Navegando por Autor "Araujo, Edcleide Maria"
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Artigo Flammability and morphology of HDPE/clay nanocomposites(Springer Science and Business Media LLC, 2013-07-26) Ito, Edson Noriyuki; Barbosa, Renata; Alves, Tatianny Soares; Araujo, Edcleide Maria; Melo, Tomás Jeferson Alves de; Camino, Giovanni; Fina, AlbertoHigh-density polyethylene/modified bentonite clay/polar compatibilizer nanocomposites were prepared through the melt intercalation process. The clay was organophilizated using different percentages of quaternary ammonium salt 100, 125, and 150 % based cation exchange capacity of the clay. The nanocomposites were prepared in a counter-rotating twin-screw extruder and then specimens were injection molded. For the evaluation of flammability of the test system was used for burning in the horizontal position according to the norm (Underwriters Laboratories, UL94HB) and to the method of cone calorimeter. The thermal behavior of nanocomposites was evaluated by thermogravimetry and X-ray diffraction techniques, and transmission electron microscopy were used to characterize the morphology and analyze the degree of expansion of the clays prepared and the degree of exfoliation of nanocomposites. It was observed that the percentage of ammonium salt and the compatibilizer polar influence on the final properties of the systems and consequently improving the thermal stability and reducing the flammability of the matrixArtigo Structure and mechanical properties of polyamide 6/ Brazilian clay nanocomposites(FapUNIFESP (SciELO), 2009-06) Ito, Edson Noriyuki; Leite, Amanda Melissa Damião; Araujo, Edcleide Maria; Paz, Rene Anisio da; Pereira, Osanildo Damião; Lira, Hélio LucenaRecent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC) of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts) and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility