Polysaccharide-based films reinforced with nanocellulose isolated from raw and bleached cotton

This study used raw and bleached cotton fibers from the textile carding process to obtain cellulose nanocrystals (CNCs) via acid hydrolysis. These materials were then used as nanofillers to improve the properties of films made of sodium alginate (ALG), carboxymethyl cellulose (CMC), and blends of ALG:CMC (1:1). The obtained materials were characterized based on their suspension stability (zeta potential), yield, thermal behavior, and crystallinity. The mechanical properties and water vapor permeability (WVP) of films with different CNC contents (1, 2.5 and 5 wt%) were analyzed. The results indicated that bleached cotton generated CNCs with a smaller size and higher yield than raw cotton. The CNCs extracted from bleached and raw cotton showed crystallinities 18% and 20% higher than the original materials, respectively, and the suspensions were stable. The incorporation of bleached CNCs increased the tensile strength of ALG films by 36% (at 5 wt%) and CMC films by 35% (at 2.5 wt%). The mechanical properties of the ALG:CMC films were not altered by adding CNCs. Raw and bleached CNCs reduced the WVP of the ALG films (up to 39%) and ALG:CMC films (32%). In general, the CNCs obtained from bleached cotton tended to act as the best reinforcing agent for ALG and CMC films, giving it the potential for use in food applications.

Automated summary

This study utilized raw and bleached cotton fibers to obtain cellulose nanocrystals (CNCs) and used them as nanofillers to enhance the properties of sodium alginate (ALG), carboxymethyl cellulose (CMC), and ALG:CMC blend films. The bleached cotton generated smaller CNCs with higher yield compared to raw cotton. The incorporation of bleached CNCs significantly increased the tensile strength of ALG and CMC films, while maintaining the mechanical properties of ALG:CMC films. Both raw and bleached CNCs reduced the water vapor permeability of the films. Overall, the bleached CNCs showed potential for use in food applications.