Chapter 4
Nanofiller Dispersion in Rubber
as Revealed by 3D-TEM
Abstract Firstly, it was found that visualization of three-dimensional structure of
rubber vulcanizate by 3D-TEM observation necessitated a removal of rubber-soluble
zinc compounds, which was derived from ZnO annexed as a vulcanization reagent.
The Zn compounds deteriorated the resolution to give enough good resolution for
3-dimensional image construction. Secondly, an experimental method how to remove
them on silica-loaded natural rubber vulcanizates was reported. Lastly, the nearest
distance (d p ) between the silica aggregates in the high-loading region was found
1.3 nm. It was suggested that this d p corresponds to the thickness of the silica/NR
interaction layer, i.e., more or less intrinsic bound rubber on particulate silica surface, and the silica network structure in the rubber matrix was clearly visualized.
Furthermore, in the case of carbon black (CB), d p in the high loading region was
found 3 nm, and the CB network was also visualized. CB network formation was
explained by the gelation theory: in the region of CB loading 20 phr pregel states,
and the transition to gel state occurred in the region of CB loading > 20 phr.
Keywords Removal of rubber-soluble zinc compounds · In situ silica ·
Hydrophobic and hydrophilic silicas · Silica network · CB network
4.1 Introduction
In this chapter, the results of 3D-TEM observation of nanofiller in the rubber matrix
are to be described. Silica and carbon black (CB) are the representative nanofillers
for rubber reinforcement among lots of known nanoparticles, and the visualized 3D
images of particulate silica and CB are to be shown. Analysis of the images has
afforded several structural features of value on their dispersion, and ultimately the
visualized nanofiller network structure would be displayed.
From a specific interest of our research team on particulate silica generated in situ,
the results of 3D-TEM on silica precede those of CB. Since CB has been the most
Electronic supplementary material The online version of this chapter
(https://doi.org/10.1007/978-981-15-3789-9_4) contains supplementary material, which is
available to authorized users.
© Springer Nature Singapore Pte Ltd. 2020
S. Kohjiya et al., Reinforcement of Rubber, Springer Series on Polymer
and Composite Materials, https://doi.org/10.1007/978-981-15-3789-9_4
57
Nanofiller Dispersion in Rubber
as Revealed by 3D-TEM
Abstract Firstly, it was found that visualization of three-dimensional structure of
rubber vulcanizate by 3D-TEM observation necessitated a removal of rubber-soluble
zinc compounds, which was derived from ZnO annexed as a vulcanization reagent.
The Zn compounds deteriorated the resolution to give enough good resolution for
3-dimensional image construction. Secondly, an experimental method how to remove
them on silica-loaded natural rubber vulcanizates was reported. Lastly, the nearest
distance (d p ) between the silica aggregates in the high-loading region was found
1.3 nm. It was suggested that this d p corresponds to the thickness of the silica/NR
interaction layer, i.e., more or less intrinsic bound rubber on particulate silica surface, and the silica network structure in the rubber matrix was clearly visualized.
Furthermore, in the case of carbon black (CB), d p in the high loading region was
found 3 nm, and the CB network was also visualized. CB network formation was
explained by the gelation theory: in the region of CB loading 20 phr pregel states,
and the transition to gel state occurred in the region of CB loading > 20 phr.
Keywords Removal of rubber-soluble zinc compounds · In situ silica ·
Hydrophobic and hydrophilic silicas · Silica network · CB network
4.1 Introduction
In this chapter, the results of 3D-TEM observation of nanofiller in the rubber matrix
are to be described. Silica and carbon black (CB) are the representative nanofillers
for rubber reinforcement among lots of known nanoparticles, and the visualized 3D
images of particulate silica and CB are to be shown. Analysis of the images has
afforded several structural features of value on their dispersion, and ultimately the
visualized nanofiller network structure would be displayed.
From a specific interest of our research team on particulate silica generated in situ,
the results of 3D-TEM on silica precede those of CB. Since CB has been the most
Electronic supplementary material The online version of this chapter
(https://doi.org/10.1007/978-981-15-3789-9_4) contains supplementary material, which is
available to authorized users.
© Springer Nature Singapore Pte Ltd. 2020
S. Kohjiya et al., Reinforcement of Rubber, Springer Series on Polymer
and Composite Materials, https://doi.org/10.1007/978-981-15-3789-9_4
57