Natural rubber/clay nanocomposites: Influence of poly(ethylene glycol) on the silicate dispersion and local chain order of rubber network

A novel preparation of natural rubber (NR)/Na⁺-montmorillonite (MMT) nanocomposites in only one step by using poly(ethylene glycol) (PEG) has been investigated. PEG behaves as dispersing agent favouring the intercalation of rubber chains into the silicate galleries and providing substantially improved clay dispersion. Intercalated/exfoliated miscible hybrids were observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The influence of PEG on the network structure has also been evaluated by static proton double-quantum nuclear magnetic resonance spectroscopy (¹H DQ NMR) at low-field. Silicate nanoparticles with a high aspect ratio (clay tactoids) and a more crosslinked rubber network have been obtained for an optimum PEG/MMT ratio. Both effects were responsible of the enhancement on mechanical properties.