NIPPON GOMU KYOKAISHI

Journal Information
ISSN / EISSN : 0029-022X / 1884-0442
Published by: Society of Rubber Industry, Japan (10.2324)
Total articles ≅ 3,581
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Latest articles in this journal

Atsushi Takai
NIPPON GOMU KYOKAISHI, Volume 94, pp 182-186; https://doi.org/10.2324/gomu.94.182

Abstract:
Natural rubber latex is widely used in medical gloves. However, it contains allergen proteins that cause symptoms such as urticaria. This article reviews the quality-control factor of deproteinized natural rubber latex, which is commercially produced by enzyme-centrifugation method.
Koichi Yamaguchi
NIPPON GOMU KYOKAISHI, Volume 94, pp 245-249; https://doi.org/10.2324/gomu.94.245

Abstract:
Many companies use molds to perform vulcanization molding of rubber. The unvulcanized rubber compound, which has been kneaded, mixed, and preformed, is loaded on the mold, and then mold vulcanization molding is applied using a compression molding machines, an injection molding vulcanization machines, and a transfer molding machines. Mold vulcanization molding, which uses a mold, involves vulcanization reaction (cross-linking reaction) and molding under high temperature and high pressure, and the goodness or badness of the resulting molded product is determined by the compound design, the accuracy of the mold, the goodness or badness of the mold, and the vulcanization molding conditions. In this section, this paper discusses the history of rubber molding, the cancellation of the technology of rubber molding and the trends to be discussed.
Yoshihide Fukahori
NIPPON GOMU KYOKAISHI, Volume 94, pp 237-244; https://doi.org/10.2324/gomu.94.237

Abstract:
In this final Part 6, the Author proposes a new theory of rubber wear connected with rubber friction through abrasion pattern formation generated by stick-slip motion. The kinetic interpretation was introduced to explain the close relationship between the wear rate and the distance of abrasion patterns named the wear-abrasion pattern diagram, which showed that two mechanisms work differently at an initial stage and a final stage of the abrasion pattern formation. After the inspection of the theory of rubber wear given by AG. Thomas theoretically and experimentally, the author proposes a new theory of the rubber wear based on the fracture mechanics treatment, where is shown that the stick-slip motion is the direct driving force to promote the rubber wear, and thus the abrasion pattern of the same length as the period of the stick-slip motion is left on the wear surface of the rubber.
Koji Matsuyama
NIPPON GOMU KYOKAISHI, Volume 94, pp 282-286; https://doi.org/10.2324/gomu.94.282

Abstract:
As for the performance evaluation of winter tires, in general, stable evaluation in the room is desired because the vehicle test is affected by the weather and the evaluation period is limited. In addition, since rubber materials and tire characteristics depend on temperature, temperature is one of the very important factors to obtain high reliable results in tire evaluation, and it can be said that it depends on how it can be tested under constant temperature conditions. We will introduce the general ice performance evaluation technology of winter tires by the indoor vehicle test, indoor drum test method, and lab evaluation technology.
Masatoshi Tosaka
NIPPON GOMU KYOKAISHI, Volume 94, pp 130-135; https://doi.org/10.2324/gomu.94.130

Abstract:
Though the inherent elasticity of rubber materials is derived from the amorphous polymer chains, crystals are also an important factor in understanding the physical properties of rubber. For example, in natural rubber, butadiene rubber, chloroprene rubber, and some others, crystallization occurs under high elongation, which is thought to exert a self-reinforcing effect. Also the hard segments of urethane rubbers are sometimes crystalline. Dynamic change of such crystal structures has a significant effect on the physical properties of rubber, and wide angle X-ray diffraction (WAXD) is a powerful tool for analyzing such dynamic structural changes. In this paper, we aim to explain the basic principles of WAXD in as simple words as possible for readers who are not familiar with WAXD measurements.
Hiroki Yamamura, Tetsuo Tominaga, Takumi Adachi, Hirofumi Senga
NIPPON GOMU KYOKAISHI, Volume 94, pp 151-157; https://doi.org/10.2324/gomu.94.151

Abstract:
Recently, we have developed a very high strength rubber by hydrogenation of styrene-butadiene rubber (SBR). Hydrogenated SBR represents the changes of stress-strain curve and viscoelastic property from conventional SBR. The changes seem to be related to an increment of entanglement density with hydrogenation. To analyze mechanical properties of crosslinked rubbers, coarse-grained molecular dynamics (CGMD) simulation has been frequently used. However, Kremer-Grest model, one of the most famous CG models, uniquely determines an entanglement density of polymer melt and isn’t suitable for studying hydrogenated SBR. Therefore, we performed CGMD simulations using KremerGrest model with angle potential in order to confirm whether the stress-strain curves and the tanδ master curves of the simulations fit that of the experiments for SBR. In this study, we made crosslinked rubber models of hydrogenated and non-hydrogenated SBRs with entanglement densities corresponding to experimental values of viscoelastic measurements. The calculated values of the stress-strain curves and the tanδ master curves roughly match the experimental values. Therefore, we conclude that the increment of entanglement density plays an important role in the changes of mechanical properties by hydrogenation of SBR.
Toshikazu Takata
NIPPON GOMU KYOKAISHI, Volume 94, pp 11-17; https://doi.org/10.2324/gomu.94.11

Abstract:
In this review, we would like to discuss on the effect of rotaxane-crosslink on the toughening of crosslinked polymer, which is obtained by copolymerization of two-vinyl group-tethering rotaxane crosslinker (RC) with a typical vinyl monomer such as n-butyl acrylate. Rotaxane-crosslinked polymer (RCP) always showed higher mechanical property than covalently crosslinked polymer (CCP). As for the effect of movable distance of the wheel component along the axle component, RCP obtained from longer axle-possessing RC showed higher toughness than that from shorter one. Meanwhile, rotaxane crosslinkers having thickness-different axle components were prepared to evaluate the effect of actual mobility on the mechanical property. RCPs derived from RC consisting of higher mobile components showed toughness stronger than that derived from RC with lower mobile components. The effect of the rotaxane crosslink on the toughening of crosslinked polymer was accounted for the high mobility and freedom of the rotaxane components, while the toughening mechanism was studied on the basis of timing of the transition from Affine deformation to Non-Affine deformation caused by the rotaxane crosslink.
Ryota Tamate, Masayoshi Watanabe
NIPPON GOMU KYOKAISHI, Volume 94, pp 39-45; https://doi.org/10.2324/gomu.94.39

Abstract:
Ion gels, soft materials that contain ionic liquids (ILs), are promising soft solid electrolytes for use in various electrochemical devices. Due to the recent surge in demand for flexible and wearable devices, highly durable ion gels have attracted much attention. In this context, the introduction of a self-healing ability would significantly improve the longterm durability of ion gels subject to mechanical loading. Nevertheless, compared to hydrogels and organogels, the self-healing of ion gels has barely investigated. In this review, we address recent our development of functional ion gels that can heal themselves when mechanically damaged. Light-induced healing of ion gels are discussed as a stimuli-responsive healing strategy, after which self-healable ion gels based on supramolecular chemistry are addressed. Tough, highly stretchable, and self-healable ion gels can be fabricated through the judicious design of polymer nanostructures in ILs in which polymer chains and IL cations and anions interact.
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