Preparation of Square-Shaped Starch Nanocrystals/Polylactic Acid Based Bio-nanocomposites: Morphological, Structural, Thermal and Rheological Properties

The development of low-cost bio-nanocomposites based on square-shaped starch nanocrystals (SNCs) is a promising approach for maintaining environmental sustainability. This study reports on a method for the preparation of bio-nanocomposites from polylactic acid (PLA) and SNC derived from acid hydrolysis of waxy maize starch. PLA-SNC bio-nanocomposites were prepared by incorporating SNC at 1, 3 and 5 wt% by dispersing them in PLA matrix using dichloromethane as a solvent. Morphological, thermal, crystalline and rheological properties of neat PLA, neat SNC and PLA-SNC bio-nanocomposites have been investigated to observe the effect of SNC loading. SNC loading at 3 wt% was found to be the optimum loading to improve the storage modulus, complex dynamic viscosity, and crystallinity, while 5 wt% loading caused agglomerations which led to a decrease in the above properties. Thermogravimetric analysis result suggested that both the SNC and PLA-SNC bio-nanocomposites were thermally stable from 25 to 240 degrees C. Electron microscopy study showed the effective dispersion of SNC in PLA.