4.3 Carbon Black Dispersion as Revealed by 3D-TEM
79
Figure 4.21 displays the change of (N.Nd/TV) as a function of W CB [34]. In the
region of W CB up to 20 phr, linearity is approximately observed with a slope of
q/ξ mTV passing through the origin in the figure. Consequently, this indicates that
the formation of the CB network in small CB-loading region follows the Charlesby’s
gelation theory. (As will be explained in Chap. 5, it is noted that in the region between
20 and 30 phr, a structural transition occurs with respect to the CB aggregates.)
Moreover, a linear relationship (shown in dashed line) is observed at the region of
larger CB loading than 40 phr, too. However, the slope is larger than that at the
smaller CB-loading region. When the m (mass of the primary CB aggregate) and
the TV are thought to be constant in Eq. (4.9), the q (hence F) and the ξ become
larger and smaller at the higher CB, respectively. On the former, the larger is the CB
aggregate, the larger is the F. On the latter, the aggregates are more packed and the
coefficient seems to be nearly unity, i.e., both the changes seem to be reasonable at
least qualitatively.
So far, the formation of CB networks has been detailed from the observation
results by 3D-TEM. These results are to be more discussed in the next chapter, in
relation with the mechanistic considerations on rubber reinforcement.
4.4 Dispersion of the Other Fillers as Revealed by 3D-TEM
Recently, nanofillers other than silica and CB have been subjected to 3D-TEM or
electron tomographic observation. Particularly, information on orientation is possibly
obtained from the 3D images, too, on non-particulate fillers, and hence the technique
is more and more widening its applicability. Some stimulating examples are briefed
in this section, including those of non-rubber arena.
Koster et al. [35] reported that the 3D-TEM images of silver/natural zeolite (modelnite) crystal (Ag/NaY) afforded the exact position of particulate Ag (diameter,
10–40 nm), and the image of acid-treated modelnite suggested a 3D mesoporous
structure (diameter, 3–20 nm). They further carried out the exact visualization of Ag
in the meso pore of zeolite crystallite, and have concluded that the 3D-TEM technique
is unparalleled for characterizing the nanostructure of solid catalysts [36]. Tanaka
[37] has compared the 3D tomographic image and the topographical one of zinc
oxide crystallites, and suggested that the tomography may possibly involve various
artifacts to result in less resolution. Selection of the most suitable method matching
with the morphological feature of the specimen may be of utmost importance in
elucidating the functional properties of a complex chemical species.
Jinnai et al. [38] showed that the distance between two closest plate-like clays
(about 2 nm thickness) is 0.83 nm from a 3D-TEM image of montmorillonite/ethylene
vinyl acetate copolymer (EVA). Nishioka et al. [39] examined the dispersion and
aggregation of organophilic montmorillonite (MMT) in MMT/EVA composite using
transmission electron tomography (TEMT). As a result, it became clear that the
volume fraction of the clay phase evaluated from the TEMT image is equal to the value
calculated from the recipe. They also showed that the anisotropy of the organophilic
79
Figure 4.21 displays the change of (N.Nd/TV) as a function of W CB [34]. In the
region of W CB up to 20 phr, linearity is approximately observed with a slope of
q/ξ mTV passing through the origin in the figure. Consequently, this indicates that
the formation of the CB network in small CB-loading region follows the Charlesby’s
gelation theory. (As will be explained in Chap. 5, it is noted that in the region between
20 and 30 phr, a structural transition occurs with respect to the CB aggregates.)
Moreover, a linear relationship (shown in dashed line) is observed at the region of
larger CB loading than 40 phr, too. However, the slope is larger than that at the
smaller CB-loading region. When the m (mass of the primary CB aggregate) and
the TV are thought to be constant in Eq. (4.9), the q (hence F) and the ξ become
larger and smaller at the higher CB, respectively. On the former, the larger is the CB
aggregate, the larger is the F. On the latter, the aggregates are more packed and the
coefficient seems to be nearly unity, i.e., both the changes seem to be reasonable at
least qualitatively.
So far, the formation of CB networks has been detailed from the observation
results by 3D-TEM. These results are to be more discussed in the next chapter, in
relation with the mechanistic considerations on rubber reinforcement.
4.4 Dispersion of the Other Fillers as Revealed by 3D-TEM
Recently, nanofillers other than silica and CB have been subjected to 3D-TEM or
electron tomographic observation. Particularly, information on orientation is possibly
obtained from the 3D images, too, on non-particulate fillers, and hence the technique
is more and more widening its applicability. Some stimulating examples are briefed
in this section, including those of non-rubber arena.
Koster et al. [35] reported that the 3D-TEM images of silver/natural zeolite (modelnite) crystal (Ag/NaY) afforded the exact position of particulate Ag (diameter,
10–40 nm), and the image of acid-treated modelnite suggested a 3D mesoporous
structure (diameter, 3–20 nm). They further carried out the exact visualization of Ag
in the meso pore of zeolite crystallite, and have concluded that the 3D-TEM technique
is unparalleled for characterizing the nanostructure of solid catalysts [36]. Tanaka
[37] has compared the 3D tomographic image and the topographical one of zinc
oxide crystallites, and suggested that the tomography may possibly involve various
artifacts to result in less resolution. Selection of the most suitable method matching
with the morphological feature of the specimen may be of utmost importance in
elucidating the functional properties of a complex chemical species.
Jinnai et al. [38] showed that the distance between two closest plate-like clays
(about 2 nm thickness) is 0.83 nm from a 3D-TEM image of montmorillonite/ethylene
vinyl acetate copolymer (EVA). Nishioka et al. [39] examined the dispersion and
aggregation of organophilic montmorillonite (MMT) in MMT/EVA composite using
transmission electron tomography (TEMT). As a result, it became clear that the
volume fraction of the clay phase evaluated from the TEMT image is equal to the value
calculated from the recipe. They also showed that the anisotropy of the organophilic