Research method

Development of High Performance,
Fuel-Efficient Tires

X-ray diffraction/scattering

Analysis of three-dimensional structure in tire material at the nano to micrometer scale

Role of SPring-8

Achievements

Development of a time resolved two-dimensional ultra-small angle X-rayscattering technique (2D-USAXS) that can measure the three-dimensional
structural information of silica nanoparticles in the rubber of tires
By combining 2D-USAXS with time resolved two-dimensional small angle
X-ray scattering (2D-SAXS)*, development of a new material using molecular
design based on the results of the two analyses
Commercialization of high performance tires, with rolling resistance** reduced by
39% and fuel-efficiency improved by about 6% compared with their predecessors
Research and development institution : Sumitomo Rubber Industries, Ltd.
*Time resolved two-dimensional small angle X-ray scattering (2D-SAXS): A method for measuring the size and shape of structures smaller thanseveral hundred nanometers (nm: 10-9m) within substances. The BL03XU completed in 2011 by the Advanced Softmaterial Beamline Consortiumand the BL40B2 Structural Biology Beamline II public beamline were used for measurement.
**Rolling resistance: A force that acts in the opposite direction to the direction of travel of the tire. This involves three factors, air resistance,ground friction, and tire deformation, but tire deformation accounts for about 90%.

BackgroundResults

The fuel-efficiency of tires has a significant
effect on improving the fuel-efficiency of vehicles.
Incidentally, deformation of the tire against theroad surface results in gripping performancethrough energy loss, thereby making driving safer.
Generally the main material of tires is rubber,
but adding nanoparticles of carbon or silica
increases their strength and enables thedevelopment of tires that resist deformation andhave high grip. However, raising gripping
performance increases energy loss, which reduces
mileage performance. This was thought to bebecause the nanoparticles in the rubber cohere in
a network configuration, but there was no methodof investigating structures in this submicrometer
range.

First, we developed a time resolved
two-dimensional ultra-small-angle X-ray scattering
method (2D-USAXS) that can measure thesubmicrometer range using the high-brightness,
highly parallel X-ray at SPring-8, and observed thenetwork structures formed by silica particles in therubber at the SPring-8 site. Then we conducted
molecular level measurement in the nanometer
range, and from the two sets of data, we identified
the part of the silica network structure that
increases frictional force and reduces mileageperformance.
In addition to this experiment, we carried out
molecular design reflecting the result ofsimulation in which temporal change is applied to
the network structure to develop a new material,with a structure in which the silica particles are
dispersed. This gave rise to a high performance tirewith outstanding grip and fuel-efficiency.

Thermographic capture comparing the temperatures of thetire surfaces when driving

Comparison of the molecular bonds in rubber
The rubber of tires is composed of synthetic rubber, natural rubber
and a stiffener. In the former tires (top), there are few links, which is afactor in heat generation.
Former tire
In addition, the silica coheres
to form a network structure.
SilicaIn the new product (bottom),

Much of the former tire is orange and yellow, indicating high temperatures. The lowtemperature of the new product reflects its excellent mileage performance.

SPring-8
Storage Ring building

Detectora “both- ends-modifiedpolymer” is used as thesynthetic rubber. The
denatured bases at the endsof the polymer and the new
bonding material work to
improve the bonding powerof the silica and polymer, andto increase the dispersibilityof the silica.

BL20XU
SampleFormer tire

Newly developed fuel-efficient tire
160 m vacuum path

Time resolved two-dimensional ultra-small-angle
X-ray scattering (2D-USAXS)A method for measuring the size and shape of structures in the submicrometer
range (10-7m) within substances. By making the 160 m long vacuum path of theBL20XU the camera length, it was possible to observe X-rays scattered at anextremely low angle of less than 1/100,000 to analyze the structures in this range.
As a result, we could identify the network structure formed by the silica particles inthe rubber.

Polymer

Denatured base
Polymer

Scattered X-ray

Incident X-ray

Transmitted X-ray Scattering angle

SilicaNew bonding material Carbon
Newly developed fuel-efficient tireSample

6Carbon

0.01nm-1

Diffraction image obtained with 2D-USAXS

7