Enhanced morphology and mechanical characteristics of clay/styrene butadiene rubber nanocomposites

• Complete exfoliation of organoclay layers was achieved by infinite swelling.
• The wide and small angle X-ray diffraction technique reveals the morphology.
• A curing mechanism was proposed for the obtained rubber/clay nanocomposite.
• Dispersed clay particles of size 6–7 nm maximize the abrasion resistance.

Achieving complete exfoliation of clay in their polymer nanocomposite is a matter of interest as it can significantly affect the material properties. Herein, an efficient way of enhancing the interlayer spaces of organically modified clays (OC) containing two types of surfactants, benzyl methyl hydrogenated tallow (Cloisite 10A) and dimethyl dihydrogenated tallow (Cloisite 20A) while mixing with the styrene butadiene rubber (SBR) is reported. The prolonged swelling of the OC in toluene helped the rubber chains to disentangle in the interlayer spaces identifiable from the morphology and the change of the d-value. The small angle X-ray scattering traces for all the Cloisite 20A/SBR composites indicated a very extensive dispersion of the OC and using the Guinier equation from SAXS, radius of gyration was calculated. An optimal size of 6–7 nm for the dispersed clay particles was found for maximizing resistance to abrasion as well as mechanical properties. Finally the enhanced tensile properties were correlated with the vulcanization behavior as well as the filler/polymer interfacial interaction from rheology through the completely exfoliated morphology observed for the swollen clay filled samples. Moreover an exclusive mechanism for curing of the composites was also derived.

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