The unique elasticity and durability of rubber makes it ideal for scores of important uses. Although you may be familiar with the use of rubber, how much do you know about the history and processing of this special substance?
The peoples of Mesoamerica, an ancient region of Central America and Mexico, are thought to be the first to have used this elastic chemical compound. They used rubber to make balls for a game that Christopher Columbus, and later the Spanish conquistadors, watched them play.
Natural rubber is made from rubber trees, and synthetic rubber is made from oil.
Charles Goodyear invented vulcanization, a process that makes rubber more durable. He mixed latex rubber with sulfur and lead oxide, then heated it. This made the rubber hard, flexible and durable.
Neoprene is a soft, foamy, insulating rubber that's often used in wet suits. DuPont chemist Wallace Carothers first invented it by turning a polymer of chloroprene into polychloroprene in 1930.
Most natural rubber comes from Asia, thanks to Latin American-derived trees that have been transplanted there.
Priced at about $2,012 per ton, there was $26.2 billion to be made in the synthetic rubber market in 2007. This is a bit more than the natural rubber market, which was worth about $22.5 billion in 2007.
In extrusion, rubber polymers are heated and mechanically mixed in a long chamber, forced through a small opening and vulcanized or cured. This method is used to make large strands for compression molding.
It takes about six years for a rubber tree to grow to a point at which it's economical to harvest the sap.
Of all of these trees, the best rubber-producing tree is H. braziliensis. It's the main source of natural rubber today.
The most common use for rubber is in automotive tires. But pencil erasers, shoes, gloves, dental dams and condoms contain the ubiquitous substance, too.