Gutta-percha
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About 100-120 species, including: |
Gutta-percha (Palaquium) is genus of tropical trees native to southeast Asia and northern Australasia, from Taiwan south to Malaya and east to the Solomon Islands. It is also an inelastic natural latex produced from the sap of these trees, particularly from the species Palaquium gutta.
The trees are 5-30 m tall, and up to 1 m trunk diameter. The leaves are evergreen, alternate or spirally arranged, simple, entire, 8-25 cm long, and glossy green above, often yellow or glaucous below. The flowers are produced in small clusters along the stems, each flower with a white corolla with 4-7 (mostly 6) acute lobes. The fruit is an ovoid 3-7 cm berry, containing 1-4 seeds; in many species the fruit is edible.
Uses
The latex is bioinert, resilient, and is a good electrical insulator, albeit with poor capacitance. The wood of many species is also valuable.
Western inventors discovered the properties of gutta-percha latex in 1842, although the local population in its Malayan habitat had used it for a variety of applications for centuries. Allowing this fluid to evaporate and coagulate in the sun produced a latex which could be made flexible again with hot water, but which did not become brittle, unlike unvulcanized rubber already in use.
By 1845 telegraph wires insulated with gutta-percha were being manufactured in England. Gutta-percha served as the insulating material for some of the earliest undersea telegraph cables, including the first transatlantic telegraph cable. Gutta-percha was particularly suitable for this purpose, as it was not attacked by marine plants or animals, a problem which had disabled previous undersea cables.
The material was quickly adopted for numerous other applications. The "guttie" golf ball (which had a solid gutta-percha core) revolutionized the game. Gutta-percha remained an industrial staple well into the 20th century, when it was gradually replaced with superior (generally synthetic) materials, though a similar and cheaper natural material called balatá is often used in gutta-percha's place. The two materials are almost identical, and balatá is often called gutta-balatá.
The same bio-inertness property that made it suitable for marine cables also means it does not readily react within the human body, and consequently it is used for a variety of surgical devices and for dental applications including padding inside fillings or inside the root-canal.
External links
- Gutta-percha on the Transatlantic cable site (http://collections.ic.gc.ca/cable/gutta.htm)
- on plastics-museum.com (http://www.plastics-museum.com/materials/naturals/gutta.htm)de:Guttapercha