3. Read the text and translate it using a dictionary.

Text A

Abs plastics

A unique family of plastics has evolved and developed during the last twenty years. These plastics are composed of three monomeric chemicals – acrylonitrile, butadiene and styrene. The name ABS, based on the first letters of each of the monomeric components has been adopted for this family. ABS plastics are composed of styrene acrylonitrile copolymer as the continuous phase and a dispersed phase of butadiene-acrylonitrile rubber or a butadiene containing rubber onto which styrene-acrylonitrile monomers are grafted.

Various combinations of properties are possible, thus making these polymers most attractive for a larger number of current and newly developed applications.

ABS polymers are true thermoplastics similar to polystyrene, polyvinyl chloride, polyolefins, nylon, etc. On application of heat they are softened, and when pressure is applied they attain viscous flow.

Upon cooling they harden and on reheating are resoftened. Thus they can be remelted and reformed into various shapes with essentially no loss in properties. As a result, ABS plastics are extremely useful and versatile, since ease of processing and forming allows them to be used for a great number of applications. In their natural form ABS plastics are opaque, similar in this respect to the impact polystyrenes.

General Properties of abs Plastics

The excellent combination of properties which ABS plastics offer has spurred the growth of these plastics into many applications. No one single property, but rather the combination of properties of ABS plastics has made them outstanding. Some of the properties, which make these plastics extremely useful, are:

1. Moderate price.

2. Ease of fabrication.

3. Good combination of toughness, rigidity and mechanical properties.

4. Wide colorability.

5. Good dimensional stability.

6. Nontoxicity.

7. Good water resistance.

8. Excellent chemical resistance.

The strength of a fabricated item produced from an ABS plastic is dependent on a number of variables, namely, the fabrication conditions used, the design and shape of the finished piece, the method of stress application, and the environmental conditions encountered. It should be stressed that the conditions under which the plastic part is formed play a very important role on the subsequent mechanical properties of ABS plastics. This is true to all thermoplastics. When ABS polymers are heated and subjected to fabricating conditions, such as injection molding, sheet or profile or pipe extrusion, or thermoforming, many of the long chain polymer molecules change their position and shape and become more aligned: in other words, they become oriented or stretched out pointing in the direction of flow. Thus, most properties of ABS plastics are not only time and temperature-dependent but are also frequently direction-dependent (anisotropic). Therefore, in describing the properties of ABS plastics, it is important, if at all possible, to specify the properties in relation to the flow direction and the degree of orientation.

4. Answer the questions:

1. What is a unique family of plastics composed of?

2. What is the name ABS based on?

3. How is significant improvement in toughness over polysty-rene attained?

4. What other properties of plastics do you know?

5. What are ABS polymers similar to?

6. What happens to ABS polymers upon cooling and heating?

7. Why are ABS plastics extremely useful?

8. What plays a very important role on the mechanical proper-

ties of ABS plastics?

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

1. The name ABS, based on the first letters of each of the monomeric components has been adopted for …

2. By introducing acrylonitrile monomer into a similar system, a significant improvement in all these properties is obtained, as well as outstanding … and … .

3. Various combinations of properties are possible, thus making these polymers most attractive for a larger number of current and newly developed … .

4. ABS plastics are extremely ... and … , since ease of processing and forming allows them to be used for a great number of applications.

5. The … of a fabricated item produced from ABS plastic is dependent on a number of variables.

6. Most properties of ABS plastics are not only time and temperature-dependent but are also frequently … .

strength; this family; versatile; resistance; applications; toughness; useful; direction-dependent (anisotropic).

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

to develop	краситель
substitute	фотосинтез
residue	вещество
dye	цепь
photosynthesis	диоксид углерода
carbon dioxide	превращать
substance	сырье
to convert	заменитель
raw materials	остаток
chain	развивать

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