Effect of incorporating cellulose nanocrystals from corncob on the tensile, thermal and barrier properties of poly(vinyl alcohol) nanocomposites

The effect of incorporating cellulose nanocrystals fromcorncob (CNC) on the tensile, thermal, and barrier properties of poly(vinyl alcohol) (PVA) nanocomposites was evaluated. The CNC were prepared by sulfuric acid hydrolysis at 45°C for 60 minutes, using 15mL of H2SO4 (9.17M) for each gram of fiber. The CNC60 presented a needle-shapedmorphology, high crystallinity (83.7%), good initial degradation temperature (236°C), average length (L) of 210.8 ± 44.2 nm, diameter (D) of 4.15 ± 1.08 nm, and high aspect ratio (L/D) of 53.4 ± 15.8. PVA/CNC nanocomposite films with different filler loading levels (3, 6, and 9% by wt) were prepared by casting. The ultimate tensile strength (UTS), thermal stability (TS), light transmittance (Tr) and water vapor permeability (Pw) of the nanocomposites were measured. When compared to neat PVA film, the UTS of the nanocomposites improved significantly, by 140.2%, Pw decreased up to 28.73%, and there were no significant changes in TS. The nanocomposites also showed excellent Tr in the visible region, maintaining substantially equivalent transparency. These improvements in the nanocomposites' properties suggest a close association between filler and matrix, besides indicating that the CNC were well dispersed and adherent to the polymer matrix.