Navegando por Palavras-chave "Clay"

Agora exibindo 1 - 3 de 3
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Pf/clay hybrid materials: a simple method to modulate the optical properties
    (Assoc brasil polimeros, 2016) Chen Em, Marcio Chao [UNIFESP]; Barbosa, Camila Gouveia [UNIFESP]; Peres, Laura Oliveira [UNIFESP]; Faez, Roselena
    The aim of this work was modulate the emission properties and improve thermal stability of a conjugated polymer incorporated into an inorganic matrix. Hybrid material was prepared based on poly(9,9-dioctylfluorene-co-phenylene (PF) and montmorillonite (Na(+)Mt) clay using wet impregnation of 10, 30 and 50 wt.% of PF into Na(+)Mt and Na(+)Mt intercalated with ammonium quaternary salts (hexadecyltrimethylammonium - HDTMA) in a different proportions (OMt-1 and OMt-2). The materials were characterized by infrared and UV-Vis spectroscopy, fluorescence, X-ray diffratometry and thermogravimetry analysis. The results show that the presence of the clay alters the photoluminescent and thermal properties. Nevertheless, the degree of the clay organophilization and the clay content influences the luminescent properties due to the diverse interaction behavior between the polymer and clay. The sodium clay acted only as dispersing agent since no intercalation process occurs and the emission displacement is assigned to this behavior. In this case the PF emission displace from 402 to 395 nm. A nonlinear displacement is observed for PF/OMt-2 due the difficulties to conclude if the intercalation of the polymer occurs (379, 403 and 412 for hybrid with 10, 30 and 50%, respectively). For PF/OMt-1 a higher displacements for lower wavelength is observed due to intercalation of polymer chains and subsequent isolation in the interlamellar space, especially with material with 10 and 30% of PF in the hybrid material, whose displacement reached to 360 nm. All these results show that is possible to try to control the emission of the conjugated hybrid material changing the rate of the material.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Preparação e caracterização de híbridos elastomericos a partir da organofilização da montmorilonita com líquido iônico
    (Universidade Federal de São Paulo, 2013-09-18) Fontana, Juliana Pedro [UNIFESP]; Faez, Roselena [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    This work aims to obtain an elastomeric hybrid based on nitrile rubber NBR and sodic clays that have been subjected to processes organophilization. Initially, thermal, structural and morphological properties when montmorillonite clay modified with quaternary ammonium salt (OMMT-n) and also when combining the salt with the ionic liquid bistrifluorometanossulfonilimideto 1-methyl-3-octilimidazólio were evaluated. Both processes organophilization clay, either with the use of quaternary ammonium salt or ionic liquid, were effective as regards increasing the basal spacing and thermal properties. In the second stage of labor, the organoclays were incorporated into the elastomeric matrix of nitrile rubber for two separate assessments: the effect of LI content employed in organophilization, from the addition of 5 phr loading in the matrix and the effect of clay content used in the blend. Processing and structural, rheological, mechanical, thermal and morphological properties were evaluated. Hybrids were prepared by mechanical mixing, using the mixing chamber of a Haake. The results show that efficient coorganofilização clay LI influenced with the processing steps of the hybrid, particularly in the addition of the vulcanizing system. The use of ionic liquid as a partial replacement of the quaternary ammonium salt influenced the thermal, mechanical, rheological and morphological properties of the nanocomposites prepared. Among these properties, the presence of IL leads to an increase of the thermal stability of hybrids, the better the reinforcing effect of the load on the matrix, improved load-matrix interactions with increasing Li content.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Probing the local environment of hybrid materials designed from ionic liquids and synthetic clay by Raman spectroscopy
    (Elsevier B.V., 2014-03-25) Siqueira, Leonardo J. A. [UNIFESP]; Constantino, Vera R. L.; Camilo, Fernanda F. [UNIFESP]; Torresi, Roberto M.; Temperini, Marcia L. A.; Ribeiro, Mauro C. C.; Izumi, Celly M. S.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Hybrid organic-inorganic material containing Laponite clay and ionic liquids forming cations have been prepared and characterized by FT-Raman spectroscopy, X-ray diffraction, and thermal analysis. the effect of varying the length of the alkyl side chain and conformations of cations has been investigated by using different ionic liquids based on piperidinium and imidazolium cations. the structure of the N,N-butyl-methyl-piperidinium cation and the assignment of its vibrational spectrum have been further elucidated by quantum chemistry calculations. the X-ray data indicate that the organic cations are intercalated parallel to the layers of the clay. Comparison of Raman spectra of pure ionic liquids with different anions and the resulting solid hybrid materials in which the organic cations have been intercalated into the clay characterizes the local environment experienced by the cations in the hybrid materials. the Raman spectra of hybrid materials suggest that the local environment of all confined cations, in spite of this diversity in properties, resembles the liquid state of ionic liquids with a relatively disordered structure. (C) 2013 Elsevier B.V. All rights reserved.