Conductive cellulose
composites have received much attention as
emerging materials due to their unique properties, such as biodegradability
and flexibility. However, the achievable levels of conductivity of
these cellulose composites are generally low due to the intrinsically
nonconductive properties of cellulose. In this study, cellulose nanocrystals
(CNC) were applied for preparation of a carbon fibers/expanded graphite
(CF/EG) dispersion which was coated on cellulose paper to prepare
highly conductive cellulose composites. Such composite materials were
characterized based on transmission electron microscopy (TEM) and
field emission scanning electron microscopy (FE-SEM) observation,
FT-IR, XPS, and XRD and by determining the zeta potential, particle
size, contact angle, and rheological behavior. It was found that the
addition of CNC resulted in a significant improvement in the stability
of the CF/EG dispersion. These results were explained by the following
facts: (1) CNC improved the surface charge of the CF and EG due to
the presence of negatively charged groups on the CNC surface, and
(2) CNC increased the wettability of the CF and EG due to large availability
of hydroxyl groups from CNC. The as-prepared CF/EG/CNC dispersion
was then applied by coating cellulose paper surfaces, and the obtained
papers presented superior conductivity and high flexibility.