A Research Group from the Department of Chemical Engineering at Tsinghua University Achieves New Progress in the Socioeconomic Metabolism of Rubber in China

Rubber, due to its unique elasticity, is widely used and is an indispensable polymer material in modern society. Among the various forms of rubber products, tires, due to their large demand, concentrated application areas, and ease of identification and collection after disposal, have become the main focus of academic research on the socioeconomic metabolism of rubber materials and the practice of recycling industries. At the same time, with the progress of economic and social development and the improvement of people's living standards, non-tire rubber products (such as shock absorbers, medical products, sealants, and footwear materials) are also playing an increasingly important role and showing great potential in emerging fields such as personal intelligence and flexible electronics. Compared to tires, non-tire rubber products are more diverse in type, formulation, and lifespan, exhibiting significant differences in production, use, disposal, and recycling. Therefore, a complete and accurate understanding of the socio-economic metabolic patterns of rubber requires considering both tires and non-tire rubber products, systematically characterizing their entire chain of material flow and stock—a research area previously lacking.

To this end, this study, building upon traditional rubber industry statistical methods, includes widely used elastic materials in non-tire sectors such as silicone rubber, polyurethane rubber, and polyurethane thermoplastic elastomers in its analysis. By constructing a dynamic material flow model covering polymer production (12 types of virgin rubber), product manufacturing (7 types of rubber products), end-use (8 application sectors), waste management (7 disposal pathways), and import/export, the study systematically quantifies for the first time the entire chain of material flow and stock of rubber in China from 1978 to 2022, spanning 45 years. The model also considers fillers and additives used in product manufacturing, as well as rubber particles released during wear and tear during use.

The results show that in 2022, China's consumption of non-tire rubber products reached 22.5 million tons, accounting for 67% of total consumption, exceeding tire consumption. Behind this structural change is the rapid rise of high-performance materials such as specialty synthetic rubbers and thermoplastic elastomers, reflecting the transformation of my country's rubber industry from meeting basic transportation needs to supporting industrial development and diversified daily consumption. By 2022, China's non-transportation sector rubber product inventory had reached 156 million tons, accounting for 89% of the total inventory, but only 27% of recycled rubber came from non-tire products. This result indicates that the current non-transportation sector recycling system is still insufficient to cope with the potentially large-scale waste rubber flow in the future, and there is an urgent need to systematically promote the closed-loop construction of a rubber recycling system to effectively reduce resource and environmental pressures.