Valorization of betel leaf industry waste: Extraction of cellulose nanocrystals and their compatibility with starch-based composite films

In the present study, betel leaf petioles, an abundant waste of betel leaf industries, were investigated as a promising source for extraction of cellulose nanocrystals (CNC) and evaluated the suitability of these CNC as a filler in biocomposites. In this context, the CNCs were isolated using sulfuric acid hydrolysis treatment and then incorporated into potato starch-guar gum (PSGG) composite films to assess their reinforcing effects. The results showed that the extracted CNCs exhibited rod-like structures with lengths ranging from 54 to 347 nm, diameters ranging from 2.82 to 10.17 nm, and a crystallinity index of 67.62 %, indicating successful removal of amorphous regions. This study also showed that adding of 1 % CNCs significantly enhanced the tensile strength and elongation at break of the PSGG films from 8.29 MPa to 11.22 MPa and 8.60 %–24.85 %, respectively. Moreover, water solubility and water vapour permeability of the PSGG films were found to decrease significantly due to the addition of the CNC. Furthermore, microstructure analysis of the films illustrated smooth, crack-free and homogenous surfaces, showcasing compatibility of the extracted CNC with the PSGG film.