Anomalously enhanced toughness of poly (lactic acid) nanocomposites by core-shell particles with high thickness soft shell

Abstract The anomalous improvement in ductility and toughness of biodegradable poly (lactic acid) (PLA) was achieved by incorporating the silica-g-poly(caprolactone-co-lactide) (SiO2-PCLLA) core-shell nanoparticle with high thickness rubber shell. The variation of mechanical properties and toughening mechanism of nanocomposites with rubber shell thickness were investigated via tensile tests and surface morphology observation, X-ray scattering (SAXS) and diffraction (WAXD). The experimental results showed that the core-shell nanoparticle with high thickness rubber shell of 25 nm extremely remarkably improved the ductility and toughness of nanocomposite, about 34 times higher than those of neat PLA, particularly nearly without reducing its strength. This considerable increment of toughness is attributed to that the cavitation occurred in thick rubber shell can induce the intense plastic flow of matrix, forming the fibrillated structure like ‘bamboo joint’. In addition, it was found that the toughening of PLA is not only related to the rubber shell thickness, but also to the added nanofiller content.