Navegando por Autor "Aroucha, Edna Maria Mendes"
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Artigo Incorporation of bentonite clay in cassava starch films for the reduction of water vapor permeability(Elsevier, 2018-03) Monteiro, Mayra Kerolly Sales; Oliveira, Victor Rafael Leal de; Santos, Francisco Klebson Gomes dos; Barros Neto, Eduardo Lins de; Leite, Ricardo Henrique de Lima; Aroucha, Edna Maria Mendes; Silva, Rayane R.; Silva, Karyn Nathallye de OliveiraComplete factorial planning 23 was applied to identify the influence of the cassava starch(A), glycerol(B) and modified clay(C) content on the water vapor permeability(WVP) of the cassava starch films with the addition of bentonite clay as a filler, its surface was modified by ion exchange from cetyltrimethyl ammonium bromide. The films were characterized by X-ray diffraction(XRD), fourier transform by infrared radiation(FTIR), atomic force microscopy(AFM) and scanning electron microscopy(SEM). The factorial analysis suggested a mathematical model thats predicting the optimal condition of the minimization of WVP. The influence of each individual factor and interaction in the WVP was investigated by Pareto graph, response surface and the optimization was established by the desirability function. The sequence of the degree of statistical significance of the investigated effects on the WVP observed in the Pareto graph was C > B > A > BC > AC. Interactions AB, BC and AC showed that the modified clay was the factor of greater significanceArtigo Influence of the ionic and nonionic surfactants mixture in the structure and properties of the modified bentonite clay(Elsevier, 2018-12-15) Monteiro, Mayra Kerolly Sales; Oliveira, Victor Rafael Leal de; Santos, Francisco Klebson Gomes dos; Barros Neto, Eduardo Lins de; Leite, Ricardo Henrique de Lima; Aroucha, Edna Maria Mendes; Silva, Karyn Nathallye de OliveiraA new surface modification in calcium bentonite clay (Bent-Ca) was investigated in this work, from the sequential intercalation of three types of surfactants: cetyltrimethylammoniumbromide (CTAB), cationic surfactant, sodiumdodecyl sulfate (SDS), anionic surfactant, and lauryl alcohol ethoxylated (ALEO), nonionic surfactant. Three modifications in the Bent-Cawere prepared in aqueous solution obtaining conventionally the OBent-Iwith CTAB and OBent-IIwith CTAB+SDS, beyond the newmodification OBent-IIIwith TAB+SDS+ALEO. The synergistic effect of the sequentialmixture of surfactants used in the surfacemodification of Bent-Ca was characterized by X-ray Diffraction (XRD), Fourier Transform by Infrared Radiation (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS), Optical Microscopy (OM), Thermogravimetric Analysis (TG), Contact Angle Test and Swelling Index. The results indicated that OBent-III was the reinforcement material among the analyzed ones that presented the highest values of basal spacing (13 nm), thermal stability (400 °C), superficial lipophilicity index (79.76°) and swelling index in polar or apolar medium (6–10 mL/g). Therefore, a reinforcing material suitable for various applications was proposedArtigo Synergistic effect of the sequential intercalation of three types of surfactants in the exfoliation degree of bentonite clay in films of cassava(Elsevier, 2018-09-15) Monteiro, Mayra Kerolly Sales; Oliveira, Victor Rafael Leal de; Santos, Francisco Klebson Gomes dos; Barros Neto, Eduardo Lins de; Leite, Ricardo Henrique de Lima; Aroucha, Edna Maria Mendes; Silva, Karyn Nathallye de OliveiraA method of obtaining exfoliated nanocomposite films based on biopolymers has been reported. The method is based on the incorporation ofmodified bentonite clay bymixing surfactants into a biodegradablematrix. The biopolymer used was cassava starch, which has a high hydrophilicity, which makes it less desirable than synthetic polymers, when used as a film matrix for coating. The improvement of this was proposed with the formation of a nanocomposite matrix by the high exfoliation of themodified bentonite clay used as reinforcement material. The degree of exfoliation of the sequential modification in bentonite with three surfactants throughout the cassava starch filmwas investigated by XRD, FTIR, AFM, SEM,OMand contact angle. The physicochemical properties of the nanocomposite films were analyzed for water vapor permeability, ductility, opacity, thermal stability and water solubility. Finally, the claymodified in the presence of the three surfactantswas the reinforcementmaterial that contributed the most to the physical/chemical properties of the control starch film, amongwhich it reduced 90.6% of the water vapor permeability, as well as 77.43% of the maximum dissolution