SPring-8, the large synchrotron radiation facility

Scientists of Sumitomo Rubber Industries, Ltd., succeeded in developing a technique for precisely measuring the three-dimensional (3D) arrangement of silica nanoparticles in rubber using the high-brilliance X-rays of SPring-8 and an earth simulator and fuel-efficient tires by applying the obtained results on the 3D arrangement to a simulation for designing new materials to be used for high-performance and high–quality tires. This study was carried out in cooperation with scientists from the University of Tokyo, the National Defense Academy of Japan, the Advanced Softmaterial Beamline Consortium, the Earth Simulation Center of JAMSTEC, and JASRI.

With the background of increasing worldwide concern over global environmental problems, the required performances for automobile tires have been diversified and become more stringent. At the G8 Summit held in Toyako, Hokkaido, in 2008, it was reported by the International Energy Agency (IEA) in their final report "Fuel-Efficient Road Vehicle Non-Engine Components" that approximately 80% of energy consumed for transportation is attributable to automobiles and that approximately 20% of fuel energy is consumed in overcoming the rolling resistance of tires, indicating that the widespread use of fuel-efficient tires is necessary. The Ministry of Land, Infrastructure, Transport and Tourism and the Ministry of Economy, Trade and Industry established the Council for the Promotion of Fuel-Efficient Tires in 2009, and in January 2010, a labeling system was introduced for summer tires used by domestic automobiles.

Thus, the development of fuel-efficient tires is very important from the viewpoint of the global environment, and the development and promotion of technologies related to fuel-efficient tires are strongly desired. Grip performance is realized owing to the energy loss due to the deformation of a tire as a result of its contact with a road surface. Therefore, the two contradictory requirements, i.e., improving the fuel efficiency and grip performance, should be balanced by advanced methods.

In this study, the research group developed the technique of time-resolved two-dimensional ultrasmall-angle X-ray scattering (2D-USAXS)^*1 with a camera length of 160 m using the high-brilliance X-rays of the Medical and Imaging Beamline II (BL20XU) of SPring-8. The two types of high-precision data obtained by time-resolved 2D-USAXS and time-resolved two-dimensional small-angle X-ray scattering (2D-SAXS)^*2 using the BL03XU Advanced Softmaterial Beamline (FSBL; a beamline dedicated for use by the Advanced Softmaterial Beamline Consortium that was completed in 2010) and the Structural Biology Beamline II (BL40B2) were analyzed by the two-dimensional pattern reverse Monte Carlo method (2Dp-RMC)^*3 developed using an earth simulator.

Using the results of this study, the research group succeeded in developing a both-ends-modified polymer in cooperation with Sumitomo Chemical Co., Ltd., which was used to develop fuel-efficient tires (Fig1). The rolling resistance of the tires was reduced by approximately 39% (approximately 6% less fuel consumption in JC08 mode) and the wet grip performance was improved by approximately 9% compared with those of conventional tires manufactured by Sumitomo Rubber Industries, Ltd.