Today, rubber materials are found everywhere, supporting areas like transportation, health services, and consumer products. Their durability, flexibility, and resistance to oils make them essential—but these same qualities, caused by strong chemical bonds known as crosslinking, also make them extremely hard to recycle. Most used rubber is either burned or sent to landfills, raising serious environmental concerns.
Dr. Shigetaka Hayano, Kazuki Kumazawa, Kosuke Isobe, Takuro Sakurai, and Dr. Shengyang Wang from Zeon Corporation, Japan have come up with a new solution to this challenge. They have shown how to break down rubber made from cyclopentene, which is a type of chemical compound used to create certain synthetic rubbers, so it can be reused. Their findings were shared in the journal RSC Advances.
Dr. Hayano’s team created three different types of rubber using cyclopentene and other ingredients. These rubber types are known for being tough and strongly bonded, making them especially hard to break apart. But with the help of a special catalyst, which is a substance that speeds up chemical reactions without being consumed in the process, they managed to break even the hardened, treated versions of these rubbers. Most notably, they were able to recover the original building block, cyclopentene, using gentler methods than usually required in factories.
Perhaps the most surprising part of their success was how quickly they could fully break down a treated rubber sample using only a small amount of the catalyst and moderate heat. Dr. Hayano repeated this process with the other rubber types and got similar results. What remained was a reusable chemical and a harmless black residue from the original materials. According to Dr. Hayano, “This study provides a new strategy for recycling of rubber wastes made from cyclopentene-based rubber under relatively mild conditions, contributing to a circular economy and resource efficiency.”
Dr. Hayano and colleagues also showed that their method works not just on pure cyclopentene rubber but also on cyclopentene-based copolymer rubbers that include other ingredients like norbornene, a substance commonly used in rubber and resin production, dicyclopentadiene to make strong plastics, and another chemical used. This opens the door to recycling a wider range of rubber products. It proves that these materials can be broken down and reused even after going through heat treatment and chemical strengthening, which are steps used to make rubber tougher and longer-lasting.
Such progress marks a valuable step forward for rubber recycling. Most existing techniques only allow for grinding up or burning used rubber, which wastes resources. This new approach, however, allows rubber to be turned back into its original parts, keeping its value and reducing harm to the planet. The benefits for industries that deal with large volumes of rubber waste could be significant.
Ultimately, Dr. Hayano’s research shows that treated rubbers—once thought impossible to recycle chemically—can in fact be converted back into useful materials. This technique offers a promising path toward more environmentally responsible use and reuse of rubber, supporting global efforts to reduce waste and promote smarter resource use.
Journal Reference
Hayano S., Kumazawa K., Isobe K., Sakurai T., Wang S. “Depolymerization of vulcanized poly(cyclopentene), poly(norbornene-ran-cyclopentene) and poly(endo-dicyclopentadiene-ran-cyclopentene) rubbers via ring-closing metathesis depolymerization for monomer recycling.” RSC Advances 2024. RSC Adv., 2024,14, 37143-37154. DOI: https://doi.org/10.1039/d4ra06914e
About the Authors
Dr. Shigetaka HAYANO is a polymer scientist working in R&D center of Zeon Corporation. After receiving his PhD from Kyoto University in 2000, he joined Zeon Corporation as a researcher. Dr. Hayano is currently responsible for maintaining and structuring the polymer core technology of Zeon. Although his major area is polymer chemistry, his research approach is broad and interdisciplinary. His research goal is not just to produce academic results, but also to implement them in our real society.
Dr. Shengyang Wang received her Ph.D. in Organic Chemistry from the University of Minnesota and joined Zeon Corporation in Japan upon graduation. She is currently based at Zeon’s Monozukuri Studio—an innovation-driven hub inspired by the Japanese concept of “the art of making things.” Her work focuses on the design, synthesis, and development of novel functional polymers aimed at real-world applications and market impact.
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