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Rio de Janeiro, Brazil

Turley J.P.,University of South Wales | Romer F.,University of Warwick | Trudeau M.L.,Hydro - Quebec | Dias M.L.,Institute Macromoleculas | And 4 more authors.
ChemSusChem | Year: 2015

Proton conductivity in a series of mesoporous niobium and tantalum metal oxide (mX2O5) composites of naphthalene sulfonic acid formaldehyde resin (NSF) that are resistant to moisture loss at temperatures greater than 50 °C is reported. The investigation focuses on the effect to proton conductivity by changing pore size and metal in the mesostructure of the mX2O5 system and thus, a series of mX2O5-NSF composites were synthesized with C6, C12, and C18 templates. These were characterized by XRD, thermogravimetric analysis, nitrogen adsorption, and scanning TEM and then studied using impedance spectroscopy to establish proton conductivity values at various temperatures ranging from 25 to 150 °C. The most promising sample displayed a conductivity of 21.96 mScm-1 at 100 °C, surpassing the literature value for Nafion 117 (ca. 8 mS cm-1). 1H and 13C solid state NMR studies the mX2O5 -NSF composites demonstrate that the oligomeric nature of the NSF is preserved while in contact with the mX2O5 surface, thus facilitating conductivity. ©2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Libano E.V.D.G.,Centro Universitario Estadual da Zona Oeste | Visconte L.L.Y.,Institute Macromoleculas | Pacheco E.B.A.V.,Institute Macromoleculas
Polimeros | Year: 2012

A Brazilian polycationic bentonite clay was used for producing an organophilic clay with the quaternary ammonium salt, cetyltrimethylammonium chloride. The salt treated clay (BENT-org) and untreated clay (BENT) were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Then, each clay was mixed with polypropylene (PP) by melt intercalation in a counter-rotating twin-screw extruder. The composites were characterized by XRD, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results from FTIR and XRD showed the presence of specific groups of the ammonium salt and their intercalation in between the clay layers. XRD analyses of the composites with 3 and 5 wt. (%) of BENT-org revealed peaks displaced towards smaller angles, suggesting the intercalation of the chain polymer into the clay layers. DSC results indicated that the clay may have acted as a nucleating agent as seen from the increase in the T∞ (crystallization temperature in the cooling) of the composites. Consistent with the TG results, the incorporation of clay into PP improved the thermal stability of the polymer in the composites with 5 wt. (%) of BENT and 3 and 5 wt. (%) of BENT-org. Source


Grance E.G.O.,Institute Macromoleculas | Souza Jr. F.G.,Institute Macromoleculas | Varela A.,Institute Macromoleculas | Pereira E.D.,Institute Macromoleculas | And 2 more authors.
Journal of Applied Polymer Science | Year: 2012

A magnetic resin based on lignin produced using the Kraft process was prepared and characterized. The material, because of its aromatic/aliphatic balance, can be used in oil-spill clean-up processes. The resin was prepared through bulk polycondensation of lignin, cashew nutshell liquid, and formaldehyde in the presence of maghemite nanoparticles. The obtained magnetic composites were studied by Fourier transform infrared spectroscopy, X-ray diffraction, and Small-angle X-ray scattering. Cure degree, magnetic force, and oil removal capability tests were also performed. The results show that the composites possess an elevated cure degree, besides a considerable magnetic force. The materials exhibit a good oil removal capability-the composite containing 3.3 vol % of maghemite can remove 11 parts of oil from water. © 2012 Wiley Periodicals, Inc. Source

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