Hybrid filler networks in hydrocarbon polymer compounds: the unexpected role of organoclay building blocks

The most promising "new nanomaterials", such as CNT, Organoclays and Graphene, consist of primary particles which are, at least in principle, individually dispersible in Nanocomposites. On the other hand, "standard nanostructured materials", such as Carbon Black and Synthetic Silica, consist of rather large aggregates, which play a mayor role in the reinforcing behaviour of such fillers. Pirelli's approach to Nanocomposites is based on the development of Hybrid Filler Systems, i.e. of compounds featuring both standard nanostructured fillers and new nanomaterials, in particular Organoclays. The study of the initial modulus of vulcanised compounds as a function of the Organoclay content gave evidence of the formation of hybrid networks. The role of the individual Organoclay Building Blocks, i.e. the pristine Clay and the Cationic Surfactant, in the formation of filler networks was investigated: unexpectedly, Ammonium Salts appeared to be the most active filler network promoters.