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Gutta Percha

plastics trees world gum

Gutta percha is a rubberlike gum obtained from the milky sap of trees of the Sapotaceae family, found in Indonesia and Malaysia. Once of great economic value, gutta percha is now being replaced by plastics in many items, although it is still used in some electrical insulation and dental work. The English natural historian John Tradescant (c. 1570-1638), introduced gutta percha to Europe in the 1620s, and its inherent qualities gave it a slow but growing place in world trade. By the end of World War II, however, many manufacturers switched from gutta percha to plastics, which are more versatile and cheaper to produce.

Sumatra, one of the largest islands of Indonesia, is the world's leading producer of gutta percha; the island is home to many plantations of Palaquium oblongifolia and Palaquium javense trees. The trees reach 66-81 ft (20-25 m) in height; the lance-shaped leaves, usually 6 in (15 cm) in length, have feather-like vein patterns called pinnate venation. The greenish flowers, about 0.4 in (1 cm) wide, contain pollen-bearing stamens and seed-bearing pistils. The seeds contain a butter-like fat that is used as food.

Gutta percha sap is extracted from the leaves—unlike rubber, which is collected by producing incisions on the tree trunk. The leaves are ground up and boiled in water, and the gum is removed. At room temperature, the resulting gum forms a hard brown substance that can be molded if softened by heat; the melting point of gutta percha is 148°F (64°C). It is dielectric, which means that it can sustain an electric field but will not conduct electrical currents; this property, combined with its resistance to alkalies and many acids, made it a good insulator for underseas cables until better synthetic insulators were developed in the 1940s. Its resistance to acids also made it a good material for acid containers, but plastics have also replaced gutta percha in these products.

The primary use of gutta percha now is in the manufacture of golf ball covers, for which hard, resilient qualities are desired to withstand the golfer's strikes without shattering or chipping. However, plastics may soon replace gutta percha in this product as well, as the Dunlop Rubber Company has produced a plastic golf ball cover that is almost identical to the covers using gutta percha.

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