All-cellulose nanocomposites film from sisal fiber

In this work, self-reinforced cellulose nanocomposite films were produced using cellulose and nanofiber from sisal fiber as matrix and reinforcement, respectively. Cellulose nanofiber was prepared via catalytic oxidation using TEMPO/ NaClO/ NaClO2 system. By mild mechanical treatment in water, oxidized celluloses could be disintegrated into individual cellulose nanofiber and utilized as nanofiller.  A morphology of TEMPO-oxidized cellulose nanofiber was characterized through transmission electron microscopy (TEM), which revealed nanosized fibrils with diameters in the range of 10–20 nm and at least 1 µm in length. These cellulosic nanofibers were subsequently impregnated in dissolved cellulose matrix which was prepared by dissolving sisal fiber in lithium chloride/N,N-dimethylacetamide solvent. The effects of reinforcement content in all-cellulose nanocomposite films were examined in terms of morphology, mechanical properties, physical properties, and thermal properties. The crystallinity of the nanocomposite films was increased as the cellulose nanofiber content went up. Even though tensile strength of 0.5% composite film was reduced from 40 to 29 MPa, elongation at break was greatly increased from 11% to 37%. These results mean that the nanocomposite films were tougher than the neat cellulose film. In addition, the cellulose nanofiber led to an improvement in the thermal stability of the nanocomposite films, as evidenced by an increment of the onset of the degradation temperature. The hydrophilicity of the nanocomposite film was decreased with an increasing amount of cellulose nanofiber. The % water absorption of the nanocomposite film was reduced from 202% to 150% with the addition of 2% nanofiber.