Papers by Author: Vicente Rives

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Authors: Margarita del Arco, Daniel Carriazo, Cristina Martín, Amalia M. Pérez Grueso, Vicente Rives
Abstract: PXRD (powder x-ray diffraction), FT-IR (Fourier Transform infrared), N2 adsorption at - 196 °C and TG/DTA (thermogravimetric and differential thermal analyses) techniques have been used for characterisation of MgAl- and ZnAl-CrO4 LDHs, which had been prepared by the ion exchange method from the corresponding chloride LDH (layered double hydroxides) precursors. The results indicates that the oxometalate intercalation in both systems produces interlayer microporosity and a basal spacing of 8.7 Å; This gallery height decreases when the samples are calcined in the temperature range 100-300 °C, due to a grafting process. A larger thermal stability is detected for MgAl-CrO4 sample than for the zinc-containing one.
Authors: Patricia Benito, Maria Herrero, Francisco Martin Labajos, Vicente Rives
Abstract: The synthesis and characterization of Co,Al Layered Double Hydroxides (LDHs) containing carbonate is reported. The solids have been submitted to several thermal treatments, hydrothermal and microwave-hydrothermal, modifying both the treatment time and temperature, with the main aim of studying their influence on the crystallinity of the solids and on the stabilization of divalent cobalt oxidation state. The results show that whichever the temperature and time used the only phase detected was the hydrotalcite, and that the cobalt cations keep the divalent oxidation state.
Authors: Vicente Rives, Jacinta Garcia Talegon
Abstract: Preservation of our Historical Cultural Heritage built in stone requires studies on the material itself, on the environment where the monument is located, and even on the microclimate affecting a particular stone in the building. The knowledge of the decay processes, as well as mechanisms governing these processes, and the real effect of factors depending on the intrinsic properties of the material to be studied, and external agents of decay, will allow a rationale use of these materials and to anticipate their behaviour beforehand, in order to success in restoration
Authors: Patricia Benito, Francisco Martin Labajos, Vicente Rives
Abstract: The thermal stability of Ni,Al-CO3 hydrotalcite-like compounds synthesized by the coprecipitation method and aged upon microwave-hydrothermal treatment for different periods of time was studied. The samples prepared were characterized by Elemental Analysis, PXRD, Thermal analyses (DTA and TG) and Temperature Programmed Reduction (TPR). The results show that the use of microwave radiation as a source of heating during the ageing treatment leads to an increase in the crystallinity of the solids, which determines their thermal stability.
Authors: S. Martínez-Gallegos, Maria Herrero, Vicente Rives
Abstract: A polyethylenterephthalate-hydrotalcite (PET-HT) composite was prepared by in situ polymerisation, using polyethylenterephthalate (PET) and different amounts of a hydrotalcite with dodecylsulphate in the interlayer space (DS-HT). The resulting material has been characterised by powder X-ray diffraction (PXRD) and thermogravimetric (TG) analysis. The thermal stability of PET is not greatly enhanced upon incorporation of the inorganic component, despite PXRD shows that the HT is exfoliated in the composite. Thus with 2-10% shows a complete dispersion of the layered component in the polymeric matrix, while if the inorganic loading is between 20-50 % (larger loadings were not tested) no complete dispersion is achieved and PXRD-detectable agglomerates are formed.
Authors: Margarita del Arco, M.J. Holgado, Charles Martin, Vicente Rives
Authors: F. Kooli, Vicente Rives, M.A. Ulibarri
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