Pranee Phinyocheep

The toughening modifcation of PLA was successfully performed by incorporating modifed natural rubber (MNR). The MNR was obtained from chemical modifcation of natural rubber (NR) in a latex system through a two-step procedure; hydrogenation followed by epoxidation reaction. Diferent amounts of NR and MNR were mixed with PLA by a physical melt-blending procedure. As a result, blending MNR (5% by weight) with PLA could efciently strengthen fracture resistance (18.89 kJ/m2 ) and stretchability (113.79%), approximately fvefold and 16-fold, respectively, compared to the neat PLA (3.58 kJ/m2 impact strength and 7.08% elongation-at-break). In comparison, impact strength (7.21 kJ/m2 ) and elongation-at-break (8.64%) of NR/ PLA were found at the same weight ratio. The high toughening efciency of MNR for PLA could be explained by their good compatibility of the two phases. The impact-fractured surface of the blend showed fne rubber particles and stretched-rubber fbrils in the scanning electron microscope (SEM) image. Furthermore, the optical properties in terms of light transmission of the MNR/PLA blend displayed higher transparency (74.62%) than the unmodifed NR/PLA blend (34.34%). The obtained results suggest that the developed MNR will ofer a potential application as a high impact modifer for PLA.