science · 27 May 1924 · 100 years ago
In 1924, Thomas A. Edison was issued a patent for a “Method of Producing Chlorinated Rubber” (U.S. No. 1,495,580), which claimed to be more economical than earlier methods. Natural rubber readily degrades and becomes brittle in the presence of oxygen or ozone in the air. Chlorine is used to replace some hydrogen atoms in the surface molecules of the rubber making it more stable. Edison's method treated very thin rubber strips in a chamber with chlorine gas mixed with the vapour of a highly chlorinated solvent of rubber such as carbon tetrachloride to soften the rubber surface for increased penetration by the gaseous chlorine, followed by other processing. In his patent, Edison envisioned further processing it with naphthaline and fillers, for use as a tough, hard veneer for phonograph records or cylinders.
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