Exploring the effect of devulcanized Nitrile Butadiene Rubber Glove (dNBRg) on the cure characteristics and mechanical properties of virgin Nitrile Butadiene Rubber (vNBR) blends

The COVID-19 pandemic led to a significant surge in the use of disposable nitrile rubber gloves, raising environmental concerns due to the large volume of glove waste generated. Devulcanization presents a sustainable approach to addressing this issue by converting waste nitrile gloves into a value-added material known as devulcanized nitrile rubber glove (dNBRg), which can be utilized as a blend component. However, the awareness and application of dNBRg in rubber-related fields remain limited. This study investigatesthe effects of incorporating dNBRg at varying loadings(0–100 parts per hundred rubbers, phr) into virgin nitrile butadiene rubber(vNBR), with a focus on curing behavior and mechanical properties such as tensile strength and abrasion resistance. The blending of vNBR and dNBRg, along with compounding additives, was carried out using a two-roll mill. The results revealed that minimum torque (ML) increased with the addition of dNBRg, attributed to its higher viscosity, which is influenced by residual additivesfrom both the original glove formulation and the newcompounding ingredients. Maximum torque (MH) decreased at lower dNBRg loadings (20–40 phr) but began to increase at higherloadings(above 40 phr). Scorch time (ts2) remained relatively constant, while cure time (t90) increased at higher dNBRg contents (70 and 80 phr), suggesting a slower vulcanization process. Fourier Transform Infrared (FTIR) analysis showed no new absorption peaks, indicating no significant chemical changes in the blend. Mechanically, tensile strength decreased with increasing dNBRg content due to a heterogeneous crosslink structure, where weakly crosslinked regions were more susceptible to chain slippage and microcrack formation under stress, leading to early failure. In contrast, elongation at break, modulus at 100% strain (M100), and volume loss all increased with higher dNBRg loadings, likely due to the increased crosslink concentration and nonuniform crosslink density within the rubber blends. These findings highlight the potential of dNBRg to partially replace vNBR in general-purpose rubber products that do not require high tensile strength, thereby promoting more sustainable rubber material development and offering a practical solution to the environmental and health hazards posed by the accumulation of rubber glove waste.