Enhanced Mechanical and Barrier Performance of Poly (Lactic Acid) Based Nanocomposites Using Surface Acetylated Starch Nanocrystals

Poly (lactic) acid (PLA) based nanocomposites reinforced with starch nanocrystals (SNC) extracted from high amylopectin waxy maize starch and acetylated starch nanocrystals (Ac-SNC), were prepared and their influence on the overall properties of PLA nanocomposites were studied. The two nanofillers (SNC and Ac-SNC) were incorporated in PLA at two different loadings (1 and 3 wt%) by solvent casting and evaporation technique. Surface acetylation of SNC was confirmed by Fourier Transform infra-red spectroscopy and nuclear magnetic resonance spectroscopy and the crystalline structure by X-ray diffraction. This paper reports the influence of incorporating unacetylated and surface acetylated starch nanocrystals on morphological, barrier, mechanical, and rheological properties of PLA based nanocomposites. While both nanofillers improved the properties of PLA, the PLA-Ac-SNC had superior properties to that of PLA-SNC nanocomposites, due to better filler dispersion and interaction with the polymer matrix. These sustainable nanocomposites with improved properties will expand the application of these bio-sourced starch nanocrystals.