Rubber

Grommets made of rubber

Rubber is a type of material called a polymer. It can be produced from natural sources (e.g. natural rubber) or can be synthesised on an industrial scale. Many things are made from rubber, like gloves, tires, plugs, and masks. Some things can be made only from rubber. Sometimes the word means only natural rubber (latex rubber). Natural rubber is made from a little wood from an oak tree such as the Hevea brasiliensis (Euphorbiaceae). Synthetic rubbers are made by chemical processes.

Properties

Rubber can stretch and shrink. Rubber can also contain gases. It is an insulator, which means that it does not conduct electricity.

Producers

Latex being collected from a rubber tree

Hevea brasiliensis is the tree that most rubber comes from. Other plants that have the special sap (called latex) are figs (Ficus elastica), Castilla (Panama rubber tree), euphorbias, lettuce, the common dandelion, Taraxacum kok-saghyz (Russian dandelion), Scorzonera tau-saghyz, and Guayule.

In the 1800s, most sap to make rubber came from South America. In 1876, Henry Wickham got seeds from rubber trees in Brazil, and took them to Kew Gardens, England, and sent them to Ceylon (Sri Lanka), Indonesia, Singapore and British Malaya. Later, Malaya (now Malaysia) made the most rubber. People tried to grow rubber in India, in 1873 at the Botanical Gardens, Kolkata. The first Hevea farms in India were made at Thattekadu in Kerala in 1902. The Congo Free State in Africa grew a lot trees for rubber at the start of the 20th century, and most of the people who worked on those farms were forced labor. Liberia and Nigeria also started growing trees to make rubber.

Industrial development

Charles Marie de La Condamine presented samples of rubber to the Académie Royale des Sciences (Royal Academy of Science) of France in 1736.^[1] In 1751, François Fresneau read a paper to the Académie (eventually published in 1755), which described many of the properties of rubber. This has been referred to as the first scientific paper on rubber.^[1]

In 1770, British chemist Joseph Priestley noticed that rubber was very good for removing pencil marks on paper. Natural rubber melts in heat and freeze in the cold.

In 1844, Charles Goodyear found a way to improve natural rubber, in a chemical process known as vulcanization, which made it useful in many more products including, decades later, tires.

Synthetic material

In the 20th century, synthetic (artificial) rubbers such as Neoprene began to be used. They were much used when World War II cut off supplies of natural rubber. They have continued to grow because natural rubber is becoming scarce and also because for some uses they are better than natural rubber.

Uses of rubber

Rubber moulded products are widely used industrially (and in some household applications) in the form of rubber goods and appliances. Rubber is used in garden hoses and pipes for small scale gardening applications. Most of the tyres and tubes used in automobiles are made up of rubber. Rubber plays a very important role in the automobile industry^[2] and the transportation industry. Rubber products are also employed in matting and flooring applications.

Rubber Media

Pieces of natural vulcanized rubber at Hutchinson's Research and Innovation Center in France.
Latex being collected from a tapped rubber tree, Cameroon
Rubber tree plantation in Thailand
Latex being collected from a rubber tree
Rubber tapping. Rubber tree. Latex. Natural rubber (polyisoprene) elasticity. Rubber band stretching causes the decrease in entropy that gives rise to the elastic force in the crosslinked rubber molecules (continuous rubber molecular network chains). In stretched rubber, the molecules chains are almost linear. Koh Chang, Thailand.
Chemical structure of cis-polyisoprene, the main constituent of natural rubber. Synthetic cis-polyisoprene and natural cis-polyisoprene are derived from distinct precursors, isopentenyl pyrophosphate and isoprene.
Rubber is generally cultivated in large plantations. The image shows a coconut shell used in collecting latex, in plantations in Kerala, India.
Natural rubber sheets, 1968