In-situ polymerization of isotactic polypropylene-nanographite nanocomposites

Abstract

Isotactic Polypropylene-Exfoliated Graphene Nanoplatelet (iPP-xGnP™) nanocomposites were prepared through an in-situ polymerization technique and compared to analogous composites prepared by melt compounding. In-situ preparation of iPP-xGnP nanocomposites was accomplished via single site metallocene polymerization of propylene within a toluene dispersion of xGnP nanoparticles. The in-situ prepared nanocomposites were compared to analogous nanocomposites prepared by melt compounding of commercial Ziegler–Natta iPP with xGnP. Optical microscopy showed the in-situ prepared nanocomposites demonstrated poorer xGnP dispersion compared to composites prepared by melt compounding. All xGnP-reinforced nanocomposites demonstrated increased crystallization temperature, as well as increases in mechanical strength and modulus, relative to neat iPP. However, the non-linear mechanical properties were found to be influenced by the both the preparation method and nanoparticle loading. Nanocomposites prepared by in-situ polymerization generally demonstrated superior ductility and fracture toughness compared to composites prepared by melt compounding. The results are discussed with regard to the preparation technique and xGnP loading.