Biopolymer Nanocomposite Films Reinforced with Nanocellulose Whiskers

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The C-13 cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating from xylan-cellulose interactions. Qualitatively, the spectral data obtained for the NCW/xylan nanocomposite films indicated that the amount of xylan adsorbed to cellulose increases with the addition of NCW. In an attempt to quantify this effect, non-linear least-squared spectral line fitting was used to deconvolute the adsorbed xylan peak at similar to 82 ppm. The peak intensity ratio of adsorbed xylan peak and xylan C-1 peak, which represents the total amount of xylan increases suggesting that upon the addition of NCW, the amount of adsorbed xylan increases. In an effort to further infer the structure-property relationships associated with the observed strength and barrier properties, H-1 NMR T-2 relaxation experiments were also conducted to investigate the change in the nature of carbohydrate water interactions as a result of NCW incorporation. Water adsorbed into the 50% nanocomposite film had significantly shorter relaxation times with respect to the control xylan/sorbitol and all other NCW/xylan nanocomposite films. Additionally, X-ray diffraction of the nanocomposite films showed increased levels of crystalline material in the nanocomposites due to NCW addition.