Prediction of compatibility of organomodified clay with various polymers using rheological measurements

Two natrified montmorillonites of different origin and three organomodified fillers (including two non-commercial experimentally prepared) were investigated either in dispersions in various solvents or in mixtures with three polymeric matrices. Rheological measurements of filler dispersions in solvents were used as a tool for determination of the affinity of modified filler's surfaces towards substrates with various polarities. These data were used for the prediction of filler structure in polymer matrices. The measurements in various liquids provide a fast and rather simple tool to determine the suitability of particular filler for certain polymer. This approach is based on the Hildebrand solubility parameter (δ) where materials with similar values of δ are likely to be miscible. The same or similar solubility parameters of chosen solvents and polymers are taken as tool for selecting appropriate pairs polymer - solvent considering the compatibility with particular filler. The predictions made according to rheological data were confirmed with rheology of real nanocomposites of the respective fillers in three polymeric matrices, namely low density polyethylene, polyamide 12 and polycaprolactone and supported by comparison with results obtained by transmission electron microscopy (TEM) as commonly used method for characterization of polymer - clay nanocomposites.