Vulcanization

Description

Vulcanization is a process used to harden and strengthen rubber. Discovered by Charles Goodyear in 1839, vulcanization also makes rubber elastic, flexible and heat resistant. In the initial process, vulcanization was done by first heating rubber till it became a viscous mass, then sulfur compounds were added and the mixture cooled. When vulcanized rubber is exposed to heat or light, it can degrade, forming a brownish, brittle material that may evolve sulfurous oxides. Copper containing alloys can accelerate oxidative degradation (Hatchfield 2002). Recently, a chemical vulcanization process has also been developed that occurs at room temperature. This room-temperature vulcanization (RTV) occurs when the rubber is mixed with a catalyst. The RTV hardening process is generally used with silicone rubbers.

Synonyms and Related Terms

vulcanisation (Br.); vulcanización (Esp.); vulcanisation (Fr.); vulcanizzazione (It.); vulcanização (Port.)

Risks

Sulfur vulcanized rubbers can evolve sulfur fumes

Physical and Chemical Properties

Spot test for vulcanized rubber: Iodine/sodium azide reagent for presence of reducible sulfur compounds - positive reaction generates bubbles (Daniels and Ward, 1982)

Resources and Citations

• P.Hatchfield, Pollutants in the Museum Environment, Archetype Press, London, 2002.

• V.Daniels, S.Ward, "A Rapid Test for the Detection of Substances which will Tarnish Silver" Studies in Conservation 27:58-60, 1982.