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Rheology and morphology of nanosilica-containing polypropylene and polypropylene/liquid crystalline polymer blend



We studied the rheology and morphology of hydrophilic and hydrophobic silica containing polypropylene (PP) and PP/liquid crystalline polymer (LCP) blend. It was found that hydrophilic silica has higher tendency for aggregation and forms bigger aggregate size. The lower percolation threshold and the higher fractal dimension for hydrophilic silica are due to its stronger particle–particle interaction compared with the hydrophobic one. Although the hydrophobic silica has lower thickening capability and lower coalescence hindrance by aggregates, its presence at the interface of PP/LCP blend results in smaller droplet size and higher elasticity of hybrid samples in comparison to hydrophilic silica. These results confirm that the hydrophobic silica has a compatibilization capability for PP/LCP blend, whereas the hydrophilic silica mostly works as a thickening agent and suppresses the coalescence. We suggested that for comparison of different particulate compatibilizers, the elasticity of filled blend sample against filled matrix phase can be used in high and low frequency ranges. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013