Hydrophilic modification of cellulose nanocrystals improves the physicochemical properties of cassava starch-based nanocomposite films

- The modified cellulose nanocrystals were beneficial for reinforcement of the films.
- The modified cellulose nanocrystals improve the mechanical properties of the films.
- The modified cellulose nanocrystals improve the barrier properties of the films.
- The films reinforced with modified cellulose nanocrystals had a cohesive structure.

Carboxymethyl cellulose nanocrystals (N-CMCs) were produced by carboxymethylation of cellulose nanocrystals (CNCs) that derived from sweet potato residue. Transmission electron microscopy showed that the N-CMCs which had a porous surface structure were more loosely packed and slightly larger with a uniform diameter ranging from 30 nm to 50 nm. N-CMCs with low viscosity (<25 mPa s) and nano-sized scale were used as reinforcement for preparing cassava starch-based films. Effect of N-CMCs varying 0.2 g/100 mL −0.5 g/100 mL was studied on physicochemical properties of N-CMCs/cassava starch films. N-CMCs/cassava starch film with 0.4 g/100 mL N-CMCs exhibited a 554% increase in tensile strength, 41% increase in elongation at break, and 123% increase in water solubility compared with the CNCs/cassava starch film. Moreover, the water vapor permeability and moisture absorption of the N-CMCs/cassava starch film decreased by 42.7% and 15.9%, respectively. Better mechanical properties, water barrier properties and water solubility was achieved for the N-CMCs/cassava starch film than for the CNC/cassava starch film, indicating N-CMCs after carboxymethylation were beneficial for reinforcement of cassava starch-based films. The moisture absorption abilities of both cassava starch nanocomposite films were comparable. The results may be applied to the development of water-soluble and biodegradable edible films for food packaging.