Goodyear, Nelson

In extensions of this work on vulcanisation, which normally involved only a few per cent of sulphur, both Goodyear and Hancock found that if rubber was heated with larger quantities of sulphur (about 50 parts per 100 parts of rubber) a hard product was obtained. This subsequently became known variously as ebonite, vulcanite and hard rubber. A patent for producing hard rubber was taken out by Nelson Goodyear in 1851. 

Vulcanization of soft or India rubber was discovered by Charles Goodyear in 1839. He was followed by Nelson Goodyear, who patented the vulcanization of hard rubber in 1851. These processes involve the treatment of natural rubber with heat, sulfur, and various metallic compounds. The resultant material is stronger and more stable than raw rubber, while still retaining the desirable properties of elasticity and flexibility. It is also resistant to heat and does not melt like raw rubber or gutta percha. 

Paradoxically, neither Goodyear nor any of his family members or de-scendents were involved with the Goodyear Tire and Rubber Company, whose founder, Frank A. eiberling, named it to honor one of America s most famous inventors and the founder of an industry that is indispensable to modern life. In 1851 Goodyear s brother Nelson used sulfur to convert natural rubber into ebonite, the first thermosetting plastic. 

Of course, the first manmade crosslinked polymer was Charles Goodyear s vulcanized rubber with low crosslink density. Since there were only a few sulfur crosslinks between the polyisoprene chains, Charles Goodyear s product, which he called vulcanite, was elastic but had a higher modulus than the original linear Hevea braziliensis. However, Nelson Goodyear s product, called ebonite, produced by the addition of larger amounts of sulfur (25-30%) to natural rubber, was a nonelastic intractable solid. 

While the exact mechanism for crosslinking with sulfur is not known, the major crosslinks are believed to be on the allylic carbon atoms. Neither Charles nor Nelson Goodyear were scientists and they had little knowledge of crosslinking or of macromolecular structure. Nevertheless, they made monumental discoveries as witnessed by the fact that sulfur continues to be the major curing agent for both natural and synthetic rubber. 

What is known as the vulcanisation of rubber is an excellent example of this in 1839, the American chemist Charles Nelson Goodyear (1800-1860) succeeded in transforming the rubber that occurs naturally into the polymer product that we now call rubber by adding sulfur and applying heat. The undesirable tendency of the rubber to become sticky when heated and crumbly when cooled was overcome as a result. 

---