"This particular project is very exciting because the Mesoamerican rubber ball game was such a fundamental ritual and political event in these societies, and the ball game could not have developed without inventing the technology to process rubber." Dr. Dorothy Hosler.

Rubber. Our cars would certainly give a worse ride without the stuff. But what is rubber, exactly? And where does it come from?

bodyOffer(26454) ANCIENT RUBBER

Until recently modern thinkers believed rubber originated in 19th century Europe. According to a Tech Talk article published by Massachusetts Institute of Technology on Wednesday, July 14, 1999, Professor Dorothy Hosler, Assistant Professor Sandra Burkett and an undergraduate named Michael Tarkanian learned that the Mayan people in ancient Mesoamerica made and used rubber as long ago as 1600 BCE.

The ancient Mayan people used latex to make rubber balls, hollow human figures, and as bindings used to secure axe heads to their handles and other functions. Latex is the sap of various plants, most notably the rubber tree. When it is exposed to the air it hardens into a springy mass. The Mayans learned to mix the rubber sap with the juice from morning glory vines so that it became more durable and elastic, and didn't get quite as brittle. Both the rubber tree and the morning glory were important plants to the Mayan people- the latter being a hallucinogen as well as a healing herb. They two plants tended to grow close together. Combining their juices, a black substance about the texture of a gum-type pencil eraser was formed.

The rubber balls were about the size of a beach ball and weighed over 15 pounds (7 kilograms). These were used in an important ritual game called Tlachtlic. The game was a cross between football and basketball, but had religious significance as recorded in the Popul Vuh, a Mayan religious document. Spanish invaders in the sixteenth century reported that the game also involved gambling for various possessions including land and slaves. It is believed that the game ended in a human sacrifice at least some of the time. Versions of the game were played in the middle American region ranging from southern Arizona to northern South America. Native peoples in the region still make rubber in the same way.

VULCANIZED RUBBER

bodyOffer2() In 1736 several rolled sheets of rubber were sent to France where it fascinated those who saw it. In 1791, an Englishman named Samuel Peal discovered a means of waterproofing cloth by mixing rubber with turpentine. English inventor and scientist, Joseph Priestly, got his hands on some rubber and realized it could be used to erase pencil marks on sheets of paper.

Charles Goodyear, an American whose name graces the tires under millions of automobiles, is credited with the modern form of rubber. Before 1839, rubber was subject to the conditions of the weather. If the weather was hot and sticky, so was the rubber. In cold weather it became brittle and hard. Goodyear's recipe, a process known as vulcanization, was discovered when a mixture of rubber, lead and sulfur were accidentally dropped onto a hot stove. The result was a substance that wasn't affected by weather, and which would snap back to its original form if stretched. The process was refined and the uses for rubber materials increased as well. This new rubber was resistant to water and chemical interactions and did not conduct electricity, so it was suited for a variety of products. The process of making the rubber product improved as time went by, and now various chemicals are added before the mix is poured into molds, heated and cured under pressure.

An Englishman named Sir Henry Wickham collected about seventy thousand rubber tree seeds in Brazil in 1876 and took them to the East Indies where he started rubber plantations. In 1877 an American named Chapman Mitchell learned to recycle used rubber into new products.

MODERN RUBBER

bodyOffer3() Today about three quarters of the rubber in production is a synthetic product made from crude oil. World War II cut the United States off from rubber supplies worldwide, and they stepped up production of synthetic rubber for use in the war effort. There are about 20 grades of synthetic rubber and the intended end use determines selection. In general, to make synthetic rubber, byproducts of petroleum refining called butadiene and styrene are combined in a reactor containing soap suds. A milky looking liquid latex results. The latex is coagulated from the liquid and results in rubber "crumbs" that are purchased by manufacturersand melted into numerous products.

There is only one kind of natural rubber. Because the rubber plant only thrives in hot, damp regions near the equator, so 90% of true rubber production today occurs in the Southeast Asian countries of Malaysia and Thailand and in Indonesia. Indonesia's production has dropped in recent years and new plantations were started in Africa to take up the slack.

Pre-Columbian peoples of South and Central America used rubber for balls, containers, and shoes and for waterproofing fabrics. Mentioned by Spanish and Portuguese writers in the 16th cent., rubber did not attract the interest of Europeans until reports about it were made (1736–51) to the French Academy of Sciences by Charles de la Condamine and Fran?ois Fresneau. Pioneer research in finding rubber solvents and in waterproofing fabrics was done before 1800, but rubber was used only for elastic bands and erasers, and these were made by cutting up pieces imported from Brazil. Joseph Priestley is credited with the discovery c.1770 of its use as an eraser, thus the name rubber.

The first rubber factory in the world was established near Paris in 1803, the first in England by Thomas Hancock in 1820. Hancock devised the forerunner of the masticator (the rollers through which the rubber is passed to partially break the polymer chains), and in 1835 Edwin Chaffee, an American, patented a mixing mill and a calender (a press for rolling the rubber into sheets).

In 1823, Charles Macintosh found a practical process for waterproofing fabrics, and in 1839 Charles Goodyear discovered vulcanization, which revolutionized the rubber industry. In the latter half of the 19th cent. the demand for rubber insulation by the electrical industry and the invention of the pneumatic tire extended the demand for rubber. In the 19th cent. wild rubber was harvested in South and Central America and in Africa; most of it came from the Pará rubber tree of the Amazon basin.

Despite Brazil's legal restrictions, seeds of the tree were smuggled to England in 1876. The resultant seedlings were sent to Ceylon (Sri Lanka) and later to many tropical regions, especially the Malay area and Java and Sumatra, beginning the enormous East Asian rubber industry. Here the plantations were so carefully cultivated and managed that the relative importance of Amazon rubber diminished. American rubber companies, as a step toward diminishing foreign control of the supply, enlarged their plantation holdings in Liberia and in South and Central America.

During World War I, Germany made a synthetic rubber, but it was too expensive for peacetime use. In 1927 a less costly variety was invented, and in 1931 neoprene was made, both in the United States. German scientists developed Buna rubber just prior to World War II. When importation of natural rubber from the East Indies was cut off during World War II, the United States began large-scale manufacture of synthetic rubber, concentrating on Buna S. Today synthetic rubber accounts for about 60% of the world's rubber production

Search for synthetic rubber

In the mid-19th century, some Western researchers became interested in finding ways to replicate rubber in the laboratory, to make synthetic rubber out of some completely different raw material.

By the 1860s, researchers knew how to distill rubber down to isoprene — a colorless, malodorous volatile liquid — and how to turn that back into rubber, and within 20 years they could speed up the rubberization of isoprene by adding heat and acid to the mix. Researchers tried that trick with isoprene isolated from other material, but those early synthetic versions of rubber were either inferior to natural rubber or more expensive to make. These early efforts were hampered by the fact that no one knew what rubber is.

Rubber, like plastic, is a polymer — large molecular compounds formed by a chain of smaller, identical molecules called monomers. The hydrocarbon monomers of liquid latex link into polymers as the latex hardens. The practical problem with natural rubber is there is very little holding each polymer chain together, which is why natural rubber cracks in cold weather and melts in hot weather. By mixing rubber with sulfur and heating the mixture, Charles Goodyear was actually crosslinking the polymer chains — sulfur molecules would link to multiple polymer chains, linking them to each other, essentially connecting the chains into one big molecule that remains elastic but retains its shape after cooling.

The theory that rubber and plastics are polymers joined in long, chainlike macromolecules was first given voice in 1917 by Hermann Staudinger, a German scientist living in Switzerland, and was proven 13 years later by Wallace Carothers, an Ohio-born chemist then working for DuPont. Among the macromolecules he made in the lab was a polymer with properties like silk, a plastic which would be called nylon. His research team is also credited for developing he first commercially viable synthetic rubber, neoprene.

Before Carothers proved the macromolecule theory, work on discovering a practical way to make synthetic rubber persisted, and with some success. Particular success was realized in Germany, whose leaders learned the hard way that you can't win a modern, mechanized war without rubber