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ABS plastic

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 - acrynitrile rubber or a butadiene containing rubber onto which styrene - acrynitrile 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 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 loss2 in properties. As a result, ABS plastics are extemely 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

1. 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:

2. Moderate price.

3. Ease of fabrication.

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

5. Wide colorability.

6. Good dimensional stability.

7. Nontoxicity.

8. Good water resistance.

9. Excellent chemical resistance.

The strength of a fabricated item produced from an ABS plastics 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 reheated 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.

Note

1. based on the first letters: (viÕt t¾t)tõ nh÷ng ch÷ c¸i ®Çu

2. with essentially no loss: vÒ c¬ b¶n kh«ng mÊt

Exercises

I. Answer the following 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 polystyrene attained?

4. What other properties of plastics do you know?

5. What are ABS polymers similar to?

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

7. Why are ABS plastics extremely useful?

8. What plays a very important role on the mechanical properties of ABS plastics?

II. Translate into Vietnamese paying attention to the prefix re-:

heat - reheat

soften - resifted

form - reform Melt - remelt

Construct - reconstruct

III. Translate the following derivative into Vietnamese:

develop, development

compose, composition

monomer, monomeric

adopt, adoptation

polymer, copolymer, polymerization, polymerize

nature, natural

improve, improvement Tough, toughness

Introduce, introduction

Rigid, rigidity

Resist, resistant, resistance

Apply, application

Viscous, viscosity

Use, useful, useless

Process, processing

IV. Translate into Vietnamese paying attention to the words in bold type:

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

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

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

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

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

V. Translate into English:

1. Mét nhãm lín c¸c chÊt dÎo mµ thµnh phÇn cña chóng cã: acryloitrin, butadien, styren ®• ®­îc t¹o ra trong 20 n¨m gÇn ®©y.

2. C¸c polime thuéc nhãm ABS lµ chÊt nhiÖt dÎo vµ gièng c¸c poly styren, poly vinylclorua, poly olefin, nil«ng.

3. Khi gÆp nhiÖt th× chóng ch¶y mÒm ra, khi gÆp l¹nh th× chóng trë lªn r¾n l¹i.

4. C¸c chÊt nhùa thuéc nhãm ABS ®­îc sö dông réng r•i v× dÔ s¶n xu¸t c¸c vËt liÖu tõ chóng.

5. CÇn ph¶i nhÊn m¹nh r»ng, nh÷ng ®iÒu kiÖn ë ®ã ng­êi ta s¶n suÊt c¸c ®å vËt b»ng nhùa cã ¶nh h­ëng nhiÒu ®Õn tÝnh chÊt c¬ häc cña ®å vËt.

6. §a sè c¸c tÝnh chÊt cña nhùa nhãm ABS phô thuéc vµo.....