Ambient Recycling of Vulcanized Rubber
In late 2025, Bridgestone and the National Institute of Advanced Industrial Science and Technology (AIST) of Japan announced a major breakthrough in their jointly developed ambient-temperature chemical recycling process, successfully overcoming a key industry challenge in vulcanized rubber recycling.
This technology can efficiently decompose vulcanized rubber under mild ambient-temperature conditions, producing high-value chemical raw materials such as isoprene, carbon black, and benzene, toluene, and xylene (BTX), injecting new momentum into the global rubber circular economy. This breakthrough not only breaks through a long-standing technical bottleneck in the industry but also precisely aligns with the global trend of efficient resource utilization under the "dual carbon" goal, conforming to the policy guidance of many countries in building waste recycling systems.
Vulcanized rubber recycling has long been considered an industry challenge, the core issue being its stable sulfur cross-linked structure. While polyisoprene from natural rubber and other materials can be decomposed through catalytic metathesis reactions, the sulfur content in vulcanized polyisoprene from waste tires inhibits these reactions, making traditional recycling technologies ineffective.
Previously, mainstream physical recycling methods could only process waste rubber into low-end rubber powder, with extremely low added value. Chemical recycling technologies such as pyrolysis require high-temperature conditions of 450-800℃, which are not only energy-intensive but also prone to generating harmful byproducts such as polycyclic aromatic hydrocarbons and sulfur oxides.
According to the latest industry data, the global annual production of waste rubber has exceeded 15 million tons, with tires accounting for over 70%, but the overall recycling rate is less than 60%. Large quantities of waste rubber are landfilled or incinerated, wasting resources and polluting the environment, becoming a significant obstacle to the development of a circular economy.
Bridgestone's two-stage chemical recycling process, with "precise catalysis + gentle reaction" as its core innovation, completely overturns traditional technological approaches. The first stage, through the selection of suitable catalyst and solvent combinations, utilizes metathesis reactions to rearrange carbon-carbon double bonds, achieving the rearrangement and shortening of the molecular chain of vulcanized polyisoprene.
The research team ingeniously utilized the synergistic effects of intermolecular and intramolecular metathesis, driving degradation through the reaction of polyisoprene with low-molecular-weight reactants and shortening the molecular chain through intramolecular reactions to generate cyclic polyisoprene, completing the process in just a few hours at room temperature.
More importantly, the researchers, for the first time, elucidated the three-dimensional molecular structure of the cyclic isoprene tetramer in the reaction products through single-crystal X-ray structural analysis, providing precise molecular-level theoretical support for process optimization. The second stage achieves efficient extraction of core raw materials such as isoprene through precise pyrolysis of the liquid polymer, forming a complete resource recycling closed loop.
This technology has significant economic and ecological value. Economically, isoprene, as a core monomer for synthetic rubber, is widely used in high-end tire manufacturing. The global isoprene rubber latex market reached $273 million in 2024, and is projected to grow at a CAGR of 4.49% from 2024 to 2029, with steadily increasing market demand. The recycled carbon black, after processing into eco-friendly carbon black, boasts performance comparable to virgin carbon black and can be directly reused in tire production.
From an ecological perspective, the ambient temperature process reduces energy consumption by over 30% compared to traditional pyrolysis, significantly decreasing energy consumption. The carbon reduction effect of recycling waste materials has been authoritatively verified, and similar recycling of resources can significantly reduce carbon emission intensity.
From a policy perspective, this technology aligns with China's "Guiding Opinions on Accelerating the Construction of a Waste Material Recycling System" and relevant EU circular economy policies, and is expected to receive policy support from multiple countries.
Currently, Bridgestone is advancing process scale-up research, planning to extend the technology to butadiene rubber and other categories, and explore new application scenarios for cyclic isoprene tetramers.
Simultaneously, the company plans to build a demonstration pilot plant for fine pyrolysis of waste tires to accumulate experience for large-scale application. Industry insiders point out that if this technology is fully commercialized, it will drive the rubber industry from a linear "resource-product-waste" model to a circular model, reducing dependence on primary resources, driving technological upgrades in the global rubber recycling industry, and providing crucial support for related industries to achieve carbon neutrality goals.
