Morphology and rheology of polystyrene nanocomposites based upon organoclay

A correlation between morphology development and rheology of polystyrene na nocomposites based upon organophilic layered silicates (organoclay) such as fluoromicas was found as a function of the silicate modification. Organocl ay was obtained by means of ion exchange of clay with protonated amine-term inated polystyrenes with molar mass of M-n = 121 and 5800 g/mol. Only when applying shear forces during melt compounding of organoclay modified with h igh molar mass polystyrene (PS), individual silicate platelets of 1 nm diam eter and 600 nm length were obtained. Dispersions of such in-situ formed na noparticles with aspect ratio of 600 accounted for unique elastic propertie s observed in the low frequency range of the dynamic modulus, whereas organ oclay modified with low molecular PS did not exfoliate and exhibited rheolo gical behavior very similar to that of conventional fillers.