II. Reading Activity and Speech Practice

II.1 While reading the text try to find the information to answer the questions.

1. What does the word “plastic” mean?

2. Who was the first scientist to make the first plastic?

3. What were the first man-made plastics?

4. How were the first plastics used?

Text A: The Plastic Age

It’s in our homes. It’s the most common material in the workplace. Sometimes it’s even in our bodies. We may be moving into the Information Age, but it’s hard to believe that we are not living in the Plastic Age.

The very name “plastic” means versatility. You can bend it, mould it, model it, twist it and play it in a number of different ways. The finished product can be soft and airy foam or a hard and strong compound rivaling the sturdiest metal alloys. In its many forms, plastic has forever changed the way we live.

The first in the long line of man-made plastics was called Bakelite, after its inventor, Leo Baekeland. Many years of work in his chemistry lab in Yonkers, New York, led him to the invention of the first synthetic polymer (plastic) in 1907, made by linking small molecules together to make larger ones.

Baekeland made his new material by mixing the carbolic acid* (phenol) with the strong-smelling formaldehyde to make a third material that was nothing like the original two. It turned out to be a substance that would change the world.

Some of the early uses for plastics were things like radio cabinets, buttons, billiard balls, pipe-stems, toilet seats, airplane parts and, the object of Baekeland’s research, shellac*. Baekeland’s trick was to take resin produced by the two chemicals and heat it under pressure to produce a soft solid that be molded and hardened or powered and set under pressure. With this innovation, the plastic revolution was under way.

Vocabulary to the text:

· carbolic acid* - я кислота;

· shellac* - шеллак.

II.2 Make lists of words connected with: a. - the ways of working plastics;

- the finished products of plastics;

- materials that were used by Baekeland;

- things made of plastics.

b. Explain what are: Bakelite and shellac.

II.3 Say if the sentences are true or false.

1. The 20^th and the 21st centuries are called the age of plastics.

2. Plastics can be worked in many ways.

3. The finished product is always the same: hard foam like substance.

4. The first plastic was made in England in the beginning of the 20^th century.

5. Leo Baekeland joined small molecules together to make large ones.

6. He mixed two different acids to make a third one different from the two first ones.

7. Early uses for plastics were very versatile.

8. Baekeland worked with resins.

II.4 Make a short story to speak about “The substance that changed the world" according to the plan:

1. Properties of plastics.
2. The first man-made plastics.
3. The early use of plastics.

II.5 Read the text and try to understand it in details; translate it into Russian.

Text B: 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 monomer (repeating unit) that makes up the chain of the polymer.

The molecules can be either natural – like cellulose, wax, and natural rubber – or - synthetic in polyethylene (polyethene) and nylon. In co- polymers, more than one monomer is used.

Most plastics are synthesized from organic chemicals or from natural gas or oil. Plastics are light-weight compared to metals and are good electrical insulators. The best insulators now are epoxy resins and teflon.

Plastics can be classified into several broad types: thermoplastics and thermosetting plastics and elastomers.

Thermoplastics soften on heating, and 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 polystyrene especially suitable for radio-frequency insulation in airplanes. PET (polyethene terephthalate) is a transparent thermoplastic used for soft-drinks bottles. Thermoplastics are also viscoelastic.

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 higher density than thermoplastics. They are less flexible, more difficult to stretch, and are lass 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.

II.6 Give full answer he questions to the text.

1. What is the basic chemical element of plastics?

2. How plastics can be worked?

3. Plastics are synthetic polymers, aren’t they?

4. What are long-chain molecules made of?

5. What kind of molecules make plastics?

6. Are most plastics synthesized from organic or synthetic chemicals?

7. What are the main types of plastics?

II.7 Define the sentences as true or false.

№	Sentences to be regarded	Yes	No
1.   2.   3. 4.   5. 6. 7. 8. 9. 10.	Thermoplastics soften on heating then harden again when cooled. Thermoplastics are highly resistant to chemical and mechanical stresses. They have also very high absorption of water. Polystyrene is a very nice insulator suitable for low temperatures in refrigerators and in airplanes. Thermosetting plastics do not soften when heated. Thermosetting plastics are stronger than thermosets. They are very flexible and easy to creep. Epoxy resins and polyurethane are typical thermoplastics. Elastomers are similar to thermoplastics. Sufficient cross-linking between molecules prevent their stretching and creep.

II.8 Compare the main characteristics of plastics. Fill in the chart.

	Physical properties	Chemical properties	Application
Thermoplastics
Thermosetting plastics

II.9 Your group mates are going to have a seminar on plastics. Choose any of the given topics to take part in the seminar and get ready to speak on it.

1. Plastics as engineering materials.

2. Thermoplastics and their properties.

3. Thermosetting plastics and their types.

II.10 Scan the text. Analyze each paragraph of it to get the general impression of the information given in them.

Text C: Plastics Today

Plastics are large and varied group of materials consisting of carbon and oxygen, hydrogen, nitrogen, and other organic and inorganic elements. While solid in its finished state, a plastic is at some stage in its manufacture, liquid and capable of being formed into various shapes. Forming is most usually done through the application, either singly or together, or heat and pressure. There are over 40 different families of plastics in commercial use today, and each may have dozens of subtypes and variations.

A successful design in plastics is always a compromise among highest performance, attractive appearance, efficient production, and lowest cost. Achieving the best compromise requires satisfying the mechanical requirements of the part, utilizing the most economical resin or compound that will perform satisfactorily, and choosing a manufacturing process compatible with the part design and material choice.

Most people have now outgrown the impression that plastics are low-cost substitute materials. Those that still view plastics as cheap and unreliable have not kept up with developments in polymer technology for the past ten years.

Many plastics did indeed evolve as replacements for natural products such as rubber, ivory, silk or wool, which became unavailable or on short supply. But the new materials did not necessarily replace the older ones permanently not made them obsolete. In many cases, they met an increased demand that neither could nor be met by the natural product alone.

Today’s engineering resins and compounds serve in the most demanding environments. Their toughness, lightness, strength, and corrosion resistance have won many significant applications for these materials in transportation, industrial and consumer products. The engineering plastics are now challenging the domains traditionally held by metals: truly load-bearing, structural parts.

II.11 Restore the correct order of sentences according to the text.

1. People still view plastics as cheap and not reliable enough as an engineering material.

2. Plastics are a large group of materials organized in 40 different families.

3. Plastics are famous for a compromise among attractive mechanical properties, cost and the efficient production.

4. Today plastics are widely used in industrial and consumer production even challenging the domains of metals.

5. Plastics have been evolved to replace natural products or such products which are on short supply.

II.12 How much do we depend on plastics? Read the following arguments and think over our own ones.

We cannot live without plastics.	We can live without plastics.
1. The soles of your shoes are made of plastics.   2. The photographic film is made of it. 3......	1. We can make leather shoes.     2.......   3.......

II.13 Express your opinion on the use of plastics in our everyday life. Don’t you think we too often use plastics and plastic materials in our life and not only in industry? (Use the information given in the text if necessary).

Дата добавления: 2015-10-30