devulcanized

Devulcanized refers to a material that has undergone devulcanization, a chemical and physical process that reverses vulcanization of elastomeric polymers. The process breaks sulfur cross-links that form the network during vulcanization, partially restoring the polymer's mobility and enabling reprocessing and reuse of scrap or end-of-life vulcanized rubber, such as tires, seals, hoses, and molded goods.

Common approaches include thermomechanical devulcanization, which uses heat and shear to cleave cross-links while preserving the main chain; chemical devulcanization, involving reagents or solvents to break cross-links; and emerging biological or enzymatic methods that cleave sulfur bonds under mild conditions. The aim is to reduce crosslink density while minimizing degradation of the rubber backbone. The resulting devulcanized rubber often requires revulcanization or compounding with fresh rubber and fillers to achieve desirable properties.

Properties and limitations of devulcanized rubber vary with original formulation, crosslink type (such as polysulfide or monosulfide linkages), and processing conditions. It typically exhibits lower modulus, strength, and elasticity than vulcanized rubber and may show greater variability between batches. Effective use often depends on careful material characterization and appropriate formulation strategies to meet target performance.

Applications include serving as a feedstock for reclaimed rubber in new rubber products, asphalt modification, polymer blends, and specialty items like footwear and seals. Revulcanization or partial blending with virgin rubber and reinforcing fillers are common steps to restore some of the mechanical properties. Devulcanization is a field of tire recycling and sustainable rubber reuse, aiming to reduce waste and conserve resources.