Because of the lack of appropriate
techniques for the measurement
of concentrated dispersions, dispersion states of carbon nanotube
(CNT) dispersions have been evaluated for dilute dispersions by assuming
the dispersion state being unchanged by dilution. In this paper, it
is clarified that this assumption does not hold true at a high concentration
region by a direct measurement of size distribution and anisotropy
for CNT dispersions in a wide concentration region. CNT dispersions
showed a dispersion-state transition as a form of rotation restriction
at a certain concentration. In addition to this, CNT dispersions whose
solutes have a large specific surface area showed another dispersion-state
transition at a certain concentration as a form of aggregation growth.
To prove these dispersion-state transitions from another point of
view, the difference in sheet resistance of conducting layers made
from different CNT dispersions coated on a glass substrate was investigated.
It was confirmed that their sheet resistance also showed a clear difference.
This difference can be explained from the viewpoint of dispersion-state
transitions induced by the drying process
