The rubber plant's sap, called latex, is a raw material whose elasticity and robustness is unbeatable and cannot be achieved by synthetic products. In its liquid state latex is used to produce thin-walled rubber goods such as balloons, dummies/pacifiers, gloves for surgeries, diaphragms, technical goods, glues and much more.
history of the natural rubber
The natural rubber is a natural material which has been used by men for thousands of years.
It is known that the Mayas in South and Central America used balls, which were made of the plant's elastic resin, for cultic games since the 4th century.
During his travel through America, in Haiti in 1492 Christoph Columbus (1451-1506) watched these cultic games and was the first in Europe to report on the natural rubber (kaou-tschou, which means "streaming bole"). This substance was used to produce balls, to seal off vessels and to impregnate clothes. In the 16th century samples of natural rubber repeatedly came to Europe, however, merely as curiosity and without any practical or economic value.
In 1740 the Frenchman De La Condamine (1701-1774) advised the French academy of the natural rubber's features, in particular of its elasticity.
In 1770 the Englishman John Priestley (1733-1804) used the natural rubber as eraser.
In the 18th century it was discovered that you could solubilize natural rubber in turpentine, paraffine or benzene and impregnate coats with this dilution. In 1825 the first *macintosh's* were produced by Charles Macintosh. On hot days these coats are soft and sticky, but when it is cold they are stiff and fragile.
Nathaniel Hayward developed the method of curing (three-dimensional interlacing) with sulfur, which was then bought by Goodyear in 1839 and constituted the large-scale use of natural rubber. During the cure the macromolecules are interlinked. Depending on the quantum of sulfur used, you can regulate the rubber's hardness between soft and hard.
extraction and handling of natural rubber:
Primarily latex is extracted from the plant called Hevea-Brasiliensis, which grows in Brazil, Malaysia, Vietnam and Cameroon. The plant's rind is scarified and the effluent latex is collected in small vessels. After the tapping, the rind's gash is closed through coagulation. The latex is then regenerated rapidly, so the plants can be tapped within the following days. Latex is a colloidal system in which, depending on the season, the weather and the plant's age, different substances are soluted.
latex's composition is specified as follows:
60% water
20% to 45% natural rubber
2% proteins
1,5% resin
0,5% fatty acids
Up to 1.5t of latex can be extracted per hectare of plantation.
After the tapping, the latex is collected in big vessels and is stabilized. Solid bodies are removed and the natural rubber's concentration is raised to at least 60% by centrifuging or creaming.