CHARACTERIZATION OF BENTONITE CLAY FOR APPLICATIONS IN NANOCOMPOSITE MATERIALS

Resumo

Polymer nanocomposites and lamellar silicates are materials that have generated high scientific and technological interest. This is due to the characteristics of different mechanical and gas barrier properties when compared to conventional polymers and composites. The lamellar silicate of the smectite group, rich in montmorillonite, is in the form of a sandwich formed by two sheets of silica tetrahedra enclosing an aluminum octahedron sheet, type 2: 1 structure. This organization gives rise to the rocks known as Bentonites. These rocks have particular characteristics such as high specific area, cation exchange capacity, and hydration properties. These characteristics give this family of clay minerals broad interest in the industrial field and a wide variety of applications, among which its use in nanocomposites, the ceramic industry, waste treatment, soil decontamination, among others. Given these characteristics, bentonite clays are a promising material for product development and innovation for different industries. Thus, the present work is an initial step of the characterization of bentonite clay for feasibility analysis of the application of this material in nanocomposite synthesis processes. To this work, samples were collected from the Bañado de Medina Reservoir in the city of Melo, Uruguay through a drill hole campaign conducted in 2009. The analysis methodology for characterization was based on Quantitative X-Ray Fluorescence Analysis (EDX) and X-Ray Diffraction Analysis (XRD). The sample subjected to the respective analyzes was previously fragmented and ground and verified by granulometry in the 325 mesh opening sieve corresponding to 0.04mm. For the chemical evaluation by the X-ray fluorescence technique, the presence of silica and aluminum oxides was determined, confirming the primordial composition of the clay. Iron oxide, calcium, and magnesium were also verified in the analysis. Regarding the evaluation of X-ray diffraction (XRD), it was found peaks of representativeness of minerals such as quartz, plagioclase and alkaline feldspar and smectites, as the only group of clay minerals present in the sample. By making a relation with the results obtained in this analysis and in the EDX analysis, where the presence of aluminum is found, it can be assumed that the analyzed sample contains montmorillonite content. As the results presented to the clay characterization goal was reached, and the presence of montmorillonite was confirmed. Given this scenario, future studies should emphasize the transformation of montmorillonite content into a nanomaterial scale so that its structure is individually laminated, thus facilitating interaction with other materiais to be mixed to form the nanocomposites.