Toughening modification of polylactic acid with modified natural materials

Abstract

This research work was to study the toughening modification of polylactic acid by the mixing with epoxidized natural rubber (ENR) and the increase of effectiveness of mechanical properties with a compatibilizer. Enhancement of properties in polylactic acid was evaluated by tensile and impact testings, Fourier-transform Infrared Spectroscopy (FTIR) technique, Differential Scanning Calorimetry (DSC) technique and Scanning Electron Microscope (SEM). For the addition of ENR, it was revealed that the increase of ENR contents improved elongation at break and impact strength but decreased tensile modulus and ultimate tensile strength. Glass transition temperature (Tg), percentage crystallinity and the melting point of polylactic acid tended to decrease with the addition of ENR. Chemical change was found that position of C=O peak in polymer blend was slightly shifted as compared to the spectrum of neat polylactic acid. The optimum formulation for toughening modification was ENR content of 30 wt%. Its impact strength was 1,982.55 % of neat polylactic acid. For increasing effectiveness of mechanical properties with a compatibilizer, it revealed that the addition of Joncryl ® ADR-4300 as compatibilizer improved both tensile and impact properties. The optimum loading of a compatibilizer for improving mechanical properties was 0.5 wt% of polylactic acid. The decreases of crystallinity and melting point of polylactic acid with adding Joncryl ® ADR-4300 might be because Joncryl ® ADR-4300 was also chain extender of polylactic acid and it might be obstructing crystallization. The presence of Joncryl ® ADR-4300 unaffected on Tg value and chemical change.