Alginate and carboxymethyl cellulose-based films incorporated with cellulose nanocrystals from cotton textile waste

Full text: Polysaccharide-based films, such as alginate and carboxymethylcellulose (CMC), have been largely researched for use as medical and pharmaceutical devices due to its biodegradable and biocompatible characteristics. However, its instability in aqueous medium as well as its poor moisture barrier may represent disadvantages for some applications. To overcome these limitations and improve the general films properties, cellulose nanoparticles (e.g cellulose nanocrystals - CNC) can be added into a polymer matrix to form a nanocomposite. CNCs can be originated from a wide variety of cellulosic materials, being cotton a good option considering its high cellulose content available. In this study CNCs were obtained by acid hydrolysis using diluted sulfuric acid and cotton fabric from textile waste. The obtained nanoparticles were characterized in terms of morphology (TEM), suspension stability (zeta potential) and crystallinity (XDR). Alginate and CMC films (1:1 in mass) were achieved by casting technique using two different CNCs proportion (2.5% and 5.0% regarding polymer mass). Cross-linking was performed by immersion of the pre-formed films in a 2.5% aqueous calcium chloride solution. The morphology (SEM), the absorption capacity and stability in water and simulated body fluid (SBF) were investigated for the films with and without CNCs. The morphology of the films showed that CNCs were homogeneously distributed into the polymeric matrix. Absorption and mass loss of the films in water and SBF were both notably reduced. The improved stability in liquid media supports the potential use of CNCs obtained from textile waste for nanocomposite bio-based films. (author)