Rheological behavior of cellulose nanofibers from cassava peel obtained by combination of chemical and physical processes

Highlights

• Cellulose nanofibers from cassava peel were isolated.

• Suspension of cellulose nanofibers (CNFs) showed gel-like behavior with G´>G´´.

• The acid hydrolysis produced CNFs that promoted a higher gel strength than the CNFs obtained by TEMPO-mediated oxidation.

• Sonication process interfered in the gel strength and degree of thixotropy of the CNFs aqueous suspensions.

Abstract

This work aimed to produce and characterize cellulose nanofibers obtained from cassava peel with a combination of pre-treatments with acid hydrolysis or TEMPO-mediated oxidation and ultrasonic disintegration. All nanofibers presented nanometric diameter (5−16 nm) and high negative zeta potential values (around −30 mV). Oscillatory rheology showed a gel-like behavior of the aqueous suspensions of nanofibers (1.0–1.8 % w/w), indicating their use as reinforcement for nanocomposite or as a thickening agent. Additionally aqueous suspensions of nanofibers obtained by acid hydrolysis presented higher gel strength than those produced by TEMPO-mediated oxidation. However, ultrasound application increased even more viscoelastic properties. Flow curves showed that suspensions of nanofibers obtained by acid hydrolysis presented a thixotropy behavior and viscosity profile with three regions. Therefore our results showed that it is possible to tune mechanical properties of cellulose nanofibers choosing and modifying chemical and physical process conditions in order to allow a number of applications.