purified cellulose fibers was observed. The increase in crystallinity
was undoubtedly due to the removal of hemicellulose and lignin,
which exist in amorphous regions. This leads to the realignment
of cellulose molecules. The increase in crystallinity after chemical
treatments has been reported by several authors (Alemdar &
Sain, 2008; Li et al., 2009). After ultrasonic treatment, no significant
differences appeared between isolated nanofibers and chemicalpurified
cellulose fibers; the crystallinity of each nanofiber was
around 69%, implying that the ultrasonic treatment had little effect
on the crystal regions of the cellulose nanofibers. These results were
also supported by the FTIR analyses. High crystalline nanofibers can
be more effective in achieving higher reinforcement for composite
materials.