Effect of nanoparticle localization on the rheology, morphology and toughness of nanocomposites based on poly(lactic acid)/natural rubber/nanosilica

In this study, poly(lactic acid)/natural rubber blends and their nanocomposites with silica nanoparticles were prepared via the melt mixing process. The rheology, morphology and impact resistance of the prepared samples were examined depending on the silica content (0-7 phr) and its localization. The results obtained showed that the incorporation of silica below its percolation threshold led to its selective localization in the matrix and mostly near the interface. This was in agreement with the results obtained by calculation of the wetting parameter. At a high content of silica, the silica nanoparticles could also be located in the dispersed phase. Energy dispersive spectroscopy and compositional mapping of oxygen and silicon atoms proved the presence of nanoparticles at the interface. The formation of a silica nanolayer with a thickness of 55-70 nm at the interface was shown by AFM. An optimum amount of nanosilica in the blend, through its interfacial localization and reduction of the natural rubber droplet size (confirmed by SEM test), caused a significant improvement in the impact strength, which was nearly 26 times that of neat poly(lactic acid). (c) 2019 Society of Chemical Industry