Use of multi-factorial analysis to determine the quality of cellulose nanofibers: effect of nanofibrillation treatment and residual lignin content

The aim of this work is to study and compare the influence of different nanofibrillation processes on the properties of cellulose nanofibers from wheat straw, and analyze the effect of the lignin in the nanocellulose quality and on the characteristics of the films produced. Wheat straw was subjected to a soda (NaOH) pulping process to obtain unbleached cellulosic pulp. The cellulosic pulp was bleached with NaClO2 in order to remove the lignin of the fiber. Both bleached and unbleached pulps were used to obtain nanocellulose using mechanical pretreatment (PFI refining) and treatments, (high pressure homogenization, twin-screw extruder and ultrafine friction grinder). The effect of the nanofibrillation treatments and the residual lignin content on cellulose nanofiber production was analyzed by means of a deep characterization. A multi-factorial quality index was used to score the cellulose nanofibers produced to enable a benchmarking study between different sources, processes and characteristics. In addition, an energetic study of the production process was carried out for the different treatments. The different nanofibers were used to produce cellulose nanofiber-based films and characterized in order to establish a relationship between the characteristics of cellulose nanofibers and the characteristics of the final product.