Revulcanization

Revulcanization is the process of re-crosslinking devulcanized rubber to form a renewed three‑dimensional network, restoring elastomeric properties after the material has had its sulfur crosslinks broken. Devulcanization is the set of methods used to break these crosslinks so that vulcanized rubber can be processed again, typically producing a reclaim that can be formulated into new products.

The revulcanization step involves reintroducing crosslinks through controlled curing. This is usually achieved by heating the devulcanized material with a curative system, most commonly sulfur and accelerators, though alternative routes exist. The objective is to generate a cohesive, elastic network without excessive chain scission or uneven cure. Processing can occur in batch mixers, extruders, or continuous reactors, often with the addition of fillers and reinforcing agents to tailor properties.

Common approaches to revulcanization include sulfur-based systems, peroxide-initiated cures, and, in some cases, radiation-induced crosslinking. The choice of method depends on the composition of the starting material, available processing equipment, and desired end-use properties. Revulcanized rubber is widely used in recycled-content products such as mats, belts, seals, and components for automotive and consumer applications.

Material performance after revulcanization depends on the extent of prior devulcanization, the integrity of the polymer chains, and the uniformity of cure. Properties such as tensile strength, elongation, and abrasion resistance may differ from those of virgin vulcanized rubber, and achieving consistent quality remains a focus of ongoing research in rubber recycling.