Pearl millet starch-based nanocomposite films reinforced with Kudzu cellulose nanocrystals and essential oil: Effect on functionality and biodegradability

This paper documents the preparation of three biopolymer films: 1) pearl millet starch (PMS) films, 2) PMS films reinforced with cellulose nanocrystals (CNCs), and 3) PMS films reinforced with CNCs stabilized Pickering emulsion of clove bud oil (CBO) and a comparison of their mechanical and water barrier properties and biodegradation behavior in soil. Reinforcing PMS films with Kudzu CNCs/CBO significantly increased tensile strength (from 3.9 to 16.7 MPa) and Young's modulus (from 90 to 376 MPa) but reduced the elongation (54.2 to 30 %) at the break of nanocomposite films. Also, the water vapor permeability of nanocomposite films decreased (from 9.60 to 7.25 × 10^-10gm^-1s^{- 1}Pa^-1) with the incorporation of Kudzu CNCs/CBO. The fastest biodegradation was observed for PMS films (98% in 15 days), followed by PMS films reinforced with Kudzu CNCs (96% in 18 days), followed by PMS films reinforced with Kudzu CNCs stabilized Pickering emulsions (94% in 21 days). The morphological analysis found hyphae-like structure formation due to microbial action, which increased over time. In general, all three biopolymer films showed good biodegradation behavior, and they all degraded between 15 and 21 days, suggesting that starch-based films reinforced with Kudzu CNCs provide a technique for the production of biodegradable packaging material.