The effect of pre-treatment on the production of lignocellulosic nanofibers and their application as a reinforcing agent in paper

In this work, three different lignocellulosic nanofibers (LCNF) were produced from unbleached wheat straw soda pulp by using different pre-treatments: mechanical, enzymatic, and TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl) oxy radical]-mediated oxidation processes. The different LCNF were characterized and studied by their chemical composition (FTIR), crystal structure (XRD), thermal degradation behaviour (TGA), morphological (TEM), and their reinforcement effect on papermaking slurries. The pre-treatment used to obtain LCNF showed significant differences on the nanofibrillation yield (37-95%), carboxyl content (74-362 A mu mol g(-1)), cationic demand (428-1116 A mu eq g(-1)), and on its dimensions (7-14 nm), thermal stability, and structure. Regarding application as reinforcement on papermaking slurries, LCNF obtained by TEMPO-mediated oxidation produced a greater reinforcing effect than the other LCNF. Nevertheless, the obtained LCNF from mechanical process produce a similar increase in the mechanical properties of the papersheets due to its high length, compared with LCNF obtained by TEMPO-mediated oxidation.