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Carbon-based nanomaterials have emerged as a subject of enormous scientific attention due to their outstanding mechanical, electrical and thermal properties. Incorporated in a polymeric matrix, they are expected to significantly improve physical properties of the host medium at extremely small filler content. In this work, we report a characterization of various carbonaceous materials by Raman spectroscopy that has become a key technique for the analysis of different types of sp 2 nanostructures, including one-dimensional carbon nanotubes, two-dimensional graphene and the effect of disorder in their structures. The dispersion behavior of the D and G' Raman bands, that is, their shift to higher frequencies with increasing laser excitation energy, is used to assess the interfacial properties between the filler and the surrounding polymer in the composites.

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Abstract. In this work Raman spectroscopy was used for extensive characterization of multiwall carbon nanotube (MWNTs) and of MWCNTs/rubber composites. We have measured the Raman spectra of bundled and dispersed multiwall carbon nanotubes. All the Raman bands of the carbon nanotubes are seen to shift to higher wavenumbers upon debundling on account of less intertube interactions. Effects of laser irradiation were also investigated. Strong effects are observed by changing the wavelength of the laser excitation. On the other hand, at a given excitation wavelength, changes on the Raman bands are observed by changing the laser power density due to sample heating during the measurement procedure.

Summary: The mechanisms involved in rubber reinforcement are discussed. A better molecular understanding of these mechanisms can be obtained by combining characterization of the mechanical behavior with an analysis of the chain segmental orientation accompanying deformation. While the strain dependence of the stress is the most common quantity used to assess the effect of filler addition, experimental determination of segmental orientation can be used to quantify the interfacial interactions between the elastomeric matrix and the mineral inclusions.

Rubber compounds based on natural rubber containing organically modified montmorillonites were prepared. The state of dispersion of the clay was characterized by scanning and transmission electron microscopies, and the spacings between the silicate layers were evaluated by X-ray diffraction. The effect of the addition of clay on the elastomeric compound was analyzed through mechanical and swelling properties and also through the determination of polymer chain orientation during elongation.

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The reinforcement of a styrene‐butadiene rubber (SBR) by single fillers—carbon black (CB) or multiwall carbon nanotubes (MWNTs)—or by mixtures of CB and MWNTs, is investigated. The morphologies, mechanical and electrical properties of the composites, are analyzed. A significant improvement in the tensile properties is observed for samples containing a dual phase. Using atomic force (AFM) and transmission electron (TEM) microscopies, we demonstrate that the double loading improves the dispersion of the nanotubes in SBR. Electrical measurements show lower resistivity and a lower percolation threshhold for composites containing blends of fillers, which provides further evidence of better dispersion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 46: 1939–1951, 2008