Improvement in Char Strength with an Open Cage Silsesquioxane Flame Retardant

Different characterization techniques were used to study the hydrolysis and condensation reaction kinetics of 3-methacryloxypropyltrimethoxysilane (MAPTMS) to obtain open cage silsesquioxane oligomers. The formation of hydrogen bonds, which condition the chemical structures of the resulting products, was identified. Improved thermal and fire resistant behavior of unsaturated polyester (UP) composites prepared with aluminium trihydroxide (ATH) and the synthesized oligomer were registered. Opened silsesquioxane structures also showed an improvement in the mechanical properties of the char formed after firin

Síntesis del pigmento de hierro-circón: Propuesta de un índice de mezclado para mezclas de materias primas

Iron zircon coral pigments are very interesting from an industrial point of view because of their high colouring power and their stability at high temperatures. However, the pigment's synthesis is particularly troublesome due to its specific reaction mechanism. As an encapsulated pigment it becomes very important how the raw materials are distributed in the reaction mixture. To evaluate the effectiveness of the mixing process, it would be convenient to define a parameter, that is the mixing index, to estimate the degree of homogeneity of the system. In the current investigation, a mixing index is proposed derived from the power spectrum of Fourier transform of scanning electron microscope (SEM) images of the raw material mixture. Concretely, the number of pixels in a certain range of values in the image of the power spectrum, seems to behave relatively well as mixing index. This index allows us to distinguish between samples with different zirconia and iron oxide used as precursors. The proposed mixing index seems to be related to the colouring power of the final pigment when the synthesis generates enough zircon to encapsulate hematite particles.Los pigmentos coral de hierro-circón son muy interesantes desde el punto de vista industrial ya que n un alto poder colorante y estabilidad a altas temperaturas. Sin embargo, la síntesis del pigmento es particularmente problemática debido a su mecanismo de reacción. Al tratarse de un pigmento encapsulado, resulta fundamental cómo se encuentran distribuidas las materias primas en la mezcla de reacción. Para evaluar la efectividad del proceso de mezclado, es conveniente definir un parámetro, que es el índice de mezclado, para estimar el grado de homogeneidad del sistema. En el presente trabajo de investigación se propone un índice de mezclado basado en el espectro de potencia de la transformada de Fourier de imágenes obtenidas con el microscopio electrónico de barrido de las mezclas de materias primas. Concretamente, el número de píxeles en un cierto rango de valores en la imagen del espectro de potencia parece funcionar relativamente bien como índice de mezcla. Este índice permite distinguir entre muestras con diferentes circonas y óxidos de hierro uitilizados como precursores. El índice de mezcla propuesto se relaciona con el poder colorante del pigmento final cuando durante la síntesis se genera suficiente cantidad de circón para encapsular las partículas de hematites

Effect of secondary thermal treatment on crystallinity of spinel-type Co(Cr, Al)2O4 pigments synthesized by solution combustion route

The effect of a post-synthesis thermal treatment on CoCr2−2ΨAl2ΨO4 (0.0 ≤ Ψ ≤ 1.0) ceramic pigments synthesized by Solution Combustion Synthesis (SCS) has been studied. As-synthesized SCS pigments were treated at two different calcination temperatures (800 °C and 1000 °C) to study changes in mineralogy, microstructure and thermal behaviour, as well as their effect over the colouring power. Spinel-type Fd-3m crystalline structure was developed in all cases. Nevertheless, crystallinity parameters were highly affected by both analysed processing parameters: composition (Ψ) and post-synthesis calcination temperature (Tc). A Cr(III) enrichment along with Tc increase favoured ion rearrangement to promote sample crystallization and crystallite growth. Fast kinetics of SCS makes Al-rich spinels with transition metals difficult to be synthesized. The application of a secondary thermal treatment resulted in a favourable evolution towards a well-crystallized structure. Lattice parameter did not seem to be affected by Tc, although it evolved indeed with composition. From a microstructural point of view, as-synthesized pigments were foamy, with a very low bulk density and nanometric grain size. After the thermal treatment, larger grain sizes were obtained, especially for the samples richer in Al and treated at higher Tc. All pigments developed intense colours in a transparent glaze without showing heterogeneities, indicating a stable behaviour against glazing process. Glaze colour evolved from green to perfectly blue shades, indicating an important dependence on composition. Nevertheless, colouring power seemed to be rather affected by calcination process

Effects of composition and furnace temperature on (Ni, Co) (Cr, Al)2O4 pigments synthesized by solution combustion route

The effects of composition and furnace temperature on Ni1-ΨCoΨCr2−2ΨAl2ΨO4 (0≤Ψ≤1) pigments prepared by Solution Combustion Synthesis were studied. As-synthesized samples showed spinel-like spongy structure, very easy to grind. However, important differences on crystallinity, crystal size, and microstructure were observed depending on composition and furnace temperature. All pigments developed intense tones, covering a wide color palette because of composition influence, although little effect was observed with furnace temperature. Stable crystalline structures, suitable grain size, and high resistance against synthesizing variables and ceramic glazes make SCS pigments perfect candidates to be used in the ceramic ink-jet decoration

Charles Palissot de Montenoy contre les encyclopédistes.

Las nuevas corrientes filosóficas desarrolladas durante el siglo XVIII produjeron grandes cambios dentro de todos los ámbitos de la sociedad de la época, provocando que los sectores más conservadores quedasen en un segundo plano. Para evitar eso, algunos autores como Charles Palissot de Montenoy llevaron a cabo una serie de protestas a través de sus obras para desprestigiar a los nuevos filósofos y ocupar el lugar que les pertenecía. De este modo, el trabajo que hemos llevado a cabo analiza en primer lugar cuáles fueron dichos cambios y la manera en la que afectaron a la sociedad del Siglo de las Luces, así como cuáles fueron sus principales precursores. Además de realizar obras por separado, estos aunaron sus fuerzas para redactar la Enciclopedia, un recopilatorio de distintos conocimientos sobre la cultura, la política y las costumbres de sus contemporáneos.A partir de aquí, y dada la posición dominante que los nuevos filósofos estaban ocupando en detrimento de los sectores más conservadores, hemos decidido tomar como ejemplo la vida y algunas de las obras de Charles Palissot para así demostrar la manera en la que estos otros autores quisieron mantener lo que ya estaba establecido durante los siglos anteriores. <br /

Vínculos entre el pasado y el futuro a través del presente. Propuesta didáctica para descubrir nuestro patrimonio.

La educación patrimonial, una temática emergente en el panorama educativo actual, desconocida a su vez por muchos profesionales de educación infantil. Con este Trabajo Fin de Grado se propone una combinación teórico-práctica que pretende contribuir al conocimiento, comprensión, valoración y respeto del patrimonio cultural, demostrando que es posible enseñarlo y aprenderlo.Para ello se estudiará el patrimonio desde su dimensión más teórica, donde se abordarán cuestiones como la ambigüedad terminológica que rodea al concepto o su evolución y estado actual en la enseñanza formal, hasta alcanzar su visión más práctica. Donde el patrimonio se convierte en un recurso didáctico de gran alcance con una indiscutible riqueza implícita.Así mismo, se ha diseñado una sugerente propuesta didáctica para la última etapa de educación infantil, con el fin de introducir al alumnado en el proceso de sensibilización hacia el patrimonio mediante aspectos orientados a la identidad y a los vínculos. De modo que, se ha creado como herramienta de guía un cuaderno didáctico, con el que se facilitará que el alumnado tenga un contacto más directo con unos valores naturales y culturales apropiados, haciendo posible su exploración, generando actitudes de valoración y conservación por el patrimonio de su lugar de residencia.<br /

Solution combustion synthesis of (Co,Ni)Cr2O4 pigments: Influence of initial solution concentration

Initial solution concentration effect was studied on the synthesis of mixed spinels Co1-ΨNiΨCr2O4 (0≤Ψ≤1) obtained by Solution Combustion Synthesis. Fd-3m spinel structure was developed in all range of compositions analysed, regardless of the concentration. However, structural characteristics such as ion rearrangement and crystal size showed a noticeable dependence on the initial concentration, being the spinel network more ordered and with higher crystallite size as the concentration increased. Cell parameter, however, presented dependence on composition but not on initial solution concentration. All as-synthesized pigments showed a significant colouring power in ceramic glazes without any significant influence of initial solution concentration. Therefore, a second thermal treatment was not needed. The coloured glazes covered a broad range of tones in the green section of colour space, which evolved as a function of composition

Characteristics reproducibility of (Fe, Co)(Cr, Al)2O4 pigments obtained by solution combustion synthesis

Synthesis reproducibility of mixed spinels Fe1−ΨCoΨCr2−2ΨAl2ΨO4 (0≤Ψ≤1), obtained by Solution Combustion Synthesis using urea as fuel, has been studied. Pigments with spinel structure Fd-3m have been obtained for all the compositional range analysed. Characteristics such as crystallinity, cell parameter, crystal size and specific surface area show a noticeable dependence with Ψ, but some of them present a low reproducibility, indicating a pronounced dependency with process conditions in each batch. Colouring power of synthesized pigments is highly significant, so they can be directly integrated in ceramic glasses without introducing a second thermal treatment. However, the generated colour also suffers from a limited reproducibilityThe authors thank Universitat Jaume I for their support in the development of this research (Project Nr. P11B2015-04)