Eliakim Martins Araújo

Efeito de sais quaternários de amônio na organofilização de uma argila bentonita nacional

Bentonite clay, mainly composed by montmorillonite that provides the physical properties, concentrates the majority of the national reserve (62%) in the Paraiba State. The transformation of bentonite clay to organoclay is made with a simple laboratory procedure and this modification can be obtained by cation (Na+ or Ca2+) exchange reaction that are present on the surface and in the interlayer space of the mineral clays by quaternary ammonium salts. In this, the organoclays bentonite were preparedwith four different types of quaternary ammonium salts such as alkyldimethylbenzylammonium chloride (Dodigen), esthearildimethylammonium chloride (Praepagen), cethyltrimethylammonium chloride (Genamin) and cethyltrimethylammonium bromide (Cetremide). The organoclays were characterized by thermogravimetry, X-ray diffraction, chemical analysis and X-ray fluorescence. The results showed that the salts were incorporated in the clay structure, confirming the organophilization. The Praepagen and Cetremide salts presented a higher range of thermal stability.

Spectroscopic and Diffractional Characteristics of Membranes and Polyamide 6/Regional Bentonite Clay Nanocomposites

Polymeric membranes are attracting attention of researchers and industries due to their lower costs. However, they also have lower mechanical resistance and chemical solvents, when compared with other materials. An improvement of polymer properties can be obtained by adding an inorganic nanoload in the structure. This study produced polyamide 6 / bentonite clay nanocomposites with a nominal content of 3%, and this was used in the processed form and in the organically modified form by cation exchange. The nanocomposites were produced by melt intercalation, and then, the membranes were obtained by the technique of immersion-precipitation. Bentonite, organophilic clay, the material processed in the extruder and the membranes were submitted to the x-ray diffraction (XRD) and infrared spectroscopy (ATR-FTIR). By both techniques, it was possible to prove the organic modification of clay and the change in the crystallinity of the nanocomposites and of the membranes.

Obtaining of Chitosan/ZNAL1,9EU0,05O4 Film for Application as Biomaterial

This work reports the development and characterization by SEM, XRD, FTIR, emission and excitation chisonan/ZnAl1.9Eu0.05O4 films with a mass proportion of 1:1. The powders were deagglomerated and passed 325 mesh screens and added to the diluted chitosan in 1% acetic acid. The materials were filtered and placed in petri dishes and placed in an oven at 60°C for solvent evaporation. After drying the film, a solution of 1M sodium hydroxide was added in order to obtain a film with neutral pH. With the XRD, it has been verified that the chitosan/ZnAl1.9Eu0.05O4 films presented the chitosan peaks and ZnAl2O4. Through the SEM, it has been observed that the chitosan/ZnAl1.9Eu0.05O4 presented a protruding surface. The results presented in emission and excitation spectra suggest that the film chitosan/ ZnAl1.9Eu0.05O4 exhibit good luminescence properties, and are promising to be applied as a luminescent marker in future applications in the field of biomaterials.

Avaliação da estabilidade térmica de sais quaternários de amônio para uso em argilas organofílicas nacionais: Parte I

The large propagation of nanotechnology in modern times requires more studies to meet their specific development. For obtaining good properties of polymer/clay nanocomposites more comprehensive studies on the thermal stability of surfactants in the processing temperatures of these materials are necessary. In this work, the thermal stability of four quaternary ammonium salts such as hexadecyltrimethyl ammonium bromide, alkyldimethylbenzyl ammonium chloride, esthearildimethyl ammonium chloride and hexadecyltrimethyl ammonium chloride was evaluated for their intercalation into national bentonite clay, with the aim to enable organophilic for using in polymer nanocomposites. The salts were thermally characterized by differential scanning calorimetry and thermogravimetryunder Ar and N2. The results indicate that the salts based on chloride ion degraded at similar temperatures and the based on the bromide anion degraded at higher temperature. Besides, these studies indicated that the esthearildimethyl ammonium chloride salt may be successful in obtaining as surfactant for the use in nanocomposite.

Influence of the Addition of Polypropylene and Compatibilizer in PA6 Membranes Obtained by Phase Inversion

Polymer blend is the name for the physical mixture of two or more polymers and/or copolymers, and this allows the obtention of new materials with superior properties to those of the pure components. The blends have been used in obtaining membranes in order to improve the barrier properties so that it can separate two phases totally or partially, restricting the transport of one or more chemical species. In this work, polymer membranes were obtained from blends of PA6/PPgAA and PA6/PP/PPgAA by phase inversion method and were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was observed through the diffractograms that there were no significant variations in the characteristic peaks of PA6, and through SEM, it was observed the formation of microporous asymmetric membranes, where they showed a surface with higher porosity to the binary and ternary blends and presented smallest pore diameter for binary blends.

Caracterizações de argilas bentoníticas e síntese de argilas organofílicas para uso em nanocompósitos poliméricos: parte II

Nanocompositos polimericos tem atraido um consideravel interesse, o que se deve a estes materiais oferecerem combinacoes incomuns de propriedades. As argilas esmectiticas sao comumente utilizadas como fase dispersa na obtencao dos nanocompositos, em particular destaque para as argilas bentoniticas. Neste trabalho, foram estudadas tres argilas bentoniticas sem modificacao e apos a modificacao ou organofilizacao com o sal cloreto de estearil dimetil amonio. A capacidade de troca cationica (CTC) das argilas bentoniticas sem modificacao foi realizada. A eficiencia da organofilizacao foi avaliada por fluorescencia de raios X e o grau de expansao das argilas organofilicas foram estudados por difracao de raios X. A argila 1346 apresentou maior CTC em relacao as demais argilas. Alem disso, os resultados indicaram a organofilizacao das argilas com o sal quaternario de amonio, o que foi observado pela presenca do sal no espacamento basal das argilas e pela expansao basal na reflexao d001 das argilas.

Influence of Speed of Processing in the Mechanical and Thermomechanical Properties of Polyamide 6 / Organoclay Nanocomposite

The improvement in the properties of nanocomposites is achieved with a load volume fraction of up to 10% due to the very high ratio of the load aspect. Moreover, they have the advantage of being processed with conventional equipment and techniques (extrusion, injection, etc.) used for polymers. In order for the clay to be uniformly dispersed in the polymer and there to be good interaction with the polymer matrix, superficial treatments of the clays with organic salts are essential for it to become organophilic, and, thus the material obtained has better performance. In this study, it was evaluated the influence of two speeds (100 and 200 rpm) of processing and thermo mechanical properties of nanocomposites with 3% of bentonite clay prepared with two speeds and two threads. The nanocomposites showed better properties as compared to properties of polyamide 6, especially the samples heated at screw speed of 100 rpm.

Morphological Comparison of PEI and PES Nanocomposite Membranes with Bentonite Clay

Obtaining membranes from polymer nanocomposites have attracted interest of researchers because they use low levels of charge for improvement in barrier properties. In this study, membranes from poly (imide ether) (PEI) and poly (sulfone ether) (PES) were produced by the solvent evaporation technique, using as solvent: chloroform to PEI and dimethylformamide (DMF) to PES; and the clay Brasgel PA was used as load. The results showed that, by XRD, PEI membranes have apparently a structure of micro-composites and / or interleaved structure. Those obtained with PES had an exfoliated structure and / or partially exfoliated one. However, for the composition of PES with 5% clay, there was a small shoulder, therefore demonstrating perhaps an intercalated structure and/or an exfoliated part. By SEM, it was observed that all the membranes are apparently dense, but the behavior is differentiated by changing the matrix of the membranes.

Effect Polymeric Modifier (Biostrength B150), and Organoclay on Properties of Poly(lactic acid) - PLA

In recent years the search for biodegradable polymers has excelled due to environmental issues. Among the biodegradable polymers from renewable sources, the poly (lactic acid) - PLA is one of the most widely used commercially, and several researches are being developed in order to improve their properties and thus increase its commercial applicability. Thus, this work aims to study the effects of incorporating polymer modifier (MBS Copolymer, Biostrength 150 - B150) and organoclay (Brasgel PA) in the properties of PLA. The study was conducted in two stages: with and without clay, and both with the B150. The concentrations used were 90/10 (PLA / modifier) and 3pcr (parts per hundred resin) of organoclay. The results showed that the mechanical properties of tensile and impact PLA significantly improved by using the polymeric modifier, indicating a gain in impact strength without a significant loss in modulus of elasticity.

Characterization of bentonite clay and synthesis of organoclay for polymer nanocomposites applications: part II

Polymeric nanocomposites have attracted considerable interest because this material offers unusual combination of properties. The smectite clays are commonly used as the dispersed phase to obtain nanocomposites, in particular, bentonite clays. In this work three bentonite clays without modification and after modification with salt or organophilization stearyl dimethyl ammonium chloride were studied. The cation exchange capacity (CEC) of bentonite clay was carried out without modification. The efficiency of organophilization was evaluated by X-ray fluorescence and the degree of expansion of the organoclay by X-ray diffraction. The 1346 clay shows higher CEC than that of other clays. In addition, the results indicate that organophilization clays with quaternary ammonium salt, which was observed by the presence of salt in the basal spacing of clay and the expansion of the basal reflection d001 clays.