Bentonites are clays whose main constituent is a clay mineral of the smectite group, mainly
montmorillonite. According to the predominant cation that occupies the interlayer space of the
smectite, they can be classified as sodium-, calcium- or magnesian-bentonites. Such clays
have wide industrial applications, such as: drilling fluids, pelletizing, foundry molds, among
others. For some specific applications that add greater value to the final product, as in the
synthesis of polymer/clay nanocomposites, it is necessary to intercalate organic ions in the
interlayer of the clay mineral. In Brazil, industrial production of organoclays is small and
geared towards the markets of paints, greases and polyester resins. Most companies that
exploit bentonites for the traditional uses and do not produce this type of material are showing
increasing interest in this new kind of application. In this context, this study aimed to evaluate
the potential of the Formosa Bentonite in the production of organoclays and its application in
the synthesis of polymer/clay nanocomposites. Formosa is a Mg-bentonite recently described
and relatively abundant in northeastern Brazil. For this purpose, synthesis experiments were
carried out by varying the concentration of two surfactants: hexadecyltrimethylammonium
ions (HDTMA+) and dodecyltrimethylammonium (DTMA+), in the concentrations 0.7, 1.0
and 1.5 times the value of CEC, with reaction time of 12 hours and temperature variation of
25 ºC and 80 ºC. The Mg-bentonite was used as starting material both in natura and activated
with sodium carbonate. Both the starting material and the organoclays obtained were
characterized by XRD, DTA/TG and FTIR. The clays that exhibited better intercalation
results were used in the proportions of 1%, 3% and 10% for further synthesis of the polymer
(PMMA)/clay nanocomposites. The XRD results confirmed the intercalation of organic ions
in the interlayer space of the Mg-smectite, for both in natura and activated samples.
According to FTIR results, it was observed that the ratio of gauche/trans conformers
decreases with the increasing of basal spacing. The results of DTA/TG confirm the thermal
stability of organoclays at a maximum temperature of 200 °C, allowing the use of such
material in the synthesis of polymer/clay nanocomposites obtained by the fusion process.
XRD patterns confirmed the intercalation of PMMA in the interlayer space of the Mgsmectite
for all nanocomposites produced. With the DSC analysis, it was possible to observe
the increase in glass transition temperature for all nanocomposites in comparison with pure
PMMA. Thus, it is possible to conclude that the Mg-bentonite can be intercalated with
alkylammonium ions, without previous sodium activation, forming organoclays, as well as
their use in the synthesis of nanocomposites. This possibility of using natural (non-activated) Mg-bentonite may represent an important difference in terms of process costs, in comparison
with existing Ca-bentonites in Brazil, or even the imported, that need to be activated during
beneficiation. Finally, one believes that the research should proceed with the evaluation of
mechanical properties of the nanocomposites produced in this work, aiming future
possibilities of application for such materials.
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