Isolation and characterisation of cellulose nanocrystals from kudzu (Pueraria montana var. lobata): a sustainable packaging material

Flexible packaging has become indispensable in the food industry due to its numerous advantages. However, it has certain drawbacks, such as limited recyclability and environmental contamination. While efforts are underway to develop more sustainable and eco-friendly packaging options, the food industry's reliance on flexible packaging made from unsustainable petro-based plastics is expected to continue in the foreseeable future. Therefore, more sustainable alternatives that do not sacrifice performance are required. One such option is to use nanocellulose, especially cellulose nanocrystals (CNCs), which can be reinforced into biopolymer to enhance mechanical and barrier properties. The present study aims to isolate kudzu CNCs by depolymerisation, bleaching, acid hydrolysis with 51% sulfuric acid, and mechanical dispersion. Thermogravimetric analysis (TGA) was conducted to assess the thermal stability of kudzu fibres. Further, the FTIR spectra were measured at wave number ranged 4000–500 cm⁻¹, which showed changes in the structure after treatments and confirmed the removal of lignin and hemicellulose from the cellulose. The isolated CNCs were found to have lengths and diameters of 285.01 ± 150.33 nm and 42.78 ± 13.26 nm, respectively, with an aspect ratio of 6.43 ± 1.78. This study showed that kudzu CNCs are a suitable reinforcing material for nanocomposites.