CBSE Class 12 Chemistry Polymers Notes Set F

POLYMERS

Points to Remember

1. Polymers are defined as high molecular mass macromolecules which consist of repeating structural units derived from the appropriate monomers.

2. In presence of an organic peroxide initiator, the alkenes and their derivatives undergo addition polymerisation or chain growth polymerisation through a free radical mechanism. Polythene, teflon, orlon etc. are formed by addition polymerisation of an appropriate alkene or its derivative.

3. Condensation polymerisation reactions are shown by the addition of bi– or poly functional monomers containing –NH_2, –OH and –COOH groups. This type of polymerisation proceeds through the elimination of certain simple molecules such as H₂O, NH₃ etc.

4. Formaldehyde reacts with phenol and melamine to form the corresponding condensation polymer products. The condensation polymerisation progresses through step by step and is called also step growth polymerisation.

5. Nylon, bakelite and dacron are some of the important examples of condensation polymers.

6. A condensation of two different unsaturated monomers exhibits copolymerisation. A copolymer like Buna-S contains multiple units of 1, 3- Butadiene and styrene.

7. Natural rubber is cis-1, 4-polyisoprene. It can be made more tough by the process of vulcanization with sulphur.

8. Synthetic rubbers like Buna-N are usually obtained by copolymerisation of alkene and 1, 3-Butadiene derivatives.

9. In view of potential environmental hazards of synthetic polymeric wastes, certain biodegradable polymers such as PHBV and Nylon-2-Nylon-6 are developed as alternatives.

QUESTIONS

VSA TYPE QUESTIONS (1 - MARK QUESTIONS)

1. Define the term copolymer.

2. Identify homopolymer from the following examples Nylon-66, Nylon-6, Nylon- 2-Nylon-6.

3. Give example of a natural polyamide which is an important constituent of diet. [Hint : Proteins]

4. Classify polythene and bakelite as thermosetting plastics or thermoplastics.

5. Among fibres, elastomers and thermosetting polymers, which one has strongest intermolecular forces of attraction?

6. Why is bakelite called a thermosetting polymer.

7. Give the monomers of bakelite.

8. Identify the monomer in the following polymeric structure.

9. Nylon-2-Nylon-6 is a biodegradable polymer obtained from glycine, H₂N – CH₂ – COOH and aminocaproic acid, H₂N–(CH₂)₅–COOH. Write the structure of this polymer.

10. Give two uses of teflon.

11. Name the polymer used for making insulation material for coating copper wire. [Hint : PVC].

12. Write the name and structure of monomer of the polymer which is used as synthetic wool.

13. How is vulcanized rubber obtained?

14. Name the polymer used for making radio television cabinets and feeding bottles of children.

15. What do the digits 6 and 66 represent in the names nylon-6 and nylon-66?

16. Write the full form of PHBV.

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