2.5 Reinforcing Factors of Particulate Nanofiller
27
to Fig. 2.3 have been repeatedly shown in lots of publications after Refs. [79] and
[80] were published, and the Fujimoto’s model has been known very well, together
with the thickness of the immobilized rubber layer (ca. 5.0 nm, estimated by him). In
other words, many papers have been published on bound rubber, but the fundamental
aspects depicted in the figure have not suffered any serious alterations since then.
2.5.3 Structuring of Nanofiller
Structure is too common a word to be understood without any ambiguity: Among
chemists, it means chemical (or molecular) structure, and physicists think the inner
structure of any bodies from micro to macrolevels. In the engineering sides, architects mind various structures when designing, civil and mechanical engineers conduct structural strength calculations almost every day, electrical engineers think of
structure of the electric devices, and so on.
In Chap. 10 of Ref. [5], the word ‘structure’ is defined as follows:
Structure is defined as the degree to which the black particles are combined to form stable
agglomerates. High structure results in high oil adsorption capacity.
Here, ‘agglomerates’ have to be understood as a generic term including primary
aggregate and higher aggregates, and our definition that the ultimate higher aggregate
is to be named agglomerate is rationally included. Taking our conclusion in advance,
structure (in its chemists’ meaning) of the agglomerate of nanofiller in rubber matrix
is a filler network (see 4.3 and 5.5). The second sentence expressed a traditional issue,
which is criticized in 2.4.2. Because of the size of the oil (e.g., DBP), besides its
adsorption on the surface, the occluded oil in the three-dimensional voids is mainly
considered. However, the presence of void, which is almost three-dimensionally
enclosed, is simply assumed. Their presence has not been substantiated nor fully
quantified, and the above interpretation remains to be a hypothesis still.
More important issue in Chap. 10 of Ref. [5] is the CB manufactured by the
oil furnace method. The product of the oil or gas furnace manufacturing process is
fundamentally primary aggregate of CB as shown in Fig. 2.4 [84]. Here, a primary
particle is produced in the furnace by surface growth (SG), which may continue SG
or instantaneously combines with the other primary particle by aggregate growth
(AG). The AG may be a random process in the furnace at very high temperature.
Repetitive dynamic growth of SG and AG results in matured aggregate (mostly
primary aggregate) at the furnace exit, and thus, we use the primary aggregates of
CB in our laboratory works.
Most of the recovered CB is possibly primary aggregates of CB. However, they
have associated further to higher aggregates, i.e., cluster of primary aggregates during
the storage, and the CB we are using for rubber compounding is a mixture of primary
and higher aggregates as shown in Fig. 2.5, which is a TEM image of a commercially
available HAF dispersed in paraffin wax. CB aggregates of various sizes are observed,
among which the largest one is of a few µm size. The higher aggregates have been
27
to Fig. 2.3 have been repeatedly shown in lots of publications after Refs. [79] and
[80] were published, and the Fujimoto’s model has been known very well, together
with the thickness of the immobilized rubber layer (ca. 5.0 nm, estimated by him). In
other words, many papers have been published on bound rubber, but the fundamental
aspects depicted in the figure have not suffered any serious alterations since then.
2.5.3 Structuring of Nanofiller
Structure is too common a word to be understood without any ambiguity: Among
chemists, it means chemical (or molecular) structure, and physicists think the inner
structure of any bodies from micro to macrolevels. In the engineering sides, architects mind various structures when designing, civil and mechanical engineers conduct structural strength calculations almost every day, electrical engineers think of
structure of the electric devices, and so on.
In Chap. 10 of Ref. [5], the word ‘structure’ is defined as follows:
Structure is defined as the degree to which the black particles are combined to form stable
agglomerates. High structure results in high oil adsorption capacity.
Here, ‘agglomerates’ have to be understood as a generic term including primary
aggregate and higher aggregates, and our definition that the ultimate higher aggregate
is to be named agglomerate is rationally included. Taking our conclusion in advance,
structure (in its chemists’ meaning) of the agglomerate of nanofiller in rubber matrix
is a filler network (see 4.3 and 5.5). The second sentence expressed a traditional issue,
which is criticized in 2.4.2. Because of the size of the oil (e.g., DBP), besides its
adsorption on the surface, the occluded oil in the three-dimensional voids is mainly
considered. However, the presence of void, which is almost three-dimensionally
enclosed, is simply assumed. Their presence has not been substantiated nor fully
quantified, and the above interpretation remains to be a hypothesis still.
More important issue in Chap. 10 of Ref. [5] is the CB manufactured by the
oil furnace method. The product of the oil or gas furnace manufacturing process is
fundamentally primary aggregate of CB as shown in Fig. 2.4 [84]. Here, a primary
particle is produced in the furnace by surface growth (SG), which may continue SG
or instantaneously combines with the other primary particle by aggregate growth
(AG). The AG may be a random process in the furnace at very high temperature.
Repetitive dynamic growth of SG and AG results in matured aggregate (mostly
primary aggregate) at the furnace exit, and thus, we use the primary aggregates of
CB in our laboratory works.
Most of the recovered CB is possibly primary aggregates of CB. However, they
have associated further to higher aggregates, i.e., cluster of primary aggregates during
the storage, and the CB we are using for rubber compounding is a mixture of primary
and higher aggregates as shown in Fig. 2.5, which is a TEM image of a commercially
available HAF dispersed in paraffin wax. CB aggregates of various sizes are observed,
among which the largest one is of a few µm size. The higher aggregates have been