Hydrophobic silica nanoparticles as reinforcing filler for poly (lactic acid) polymer matrix

Properties of poly (lactic acid) (PLA) and its nanocomposites, with silica nanoparticles (SiO2) as filler, were investigated. Neat PLA films and PLA films with different percentage of hydrophobic fumed silica nanoparticles (0.2, 0.5, 1, 2, 3 and 5 wt.%) were prepared by solution casting method. Several tools were used to characterize the influence of different silica content on crystalline behavior, and thermal, mechanical and barrier properties of PLA//SiO2 nanocomposites. Results from scanning electron microscope (SEM) showed that the nanocomposite preparation and selection of specific hydrophobic spherical nano filler provide a good dispersion of the silica nanoparticles in the PLA matrix. Addition of silica nanoparticles improved mechanical properties, the most significant improvement being observed for the lowest silica content (0.2 wt.%). Barrier properties were improved for all measured gases at all loadings of silica nanoparticles. The degree of crystallinity for PLA is slightly increased by adding 0.2 and 0.5 wt.% of nanofiller.