Dispersion of chitin nanocrystal in Polylactic acid nanocomposites prepared via liquid assisted extrusion by triethyl citrate

Efforts to replace petroleum-based polymers with environmental-friendly biopolymers have been intensified during recent years. Presently, polylactic acid (PLA) is one of the most developed biopolymers and chitin nanocrystals (ChNCs), a nano-reinforcement extracted from chitin in crustacean waste, can provide enhanced structural, barrier and bioactive properties to PLA. Hence, the PLA/ChNC combination is promising to produce nanocomposite films for sustainable packaging applications. In this work, PLA/ChNC nanocomposites wereprepared by a novel liquid-assisted extrusion method. To improve the compatibility between ChNCs and PLA matrix, triethyl citrate (TEC), a bio-based plasticizer, was added to the nanocomposites with different concentrations (7.5%-15%). The main objective here is to identify the minimum amount of TEC needed to improve the ChNC dispersion and toughness of the nanocomposites. The plasticized PLA/ChNC nanocomposites were investigated by microcopy techniques to determine the dispersion of ChNCs in PLA. Moreover, their transparency, mechanical performance and thermal behaviors were characterized. All results reveal that TEC plays an important role as a dispersant in the processing of PLA/ChNC nanocomposites and significant toughening effect was obtained when the TEC concentration exceeds 12.5 wt%. This project is funded by the Bio-Based Industries Joint Undertaking under the European Union’s Horizon 2020 (Grant No. 792261)