Harnessing the ductility of polylactic acid/ halloysite nanocomposites by synergistic effects of impact modifier and plasticiser

This study explores the efficacy of different additives for tuning ductility of polylactic acid (PLA) composites without significantly affecting their mechanical and thermal properties. Selective additives with unique characteristics, namely an impact modifier (lotader AX8900), a plasticiser (triethyl citrate- TEC), and a reinforcement (halloysite nanotubes-HNT) were extruded with PLA in different mass ratios, and resulting composites were evaluated for rheological, mechanical and thermomechanical characteristics. The thermomechanical analysis showed that PLA/HNT nanocomposites had 20 times higher storage modulus after rubbery stage, indicating excellent interaction of PLA/HNT. Addition of lotader in PLA/HNT composites reduced the crystallinity to 2% from 21% without affecting the glass transition (T-g) temperature. In contrast, addition of TEC yielded just the opposite effect. Lotader, individually and in combination with TEC, improved the elongation at break by 14 and 18 times, respectively. The addition of HNT in presence of lotader and TEC also improved the elongation by 19 times. However, lotader and TEC worked synergistically to improve the most sought-after characteristic of PLA, i. e., ductility while maintaining the similar tensile properties.