries, commercial polyolefin-based separators operate in a limited temperature range, mainly ranging from -20 degrees C to + 60 degrees C. The purpose of this contribution is to assess the possibility to use these separators in lithium-ion batteries operating at extended temperatures, i.e. between -20 degrees C and 120 degrees C. For this purpose, four commercially available macroporous separators based on polyethylene and polypropylene, were investigated. To determine the effect of temperature on their performance, they were aged for one week at 120 degrees C. Evolution of their morphology and thermomechanical behavior was investigated using XRD, SEM, DSC, TGA and DMA. The thermal aging impact on the ionic conductivity was also investigated using LP30 (R) as reference electrolyte. Thermal aging, i.e. partial clogging of the porosity, was found to have significant effects mainly on mechanical strength, morphology and conductivity. (C) 2016 Elsevier Ltd. All rights reserved.This work has been supported by Projects funded by the regional government (Comunidad de Madrid through MATERYENER3CM S2013/MIT-2753) and the Spanish Government, MICINN (MAT2013-46452-C4-3R).J-Y Sanchez acknowledges the CONEX Programme, funding received from Universidad Carlos III de Madrid, the European Union’s Seventh Framework Programme for research, technological development and demonstration (Grant agreement n 600371), Spanish Ministry of Economy and Competitiveness (COFUND2013- 40258) and Banco Santander

Synthesis and characterization of new membranes based on sulfonated polysulfone/Zn,Al-heptamolibdate LDH

New proton conducting organic/inorganic nano-hybrid polymer electrolyte membranes were synthesized by solving casting method. Inorganic nanopowders were a layered double hydroxides (LDH) with Zn,Al cations in which heptamolybdate were inserted. These nanopowders were prepared by anion exchange method from hydrotalcite (LDH) with interlayer anions (NO₃). The sulfonated polymers were prepared by an electrophilic aromatic substitution reaction between the polymer and trimethylsylil cholorosulfonate (TMSCS). The composites membranes were characterized by FTIR and TGA and water uptake was determined. Electrochemical impedance spectroscopy (EIS) was used to study the proton conductivity of the membranes. EIS measurements were performed facing the membrane to different HCl concentrations (103 ≤ c ≤101 M). It was concluded that these new composite membranes present good thermal properties and proton conductivity slightly higher than SPSU.This work has been supported by the Projects from the regional government (Comunidad de Madrid through MATERYENER3CM S2013/MIT2753) and Spanish Government, MINECO (MAT2013 46452C43R)

Electrochemical and structural characterization of sulfonated polysulfone

We describe the synthesis, as well as the electrochemical and structural characterization, of sulfonated polysulfone intended for use in PEM fuel cells. Starting from a commercial polysulfone, we assessed the performance of these prepared ionomers using synthesis protocols compatible with industrial production. The efficiency of the trimethylsilyl chlorosulfonate and chlorosulfonic acid reagents in the sulfonation process was confirmed by H-1 NMR, FTIR, elemental analysis, chemical titration and thermal analysis (DSC and TGA). Chlorosulfonic acid was the most effective sulfonation reagent. However, based on SEC-MALLS, this reagent induced degradation of the backbone that is detrimental to the thermomechanical stability and lifespan of the membranes. The electrical characterization of the membranes was undertaken using impedance spectroscopy in contact with different HCl aqueous solutions at various temperatures. The activation energies, which ranged from 8.2 to 11 kJ/mol, were in agreement with the prevailing proton vehicular mechanism. (C) 2015 Elsevier Ltd. All rights reserved.This study was supported by the Ministry of Science and lnnovation with a project MAT2013 46452 C4 3 R and the Regional Program MATERYENER3CM S2013/MIT 2753 of the Community of Madrid. J Y Sanchez also wishes to thank "Catedras de Excelencia" of Universidad Carlos III de Madrid for providing a grant. A.M. Martos wishes to thank the mobility grant of Universidad Carlos III de Madrid

Sodium polymer electrolytes composed of sulfonated polysulfone and macromolecular/molecular solvents for Na-batteries

Polysulfone acidic ionomers have been extensively used as Fuel Cell membranes, mainly because of their mechanical, thermal, chemical and electrochemical stability as well as their excellent film-forming capability. This contribution deals with the development of blends based on polysulfone-sodium sulfonate and macromolecular/molecular solvents, consisting of poly(oxyethylene), POE, and propylene carbonate, PC, respectively. The objectives were to take advantage of both the thermomechanical performances and the macromolecular polyanions provided by the polysulfone ionomer. Combining POE/PC solvents, didn't allow obtaining sufficient blend's conductivities. Nevertheless, the addition of very low amounts of sodium perchlorate led to appreciable conductivities.This work has been supported by Projects funded by the regional government (Comunidad de Madrid through MATERYENER3CM S2013/MIT-2753), the Spanish Government, MICINN (MAT2016-78362-C4-3-R) and Fundación Iberdrola España for the Energy and Environment Research Grants 2016. J-Y Sanchez acknowledges the CONEX Programme, funding received from Universidad Carlos III de Madrid, the European Union’s Seventh Framework Programme for research, technological development and demonstration (Grant agreement nº 600371), Spanish Ministry of Economy and Competitiveness (COFUND2013-40258) and Banco Santander

Relación de la estructura con las propiedades eléctricas en solución sólida La2/3-xLi3xTiO3 (0.03 x 0.167)

En este trabajo se investigó la solución sólida La2/3-xLi3xTiO3 (0.03<x<0.167) por las técnicas de difracción de rayos-X en polvos (DRX), espectroscopía de impedancias (EI) y resonancia magnética nuclear (RMN) de 7Li. En estas muestras se observó un cambio en la simetría de tetragonal a ortorrómbica cuando disminuye el contenido de litio por debajo de x=0.06. Hallamos que las modificaciones estructurales producidas se deben principalmente al ordenamiento de las vacancias a lo largo del eje c. Estas modificaciones disminuyen gradualmente al incrementarse el contenido de litio en la solución sólida. Se detectaron dos señales de litio con diferente constante cuadrupolar para el espectro de RMN del 7Li en las perovskitas ortorrómbicas/tetragonales, las cuales asociamos con dos sitios cristalográficos para el litio dentro de la estructura. Para la perovskita de composición La0.5Li0.5TiO3, se realizó un experimento enfriándola rápidamente desde 1300° C en nitrógeno líquido. En ésta se detectó una elevada movili- dad del litio en el espectro de RMN del 7Li. Para las perovskitas analizadas, la dependencia de la conductividad eléctrica con el contenido de litio no sigue el comportamiento esperado, basado en la teoría de una distribución aleatoria de los átomos de La y Li sobre los sitios A. La conductividad DC aumenta rápidamente con el contenido de litio en las muestras ortorrómbicas, aunque el cambio es mucho más gradual en las tetragonales, donde la distribución de las vacancias se desordena progresivamente. En todas las perovskitas analizadas, la dependencia de la conductividad dc con la temperatura muestra un comportamiento no-Arrhenius con energías de activación de 0.39±0.02 eV y 0.29±0.02 eV en los rangos de temperatura de 160 – 250 y 250 – 360 K, respectivamente

Synthesis and characterization of polysulfone/layered double hydroxides nanocomposite membranes for fuel cell application

In the present study, sulfonated polysulfone (SPSU)/layered double hydroxide (LDH) composite membranes for use in proton exchange membrane fuel cells (PEMFCs) were investigated. Polysulfone (PSU) was sulfonated with trimethylsilyl chlorosulfonate in 1,2 dichloroethane at room temperature. Composite membranes were prepared by blending different amount (0, 1, 2, and 5%) of LDH nanoparticles with SPSU in dimethylacetamide (DMAc). The membranes were prepared by the casting method and the samples obtained were characterized by XRD, FTIR spectroscopy. The thermal behavior for all samples was evaluated by thermogravimetrical analysis (TGA). Finally electrochemical impedance spectroscopy (EIS) was used to study the membranes electrical properties. The EIS measurements were carried out with the membranes in contact with HCl solutions at different concentrations (103 ≤ c ≤101). Results show a clear dependence of the membrane electrical resistance with the sulfonation degree and the amount of the LDH addedAuthors thanks financial support received from the regional government (Comunidad de Madrid through MATERYENER S2009 PPQ-1626), and Spanish Government,MICINN (MAT2010-19837-CO6)

Synthesis and characterization of novel hybrid polysulfone/silica membranes doped with phosphomolybdic acid for fuel cell applications

Novel proton conducting composite membranes based on sulfonated polysulfone (sPSU)/SiO₂ doped with phosphomolybdic acid (PMoA) were synthesized, and their proton conductivity in acid solutions was evaluated. The hybrid membranes were prepared by casting and the characterization by scanning electron microscopy (SEM), Fourier transform infrared (FIR) and X-ray diffraction (XRD) confirmed the presence of the inorganic charges into the polymer. Thermal properties and proton conductivity were also studied by means of thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS), respectively. The incorporation of the inorganic particles modified the thermal and mechanical properties of the sPSU as well as its proton conductivity. Taking into account that a compromise between these properties is necessary, the hybrid membrane with 2%SiO₂ and 20%PMoA seems to be a promising candidate for its application in proton-exchange membrane in fuel cells (PEMECs) operated at high temperatures.This work has been supported by the Projects from the Regional government (Comunidad de Madrid through MATERYENER3CM S2013/MIT 2753) and MINECO (MAT2013 46452 C4 3R) from Spanish Government

Influencia del enfriamiento en las propiedades de titanatos de lantano y litio

Se ha estudiado el efecto de los tratamientos a alta temperatura sobre la estructura y la movilidad del litio para la solución sÛlida Li3xLa2/3-xTiO3 (0.03<x<0.167) con difracciÛn de rayos X a alta temperatura (DRXAT), espectroscopia Raman, RMN y de impedancias. Los patrones de difracción de rayos X (DRX) a temperatura ambiente de muestras enfriadas lentamente muestran una estructura tipo perovskita doblada en el eje c con simetrÌas tetragonales u ortorrómbicas, mientras que las muestras con un enfriamiento r·pido muestran una estructura tipo perovskita c ̇bica simple. Sin embargo, el espectro Raman de las muestras analizadas se interpreta, en todos los casos, con una simetrÌa tetragonal en la que el desorden catiónico se incrementa con el contenido de litio y el tratamiento de enfriamiento. La existencia de microdominios de maclado, orientados a lo largo de las tres direcciones de la perovski- ta, favorece la detecciÛn de la fase c ̇bica en los patrones de DRX. A partir de la espectroscopia de RMN del 7Li, se ha detectado un movimiento bidi- mensional del litio en las muestras ordenadas, el cual se convierte progresivamente en un movimiento tridimensional conforme se incrementa el desorden catiÛnico. Asimismo, la presencia de microdominios hace disminuir la conductividad dc de muestras con contenidos bajos de litio

Synthesis and characterization of benzimidazolium-functionalized polysulfones as anion-exchange membranes

Anion-exchange membranes containing pendant benzimidazolium groups were synthesized from polysulfone by chrolomethylation followed by nucleophilic substitution reaction with 1-methylbenzimidazole. The structures of the polymers were characterized by H-1-NMR and FTIR analysis. The resulting membranes showed high thermal stability below 200 degrees C. The values of water uptake and swelling degree increased with the ion-exchange capacity of the polymeric membrane. The ionic conductivity was measured by means of impedance spectroscopy in aqueous solution of potassium hydroxide (10(-4)-10(-1) M). The results show not only a clear correlation between the membrane's electrochemical behavior with the electrolyte solution embedded in the membrane, but also with the degree of the polysulfone's chloromethylation.Thus, the ionic conductivity increased more than two orders of magnitude when the degree of chloromethylation increased from 40 to 140%. Benzimidazolium-functionalized polysulfones exhibited better thermal, mechanical, and electrochemical properties than the widely used polymeric membranes containing quaternary ammonium groups.This work has been supported by the Projects from the regional government (Comunidad de Madrid through MATERYENER3CM S2013/MIT-2753) and Spanish Government, MINECO (MAT2013‐46452‐C4‐3R)