Questions - Answers

2 Marks Questions

1.   What is PHBV? How is it useful to man?

A:  PHBV is poly β- hydroxy butyrate Co-β hydroxy valerate. It is a copolymer of 3- hydroxy butanoic acid and 3-hydroxy pentanoic acid formed due to condensation. This biodegradable polymer is used for making capsules and orthopedic devices.
 

2.  Mention the names of the monomers used for preparing the polymers

     (a) Bakelite              (b) Terylene                (c)  Nylon 6, 6           (d) Neoprene

A: * Bakelite: Phenol & Formaldehyde

    * Terylene: Terepthalic acid & Ethylene glycol

    * Nylon 6, 6: Adipic acid & Hexa methylene diamine

    * Neoprene: 2 - Chloro 1, 3 - Buta diene
 

3. What is vulcanization?

A: The process of improvisation of physical properties of natural rubber by heating it with sulphur at 373 - 415 K.

4.  What is a "bio degradable polymer"?

A: The polymer that degrade easily by enzymatic oxidation or hydrolysis. eg: PHBV, Poly glycolic acid.
 

5.   What do you mean by "Poly dispersity index"?

A: The ratio of weight average molecular weight () and the number average molecular
weight ( ) of a polymer. P.D.I. =  / 

 

6.   Define "elastomer".

A: The polymer that can be stretched on applying force and returns to its normal shape and size on removal of the force.  eg.: Buna -N,  Buna-S.
 

7. Mention the type of polymerization in the formation of the following polymers?

     a) Bakelite               b) Polyvinyl Chloride               c) Polythene                 d) Terylene

A:   a) condensation 

       b) addition

       c) addition 

       d) condensation

8. Write the names and structures of the monomers used for getting the polymers

         a) Nylon 6, 6                                       b) Bakelite.

A: a) Nylon 6, 6:

         
     b) Bakelite:

9. A polymer contains 10 molecules with molecular mass 10,000 and 10 molecules with molecular mass 1,00,000. Calculate number average molecular mass () and weight average molecular mass () of the polymer.
A:

 
            
 

10. What is the difference between Buna - N and Buna - S?
A: Buna - N: Copolymer of 1, 3 Butadiene & Acrylonitrile.
     Buna - S: Copolymer of 1, 3 Buta diene & Styrene.
 

11. What is Ziegler - Natta catalyst? Give its use.
A: TiCl₄ (Titanium tetrachloride) + Al(C₂H₅)₃ (Triethyl aluminium) is called Ziegler - Natta catalyst. It is used to polymerise ethene during the preparation of high density polyethene.

12. What is "Polymer"? What is "Polymerisation"?
A: A large molecule having high molecular mass is called "Polymer". The process of formation of polymer from monomer is called Polymerisation.

       
 

13. What are "Homopolymers"?
A: The polymer which is formed due to polymerisation of one kind of monomers.

       
 

14. What are "Copolymers"?
A: The polymer which is formed due to polymerisation of two or more kinds of monomers.
     e.g.: Nylon 6, 6 (Monomers: Adipic acid & Hexamethylene diamine).

15. What are "Thermoplastic Polymers"?
A: The polymers having linear structure are formed either by addition or by condensation polymerisation which are soften on heating and hardening on cooling.
e.g.: P.V.C., Polyethene, Polystyrene.
 

16. What are "Thermosetting Polymers"?
A: The polymers having cross linked or heavily branched structure are formed by condensation polymerisation which becomes hard on heating.
    e.g.: Urea - Formaldehyde resin, Bakelite.