Influence of hemicellulose content and cellulose crystal change on cellulose nanofibers properties

Abstract

This study aimed to evaluate the properties of cellulose nanofibers (CNFs) with different hemicellulose contents and cellulose II polymorphs. A link was found between these polysaccharides and the properties of CNFs. A decrease in crystallinity (from 69 to 63%) and changes in the crystalline structure of cellulose subjected to an alkaline environment were observed, promoting the partial conversion of cellulose I to cellulose II (from 2 to 42%) and preventing CNFs production at NaOH concentrations higher than 5%. Most treatments showed pseudoplastic fluid behavior, except for the 10% NaOH treatment over 2 h, which showed Newtonian fluid behavior. The quality index of the reference CNFs (TEMPO-oxidized) was the highest (80 ± 3), followed by that of the 5% NaOH-treated (68 ± 3 and 22% energy savings compared to the untreated sample), and the untreated (63 ± 3) samples; and the 10% NaOH treatments had quality indices of 51 ± 3 and 32 ± 1, respectively.