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In this work nanocomposites of styrenic polymers and organoclays were prepared. The polymers studied were polystyrene (PS), a polystyrene-b-polybutadiene-b-polystyrene triblock copolymer (SBS) and four polystyrene-b-poly(ethylene-co-butylene)-polystyrene triblock copolymers (SEBS), with one containing maleic anhydride. The nanocomposites were prepared using three different techniques: melt mixing, solution casting and a hybrid technique combining the former two. The materials obtained were characterized by x-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM), small angle x-ray scattering (SAXS) and by rheological studies, through small amplitude oscillatory shear tests (SAOS). The degree of clay dispersion was evaluated in some samples using a TEM image analysis technique. The results have shown that in most cases intercalated nanocomposites were obtained, due to the PS phase present in each polymer. Samples prepared by solution had the highest degree of clay dispersion, and the maleated SEBS was the polymer which originated the most exfoliated nanocomposite. The results have also shown that rheological studies are very sensitive to the formation of clay networks within the nanocomposites, which behave more solidlike. The combination of SAXS techniques and rheology was very useful to study the morphology of ordered phases in block copolymers, allowing to identify and distinguish the different structures of each copolymer, such as the lamellar, cylindrical and spherical phases. It was possible to verify that the presence of clay disturbs the phase order in the copolymers and has different effects on the rheological properties of these materials.

Obtenção e caracterização reológica de nanocompósitos de polímeros estirênicos.