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Bentonites, which the main clay mineral is montmorillonite, are commercially attractive because of its abundance in nature. The clays can be modified by ion exchange reactions of ions contained in the interlayer region with cationic surfactants that include ammonium or phosphonium salts. The clays origin and the type of surfactants (modifiers) are the main factors in the alteration of physical and chemical properties of these materials. This study aims to characterize and compare the results of natural bentonites commercially available and the effect of treatments with quaternary ammonium salt and an organic compound free of ammonium salt. The FTIR and XRD results indicate the process of organophilization of clays after treatment with the surfactants. These treatments have altered the average particle size, suggesting the formation of agglomerates, which was showed in the SEM images. The results of surface area and particle size data indicated the presence of larger particles. Although the two surfactants have shown similarities in the investigated properties, the organoclays free of ammonium salt are more promising in terms of its use as well as for their preparation and solubility.Keywords: Bentonites; organoclays; surfactante. ResumoAs bentonitas, que tem como principal argilomineral a montmorilonita, são comercialmente atraentes devido sua abundância na natureza. Estas podem ser modificadas geralmente, através de reações de troca iônica dos íons contidos da região interlamelar com os surfactantes catiônicos, que incluem sais de amônio ou fosfônio. A origem das argilas e o tipo dos surfactantes (modificadores) são os principais fatores na alteração das propriedades físicas e químicas destes materiais. Este estudo tem como objetivo caracterizar e comparar os resultados de bentonitas naturais, comercialmente disponíveis, e o efeito dos tratamentos utilizados com sal quaternário de amônio e um composto orgânico livre de sal de amônio. Os resultados de FTIR e DRX indicam o processo de organofilização das argilas naturais após o tratamento com os surfactantes. Estes tratamentos alteraram o tamanho médio das partículas, sugerindo a formação de aglomerados, fato observado nas imagens de MEV. Os resultados das áreas superficiais e os dados de granulometria indicaram a presença de partículas de maior tamanho. Embora os dois surfactantes tenham apresentado similaridades nas propriedades investigadas, as argilas organofílicas livre de sal de amônio são mais promissoras quanto sua utilização, quanto ao seu preparo e solubilidade.Palavras-chave: Bentonitas; argilas organofílicas; surfactantes.

Disposal of petroleum-derived polymers is a growing global environmental problem of alarming proportions, which has increased interest in the use and production of biodegradable materials. In addition to biodegradation, investment in research and development in the nanotechnology area is also significant. This study evaluated the effect of incorporation of an organophilic nanoclay ammonium-free salt (Novaclay TM ) on the mechanical properties and biodegradation of a biodegradable polyester (Ecoflex 1 ), according to ASTM G 160. Ecoflex with and without incorporated Novaclay was characterized before and after biodegradation in organically enriched soil for up to 180 days, by visual analysis, optical microscopy, weight loss, differential scanning calorimetry, dynamic mechanical analysis, mechanical testing, and scanning electron microscopy. The pure Ecoflex and the Ecoflex/Novaclay nanocomposite were partially biodegraded by the method used, and showed changes in their morphological and mechanical properties.

Summary In this study, poly(ethylene‐co‐vinyl acetate) (EVA) with different organophilic bentonites were prepared by melt‐blended and evaluated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the tensile properties. The results showed that the modification of bentonite with the two different surfactants presented distinct thermal and tensile behaviors of the samples containing natural bentonite. Both modifiers acted on the compatibility of the filler with the polymer matrix, obtaining injected‐specimens that were visibly homogeneous. The samples containing the Cloisite® bentonite modified with ammonium salt‐free surfactant (eBI‐AM) presented a different behavior from the others, in that increased crystallinity, which was verified through DSC, due to the nucleating effect of the filler influenced the flexible character of the EVA materials, thus increasing the rigidity and decreasing elongation. Therefore, it was of utmost importance the use and the proposal of an ammonium salt‐free modifier due to the low thermal stability that are caused by them in polymer/organophilic bentonite, as it has already been reported in the literature.