Effect of xylan content on mechanical properties in regenerated cellulose/xylan blend films from ionic liquid

We report of cellulose and arabinoglucuronoxylan (AGX) blend films made from wood polymers extracted from one and the same tree. Blends were prepared by dissolution of wood polymers in 1-ethyl-3-methylimidazolium acetate (EmimAc). Films were produced by casting EmimAc solution followed by coagulation in ethanol. The films were optically transparent, fully amorphous as shown by wide angle X-ray scattering, and free from EmimAc residues as shown by Fourier transform infrared spectroscopy. Mechanical properties were analyzed as a function of water content. The plasticizing effect of water on the films was evidenced by both tensile and dynamical mechanical analysis measurements with humidity scans. Equilibrium moisture content (w/w) was measured at different relative humidities and the proportional water uptake was clearly related to the mechanical properties. We found good mechanical properties independent of the polysaccharide composition and an increased Young's modulus at low humidities with a maximum at approximately 20 % AGX content. The strengthening effect was removed after leaching the AGX from the films This study shows potential applications of biopolymer extracted from trees as future packaging.