Improving cellulose nanofibrillation of non-wood fiber using alkaline and bleaching pre-treatments

Abstract

This study aimed to investigate the effect of alkaline and bleaching pre-treatments on nanofibrillation of jute fibers and on mechanical performance of the ensuing cellulose films. Fibers were submitted to mild or strong alkaline pre-treatments. Then, only after mild alkaline pre-treatment, the fibers were pre-treated with two different bleaching pathways. Succeeding, cellulose nanofibrils were produced by mechanical defibrillation of the pre-treated fibers, while cellulose films were obtained by dewatering (suction) of the cellulose suspensions. Commercial bleached wood (Eucalyptus and Pinus) pulps were used as reference sources of cellulose fibers. Transmission electron microscopy (TEM) was used to investigate the morphology of the obtained cellulose nanofibrils. Cellulose films were compared by their Tensile properties. Defibrillation process was highly influenced by chemical pre-treatments. By the morphological analyses, the most effective nanofibrillation was observed for fibers pre-treated with tetraacetylethylenediamine (TAED), leading to nanofibrils with average diameter of around 20 nm. The crystalline index (CI) was higher for nanofibrils from pre-treated fibers (CI > 80%) when compared to the raw fibers (CI = 61%). Jute fibers pre-treated with TAED bleaching led to higher nanofibrillation, resulting on films with higher Tensile strength and Young's modulus, which were similar to mechanical properties of those from commercial wood pulp.