Rubber

Natural and synthetic.
Natural rubber is made from the sap, called latex, of the rubber tree. Synthetic rubber is manufactured from chemicals. Rubber trees originated in Central and South America. The Indians collected drops of sap which oozed from the bark. When explorers first went there, they saw the Indians playing with rubber balls and using rubber in a number of ways..............Latex dripping from the tree into a cup

Early development
In 1735 a French explorer, Charles de la Condamine, took home some hardened rubber latex from Peru. In 1770 an English chemist discovered that the material rubbed out pencil marks, and so we get the name rubber. Scientists discovered that latex dissolved in turpentine made a liquid that could make fabric waterproof. In the 1820s English inventor Thomas Hancock built a machine that kneaded scraps of latex into a solid mass, and this led to the rubber processing of today. In 1832 Scottish chemist Charles Macintosh began making raincoats by putting a layer of rubber between two layers of cloth. This kind of coat is still called macintosh. Manufacturers started making rubber products, including shoes, elastic bands, hoses and tubes.

These early products got sticky in hot weather and stiff in cold. In 1839 American inventor Charles Goodyear (left) discovered a way to make rubber stronger and less likely to be affected by seasons. He called the process vulcanisation, and it meant that rubber could be used in more products, such as between moving parts of machinery.

Plantations
The invention of the automobile increased the demand for rubber, and by 1914 wild rubber plants could not supply enough. Rubber plantations were established in Africa, Central and South America and in Asian countries such as Indonesia, Thailand, Vietnam and the Philippines. The cultivated rubber trees produce more latex than the wild trees.

Today, more than 80% of the world's natural rubber is grown in Thailand, Indonesia and Malaysia.

Processing natural rubber
Rubber trees grow best in hot, moist climates. The trees grow straight, 18-20 metres high with smooth bark and dark, shiny leaves. The tree has pale yellow blossoms, which give way to seed pods containing 3 brown seeds about 2-3 cm long. Latex containing rubber flows through the outer wood of the trunk, just under the bark. Workers called tappers collect the latex. They cut a shallow groove in the bark about 1 metre from the ground. At the bottom of the cut, a small spout is inserted into the tree, and a cup hangs below it to catch the drops of latex that ooze from the cut. Trees are generally tapped every day for 15 days, then rested for 15 days.

The latex is poured into tanks, and an equal amount of water is added. This liquid is strained to remove dirt. Formic acid is added to make the mixture form solid particles, which rise to the surface to form a crust of rubber. This is fed through rollers to squeeze out the water to make a solid sheet of rubber. This rubber is crude rubber, and is ready to be shipped to factories to be processed in different ways to make many different products.

Uses
Most rubber is used for tyres for cars, large vehicles and planes. Rubber is also used to make many mechanical parts such as gaskets, belts and seals.

Rubber products include waterproof clothing, gloves, hats, shoes and household products. Medical equipment made of rubber includes hot water bottles, gloves, syringes, tapes, oxygen tents, hearing aids and many more. Swimmers wear goggles,caps and flippers made of rubber. Many sports have rubber equipment, such as golf balls and other rubber balls. Rubber products seal jars, are used in toys and paints and for recreation. Sponge and foam rubbers are used to make bedding and other furniture, cushions and pillows, and as insulation.

Acknowledge this source in your bibliography like this:
A Trip to Indonesia (2001). [Online], Available: www.kidcyber.com.au

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updated 4 February, 2001