Enhanced mechanical properties of polypropylene/silica nanocomposites with surface modification of nano-silica via in situ copolymerization of methyl methacrylate and butyl acrylate

Nano-sized silica particles were modified with methacryloxy- propyltrimethoxysilane (MPS) followed by in situ copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). These modified nanoparticles were compounded with polypropylene (PP) to prepare PP/silica nanocomposites. PMMA grafted on nano-silica enhances the dispersion of the nanoparticles and interfacial adhesion, decreases the size of PP spherulites in nanocomposites and leads to increasing the Youngs modulus and toughness of PP/silica nanocomposites at the same time. PBA grafted on nano-silica further improves the dispersion and the interfacial interaction, decreases the size of PP spherulites in PP/silica nanocomposite and leads to further toughening the PP/silica nanocomposite. But, its low modulus decreases the modulus of the PP/silica nanocomposite. The nanocomposites with PP and nano-silica particles modified by P(MMA-co-BA) have balanced stiffness and toughness due to the moderate modulus and solubility parameter of P(MMA-co-BA).