Production of nanocellulose gels and films from invasive tree species

Wood from invasive tree species Acacia dealbata and Ailanthus altissima was used to produce high value-added nanocellulose. Firstly, bleached pulps were produced from the wood of these tree species after kraft cooking. Afterwards, the resultant pulps were pre-treated by TEMPO-mediated oxidation (Acacia dealbata) or enzymatic hydrolysis (Ailanthus altissima) followed by high-pressure homogenization. Hydrogels were obtained and characterized for their main physical and chemical properties, including rheology measurements. After freeze-drying, the surface properties of the materials were evaluated by inverse gas chromatography. Results showed that nano/ micro fibrils could be obtained from the wood of these invasive species. Rheometry studies showed that Acacia-TEMPO cellulose nanofibrils form strong gels with high yield stress point and viscosities (reaching ca. 100,000 Pa.s). Additionally, the surfaces of the obtained nanocelluloses showed a dispersive component of the surface energy near 40 mJ/m(2) and a prevalence of the Lewis acidic character over the basic one, as typical for cellulosebased materials. Finally, films with good mechanical and optical properties could be obtained from the cellulose hydrogels. Acacia-TEMPO film (produced by filtration/hot pressing) showed a tensile strength of 79 MPa, Young's modulus of 7.9 GPa, and a transparency of 88%. The water vapor barrier, however, was modest (permeability of 4.9 x 10(-6) g/(Pa.day.m)).

Automated summary

The wood from invasive tree species Acacia dealbata and Ailanthus altissima was used to produce high value-added nanocellulose, with hydrogels obtained and characterized for their properties including rheology measurements. The resulting nanocellulose materials showed strong gels with high yield stress point and viscosities, as well as specific surface energy properties typical for cellulose-based materials. Films with good mechanical and optical properties were derived from the cellulose hydrogels, showing promising results for potential applications.