Ltd. SRI

Chūō-ku, Japan
Chūō-ku, Japan
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Nakazono T.,Ltd. SRI | Nakazono T.,Osaka City University | Matsumoto A.,Osaka City University
Journal of Applied Polymer Science | Year: 2011

The ring-shaped styrene-butadiene rubbers (SBRs) test pieces ran on a rotating stainless-steel ring using an abrasion tester to evaluate the changes in the mechanical properties, such as the tensile storage modulus and tan δ values, the modulus at 300% elongation, and the strength and extension ratio at the breaking point, after a mechanical aging process. The surface of the SBR test pieces and the formed rubber debris after the running experiment was investigated using scanning electron microscopy. A change in the crosslinking density of the SBRs and the analysis of the isolated free polymers showed the occurrence of bond scission of the copolymer chains. On the other hand, the mechanical properties of whole SBR samples showed only a small change during the mechanical aging test. © 2010 Wiley Periodicals, Inc.


Nakazono T.,Ltd. SRI | Nakazono T.,Osaka City University | Ozaki A.,Osaka City University | Matsumoto A.,Osaka City University
Chemistry Letters | Year: 2010

Styrene - butadiene rubber (SBR) vulcanizates were prepared using liquid polyisoprene (PI) and hydrogenated polyisoprene (HPI) as the plasticizers, and their structure and mechanical properties were investigated. The effect of the phase-separated structures of the SBR and the liquid polymers on the mechanical properties of the SBR vulcanizates was investigated. The constant physical properties were observed for the SBR vulcanizates during the thermal aging process when SBR and the plasticizer were miscible with each other in the vulcanizates. © 2010 The Chemical Society of Japan.


Nakazono T.,Ltd. SRI | Nakazono T.,Osaka City University | Ozaki A.,Osaka City University | Matsumoto A.,Osaka City University
Journal of Applied Polymer Science | Year: 2011

Styrene-butadiene rubber (SBR) vulcanizates were prepared using plasticizers including the four liquid types of styrene-butadiene copolymers (LPSB), polybutadiene (LPB), polyisoprene (LPI), and the hydrogenated polyisoprene (LHPI) as well as the conventional process oil, and their phase-separated structures and mechanical properties were investigated by differential scanning calorimetry and dynamic mechanical spectroscopy. The phase separation was observed for the SBR vulcanizates when LPI and LHPI were used as the plasticizers, while the LPSB and LPB gave homogeneous structures because of the good miscibility with the SBR. The phase-separated structure of the SBR vulcanizate prepared using LPI changed to the homogeneous during the thermal aging. We revealed the role of the liquid polymers as the plasticizers in maintaining the physical and mechanical properties of the SBR vulcanizates during the thermal aging process when the plasticizers were miscible to the SBR. © 2010 Wiley Periodicals, Inc.


Nakazono T.,Ltd. SRI | Nakazono T.,Osaka City University | Matsumoto A.,Osaka City University
Journal of Applied Polymer Science | Year: 2010

The mechanical properties of styrene-butadiene rubber (SBR) vulcanizates prepared using various plasticizers including liquid polybutadiene and styrene-butadiene copolymers were investigated. The effect of the liquid polymers as the plasticizers on the mechanical properties of the polymers, such as the hardness, tensile storage modulus, tanδ, and the modulus at 100% elongation values, were determined before and after the thermal aging. As a result, it was revealed that the use of these liquid polymers gave less amount of change in the measurement values for the mechanical properties during the aging. The crosslinking density and the amount of free polymers were also determined on the basis of the swelling and extraction data, respectively, using several organic solvents. These results support the fact that the added liquid polymers are fixed to the SBR networks. We revealed the superiority of the liquid styrene-butadiene copolymers as the plasticizer, which provides sufficient mechanical properties after vulcanization and the excellent maintenance of the properties during the thermal aging process. © 2010 Wiley Periodicals, Inc.


Tomita Y.,Fukui University of Technology | Naito M.,SRI Ltd | Mochizuki T.,Kobe University
Materials Research Innovations | Year: 2011

A new constitutive equation of rubber is derived by employing a non-affine molecular chain network model for an elastic deformation behaviour and the reptation theory for a viscoelastic deformation behaviour. The deformation behaviours of two-dimensional rubber unit cells containing silica fillers under monotonic and cyclic straining are investigated by computational simulation with the proposed constitutive equation and the homogenisation method. The effect of a silica coupling agent, whose condensation reaction creates a cross-linking agent that increases the number of entangled points, on the deformation behaviour is introduced through the nonaffine constitutive equation of rubber. The precise TEM observation suggests the generation of complex interfillers connecting phases where the characteristics of rubber intricately changed depending on the volume fraction of the silica coupling agent and the location of rubber phase. The obtained results clarified the essential physical enhancement mechanisms of deformation resistance and hysteresis loss, i.e. the Mullins effect, for rubber filled with silica. The volume fraction of the silica coupling agent essentially affects the deformation behaviour of silica filled rubber, suggesting the high controllability of the material characteristics of silica filled rubber compared with carbon black filled rubber. © W. S. Maney & Son Ltd. 2011.

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