Isotactic polypropylene metal oxide and silica nanocomposites by a two‐step process comprising in situ olefin polymerization and melt compounding

Nanocomposites of isotactic polypropylene (iPP) with 0.5 wt% filler of MgO@Mg(OH)₂ (35 nm) or silicon dioxide (20–60 nm) or barium titanate (50 nm) nanoparticles were obtained from melt compounding of filler masterbatches with commercial iPP. The masterbatches with 5 wt% nanofiller were prepared in an in situ polymerization procedure using a metallocene/methylaluminoxane (MAO) catalyst system that was supported on the respective oxides. The original agglomerates of the nanoparticles were broken up by treatment with dibutylmagnesium for MgO@Mg(OH)₂, and with ultrasound in the presence of MAO for SiO₂ and BaTiO₃. The tacticity (98% mmmm) of the in situ formed PP was not influenced by the presence of the nanofillers. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy mapping show a fine dispersion of single particles and small clouds or clusters. The primary nanoparticles appear to be surrounded by polymer. The elongation at break was decreased to 50, 17 and 9% for MgO@Mg(OH)₂), SiO₂ and BaTiO₃, respectively. After melt compounding with iPP, a homogeneous single‐particle distribution of the oxidic nanoparticles was found in the resulting composites with 0.5 wt% filler content. © 2019 Society of Chemical Industry