The Para Rubber Tree

Weir, J. R., Pathological Survey of the Para Rubber Tree (Hevea brasiliensis)... 

R. are systematically classified into "natural rubber and synthetic rubber. In 1994, the world market for R. amounted to a production volume of ca. 14500000 t, of which ca. 9 000 0001 were synthetic R. and 5 400000 t natural R. from the para rubber tree (Hevea brasilien-sis) . 

An elastomer may be defined as a natural or synthetic material that exhibits the rubberlike properties of high extensibility and flexibility. Although the term rubber originally meant the TS elastomeric material obtained from the para rubber tree (Hevea braziliensis) it now identifies any thermoset elastomer (TSE) or thermoplastic elastomeric (TPE) material. Such synthetics as neoprene, nitrile, styrene butadiene, and butadiene are now grouped with natural rubber. 

Coagulation of the Latex.—Pure rubber or caoutchouc is an emulsion colloid and in most cases is held in emulsion by the protective action of other colloids, principally proteins. The breaking up of the emulsion with the coagulation of the caoutchouc depends thus upon the removal or destruction of the protective colloids. This is accomplished by different means. The latex of the para rubber from the Amazon is coagulated by heat and smoke, while the latex from the same species of tree on the plantations of the Malay States is usually coagulated by treatment with acid. Boiling of the latex, the addition of formaldehyde, and simple dilution with water are other methods in use. Enzymes are also present associated with the protective colloid proteins but their function seems not to be connected with the coagulation of the caoutchouc. 

Hevea rubber from uncultivated trees growing in the Amazon Valley of Brazil and exported from Para, a town at the mouth of the river. Para rubber was the best variety of all wild rubber but the advent of plantation rubber steadily reduced its importance until it is now of no significance in world rubber production. 

The best grade of wild rubber formerly obtained from Hevea trees indigenous to the Amazon Valley, and originally exported from the town of Para. 

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