RAPID EXTRACTION OF RESINS FROM WILD RUBBERS
Chemists of the National Bureau of Standards have developed a simple method for converting wild rubbers having a high resin content into a product comparable to plantation rubber. This is accomplished by extracting a large portion of the natural resins from the wild rubbers.
The deresination studies were conducted by J. W. Wood i and Rachel J. Fanning of the Bureau staff as part of a research and testing program on natural rubbers sponsored at the Bureau by the Rubber Development Corporation of the Reconstruction Finance Corporation. Two Mexican wild rubbers obtained from the shrubs of Chilte and Guayule were chosen for the investigation.
Although synthetic rubber can be substituted for natural in the manufacture of many rubber products, and is actually superior for some of these uses, there are still other products which can be made only from natural rubber. This is true for many materials used by the armed forces. It was, therefore, necessary during World War II, when about 95 per cent of the world's supply of natural rubber was cut off, to r/lake use of every bit of available natural rubber whether it was of good or inferior quality. Many types of wild rubber were collected from tropical America and Africa. Some were of such inferior quality that they had to be blended with better grades of rubber before they could be used. Others could be improved in quality by the extraction of their resins, which would give the resulting rubber a higher percentage of rubber hydrocarbon.
For experimental extraction of resins from wild rubber, the Bureau's chemists used a modification of a commercial solvent-tight mixer, designed for compounding heavy industrial pastes. Two S-shaped stainless-steel blades, operating within the extraction chamber, were rotated while solvent was passed into the chamber from a glass distilling apparatus. The same apparatus was also operated in another set of experiments without the blades rotating in order to compare the rubbers made both with and without mastication.
The Chilte rubber, which contained originally over 50 per cent of resinous material, required only 4 hr. of extraction when accompanied by mastication in order to reduce the resin content to that customarily found in plantation rubber of high quality. Even less time was required * Communicated by the Director.