Deeply reclaimed waste tire rubber compounding with styrene-butadiene rubber for green tire applications

The disposal of waste tires has become a major environmental challenge worldwide. Recycling waste tires presents an effective approach to alleviate this issue; however, the direct incorporation of ground tire rubber (GTR) into virgin rubber is hindered by poor interfacial compatibility. In this study, waste tire rubber was reclaimed to three different degrees: low, high, and deeply reclaimed rubber via a thermo-oxidative reclamation process involving sulfur cross-links and particle main-chain scission. The structural and properties of the reclaimed rubbers were analyzed through Mooney viscosity, molecular weight distribution, sol fraction, SEM, TEM, TGA and FTIR spectroscopy. Each reclaimed rubber was blended with styrene-butadiene rubber (SBR) at various substitution ratios to evaluate its compounding performance. Vulcanization characteristics, SEM morphology, mechanical properties, abrasion resistance, aging resistance and dynamic mechanical properties were systematically investigated. The results showed that deeply reclaimed rubber exhibited improved dispersion within the SBR matrix, and, at 20 phr substitution, delivered comparable initial tensile strength (18.66 MPa vs. control sample 18.86 MPa) and improved tensile strength after aging (11.23 MPa vs. control sample 9.95 MPa). It also improved abrasion resistance by 26% and reduced rolling resistance by 11% at a substitution level of 20 phr. This study offers a comprehensive understanding of how reclamation degree influences the properties of SBR compounds and provides practical guidance for scalable, sustainable utilization of waste tire rubber in green tire manufacturing.