Rubber is a gummy substance exuded by a wide variety of trees and plants, especially the trees Hevea brasiliensis, and several other species of Hevea which grow in the East Indies, particularly the Malaypeninsula, and other parts of the world. Rubber is also obtained from the large tree Castilla elastica, found in Mexico. So-called dandelion rubber is derived from the roots of various species of dandelion plant Taraxacuin, chiefly Kok sagyz, etc., grown in Turkestan.
Rubber trees are tapped and the latex, a milk-like juice, containing about 30-40% rubber, is coagulated by exposing it to heat and wood smoke, or by mechanical means, so as to separate the
rubber from the water, mineral salts, sugars, resins, and protein matters. The rubber obtained in this way is known as 'crude'. Latex is also extensively used in industry for making foam rubber products, footwear, dolls, etc.
Untreated crude rubber is naturally soft and lacks the requisite strength for making into manufactured articles. To improve its strength and usefulness it is vulcanised or heated with sulphur, the proportion of sulphur used determining the hardness and elasticity of the rubber. Fillers such as carbon black or channel black are also vital constituents of rubber, particularly tyre rubber. About 75% of the rubber produced goes into the manufacture of tyres, the remainder being utilised for cable sheathing, wire covering, footwear, flooring, proofing of clothing, togs, upholstery material, hose, etc. Latest developments include bullet-proof tyres, non-tear rubber for fuel tanks, flame-proof hose, suits for frogmen. Research Rubber
Abbreviations
SciTech
Research Rubber