vulkanisasi

Vulcanization is a chemical process by which natural or synthetic rubber is cross-linked through covalent bonds, typically by heating with sulfur and accelerators. The resulting three-dimensional network improves elasticity, resilience, heat resistance, abrasion resistance, and dimensional stability, producing rubber that is less tacky and more durable under mechanical stress.

In classic sulfur vulcanization, sulfur forms bridges between polymer chains, creating disulfide and polysulfide cross-links. Accelerators such as zinc oxide, stearic acid, and organic compounds shorten cure times and influence the type and density of cross-links. Peroxide vulcanization uses organic peroxides to generate carbon–carbon cross-links, yielding different aging behavior and often higher heat resistance, but different elasticity compared with sulfur-cured rubbers. Other curing systems include resin-curing blends and radiation vulcanization, each imparting distinct property profiles.

History and origins: Vulcanization was discovered by Charles Goodyear in 1839, when rubber mixed with sulfur and subjected to heat gained useful properties for broad applications. The name reflects Vulcan, the Roman god of fire. Over the years, formulations and accelerators were refined to tailor cure rates, mechanical properties, and resistance to solvents and oils.

Applications and variants: Vulcanization is essential in tire production and numerous rubber goods such as belts, hoses, seals, and footwear. In modern materials science, dynamic vulcanization is used to create thermoplastic elastomers, where rubber is cross-linked within a thermoplastic matrix to combine elasticity with recyclability. Recycling remains challenging due to the stability of cross-links, prompting research into devulcanization approaches.