Producing Rubber at Home
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War-time Experiments and Research May Result Our Being No Longer Dependent Upon Supplies Natural Rubber from the Far East in of
By " Azote "
the present time we are not ri uchily concerned with
AT
the fact that there was 1 cwt. or so of rubber used in the construction of the average motor vehicle, but there will came a time when we shall he compelled to give the matter more thought. In the meantime, many who read the Government's statement that we were taking to steps to replace the production of the lost rubber planta tions are wondering what is going to happen, and where the rubber is coming from to make our tyres and the various other comparatively minor, but no less important. corn • ponents.
"Oh," comes the reply, " we shall get the. plantations back from the Japanese and everything will go on as it used to."
But will it In the first place, will the nice, kind Japanese leasie those rubber trees standing as they found them, ready for us to tap again, as though nothing had happened? Are the Germans showing the same consideration for Russian property which they are being forced to relinquish as they are being pushed back by the Soviet armies?
There will not be a rubber tree left standing, and as it takes from five to seven years to grow a fresh one to the state of productive maturity, how much will it matter even if the plantations be handed back to the original owners? Such a condition is suggested by a letter recently addressed to the Chancellor of the Exchequer, asking for Government guarantees of compensation to the owners of the plantations.
It is also a fact that there are other sources of natural rubber besides the plantation hevea brasiliensis tree.. There is the Mexican guayule, and the Russian tau-sagyz, and several other species of latex-bearing shrubs, now grown in Russia.
The greatest source of production of the immediate future, however, and it may be a permanent source, is that of synthetic rubber. In peace-time the annual consumption of rubber in the U.S.A. was 600,000 tons; this year, the estimated total requirements for all purposes are said to be over 800,000 tons. The officially organized production is estimated to reach 1,000,000 tons in 1944, all of which is to be synthetic. In 1940, the total production of the rubber plantations of the Far East reached a figure as high as 1.400,000 tons. In pre-war days the-U.5.A. bought no less than 65 per cent, of the total production from this source.
U.S. Will be Independent of Far Eastern Supplies The United States Government scheme for the construction of synthetic-rubber production plants of 1.000,000 tons capacity per annufa is a forerunner of the complete reversal of the world's rubber supplies. It must be perfectly clear, even to those with eyes half open, that the rubber industry is, at this moment, passing from the Far Eastern plantations to Akron, Ohio (the rubber town of America), the oilfield districts, and the wheat belt,' assisted by the small amount of natural guayule rubber from Texas and California.
In this gigantic rubber-production scheme, the American authorities have called into active participation the rubber manufacturers, the oil interests and a certain proportion of the farming interests. There are six main processes included in the programmes, and these are set out in the following table. It will be noted that the large percentage of production is based upon crude petroleum.. This significant•fact indicates the strength of the American position in the--future of rubber; its raw material, which, as naturalrubber,' was .12,000. iniles away, is now at home, and the importance Of this fact, in the post-war era, can hardly be over-estimated. Processes of Synthetic-rubber Production in U.S.A. Programme Rated capacity in tons.
(1) Alcohol, by the Carbide and Carbon Chemicals Corporation process ... 242,000 (2) Butane (in natural gas), by a process developed by Phillips Petroleum Co. 50,000 (3) Butane, by the Hondry process ... 16,500 (4) Butylene (obtained by cracking petroleum), by a process developed by Standard Oil Co., of New Jersey ... 283,000 (5) High-temperature cracking of gas and heavy oils (so-called thermal or refinery conversion process)... ... 20,000
(6) By the combination of (4) and (5) in
one locality ... 93,500 Total ... ... ... 705,000 When Japan struck at rubber, it was Just as serious as if oil had been the objective, because such a large part of oil utilization is made possible only in conjunction with rubber. By that blow, 90 per cent, of the world's rubber passed into the hands of the enemy, and with it a serious poSsibility of a breakdown in fighting operations, with a risk, in copse• quence, of losing the War.
Now Growing Rubber 10,000 Mlles Nearer Home For a number of years the American Government and industrial interests had essayed to grow rubber in countries closer home than the Far Eastern plantations, which activities have under the necessities of war, been extended until 11 of the Latin American countries are now collaborating in the attempts to produce natural rubber some 10,000 miles nearer home. These countries are Brazil, Haiti, Peru, Mexico, Ecuador, Colombia, Venezuela, Panama, Honduras, Guatemala and Nicaragua. .
From the point of view of American interests, another factor plays a most providential part. For many years American buyers had considered that they had suffered from an artificial price control, exercised by the British owners of the Far Eastern plantations through the Stevenson plan. A table of prices over the years is given below: Americans point to the violent fluctuations and remark, cynically, that they bear no relation to costs:—
At the time when prices were pushed up to 2.07 dollars a pound in 1910, synthetic-rubber interests were . encouraged to try to get a look in, and although it gave a fright to the producers of natural rubber, who dropped the bottom out of the price market SD aS to throttle the synthesists, it gave them the start which, to-day, is about to throttle the plantations.
Plantation rubber started to compete with para rubber from the Amazon Valley in 1900, with a production of 18,000 tons against that of 26,000 tons from the Amazon. Tin wild-rubber trees—hevea brasiliensis—of the Amazon
• were, at the time, hard put to it to supply the growing world demand. In their ignorance, the natives stretched production beyond the possibilitiei of the trees, and output .began to decrease.
A group of Englishmen cocked an eye on the situation and visualized a great demand impending for this product, which was extending its applications in many directions. It was obvious to them that the infant motor trade was bound to grow up and call for untold quantities of rubber.
One of the far-seeing crowd of Englishmen, Sir Henry Wickham, smuggled seeds of -the para tree over to Kew Botanical Gardens, where they were germinated, the seedlings being sent out to Ceylon, where they were cultivated in reserves, or plantations. That was in 1876.
Scientific cultivation improved the race and yield, which went up to at least five times that of wild-rubber trees. By 1910, plantation rubber had surpassed the production of the wild Brazilian type with 49,000 tons, as against 38,000 tons. That was the Amazon's peak year; by 1934, plantation rubber had passed the 1,000,000 tons per annum mark, and Brazil had gone down to 9,000 tons.
The discovery of synthetic rubber dates back to 1860, When Williams isolated the parent substances of natural rubber, which turned out to be a hydrocarbon and which hecalled isoprene; its chemical formula is C5I-18, Later on, 'in 1884, Tilden worked on this knowledge and, by the pyrole.sis of turpentine, synthesized isoprene. From these beginnings Germany and Russia took up the research Ind have maintained it ever since.
In many countries rubber production has been carried on, but at such a small rate that less than 1 per cent, of the synthetic product has been produced, Of recent years, up to the outbreak of war, probably the greatest amount of development has been accomplished by allied German and American interests..
The raw material for the synthesis of rubber is butadiene, which is also a hydrocarbon (Ce1-16), and is produced in the. processes used in the manufacture of petrol. It occurs in much larger quantities in the production of 100-octane petrol and, in a recently invented process, the conditions of butadiene production are stated to be such that its cost is considerably reduced as compared with any process pre
• viously used.
Polymerization of the Raw Material Butadiene
The mechanics of the synthesis of rubber from butadiene are but imperfectly understood, as is also the nature.of the rubber so made. Butadiene, which is a liquid, gradually changes to a solid if left standing; it takes months to carry out the change, which is called polymerization.
Polymerization is a uniting together into long chains of the single molecules or monomers of butadiene, In this union, they gain in atomic weight and so pass from the liquid to the solid state. The following is a representation of the structural formula and its change in polymerization, the natural and synthetic processes being represented :— Isoprene Monomer polymerizes to Natural Rubber Polymer CH„ = C—CH= CH, —CH,---CCU—CH I I
CH, ' CH3
Butadiene Monomer polymerizes to Butadiene Polymer
CH,=C.FICH=CH, —C112—CH= CH—CH— The polymer has a bond at each end of 'the molecule on to which successive molecules attach themselves, some say up to thousands, but opinions differ on the actual number. As already indicated, there are various processes of synthetic-rubber production, and numbers of brands are on the market. They have been developed chiefly for special purposes, where cost is not the prime consideration, but where some particular property they possess is of value.
Generally speaking, synthetic rubber has not been able, up to the present, to 'fulfil all the conditions met by the natural product, although • it has some properties not possessed by natural rubber, for example, a resistance to oils and hydrocarbons. Here are a few of the synthetic rubbers at present available:—
Neoprene Polymers Of T Ohloropreue• Carbide Buns. 85 Butadinno Carbide .
liu Butadiene and styrene Carbide and coal Pernba 8
n na Butt:Alamo acrylic oitrile Carbide and coal
Cbemignm Butadiene acrylics Oil waste and mat
Itycar Ratad ac $eno rylics Oil waste and coal Olefines and diolefine,s' Oil waste and coal
risttva!nea isobutylene Oil waste and coal
Oppancd Isobuty [One Carbide
In some cases, it will be noted, more than one raw material is used; the process is then referred to as co-polymerization. With a rubber situation so desperate as the U.S.A. found herself in, the only course to take was an heroic one; so much so, that many questions doubtless. arose, and the President of the U.S.A. appointed an influential and authoritative committee, commanding general confidence, to report to him on the situation.
• This Baruch Committee, the report of which has been widely read, found that, on the whole, the Government • scheme was sound, arid that the skill of the technicians and the energy of the administrators of the various production plants, with ordinary luck, were likely to bring the scheme through to a successful conclusion, in such manner ;that' the synthetic production would in time be able to replace the . rigidly conserved stocks of rubber, reclaims and what small supplies of natural rubber were available.
' How Farming Interests Helped in Increasing Output The committee recommended an increase in the original programme, in
of .705;000 tons which was to be obtained-from alcohol from grain,-'thus bringing. the farming interests into the picture.This Was undoubtedly, due to Their efficient. representation in the councils. and a thorough knowledge of their process of obtaining alcohol from wheat, such as has been employed both in Russia and Germany. The increase recommended from this source was 140,000 tons.
Doubts as to the wisdom of using food as a raw •material for rubber were expressed, but the. Agricultural Secretary affirmed that 'there would be a surplus, after all, food demands had been met, of 1,250,000,000 bushels of -wheat. Outside this gigantic synthetic production, there is also the natural tree-rubber referred to, a small amount of which is just beginning to come from the plantations in Latin America. Further, there is the guayule shrub, of which there are large tracts now growing. This shrub reaches maturity at an earlier period than. the seven years necessary' in the case of the hevea tree, .
Another Source is that of seeds from the Russian tausagyz -shrub, which is a native of the Tien Shan Mountains of Central Asia, lout which the Russians have acclimatized as far north as Archangel. Many thousands of 'acres are under cultivation and much production is obtained therefrom. Seeds of the shrub have been flown to England, Australia, 'New Zealand, Canada and America.
As '65 years ago the hevea seeds, which started 'a new industry, were germinated at Kew, so, also, have these tau-sagyz seeds been germinated there, and are now planted up and down the country, even in the north of Scotland. It may be that,. should these seedlings successfully weather. our winter, we may find ourselves independent of rubber supplies from the Far East, and that we can, as it were, grow onr own tyres in, the back garden.