Bridgestone Corp. announced that it has developed a new polymer, the first of its kind, using advanced synthetic technology for macromolecular conjugates. 　　 　　By combining rubber and resin at a molecular level, Bridgestone has become the first in the world to develop what it calls High Strength Rubber (HSR), a hybrid material able to freely exhibit the superior capabilities of each component material. 
　　HSR’s notable point as an innovative new polymer lies in the fact that it is a hybrid material developed using a special gadolinium (Gd) catalyst recently improved by Bridgestone. This catalyst allows for the molecular-level copolymerization of conjugated dienes such as butadiene and isoprene – which form the rubber component of the new material – with olefins such as ethylene, which form its resin component. 
　　Butadiene and isoprene are elsewhere used in common synthetic rubber, with ethylene also being commonplace. Bridgestone researcher Shojiro Kaita noted that while blends of rubber and resin already exist, HSR is the only polymer in which the ethylene resin component is spread throughout the rubber at a nano level. The company, Kaita continued, is already working on prototypes for tire use. Although vulcanization is required for use in tires, the material can also be commercialized without vulcanizing, and this has positive effects on its recyclability, he said. 
　　Despite natural rubber already providing a higher fracture resistance than regular synthetic rubber, tests based on the Japan Industrial Standards (JIS) show that HSR’s crack resistance is five times higher again than natural rubber. The material’s wear resistance when vulcanized was found to be roughly 2.5 times that of natural rubber, with tensile strength about 1.5 times higher in the same comparison. Meanwhile, ozone resistance tests found HSR to be more resistant to deterioration here due to its inclusion of resin, illustrating its superior weather resistance compared to natural and synthetic rubber.