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Aviation History
1943
1943 - 0040.PDF
i6 FLIGHT JANUARY 7TH, 1943 RUBBER is extracted from apples. The mashed material is then simply purified and the residue is rubber. The quality of it differs, however, substantially from the usual Hevea rubber; it has a resin content of 18 to 20 per cent., as against 4 per cent, in tree rubber. Furthermore, and most important from the engineering application point of view, the best grades of Quay ale rubber have a tensile strength of only two-thirds that of Hevea rubber. Thus what is gained in the short lapse of time before the first yield, is lost in quality. In the aircraft industry Guayale rubber is likely to find its application for compounding rubber mixtures of the necessary quality. Guayale Yield Between 1907 and 1912 this shrub, which then showed only 10 per cent, in rubber yield, contributed some 12 per cent, of the world's supply. At present it seems to be improving in its rubber yield and moving up to a significant position in the supply plan of the U.S. In the spring of 1942 45,000 acres were planted on an experimental station purchased by the U.S. Government at Salinas, California. By 1943 enough seeds are expected to be available to plant 456,000 acres, and since the shrub requires four years to mature the, rubber yield in 1947 is estimated at 213,000 tons (!). Plans exist to expand the cultivation of Guayale in different parts of the United States as more seeds become available. The ultimate goal is one million acres, estimated to supply one-quarter of the total rubber consumption. It has been estimated that if all wild-growing Guayale plants in Mexico were collected one could obtain 25,000 tons of rubber, but this would mean the loss of any further crops for a number of years. To solve the rubber problem, the Russians have en- deavoured to develop their synthetic production as well as to cultivate rubber-yielding plants. Between 1930 and 1931 about 1,000 wild-growing plants of Russia were care- fully examined as to, their contents of oils, fats, rubber, etc. In the course of these investigations a number of unknown plants were found, the roots of which contain rubber. BUTYL BUNA-S BUNA-N NEOPRENE ICHLOROP OIL ALCOHOL (Cereals, Vegetables, etc.) LIMESTONE.COKE, SULPHURIC ACID GETTING INTO SHAPE : Sheets of synthetic rubber emerge from these rolls which squeeze out any surplus liquid. The material is then compressed again into block- shaped cakes, ready for use by the rubber industry. THE TRANSFORMATION : Synthetic rubber can be manu- factured from a variety of basic materials, some of which exist in abundance in practically any country. Of * special interest were some dandelion species (Teraxacum), locally called by the Kirghise "sagys," found in Tianschan and in the Altai Mountains. Three "sagys" plants attracted particular attention: (i) the Kok-sagys ; (2) Krim-sagys; and (3) Tau-sagys. After initial experiments it was found that Tau-sagys and Kok- sagys are a most promising source of rubber. Russian Cultivation The Russian experience in this field is indeed quite unique ; the Ukraine, and White Russia, were found to be most suitable for cultivation, but the plant is so versatile that it grows successfully under a variety of climatic and soil conditions. In 1940 the area under cul- tivation in Russia was 320,000 acres; this was to be increased by 1942 to 1,250,000 acres. A number of plants for the manufacture of rubber from roots were established, and distribution centres and storage silos were organised. According to Soviet reports, Kok-sagys harvested after one year produces 52 to 88 lb. of rubber per acre. In Latvia, where the Soviet Government had 2,500 acres planted with Kok- sagys in 1941, the yield was as high as 132.1b. per acre. The bi-annual Krim-sagys yields 88 to 160 lb. per acre, and the tri-annual Tau-sagys 154 lb. The Kok-sagys can be har- vested after one year, but if it is left for another year it improves the rubber contents of its roots. The rubber yields of these plants are still liable to serious fluctuations, but, with the gradual improvement and standardisation of cultivation methods, even better results are expected. Incidentally, the Germans have gained valuable experience from some Kok-sagys plantations in the occupied territories. While previously this source' of rubber was a mystery to them, the Germans are now try- ing to lay out plantations on re- claimed moorlands in Hungary, Occupied Poland and Rumania. Since Kok-sagys succeeds best on drained moorlands, it may yet pro- duce a by no means negligible con- tribution to Germany's rubber supply. That Germany is at present seeking to secure sources outside her synthetic production may be due to the inadequacy of the synthetic rubber output, to the shortage of
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