Tailor made nanostructures for improved properties of tyre compounds

Nanocomposites were prepared by melt compounding a layered clay, an alkyl quaternary ammonium cation and a diene rubber (styrene-butadiene copolymer or 1,4-cis-poly-isoprene, synthetic or naturally occurring). No evidence was found for the intercalation of polymer chains: only isolated lamellae and crystalline organoclays with only the ammonium cation intercalated between silicate layers were found. A vis a vis comparison of tailor made nanostructures, i.e. intercalated and delaminated organoclays, was performed by investigating rheological, cure, tensile and dynamic-mechanical properties of compounds with carbon black as the main filler. The organoclay brought about an improvement of ultimate tensile properties and, in particular the delaminated one, a reduction of Mooney and shear viscosity. The intercalated organoclay gave an increase of compound storage modulus E’ at low temperature, energy dissipation and thermoplasticity. The delaminated homologue allowed to achieve at least the same E’ value as carbon black based compounds with reduced thermoplasticity. A delaminated organoclay seems thus an ideal ingredient in a compound suitable for a tyre application, as it gives rise to a reinforcement at least similar to the one given by carbon black, in the presence however of a much better compound processability