A sustainable approach of virgin nitrile butadiene rubber and devulcanized nitrile butadiene rubber glove (vNBR/dNBRg) blends: The influence of blend ratio on physico-mechanical properties

The rising global use of nitrile butadiene rubber gloves (NBRg) has heightened environmental concerns, as cured rubber with sulphur crosslinks is non-biodegradable and accumulates in landfills. Devulcanization provides a sustainable solution by breaking these crosslinks to restore partial processability and performance. However, the use of devulcanized NBR gloves (dNBRg) as a substitute for virgin NBR (vNBR) in general-purpose rubber products is still underexplored. Incorporating dNBRg partially or fully can reduce dependence on petroleum-based materials, convert glove waste into value-added products, and advance ESG goals through improved resource efficiency, lower carbon footprint, and circular economy practices. In this study, vNBR and dNBRg were blended with compounding additives using a two-roll mill at ratios ranging from 0 to 100 phr, and the resulting composites were characterized through Differential Scanning Calorimetry (DSC), swelling percentage (SP), abrasion resistance, compression set (CS), hardness, density, and Scanning Electron Microscopy (SEM). DSC revealed a single glass transition temperature (Tg) across all blends, indicating good compatibility, while SP decreased with higher dNBRg content, reflecting increased crosslink density. Incorporation of 20–80 phr dNBRg reduced the abrasion resistance index (ARI) by 51% compared to vNBR, while CS decreased by 38% with 70 phr dNBRg but increased sharply to 50% and 69% for 20/80 blends and 100% dNBRg, respectively, due to non-uniform crosslink distribution and localized weak zones. Hardness increased by up to 8.5% with dNBRg, suggesting enhanced rigidity, though excessive substitution risked structural irregularities. Overall, the results confirm technical feasibility and sustainability potential of dNBRg, particularly at 20–30 phr substitution, which effectively replaces vNBR for outsole safety shoes and other rubber products depending on property requirements, thereby reducing petroleum dependence, extending material life cycles, and converting glove waste into valuable resources in line with ESG-driven sustainable manufacturing practices.