Charles Goodyear’s process for vulcanizing India rubber by heating natural rubber with sulfur improved rubber’s physical properties. Vulcanization gives rubber a higher tensile strength, greater resistance to swelling, and more elasticity over a wide temperature range.
India, or natural, rubber, which comes from trees, originated in the New World. The first European to notice it was the late fifteenth century explorer Christopher Columbus
Fanciful painting by Christian Schussele (1824-1879) of important American inventors, including Charles Goodyear.
India rubber comes from the sap of Hevea brasiliensis, a softwood tree native to Brazil
One of the first major European uses of India rubber was in raincoats invented in 1823 by Scottish chemist Charles Macintosh.
In 1830, after his hardware business went bankrupt, Charles Goodyear was determined to find a rubber that would lose its summer stickiness and winter brittleness. He purchased from Nathaniel Hayward
Vulcanization is a chemical process that gives rubber a higher tensile strength, making it more resistant to tearing when stretched. It also gives rubber a greater resistance to swelling and greater elasticity over a greater temperature range. The simplest process, which was discovered by Goodyear, mixes rubber and sulfur, which are then heated. The chemical reaction between rubber and sulfur causes sulfur to combine with the rubber, which is initially composed of chains of carbon-containing isoprene units. In the nonvulcanized state, each chain, a polymer molecule, can be likened to a strand of cooked spaghetti. Nonvulcanized rubber, a heap of unconnected isoprene-containing polymer molecules sliding over one another, looks like the contents of a bowl of spaghetti, but in this state the molecules have a weak attraction for one another.
The polymer molecules’ ability to slide over one another—despite their tendency to fall back into the heap—is thought to be the basis for elastic stretch. Using a stretching force can be likened to inserting a fork into a bowl of spaghetti and lifting some strands from the main heap. Physical interactions between the individual polymer molecules lead them to contract when the stretching force is released (for example, when the fork is removed from the spaghetti). However, if the stretching agent (the fork) is lifted too far from the heap, some strands will break away from the agent.
Tensile strength in rubber develops when vulcanization produces chemical cross-links (bridges) between individual polymer molecules. These bridges are short chains of sulfur atoms joining the polymer molecules into a main mass, or heap. The chemically conjoined polymer molecules cannot easily be separated from the main mass by stretching.
Goodyear was granted his first patent on rubber vulcanization on June 15, 1844. Vulcanization led to the improvement of almost every item previously made of India rubber, from macintoshes to rubber overshoes. The items became much more durable and did not become sticky and smelly in the summer or brittle in the winter. Many individual people and companies bought licenses from Goodyear to make their products from the new material, but he also had to fight many patent infringements in court between 1844 and 1852. A major infringement case involved Goodyear with Thomas Hancock
Meanwhile, in the United States, patent infringements of Goodyear’s process continued. Vulcanization later made millions of dollars for others, but Goodyear was $250,000 in debt when he died. His failure to profit from the commercialization of his invention, even with his sixty patents on vulcanized rubber, can be attributed to his poor business acumen, his more accomplished competitors, and his death before the invention of the automobile,
The commercialization of Charles Goodyear’s vulcanized India rubber led to its widespread application. In addition to rubber-based products such as raincoats and rain boots, carriages ran on vulcanized India rubber tires. Furthermore, the running boards of the carriages were topped with rubber and the seats were padded with rubber, making travel much more comfortable.
The small yield of each rubber tree became a problem for manufacturers, however. (For example, the sap from a two-year-old tree could make just one auto tire.) The problem was initially solved by exporting South American hevea seeds—traditionally smuggled—to Europe. The seeds were then disseminated to the Far East (especially Malaysia) for rubber tree cultivation. The Far East became the main source of India rubber.
With advancements in technology, vulcanized India rubber was used in a wide variety of motor vehicle tires (such as those manufactured by Firestone) and aircraft tires, and in rubber bands, surgical gloves, rubber protective sheeting, hot-water bags, ice bags, and electrical insulation.
World War II
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Barker, Preston W. Charles Goodyear: Connecticut Yankee and Rubber Pioneer. Boston: G. L. Cabot, 1940. This brief biography provides a useful description of Goodyear’s life and explores the process of vulcanization. -
Korman, Richard. The Goodyear Story: An Inventor’s Obsession and Struggle for a Rubber Monopoly. San Francisco, Calif.: Encounter Books, 2002. A biography recounting Goodyear’s invention, patent battles, and other business struggles. The book features nontechnical explanations of vulcanization and descriptions of conditions in a nineteenth century rubber factory. Includes an index and photographs of Goodyear and his competitors. -
Noonan, Jon. Nineteenth-Century Inventors. New York: Facts On File, 1992. Describes the lives and achievements of eight nineteenth century inventors, including Goodyear. Includes bibliographical references and an index -
Slack, Charles. Noble Obsession: Charles Goodyear, Thomas Hancock, and the Race to Unlock the Greatest Industrial Secret of the Nineteenth Century. New York: Hyperion, 2002. Describes the rivalry between Goodyear and Hancock over vulcanization, a process that engendered business speculation similar to the Internet boom of the 1990’s. Although Slack discusses both individuals, he focuses on Goodyear, crediting him with greater persistence and business acumen than Hancock. -
Wolf, Ralph F. India Rubber Man: The Story of Charles Goodyear. Caldwell, Idaho: Caxton, 1939. Another earlier discussion of Goodyear’s life. Includes a number of good illustrations.
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Carl Benz; Charles Goodyear; Justus von Liebig.