A brief history of rubber
Natural rubber (also known as gum rubber and latex) is believed to have been first discovered by Mesoamericans more than 1000 years ago. Although a variety of trees around the world exude latex, none is more productive than the Para Rubber Tree (Hevea Brasiliensis), native to Brazil. The milky fluid that exudes from the tree found uses in lining clay pots and, more famously, making rubber balls for games.
Latex was possibly first introduced to the Europeans in Haiti during Christopher Columbus’ second voyage in the 15th century. Three hundred years later, a small market had evolved in Europe for shoes and raingear. To meet the demand of this market, slave plantations developed in South and Central America, which maintained a near monopoly on supply until 1876 when an Englishman named Henry Wickham smuggled 70,000 seeds out of Brazil. The British then created rubber plantations in Ceylon, Singapore, and elsewhere. Today 90% of natural rubber comes from Asian countries.
Natural rubber has excellent abrasion resistance (and even today is the main ingredient in rubber tires) but it degrades quickly, gets sticky when hot, and stiff when cold. In 1839, Charles Goodyear overcame many of these shortcomings when he discovered that natural rubber could be cured (vulcanized) with heat and sulfur. He patented his discovery, although he died in poverty. The Goodyear Tire Company was only founded after his death.
The first major market for rubber started when Englishman John Dunlap introduced rubber tires for bicycles in 1889 and for automobiles in 1906. Rubber quickly found many other uses and became increasingly critical for industry and military. Demand outgrew supply. Moreover, by 1940, Japan had gained control over 90% of the world’s natural rubber supply. The race was on to develop alternatives.
In 1931, Dupont introduced the first synthetic rubber, neoprene. In the decades that followed, Dupont, Shell, Goodyear, and others created other synthetic elastomers, such as silicone, butyl, SBR, and nitrile. In the 1950s, Dupont developed EPDM rubber, which was low-cost, aged well, and performed well in high temperatures. It is still widely used today especially as a roofing membrane and for wire and cable.
Thermoplastic elastomers, a class of rubbery materials that process like plastic, was first developed in the 1950s with polyurethane. This was followed in the 1960s with the development of styrenic block copolymers, and in the 1970s thermoplastic vulcanizates. The advantage of these materials is that they are lightweight, can be recycled, can be colored, and can be bonded without the use of adhesives. However, depending on the application requirements, such as oil resistance, abrasion resistance, or very high heat requirements, thermoset elastomers are still often required.