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Synthetic rubber


Synthetic rubber
Europe first learned of the rubber in the XVI century. Christopher Columbus brought it back from America, along with many other curiosities. During the stay of ships off the island of Haiti, Columbus and his companions watched the game in the natives ball made of some elastic material, completely unknown in Europe. Balls bouncing easily when hitting the ground, compressed and then restored the original shape. Returning to Spain, Columbus took with him samples of this wonderful material, which was later known in the Old World as "rubber". Translated from the Native American "rubber" means "wood tears." As it became known later, he was a juice collected from incisions tropical tree bark - the Brazilian rubber trees. He took from the tree when gevee Seven years ago: at the height of half a meter made an incision in the bark, and when from under it began to flow as white as milk, juice, collected in a cup suspended, and then poured into a large vessel. In air, the juice relatively quickly rolled up and turned into a dark resinous product - rubber.

The Europeans did not immediately appreciated the dignity of this material. For two centuries they belonged to the rubber as a savage gimmick. Meanwhile, travelers, get in South America continued to deliver to Europe more and more objects made of rubber. Among them were bottles, waterproof boots and clothing from the rain. It was all very interesting, but had no practical value. Only after a long time, Europeans have found for the first use of rubber - began to use it in the form of washing gum resembling modern school erasers.

At the end of the XVIII century English chemist Mack took out a patent for the manufacture of rubber raincoats. They are called Macs. Raincoats, however, were not good enough for the European climate at low temperatures they became rigid as a gesture, but in the heat - sticky. After many experiments have found a way to avoid these unpleasant features rubber vulcanization by it. (This is an important discovery was made in 1839 by the American chemist Goodyear.) It was found that by heating rubber with sulfur it quite changes its properties - becoming more flexible, resilient and less susceptible to changes in temperature. This new rubber vulcanized rubber became known. He quickly gained popularity, as proved to be extremely useful in many ways. Demand for it has grown every year. Another similar product with the rubber in the nature does not exist - it is waterproof, has electrical insulation properties, is flexible and is able to very large changes in shape. The external force it can be stretched to several times and then compressed. It does not have such elasticity no other substance. However, he is strong, durable, resistant to abrasion and is easily processed. Therefore, rubber has been and remains an ideal material for the manufacture of tires, all kinds of power transmission belts, conveyor belts, hoses, dampers, gaskets, flexible insulation, and more. Without rubber life of modern industrial society is simply impossible.

From the middle of the XIX century unfolded mass production of rubber products. This gave rise to the present rubber fever. Area where rubber trees grew, turned into an object of speculation and wars. Wild Hevea soon ceased to satisfy the needs of industry. In addition, to produce rubber in the jungle was difficult and costly. successful experiments on the creation of rubber plantations have been made. Hevea moved to the tropics of Java, Sumatra, the Malay Archipelago. rubber production has increased several times, but the demand for it continues to grow.

For a hundred years the scientific world was looking for the answer to the mysteries of the rubber, to learn how to do it artificially by chemical means. Gradually, it became clear that a natural rubber from Hevea juice is a mixture of several substances, but 9/10 of its mass accounts for hydrocarbon polyisoprene formula (C5H8) n, where n is very large - over a thousand. The substances with a similar structure refers to a group of high molecular weight products - polymers, which are formed by connecting several, sometimes many, identical molecules simpler substances monomer (in this case, the molecules of isoprene C5H8). Under favorable conditions, the individual molecules monomers connected to each other in a long and flexible linear or branched chain strand. This polymer formation reaction called polymerization. It occurs only with organic compounds having multiple bonds (double or triple). As a result, separation of these links takes place (due to the liberated valences) connection between the individual molecules themselves. Furthermore polyisoprene rubber includes a natural resinous protein and minerals. Pure polyisoprene purified from resins and proteins, is very unstable in air and rapidly loses its valuable technical properties: elasticity and strength.

Thus, in order to produce synthetic rubber, it was necessary to learn at least three things: 1) to obtain other compounds of isoprene; 2) carry out the reaction of isoprene polymerization; 3) treating the resulting rubber suitable materials to protect it from degradation. All these tasks were extremely difficult. In 1860, English scientist Williams by dry distillation of the rubber singled him isoprene, which was an easy mobile colorless liquid with a distinctive odor. In 1879, French chemist Gustav Bouchard, heating isoprene and acting on it with hydrochloric acid, the reverse reaction - was rubbery product. In 1884, English chemist Tilden got isoprene by high-temperature expansion of turpentine. Although each of these scientists contributed to the study of rubber properties, the mystery of its synthesis and remained in the XIX century unsolved - all open methods were not suitable for industrial use or as a result of the high cost of raw materials, or because of the small isoprene output, or because of the complexity technical processes, ensuring the reaction.

But is it really so necessary for isoprene rubber production? Perhaps macromolecule with similar properties may be formed from other hydrocarbons? In 1901, the Russian chemist Kondakov found that the rubber-like substance is transformed as dimethyl, if you leave it for about a year to stand in the dark or in diffuse light. (During the First World War in Germany, cut off from natural rubber sources, the production of synthetic rubber has been adjusted from dimethylbutadiene. However, products made of it coming out of very poor quality, the price is their due to technical difficulties rendered prohibitive. After the war, the methyl rubber never produced.)

Later it was discovered that the rubbery substance may be synthesized with all hydrocarbon backbone molecule

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- C = C - C = C -

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The first member of this series is butadiene (or butadiene)

CH2 = CH-CH = CH2

Even in 1914, the British and Matthews Strange got a very good rubber of butadiene in the presence of sodium metal. However, laboratory experiments on their work did not go due to the fact that, first, the method was not found divinyl production, and secondly, the installation could not be created, which could be synthesized rubber industrially. Both of these problems fifteen years were allowed Russian chemist Sergei Lebedev.

Before World War I Russian refineries produced from imported rubber to 12 thousand tons of rubber. After the revolution, when the industrialization of the industry, the needs of the Soviet Union in the rubber repeatedly increased. A ship required 68 tons of rubber, each tank - 800 kg, 600 kg of the plane, the car - 160 kg. Every year, I had to be bought abroad, more and more rubber. Meanwhile, in the years 1923-1924 the price of natural rubber reached 2400 rubles per ton gold. Having to pay so much money, and even more dependence, which thus fell from suppliers young Soviet state, put before the leadership of the country's serious problems. Solve them to be only one way - to develop an industrial process for the production of synthetic rubber.

In late 1925 the Supreme Economic Council announced an international competition for the best method of producing synthetic rubber. Competition conditions were quite tough: rubber had to be made in the Soviet Union of the products produced in the USSR, the price of synthetic rubber may not exceed the average world market price for the last five years. By January 1, 1928 were required to deliver to Moscow 2 kg of the finished sample.

Lebedev at that time headed the department of general chemistry at Leningrad University. Even before the Revolution, he spent several years in the problem of synthetic rubber and was well aware of the difficulties faced by all participants of the competition. Nevertheless, he decided to take part in it. Several pupils and students agreed to help him in his work. The time was very difficult. All assistants and Lebedev himself worked completely free during off-duty hours, on evenings and weekends. To keep up to date, working with the greatest stress. Sophisticated technological experiments had to be carried out in the most unfavorable conditions. It lacked literally everything. As recalled later, participants of this wonderful enterprise, everything you need they have done with their own hands. Lebedev had to work not only a chemist, but as a glassblower, a mechanic and an electrician. For cooling in chemical processes needed ice - it all together they prepare on the Neva. Still, the matter progressing well.

During the previous years of research Lebedev made sure to get a synthetic rubber, fully reproduces the properties of natural - a very complex task, and in those circumstances is hardly achievable. He immediately abandoned experiments with isoprene and as a raw material butadiene decided to take. After research and Matthews Strange in the production process divinyl (butadiene) rubber was still one missing piece - it was necessary to develop a method for the production of butadiene from cheap and readily available raw materials. First, as such Lebedev wanted to take the oil, but then all the attention focused on alcohol. The alcohol then was the actual source material. If the problem of the synthesis of butadiene has been successfully resolved, it would be possible immediately to produce rubber in any desired quantity, but it was just what the country needed.

The essence of the reaction in which ethyl alcohol is decomposed into butadiene, hydrogen and water (it is generally described by the equation: 2CH3CH2OH = C4H6 + 2H2O + H2), Lebedev was clear. But the biggest challenge was the selection of a suitable catalyst. Deeply understand the essence of the processes, Lebedev suggested that such a catalyst may be one of the most active natural clay. During his vacation in the Crimea and the Caucasus in the summer of 1927, he is constantly collected and studied clay samples. In the end he found the right clay to Koktebel. The reaction in her presence, gave excellent results. reaction went in the right direction, and the alcohol was obtained from butadiene - So, the first success was achieved in mid-1927.

The following process - polymerization of butadiene - Lebedev decided to carry out according to the method Matthews and Strange. For this special installation sodium uniformly distributed on divinyl and then the reaction was continued for 3-5 days. However, the final product was not her trademark rubber. He was imbued with gases, it is unevenly distributed sodium, the mixture was unstable and quickly oxidized in the air, losing elasticity. Therefore, the resulting rubber is treated in a mixer, where it is warmed up, together with the inclusion of sodium. Then, it was mixed with amplifiers, carbon black, kaolin, magnesium and other components, which were supposed to protect the rubber from disintegration.

Ready rubber obtained puny portions - just a few grams per day. Therefore, the work lasted literally until the last minute. At the end of December, when the deadline to have remained a matter of days, the synthesis of 2 kg rubber was finished, and he was urgently sent to Moscow. In February 1928 the jury, having considered all the samples sent (which, incidentally, has received quite a bit), recognized the rubber grown in the laboratory Lebedev best.

However, this was only the beginning. Laboratory methods are often inappropriate in the factory. Lebedev instructed to continue to research and develop industrial technology of its method of production of rubber. Again began painstaking work. However, now the means and capabilities at the Lebedev was much more. Well aware of the importance of his work, the government provided him with all necessary. Soon, a special synthetic rubber laboratory was established at the Leningrad University. During the year, a pilot plant was designed and constructed in the laboratory, which gave out 2-3 kg of rubber per day. all the technology of the factory process was developed by the end of 1929.

In February 1930, in Leningrad began the construction of a pilot plant at Gutuevsky Island. In the summer of factory laboratory was opened. Equipped for personal Lebedev instructions, she was one of the best chemical laboratories of the time and turned in at the Research Center of synthetic rubber. In addition to the laboratory, Lebedev has at its disposal the best specialists, which have only been able to find. For any questions he may appeal personally to the secretary of the Leningrad party Kirov.

The great difficulty was to establish the necessary equipment. Chemical engineering infancy. Orders were distributed to all the Leningrad plant, but their implementation was slow, as lacking the necessary experience. Even the Lebedev sometimes found it difficult to give a precise technical advice. Nevertheless, the construction of the pilot plant was completed in January 1931. In February, it first 250 kg of rubber were obtained. It was the first in the world of cheap synthetic rubber produced by the factory. In the same year, three giant rubber factory were laid - in Yaroslavl, Voronezh and Yefremov. All of them were declared Komsomol construction projects and were built with amazing speed. In 1932 Yaroslavl factory had already given the first rubber. At first, the synthesis of butadiene factory held with great difficulty. Instead of a simple mixture of alcohol decomposition products consisting of butadiene, water and hydrogen, obtained complex "salad" of 30 components, the yield of butadiene in the weight does not exceed 20-25%. Lebedev had to urgently go to Yaroslavl with a group of its employees to help organize the production. Then the same difficulties arose in Voronezh and Yefremov. In the spring of 1934 during a visit to the plant in Efremov Lebedev he contracted typhus and died shortly after his return to Leningrad. But the fact that he had put such an important base grew stronger and developed. Following the first three synthetic rubber plants were built several new.

25 thousand, in 1936 - - 40 thousand 11 thousand tons of synthetic rubber in 1935 was released in 1934. In 1937, the share of synthetic rubber in total rubber production has amounted to 73%. Difficult to scientifically and technically the problem was successfully resolved.

However, the method of production of synthetic rubber designed Lebedev was not unique. He knew it, and in recent years a lot of thought about how to replace food raw materials (alcohol produced from foods and consumed 12 tons of potatoes to obtain 1 ton of alcohol) to other, more expensive, such as oil. Another disadvantage of divinyl rubber was its low tack. In the manufacture of rubber products it was necessary to go to additional costs. Subsequently, we developed several ways to produce synthetic rubber, and in 1965 in the USSR in the industrial environment was first obtained from a synthetic isoprene rubber.

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