Devulcanization of ground tire rubber using a plasma-assisted fluidized-bed system

The disposal of ground tire rubber (GTR) poses a significant environmental threat, necessitating the development of sustainable regeneration strategies. As an attractive alternative to traditional recycling techniques, plasma-based method is being actively explored for GTR devulcanization. To address the critical issue of poor contact between rubber and reactive species in plasma fixed-bed reactor, a novel plasma fluidized-bed system based on wire-cylinder configuration is designed and employed to regenerate GTR in this work. The results demonstrate that plasma treatment effectively breaks C-S and S-S bonds within the rubber matrix, indicative of partial de-crosslinking of the network structure. This structural alteration is manifested in a decreased crosslinking density, facilitating the partial restoration of flowability in the regenerated GTR. Notably, after 30 min of plasma treatment, the tensile strength of regenerated rubber increased significantly from 6.4 MPa to 9.4 MPa, and the elongation at break rose from 362 % to 390 %, thereby satisfying the performance requirements of superior-grade rubber materials. An underlying plasma devulcanization mechanism is proposed through a comprehensive analysis that integrates both experimental data and characterization results. The developed plasma fluidized-bed system offers an eco-friendly method for GTR devulcanization, holding significant potential to contribute to environmental sustainability and bolster circular economy efforts.