Characterization and thermal degradation of polypropylene-montmorillonite nanocomposites

Polypropylene (PP)-montmorillonite nanocomposites have been prepared using isotactic PP homopolymers with different rheological properties, and a maleic anhydride grafted PP. Morphology and structure of the composites were investigated by using X-ray techniques (WAXD, SAXS) and transmission electron microscopy (TEM). The absence of pristine clusters of the clay and the presence of intercalated and exfoliated structures were shown for all the investigated samples. The nanocomposite prepared by using maleic anhydride grafted PP showed a widespread exfoliation. The thermal behaviour and degradation have been studied by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The incorporation of the montmorillonite improves the thermal stability in air atmosphere of all the investigated PPs, thanks to a physical barrier effect of the silicate layers.