Synthesis and properties of polystyrene-g-mSiO2 filled polypropylene nanocomposites

Hydrophobically modified nanosilica was prepared from tetraethoxysilane (TEOS) and γ‐methacryloxypropyltrimethoxysilane (MPS) by a two step sol‐gel process. The polystyrene‐grafted‐modified nanosilica (PS‐g‐mSiO2) hybrid particles were prepared by grafting polystyrene onto the resulting hydrophobically modified nanosilica by dispersion polymerization. The hybrid nanoparticles were subsequently used as the filler to fabricate polypropyrene (PP) nanocomposites. The crystallization kinetics, crystal morphology and crystallization phase component of PS‐g‐mSiO2/PP nanocomposite were studied using a differential scanning calorimeter (DSC), polarizing optical microscopy (POM) and X‐ray diffraction (XRD). Crystallization half life (t1/2) decreased, while the Arami exponent (n) of PS‐g‐mSiO2/PP nanocomposite increased compared with that of virgin PP. A rheological study allowed the unambiguous characterization of the dispersibility of nanosilicas in PS‐g‐mSiO2/PP nanocomposite. The storage modulus, melt viscosity and the elongation to break of the PS‐g‐mSiO2/PP nanocomposite were found to be strongly dependent on the grafting of PS on nanosilicas. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers