Morphological Stability of Poly(propylene) Nanocomposites

Poly(propylene) compounds containing organophilic layered nanosilicates were prepared by means of melt extrusion at 210°C in order to investigate the influence of maleic anhydride-grafted poly(propylene) (PP-g-MA) as a compatibilizer on morphology development and rheological properties. It was found that the addition of PP-g-MA leads to the strong exfolliation of silicate layers within the matrix as investigated by WAXS. This process is associated with the build up of an unstable morphology as probed by dynamic rheology and with the violation of the time-temperature superposition principle. Annealing of the samples at extrusion temperature level leads to a coarsening of the silicate superstructure and further improvement of the exfoliation at the same time. This process results in a stable morphology with unique rheological properties indicating network-like superstructure of silicate layers.