2015-04-01
552
The polymer chemistry
The polymer chemistry or, as it is known, the chemistry of large molecules, has made a great progress in the last two or three decades. Before the war world production of polymers was only a few thousand tons, now the output reaches millions of tons. The annual increase in production is over 1,000,000 tons.
To have an idea of what polymer chemistry can do one should know that one ton of polyethylene replaces six tons of lead in the manufacture of electric cables. Ball bearings made of synthetic plastic have a much longer life and don't have to be lubricated. Higher speed are one of the basic features of modern technical progress. The speed of all types of transport is growing and so the number of revolutions in engines is increasing. This calls for new materials which can withstand higher temperatures. Not long ago chemists developed such materials. Polyacrilates compounds have a great many useful properties and are applied in many different ways. For instance, a film coated with this compound becomes noninflammable. The compound can be also used electrical insulation and as a material for the production of foam plastics. It is resistant to concentrated acids, oils, benzene and solvents. New polymers were synthesized to obtain highly durable glass plastic which can operate for a long time at temperatures +250to +300 C.
The plastics made from these polymers will be widely used in the construction of airplanes, in engineering, ship building, etc. Nature spent hundreds of millions of years on reconstructing the complex molecules of organic substances and still didn't create all the materials that man needs. Man had to create materials that don't exist in natural form and man really creates such materials in ever increasing quantities. Half a century is not long in the history of civilization. Synthetic polymers are still young and they have a big future.
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Вариант № 3
1. Вставьте один из модальных глаголов по смыслу и переведите предложения:
1. You have been absent very long. You … be hungry.
2. … I take your book?
3. Take your raincoat it … rain today.
4. They … not translate this article.
5. You … stay home for a week.
2. Дайте правильный перевод следующих предложений, обращая внимание на инфинитив:
1. I am awfully glad to have met you.
2. Nature has many secrets to be discovered.
3. Who is to blame?
4. She is too busy to talk to you.
5. Their house is pleased to look at.
3. Раскройте скобки, употребляя глагол в Passive или Active:
1. You can (to find) information about the life in USA in this book.
2. It seems to me that music (to hear) from the next room.
3. The rule explained by the teacher (to understand) by all of us.
4. We (to call) Zhukovski the father of Russian aviation.
5. The article (to publish) last week.
4. Переведите предложения, обращая внимание на причастие:
1. When sending the telegram she forgot to write her name.
2. The girl writing on the blackboard is our best student.
3. Having descended the mountain they heard a man calling for help.
4. Written in pencil the letter was difficult to read.
5. People living in the city could see a great fire.
