Effectiveness of original additives in waste rubbers for revulcanization after reclamation with a low-temperature mechanochemical devulcanization method

Abstract

The low-temperature mechanochemical devulcanization (LTMD) method can maintain the effectiveness of the original additives in waste rubbers after rubber reclamation. To confirm this discovery, the LTMD method and the traditional high-temperature atmospheric devulcanization (HTAD) method are used to reclaim waste rubber powders. The reclaimed rubbers are mixed with different amounts of additional additives and then revulcanized alone or revulcanized after blending with all-terrain vehicle (ATV) tread rubbers. The properties of the reclaimed rubbers and the revulcanized rubbers are characterized, and the results reveal that the original sulfur agent is inactive in both the LTMD and HTAD processes and that the original curing assistants maintain high effectiveness after the LTMD process but not after the HTAD process. The tensile strength of the revulcanized LTMD-reclaimed rubbers with no additional curing assistants reaches 97% of that of the revulcanized LTMD-reclaimed rubbers with full additional curing assistants, and 30% higher than that of the revulcanized HTAD-reclaimed rubbers with full additional curing assistants. When blended with 40% reclaimed rubber from ATV tread rubber, the tensile strength of the vulcanized LTMD blends with only the sulfur agent reaches 89% of the pristine ATV tread rubber while that of the vulcanized HTAD blends with full additives only reaches 76% of the pristine ATV tread rubber. The LTMD method not only achieves high-value recycling of waste rubbers but also avoids the failure of the original curing assistants in waste rubbers, thereby saving large amounts of materials and showing great application prospects.