Early Developments in Thermosetting Plastics

Some scientists credit John Wesley Hyatt with the invention of synthetic plastics. However, ebonite, which is 

Seymour (ed.). Pioneers in Polymer Science, 81-92. 1989 by Khmer Academic Publishers. 

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. 

It should be noted that Charles Goodyear died penniless and was not absolved of his crime of having wasted money in attempts to protect his vulcanization patent, until 1982. Goodyear was involved in 60 infringement suits having been awarded the vulcanization patent in 1839. His last trial lawyer, Daniel Webster, won his patent infringement suit in 1852. 

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