The study
on low-cost drying–redispersion process for the storage and
transport of nanocellulose has been a great challenge in practical
applications. The existence of abundant hydroxyl groups on the nanocellulose
surface causes a strong tendency of agglomeration of the nanoparticles
in the dry state. In this paper, we propose a new method to solve
this problem by controlling the solid content of cellulose suspension
to obtain a well-dispersed nanocellulose with reduced fibrillar alignment
in the following freeze-drying treatment. The results show that when
the solid content in the original suspension varied between 4 and
10 wt %, the morphology of the aerogel transformed from the membranous
to fibrillar network with increasing specific surface area and redispersibility,
and further dehydration was detrimental. This phenomenon is mainly
attributed to the entanglement of cellulose fibrils in the cellulose
network, which suppressed the growth of ice crystal during the dry-freezing
process. In addition, the interaction between intra-/intermolecular
hydrogen bonds is also proved to be responsible for the variation
of the cellulose morphologies and the thermal decomposition temperature.
This research will provide an effective and convenient way for the
transportation and storage of nanocellulose, aiming at its large-scale
industrial applications.
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