Read the text and translate it using a dictionary

NATURE OF MANUFACTURING PLASTICS

GRAMMAR: Subjunctive Mood. Conditional Sentences.

1. a) Translate the following words, word combinations and chemical terms into Russian:

organic, polymers, resins, glycerol, rubber, compound, fatty acids, proteins, fibres, solution, cellulose, resistance, viscosimeter, starch, durability, substance.

b) Translate into Russian paying attention to the Subjunctive Mood and conditional sentences:

1. It is doubtful whether the observations of these scientists represent a new field of chemistry.

2. This procedure might be expected to support the claims of the Japanese scientists.

3. Magnetically induced changes as small as 0.04 pH unit would have been detectable by the method of measurements at constant flow rate.

4. Several theories have been proposed as to how mercury might go from inorganic form in water or a bottom sediment, into a methylated form of a fish.

5. We might expect that the activation energy necessary to start up a reaction would be equal to the energy needed to break the weakest chemical bond among the reactants.

6. If a substance conducts electricity, it will be heated.

7. If a metal were heated, it would be melt.

8. If a nonmetal had been cooled, it would have become brittle.

9. Provided the temperature were high, a metal would melt.

10. Had the temperature been raised, we should have got a new alloy.

11. If a chemical substance were heated, it might decompose.

2. Choose the correct forms:

1. If life (didn’t depend on, depended on) organic polymers, we (wouldn’t have, would have) food, clothing, shelter and transportation.

2. But for the complexity and fragility of the molecules of the natural organic polymers they (wouldn’t have defied, would have defied) the attempts to analyze their molecular structure until very recently.

3. There (would, will) be no industry of man-made organic polymers, (was, were) it not for modern methods of physical and chemical analyses.

4. It (would, will) be necessary to add that polymers have long-lived durability and resistance to high temperatures.

5. If the chemists (had not, did not) found out that many polymers have the form of long, flexible chains, they (wouldn’t, won’t) have been able to synthesize artificial polymers.

Text A

THE AGE OF POLYMERS

Life depends fundamentally on organic polymers. If it were not so, we wouldn’t have food, clothing, shelter and transportation.

Indeed, nearly all the material needs of man could be supplied by natural organic products. The list of these materials and things made from them might be very long: wood, fur, leather, wool, cotton, silk, rubber, oils, paper, paint and so on. The organic polymers which these things are made from include: proteins, cellulose, starch, resins, and a few other classes of compounds.

There would be no industry of man-made organic polymers, were it not for modern methods of physical and chemical analyses which uncovered the principles that govern the properties of the natural polymers. One could list the principal products as fibres; synthetic rubbers, coatings, adhesives and a lot of materials called “plastics”. Plastics and synthetic coating are already in common use. It is desirable that they should be used on a large scale, and get further developed.

Synthetic polymers now available already possess several of the properties required in a structural material. They are light in weight, easily transported, easily repaired, highly resistant to corrosion and solvents, and satisfactorily resistant to moisture. It would be necessary to add that they have long-lived durability and resistance to high temperatures. A very important question could arise over whether synthetic polymers could be made inexpensive enough to compete with the structural materials such as metals and ceramics. The answer could be – “yes”.

It might seem odd that man came rather late to the investigation of organic polymers as the principal means of supporting life. The natural polymers such as proteins, cellulose and others dominated his existence and even in ancient times people used these materials.

Yet as late as the end of the 19th century polymer chemistry got little attention.

Chemists attacked sugar, glycerol, fatty acids and other ordinary organic compounds – dissolving, precipitating, crystallizing and distilling them to learn what these substances were composed of.

But only feeble efforts were made to investigate such common materials as wood, starch, wool, and silk. The substances composing these materials couldn’t be crystallized from solutions, nor could they be isolated by distillation.

It was only in the 20th century that the scientists began thorough investigation of these materials. Having used some powerful physical instruments, an electron microscope, viscosimeter, X-ray diffraction apparatus; they could have revealed the polymers in all their intricacy.

Their molecules were incredibly large, the molecular weights running as high as millions of unit, whereas simple organic substances such as, for instance sugar and gasolene have molecular weights in the range of only about 50-500.

The giant molecules can be composed of a large number of repeating units, they being given the name “ polymer ” from the Greek word poly (many) and meros(a part). Many polymers have the form of long, flexible chains. If the chemists had not found that out, they wouldn’t have been able to synthesize artificial polymers. This has led to the establishment of industries producing synthetic fibres and numerous polymeric materials, many of which were less expensive and superior in various ways to the natural materials.

4. Answer the questions:

1. What does the life depend on?

2. Why does life depend upon organic compounds?

3. What is the list of materials needed for life?

4. What do organic polymers include?

5. What have modern methods of physical and chemical analyses uncovered?

6. What products appeared on the basis of the discovery of polymers?

7. What properties do synthetic polymers possess?

8. Did people use natural polymers in ancient times?

9. What were those polymers?

10. When did the scientists begin thorough investigation of natural organic polymers?

11. What have they found out about polymers?

12. What are the molecules of polymers composed of?

5. Complete the following sentences using some active words and word combinations (see below):

1. Life depends fundamentally on …

2. Nearly all materials needs of man could be supplied by …

3. One could list the principal products as fibres, synthetic rubbers, coatings, adhesives and a lot of materials called …

4.... now available already possess several of the properties required in a structural material.

5. Synthetic polymers have long-lived … and … to high temperatures.

6. Having used some powerful physical instruments, ……, the scientists could have revealed the polymers in all their intricacy.

7. The name “polymer“ came from … poly (many) and meros (a part).

8. Many polymers have the form of …

plastics; durability; long, flexible chains; organic polymers; resistance; synthetic polymers; the Greek word; an electron microscope; viscosimeter; X-ray diffraction apparatus; natural organic products.

6. Retell the text using the scheme (see Un.1).

Text B

1. Match the English words and word combinations in A with their Russian equivalents in B.

A B

fibre	синтетические полимеры
synthetic polymers	смола
thermosetting plastics	волокно, нить
branch	молекула
chemicals	разветвленный
molecule	химические вещества
to synthesize	термореактивные пластмассы
resin	синтезировать
cellulose	клетчатка, целлюлоза
chain	цепь

2. Read the text trying to understand its main idea.

PLASTICS

Plastics are non-metallic, synthetic, carbon-based materials. They can be moulded, shaped, or extruded into flexible sheets, films, or fibres. Plastics are synthetic polymers. Polymers consist of long-chain molecules made of large numbers of identical small molecules (monomers). The chemical nature of a plastic is defined by the monomer (repeating unit) that makes up the chain of the polymer. Polyethene is a polyolefin; its monomer unit is ethene (formerly called ethylene). Other categories are acrylics (such as polymethylmethacrylate), styrenes (such as polystyrene), vinys (such as polyvinyl chloride (PVC), polyesters, polyurethanes, polyamides (such as nylons), polyethers, acetals, phenolics, cellulosic, and amino resins. The molecules can be either natural – like cellulose, wax, and natural rubber – or synthetic – in polyethene and nylon. In co-polymers, more than one monomer is used.

The giant molecules of which polymers consist may be linear, branched, or cross-linked, depending on the plastic. Linear and branched molecules are thermoplastic (soften when heated), whereas cross-linked molecules are thermosetting (harden when heated).

Most plastics are synthesized from organic chemicals or from natural gas or coal. Plastics are light-weight compared to metals and are good electrical insulators. The best insulators now are epoxy resins and teflon. Teflon or polytetrafluoroethene (PTFE) was first made in 1938 and was produced commercially in 1950.

Plastics can be classified into several broad types.

Thermoplastics soften on heating, then harden again when cooled. Thermoplastic molecules are also coiled and because of this they are flexible and easily stretched.

Typical example of thermoplastics is polystyrene. Polystyrene resins are characterized by high resistance to chemical and mechanical stresses at low temperatures and by very low absorption of water. These properties make the polystyrenes especially suitable for radio-frequency insulation and for parts used at low temperatures in refrigerators and in airplanes. PET (polyethene terephthalate) is a transparent thermoplastic used for soft-drinks bottles. Thermoplastics are also viscoelastic, that is, they flow (creep) under stress. Examples are polythene, polystyrene and PVC.

Thermosetting plastics (thermosets) do not soften when heated, and with strong heating they decompose. In most thermosets final cross-linking, which fixes the molecules, takes place after the plastic has already been formed.

Thermosetting plastics have a higher density than thermoplastics. They are less flexible, more difficult to stretch, and are less subjected to creep. Examples of thermosetting plastics include urea-formaldehyde or polyurethane and epoxy resins, most polyesters, and phenolic polymers such as phenol-formaldehyde resin.

Elastomers are similar to thermoplastics but have sufficient cross-linking between molecules to prevent stretching and creep.

3. Divide the text into some logical parts and entitle them.

4. Translate the following sentences into English using lexical material of the text:

1. Длинные цепи молекул полимеров состоят из одинако-вых небольших молекул мономеров.

2. Сополимеры состоят из двух и более мономеров.

3. Пластмассы можно получать в виде листов, тонких пленок, волокон или гранул.

4. Молекулы полимеров могут быть линейными, ветвящимися или с поперечными связями.

5. Малый вес пластмасс и хорошие электроизоляционные свойства позволяют использовать их в радиоэлектронике и электроприборах, а также вместо металлов.

6. Молекулы термопластов имеют извитую форму, и поэтому они гибкие и легко растяжимы.

7. Эластомеры имеют большое число поперечных связей между молекулами.

Text C

1. Pay attention to the following words and word combinations:

epoxy resin – эпоксидная смола;

polyvinyl chloride – поливинил-хлорид;

adhesion – прилипание;

polythene – полиэтилен;

strong bond – прочная связь;

lattices – латексы;

insulation – изоляция;

modifiers – модификаторы;

void – пустота;

light-duty component – неответственный компонент;

alkali – щелочь;

casting – литье.

2. Read the text and be ready to say if the following statements are true or false. Use the following phrases:

I think it’s right.

It seems to be wrong.

I can’t agree with it.

As far as I know …

To my mind

On the contrary

1. Polythene is a plastic made from vinyl chloride.

2. Epoxy resins have outstanding adhesion, toughness and resistance to attack from chemical.

3. PVC is a colorless solution with outstanding resistance to water, alcohols, and concentrated acids and alkalis.

4. Polystyrene is a thermoplastic produced by the polymerization of ethane.

5. Polythene is a white waxy solid with very low density, reasonable strength and toughness but low stiffness.

TYPES OF PLASTICS

Epoxy resin is a thermoset plastic containing epoxy groups. Epoxy resin hardens when it is mixed with solidifier and plasticizer. Plasticizers make a polymer more flexible.

Epoxy resins have outstanding adhesion, toughness, and resistance to attack from chemicals. They form strong bonds and have excellent electrical insulation properties. Large, complex, void-free castings can be made from them. They are also used as adhesives, and in composites for boat building and sports equipment.

PVC (polyvinyl chloride) is a thermoplastic polymer made from vinyl chloride is a colourless solid with outstanding resistance to water, alcohols, and concentrated acids and alkalis. It is obtainable as granules, solutions, lattices, and pastes. When compounded with plasticizers, it yields a flexible material more durable than rubber. It is widely used for cable and wire insulation, in chemical plants, and in the manufacture of protective garments. Blow moulding of unplasticized PVC produces clear, tough bottles which do not affect the flavour of their contents. PVC is also used for production of tubes or pipes.

Polystyrene is a thermoplastic produced by the polymerization of styrene. The electrical insulating properties of polystyrene are outstandingly good and it is relatively unaffected by water. Typical applications include light fixtures, toys, bottles, lenses, capacitor dielectrics, medical syringes, and light-duty industrial components. Extruded sheets of polystyrene are widely used for packaging, envelope windows, and photographic film. Its resistance to impact can be improved by the addition of rubber modifiers. Polystyrene can be readily foamed; the resulting foamed polystyrene is used extensively for packaging.

Polythene (polyethene, polyethylene) is a plastic made from ethane. It is one of the most widely used important thermoplastic polymers. It was first developed by the polymerization of ethane at a pressure of 2,000 bars at 200 ºC. This produced low-density polythene (LDPE). A relatively high-density form (HDPE) was synthesized in the 1950 s using a complex catalyst. Polythene is a white waxy solid with very low density, reasonable strength and toughness, but low stiffness. It is easily moulded and has a wide range of uses in containers, packaging, pipes, coatings, and insulation.

3. Make up the plan of the text.

4. Give a brief summary of the text.

Text D

1. Read the text and choose the most suitable title out of the given once:

a) Advanced Composites.

b) Composit Materials.

c) Composites.

The combinations of two or more different materials are called composite materials. They usually have unique mechanical and physical properties because they combine the best properties of different materials. For example, a fibre-glass reinforced plastic combines the high strength of thin glass fibres with the ductility and chemical resistance of plastic. Nowadays composites are being used for structures such as bridges, boat-building etc.

Composite materials usually consist of synthetic fibres within a matrix, a material that surrounds and is tightly bound to the fibres. The most widely used type of composite material is polymer matrix composites (PMCs). PMCs consist of fibres made of a ceramic material such as carbon or glass embedded in a plastic matrix. Usually the fibres make up about 60 per cent by volume. Composites with metal matrices or ceramic matrices are called metal matrix composites (MMCs) and ceramic matrix composites (CMCs), respectively.

Continuous-fibre composites are generally required for structural applications. The specific strength (strength-to-density ratio) and specific stiffness (elastic modulus-to-density ratio) of continuous carbon fibre PMCs, for example, can be better than metal al1oys have. Composites can also have other attractive properties, such as high thermal or electrical conductivity and a low coefficient of thermal expansion.

Although composite materials have certain advantages over conventional materials, composites also have some disadvantages. For example, PMCs and other composite materials tend to be highly anisotropic – that is, their strength, stiffness, and other engineering properties are different depending on the orientation of the composite material. For example, if a PMC is fabricated so that all the fibres are lined up parallel to one another, then the PMC will be very stiff in the direction parallel to the fibres, but not stiff in the perpendicular direction. The designer who uses composite materials in structures subjected to multidirectional forces, must take these anisotropic properties into account. Also, forming strong connections between separate composite material components is difficult.

The advanced composites have high manufacturing costs. Fabricating composite materials is a complex process. However, new manufacturing techniques are developed. It will become possible to produce composite materials at higher volumes and at a lower cost than is now possible, accelerating the wider exploitation of these materials.

2. Write out:

a) key worlds and terms;

b) the sentences expressing the main idea of each paragraph.

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