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2020 | Buch

Reinforcement of Rubber

Visualization of Nanofiller and the Reinforcing Mechanism

verfasst von: Dr. Shinzo Kohjiya, Dr. Atsushi Kato, Prof. Dr. Yuko Ikeda

Verlag: Springer Singapore

Buchreihe: Springer Series on Polymer and Composite Materials

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This book presents the most recent description of rubber reinforcement, focusing on the network-like structure formation of nanofiller in the rubber matrix under the presence of bound rubber. The resultant filler network is visualized by electron tomography applied to rubber. In the case of natural rubber, the self-reinforcement effect is uniquely functioning, and new template crystallization is suggested. Here, the crystallites are also believed to arrange themselves in a network-like manner. These results are of great use, particularly for engineers, in designing rubber reinforcement.

Inhaltsverzeichnis

Frontmatter

Filler Reinforcement of Rubber

Frontmatter
Chapter 1. Rubbery Materials and Soft Nanocomposites
Abstract
Rubbers are to be vulcanized and reinforced for their applications. Vulcanization is the most important prerequisite for displaying a stable rubber elasticity for practical utilization, while rubber reinforcement is to meet the demands of practical uses in terms of mechanical and some other functional requirements. Among lots of ingredients for rubber compounding, carbon black (CB) was found to afford several crucial characteristics for rubber tires as well as mechanical strength, early in the twentieth century. Since then, CB has been the most important filler for rubber industry, and the natural rubber (NR)-CB combination pioneered a new concept, polymer composite, together with the use of the rubber/fiber composition. This chapter gives a highly scientific but still general introduction to rubber reinforcement by means of filler. Traditional approaches are briefly described, too, from a retrospective point of view, which are expected to afford an excellent base for a modern approach to rubber reinforcement in this century.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda
Chapter 2. Filler and Rubber Reinforcement
Abstract
In a sense, rubber reinforcement is very unique because it includes several functional properties other than mechanical ones. Among quite a number of compounding ingredients, reinforcing fillers, carbon black (CB) in particular, were focused in 1930s, and the effect has been actively researched for several decades. Ability of CB to immobilize rubber on its surface (known as bound rubber, CB-to-rubber interaction) and clustering tendency of CB in rubber matrix (known as CB structuring, filler-to-filler interaction) have been recognized and studied for many years. Together with the third, hydrodynamic volume effect, the three factors have been extensively researched, but the acting mechanism of the three factors for rubber reinforcement has remained unsolved up to the end of the twentieth century. This chapter presents the most recent elucidations related to the reinforcement mechanism.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda

Analysis of Nanofiller Dispersion in Rubber Matrix

Frontmatter
Chapter 3. Principle and Practice of Three-Dimensional Transmission Electron Microscopy (3D-TEM)
Abstract
TEM observation principle is outlined at first. In TEM, electron is irradiated onto the sample, followed by an image formation using the transmitted electron by the bright-field method. A certain amount of defocusing of the objective lens can give a beneficial phase difference between the scattered and un-scattered electron waves to produce a necessary contrast on the screen, which is the phase contrast. Secondly, the observation principle of 3D-TEM and TEM-tomography were explained. In order to construct the 3D images, we have to make use of computerized tomography. Moreover, the new developments of 3D-TEM were touched on.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda
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 (dp) between the silica aggregates in the high-loading region was found 1.3 nm. It was suggested that this dp 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), dp 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.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda
Chapter 5. Reinforcing Mechanism of Rubber by Nanofiller
Abstract
CB is highlighted for the reinforcement of NR. Firstly, some historical considerations on the rubber reinforcement by nanofillers are given. Secondly, the most recent relevant studies on the aggregation of CB were critically reviewed, and the semiflexible CB network structure in the rubber matrix is proposed, which has unified the traditional ideas on bound rubber and structuring or clustering of CB. This CB network has maintained a little flexibility due to the presence of 3 nm rubber layer (intrinsic bound rubber) between the primary CB aggregates, which are rigid. Thirdly, our semiflexible CB network model is applied to explain a mechanical property of CB-loaded rubber vulcanizates, and the crucial utility of the CB structuring involving bound rubber is concluded. In other words, rubber reinforcement is due to a cooperation of the bound rubber absorbed on the nanofiller surface (wetting by rubber, due to rubber-to-filler interaction) and the 3D clustering ability of nanofillers (filler-to-filler interaction) even overcoming the wetting by rubber, suggesting a feature of nanoparticles in general. Nanofiller network formed by intermediation of bound rubber is certainly the most important result obtained by 3D-TEM studies on rubber reinforcement by nanofillers.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda

Non-Carbon Reinforcement of Rubber

Frontmatter
Chapter 6. Particulate Silica Reinforcement of Rubber
Abstract
Use of particulate silica for rubber is recently increasing, which may continue during this century. So far, wet (or precipitated) silica has been employed for rubber, especially for tire tread, in combination with silane coupling agent. Filler-to-filler interaction between silica particules is stronger than that of filler-to-rubber, in contrast with carbon black (CB). Hence, silica has been considered inferior to CB in terms of processability, in which good dispersion of filler is one of the key objectives. Coupling agents are assumed to increase the filler-to-rubber interaction of wet silica. On the other hand, in situ silica, which is generated in rubber matrix at place, suggests a better processability than wet silica. This relatively novel technique of nanofiller dispersion into rubber matrix is introduced and discussed in detail, together with the advantages of new soft processing method of rubber.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda
Chapter 7. Rubber Reinforcement with Lignin
Abstract
Lignin has been one of the biomass to be utilized more effectively from the viewpoint of sustainable development. In spite of the increasing interest in lignin wastes, a few industrialization of the lignin has been successful. Here, lignin as a rubber reinforcing filler is evaluated, and a soft processing method of lignin-loaded rubber vulcanizates is proposed. The traditional rubber processing, which is a highly mechanical method, has not worked well for the powdered lignin as a rubber compounding ingredient. Some ideas on the soft processing method of rubber–lignin mixtures are suggested for further developmental research. If in success, unique bionanocomposites are to be prepared, when natural rubber is employed as a matrix rubber.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda
Chapter 8. Self-Reinforcement in Natural Rubber (NR): Template Crystallization
Abstract
Natural rubber (NR) is unique in its characteristics. The most notable among them is its self-reinforcing ability. Namely, it is not necessary to mix carbon black (CB) onto NR simply for mechanical strength. The use of CB on tire rubber is for controlling tack, wear or abrasion, and dynamic friction-related properties such as grip and traction. To explain the self-reinforcement of NR, strain-induced crystallization (SIC) has been reasonably assumed, and now, it is accepted widely. However, most researchers have adopted the traditional nucleation mechanism for SIC, even though SIC is due to fully extended network rubber chains. The extended chain formation upon elongation is a matter of necessity. In other words, nucleation is a stochastic process, while SIC is a deterministic process upon straining of NR vulcanizates. Thus, a new concept, template crystallization mechanism, is introduced here in order to rationally explain the SIC behaviors of NR vulcanizates. Template crystallization may be an important concept in ‘elastocaloric’ contractile process, which has been proposed for some functional applications of NR vulcanizates such as a shape memory device.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda

Prospective Views on Rubber Reinforcement

Frontmatter
Chapter 9. Reinforcement in the Twenty-First Century
Abstract
In the twenty-first century, we have to practice sustainable development (SD) in all our activity under an increasing globalization trend. Technically speaking, globalization is supported by the developments of transportation and information. The latter is, in essence, a transportation of information, i.e., communication, while the former is concerned with that of humankind and cargoes. Reinforcement of rubber is an important issue related to transportation by bicycles, automobiles, and aircraft via tires. Prospective considerations on them are given from a few viewpoints of materials (rubber, nanofiller, cross-linking, etc.), soft processing, and new devices. Particularly, new types of device are to be developed, e.g., airless (non-pneumatic) tires. Overall, it is predicted that rubber reinforcement remains to be an indispensable issue until early in the twenty-second century.
Shinzo Kohjiya, Atsushi Kato, Yuko Ikeda
Metadaten
Titel
Reinforcement of Rubber
verfasst von
Dr. Shinzo Kohjiya
Dr. Atsushi Kato
Prof. Dr. Yuko Ikeda
Copyright-Jahr
2020
Verlag
Springer Singapore
Electronic ISBN
978-981-15-3789-9
Print ISBN
978-981-15-3788-2
DOI
https://doi.org/10.1007/978-981-15-3789-9

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