Modified nanosilica-filled polypropylene composites with glycidyl methacrylate grafted ethylene/n-octene copolymer as compatibilizer

Modified nanosilica-filled polypropylene composites were manufactured by in situ reactive processing. The key issue lies that amine functional groups of silica nanoparticles reacted with glycidyl methacrylate grafted ethylene/n-octene copolymer (EOC-g-GMA) in order to improve nanofiller dispersion and increase compatibility between silica and PP matrix. Taking the advantages of rubber-type grafted polymer (ethylene/n-octene copolymer) and reactive compatibilization with NH2 -SiO2, a synergetic toughening effect was observed for the PP composites. Just very low concentrations of silica nanoparticles (2 wt %) and EOC-g-GMA (4 or 6 wt %) were sufficient to increase significantly notched impact strength and elongation at break of PP. On the contrary, tensile strength of the composites is slightly decreased. Improved dispersion of silica and increased compatibility between silica and PP matrix were observed in the presence of EOC-g-GMA. The crystalline features of PP have not been influenced greatly by addition of both modified silica and compatibilizer. However, the spherulite size of PP dramatically decreased in all composites. The thermal stability of the composites was significantly better compared to PP. Improved stiffness due to increased both storage and loss moduli indicating very good interfacial adhesion was observed.