A comparative study on cellulose nanocrystals extracted from bleached cotton and flax and used for casting films with glycerol and sorbitol plasticisers.

Cellulose nanocrystals (CNCs) were released from bleached cotton and flax by a sulphuric acid hydrolysis with about 40 and 34% yield, respectively. The rod-like cotton-CNC particles were slightly longer and wider and had a less pronounced aggregation ability in aqueous suspension than the flax-CNC ones. Films were cast from the CNC suspensions with sorbitol and glycerol plasticisers. The concept behind this research was to explore how the plasticisers - with similar structure but different molecular weight - and their concentrations affect the perceptible and measured properties of CNC films. Results revealed that the type of plasticiser determined the morphology and the optical and tensile properties of films. The best quality CNC film with an averaged thickness of 50µm was obtained with 20% sorbitol from cotton-CNC. It was proved that behaviour of sorbitol and glycerol plasticisers in CNC films was very similar to that reported previously for starch films.