Easy production of acetylated cellulose nanofibers from sisal fibers by conventional high-speed blender

This work aimed to isolate cellulose nanofibers (CNF) from sisal fibers and to impart hydrophobic characteristics through acetylation with acetic anhydride. The sisal fibers were pre-treated using alkaline hydrogen peroxide (AHP) followed by acetylation using acetic anhydride. Acetylated and non-acetylated CNF were then isolated by mechanical defibrillation of pre-treated fibers using a high-speed blender. Both resulting CNF were evaluated using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), transmissions electron microscopy (TEM), thermogravimetric analysis (TGA), and water contact angle measurement. ATR-FTIR results revealed the substitution of hydroxyl groups by some acetyl groups as indicated by the presence of carbonyl and methyl groups for the acetylated CNF (ACNF). The yield of ACNF and CNF obtained in this work was 90% and 86%, respectively. The dispersion studies exhibited that ACNF formed a more stable suspension and dispersed better in acetone than CNF. XRD analysis indicated that the acetylation process decreased the crystallinity index of CNF from 79 to 66%. The average diameter distribution of ACNF and CNF was 5.59 +/- 1.45 nm and 6.22 +/- 1.97, respectively. Furthermore, without lowering the thermal stability of CNF, ACNF exhibited higher hydrophobicity as high as 87 degrees compared with that of CNF with a 12 degrees contact angle. The resulting ACNF extracted from sisal fibers had great potential application as reinforcement for nanocomposites with a nonpolar polymer matrix.

Automated summary

This study aimed to isolate cellulose nanofibers (CNF) from sisal fibers and enhance their hydrophobic characteristics through acetylation. The sisal fibers were pre-treated with alkaline hydrogen peroxide (AHP) before being acetylated with acetic anhydride. Acetylated and non-acetylated CNF were then obtained by mechanically defibrillating the pre-treated fibers. Various analyses showed that the acetylated CNF (ACNF) exhibited a more stable suspension and better dispersion in acetone compared to CNF. The acetylation process also reduced the crystallinity index of CNF and increased its hydrophobicity without compromising thermal stability. ACNF extracted from sisal fibers showed great potential as a reinforcement for nanocomposites with nonpolar polymer matrices.