Synthesis and characterization of cellulose/polylactic acid/MnO2 bio-nanocomposite as a promising coating of paper sheet for food packaging application

Polymeric materials used in food packaging must possess unique mechanical, antibacterial, and permeability properties to successfully preserve the quality of food. Herein, a low-cost bio-nanocomposite film was coated on a paper sheet (PSH) for use in food packaging. The bio-nanocomposite film was based on cellulose nanocrystals (CNCs), polylactic acid (PLA), and MnO 2 nanoparticles at different loadings (0, 1, 2, 3 wt % of PLA) to obtain CNCs/PLA, CNCs/PLA@1 %MnO 2 , CNCs/PLA@2 %MnO 2 , and CNCs/PLA@3 %MnO 2 , respectively. The crystallinity index of CNCs is 65 % using the Segal approach. The surface morphology of PSH, studied by scanning electron microscopy (SEM), showed a good distribution of MnO 2 NPs in the bio-nanocomposite films, which in turn demonstrated good compatibility with PSH. The biodegradability increased by about 29 % in CNCs/PLA@3 %MnO 2 due to the induced and induction effects of CNCs and MnO 2 -NPs as micronutrients, respectively. The water vapor transmission rate dropped from 890.34 in PSH to 145.46 g/m 2 .day in PSH coated by CNCs/PLA@3 %MnO 2 . Conversely, the oxygen transmission rate increased from 2.84 to 5.23 g/(m 2 .day). PSH coated with CNCs/PLA@2 %MnO 2 showed the best tensile strength with an increase of about 147 %. The study presented a bio-nanocomposite coating that can be used to enhance packaging properties by preserving food during storage and preventing microbial growth.